/*
    Title:  An interpreter for a compact instruction set.
    Author:     Dave Matthews, Cambridge University Computer Laboratory

    Copyright (c) 2000-7
        Cambridge University Technical Services Limited
    Further development Copyright David C.J. Matthews 2015.

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License version 2.1 as published by the Free Software Foundation.
    
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
    
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#elif defined(_WIN32)
#include "winconfig.h"
#else
#error "No configuration file"
#endif

#ifdef HAVE_STDIO_H
#include <stdio.h>
#endif

#ifdef HAVE_ASSERT_H
#include <assert.h>
#define ASSERT(x) assert(x)
#else
#define ASSERT(x) 0
#endif

#include "globals.h"
#include "int_opcodes.h"
#include "machine_dep.h"
#include "sys.h"
#include "profiling.h"
#include "arb.h"
#include "processes.h"
#include "run_time.h"
#include "mpoly.h"
#include "gc.h"
#include "basicio.h"
#include "timing.h"
#include "arb.h"
#include "reals.h"
#include "objsize.h"
#include "xwindows.h"
#include "foreign.h"
#include "process_env.h"
#include "network.h"
#include "basicio.h"
#include "sighandler.h"
#include "os_specific.h"
#include "diagnostics.h"
#include "polystring.h"
#include "save_vec.h"
#include "memmgr.h"
#include "poly_specific.h"
#include "scanaddrs.h"
#include "polyffi.h"

#define arg1    (pc[0] + pc[1]*256)
#define arg2    (pc[2] + pc[3]*256)
#define arg3    (pc[4] + pc[5]*256)
#define arg4    (pc[6] + pc[7]*256)

const PolyWord True = TAGGED(1);
const PolyWord False = TAGGED(0);
const PolyWord Zero = TAGGED(0);

#define CHECKED_REGS 2
#define UNCHECKED_REGS 0

#define EXTRA_STACK 0 // Don't need any extra - signals aren't handled on the Poly stack.

/* the amount of ML stack space to reserve for registers,
   C exception handling etc. The compiler requires us to
   reserve 2 stack-frames worth (2 * 20 words) plus whatever
   we require for the register save area. We actually reserve
   slightly more than this. SPF 3/3/97
*/
#define OVERFLOW_STACK_SIZE \
  (50 + \
   sizeof(StackObject)/sizeof(PolyWord) + \
   CHECKED_REGS + \
   UNCHECKED_REGS + \
   EXTRA_STACK)

class StackObject {
public:
//    POLYUNSIGNED    p_space;
//    POLYCODEPTR     p_pc;
//    PolyWord        *p_sp;
//    PolyWord        *p_hr;

//    POLYUNSIGNED    p_nreg;
//    PolyWord        p_reg[CHECKED_REGS];
//    POLYUNSIGNED    p_nUnchecked;
};

class IntTaskData: public TaskData {
public:
    IntTaskData(): interrupt_requested(false) {}

    virtual void GCStack(ScanAddress *process);
    virtual Handle EnterPolyCode(); // Start running ML

    // Switch to Poly and return with the io function to call.
    int SwitchToPoly();
    virtual void SetException(poly_exn *exc);
    virtual void InterruptCode();

    // GetPCandSPFromContext is used in time profiling.  We can't get accurate info so return false.
    virtual bool GetPCandSPFromContext(SIGNALCONTEXT *context, PolyWord * &sp,  POLYCODEPTR &pc)
        { return false; }

    virtual void InitStackFrame(TaskData *newTask, Handle proc, Handle arg);

    // These aren't implemented in the interpreted version.
    virtual Handle EnterCallbackFunction(Handle func, Handle args) { ASSERT(0); return 0; }

    virtual int GetIOFunctionRegisterMask(int ioCall) { return 0; }

    // Increment or decrement the first word of the object pointed to by the
    // mutex argument and return the new value.
    virtual Handle AtomicIncrement(Handle mutexp);
    virtual Handle AtomicDecrement(Handle mutexp);
    // Set a mutex to one.
    virtual void AtomicReset(Handle mutexp);

    virtual POLYCODEPTR pc(void) const { return p_pc; }
    virtual PolyWord *sp(void) const { return p_sp; }
    virtual PolyWord *hr(void) const { return p_hr; }
    virtual void set_hr(PolyWord *hr) { p_hr = hr; }
    // Return the minimum space occupied by the stack if we are considering shrinking it.
    virtual POLYUNSIGNED currentStackSpace(void) const { return (this->stack->top - this->p_sp) + OVERFLOW_STACK_SIZE; }

    virtual void CopyStackFrame(StackObject *old_stack, POLYUNSIGNED old_length, StackObject *new_stack, POLYUNSIGNED new_length);

    bool interrupt_requested;

    POLYCODEPTR     p_pc;
    PolyWord        *p_sp;
    PolyWord        *p_hr;
    PolyWord        p_exception_arg;
    unsigned        p_lastInstr;
};

// Special values for return addresses or in the address of an exception handler.
// In an exception handler SPECIAL_PC_TRACE_EX means trace this exception, as
// a return address it means exception_trace has returned.
#define SPECIAL_PC_TRACE_EX_RETURN      TAGGED(0)
#define SPECIAL_PC_END_THREAD           TAGGED(1)
#define SPECIAL_PC_TRACE_EX_FN          TAGGED(2)

class Interpreter : public MachineDependent {
public:
    Interpreter() {}

    // Create a task data object.
    virtual TaskData *CreateTaskData(void) { return new IntTaskData(); }
    virtual void InitInterfaceVector(void);
    virtual Architectures MachineArchitecture(void) { return MA_Interpreted; }
};

void IntTaskData::InitStackFrame(TaskData *parentTask, Handle proc, Handle arg)
/* Initialise stack frame. */
{
    StackSpace *space = this->stack;
    StackObject *stack = (StackObject *)space->stack();
    PolyObject *closure = DEREFWORDHANDLE(proc);
    POLYUNSIGNED stack_size = space->spaceSize();
    this->p_pc = *(byte**)(closure);
    this->p_sp  = (PolyWord*)stack + stack_size-3; /* sp */
    this->p_exception_arg = TAGGED(0); /* Used for exception argument. */
    this->p_lastInstr = 256; /* No instruction. */
    this->p_sp  = (PolyWord*)stack + stack_size;

    /* Set up exception handler */
    /* No previous handler so point it at itself. */
    this->p_sp--;
    *(this->p_sp) = PolyWord::FromStackAddr(this->p_sp);
    *(--this->p_sp) = SPECIAL_PC_END_THREAD; /* Default return address. */
    *(--this->p_sp) = Zero; /* Default handler. */
    this->p_hr = this->p_sp;

    /* If this function takes an argument store it on the stack. */
    if (arg != 0) *(--this->p_sp) = DEREFWORD(arg);

    *(--this->p_sp) = SPECIAL_PC_END_THREAD; /* Return address. */
    *(--this->p_sp) = closure; /* Closure address */
}

void IntTaskData::InterruptCode()
/* Stop the Poly code at a suitable place. */
/* We may get an asynchronous interrupt at any time. */
{
    IntTaskData *itd = (IntTaskData *)this;
    itd->interrupt_requested = true;
}


void IntTaskData::SetException(poly_exn *exc)
/* Set up the stack of a process to raise an exception. */
{
    this->p_lastInstr = INSTR_raise_ex;
    *(--this->p_sp) = (PolyWord)exc; /* push exception data */
}

int IntTaskData::SwitchToPoly()
/* (Re)-enter the Poly code from C. */
{
    register PolyWord *sp; /* Stack pointer. */
    register byte *pc; /* Program counter. */
    register PolyWord *sl; /* Stack limit register. */
    register int  li;  /* Last instruction. */
    POLYUNSIGNED tailCount;
    PolyWord *tailPtr;
    POLYUNSIGNED returnCount;
    POLYUNSIGNED storeWords = 0;
    int instrBytes;

    RESTART: /* Load or reload the registers and run the code. */

    if (this->allocPointer <= this->allocLimit + storeWords)
    {
        if (this->allocPointer < this->allocLimit)
            Crash ("Bad length in heap overflow trap");

        // Find some space to allocate in.  Updates this->allocPointer and
        // returns a pointer to the newly allocated space (if allocWords != 0)
        PolyWord *space =
            processes->FindAllocationSpace(this, storeWords, true);
        if (space != 0) // Undo the allocation just now.  We'll redo it now we have the store.
            this->allocPointer += storeWords;
    }
    storeWords = 0;
    sp = this->p_sp; /* Reload these. */
    pc = this->p_pc;
    li = this->p_lastInstr;
    sl = (PolyWord*)this->stack->stack()+OVERFLOW_STACK_SIZE;

    if (li != 256) goto RETRY; /* Re-execute instruction if necessary. */

    for(;;){ /* Each instruction */

//        char buff[100];
        li = *pc++; /* Get next instruction. */

        RETRY:
//      sprintf(buff, "PC=%x, i=%x\n", pc, li);
//      OutputDebugString(buff);

        // Check for stack overflow and interrupts. These can be done less
        // frequently than every instruction.
        // Don't do this if we're raising an exception: we may be raising
        // it because we can't grow the stack.  Once we've processed the
        // exception and produced any exception trace the stack will have been
        // reset to the last handler.
        if (sp < sl && li != INSTR_raise_ex) {
            this->p_sp = sp;
            this->p_pc = pc;
            this->p_lastInstr = li;
            Handle marker = this->saveVec.mark();
            POLYUNSIGNED min_size = this->stack->top - this->p_sp + OVERFLOW_STACK_SIZE;
            CheckAndGrowStack(this, min_size);
            this->saveVec.reset(marker);
            goto RESTART;
        }

        if (this->interrupt_requested) {
            this->interrupt_requested = false;
            this->p_sp = sp;
            this->p_pc = pc;
            this->p_lastInstr = li;
            return -1;
        }

        switch(li) {

        case INSTR_enter_int: pc++; /* Skip the argument. */ break;

        case INSTR_jump_false:
            {
                PolyWord u = *sp++; /* Pop argument */
                if (u == True) { pc += 1; break; }
                /* else - false - take the jump */
            }

        case INSTR_jump: pc += *pc + 1; break;

        case INSTR_push_handler: /* Save the old handler value. */
            *(--sp) = PolyWord::FromStackAddr(this->p_hr); /* Push old handler */
            break;

        case INSTR_set_handler_new: /* Set up a handler */
            *(--sp) = PolyWord::FromCodePtr(pc + *pc + 1); /* Address of handler */
            this->p_hr = sp;
            pc += 1;
            break;

        case INSTR_set_handler_old: /* Set up a handler */
            // Legacy version.  The handler pushes an exception id.
            *(--sp) = PolyWord::FromCodePtr(pc + *pc + 1); /* Address of handler */
            this->p_hr = sp-1; /*Point to identifier about to be pushed*/
            pc += 1;
            break;

        case INSTR_del_handler: /* Delete handler retaining the result. */
            {
                PolyWord u = *sp++;
                sp = this->p_hr;
                if (*sp == TAGGED(0)) sp++; // Legacy
                sp++; // Skip handler entry point
                // Restore old handler
                this->p_hr = (*sp).AsStackAddr();
                *sp = u; // Put back the result
                pc += *pc + 1; /* Skip the handler */
                break;
            }

        case INSTR_jump_i_false:
            if (*sp++ == True) { pc += 1; break; }
            /* else - false - take the jump */

        case INSTR_jump_i_u: /* Indirect jump */
            {
                // This is always a forward jump
                pc += *pc + 1;
                pc += arg1 + 2;
                break;
            }

        case INSTR_jump_i: /* Indirect jump */
            {
                // This is only for backwards compatibility
                pc += *pc + 1;
                /* This may jump backwards. */
                int u = arg1;
                if (u > 32767) u -= 65536;
                pc += u + 2;
                break;
            }

        case INSTR_set_handler_new_i: /* Set up a handler */
            {
                byte *u = pc + *pc + 1;
                *(--sp) = /* Address of handler */
                    PolyWord::FromCodePtr(u + u[0] + u[1]*256 + 2);
                this->p_hr = sp;
                pc += 1;
                break;
            }

        case INSTR_set_handler_old_i: /* Set up a handler */
            {
                byte *u = pc + *pc + 1;
                *(--sp) = /* Address of handler */
                    PolyWord::FromCodePtr(u + u[0] + u[1]*256 + 2);
                this->p_hr = sp-1;
                pc += 1;
                break;
            }

        case INSTR_del_handler_i: /* Delete handler retaining the result. */
            {
                PolyWord u = *sp++;
                PolyWord *t;
                sp = this->p_hr;
                PolyWord *endStack = this->stack->top;
                while((t = (*sp).AsStackAddr()) < sp || t > endStack) sp++;
                this->p_hr = t;
                *sp = u;
                pc += *pc + 1; /* Skip the handler */
                pc += arg1 + 2;
                break;
            }

        case INSTR_case:
            {
                POLYSIGNED u = UNTAGGED(*sp++); /* Get the value */
                if (u > arg1 || u < 0) pc += (arg1+2)*2; /* Out of range */
                else {
                    pc += 2;
                    pc += /* Index */pc[u*2]+pc[u*2 + 1]*256; }
                break;
            }

        case INSTR_call_sl: /* Static link call */
            {
                /* Get static link value. */
                PolyWord *t = sp+arg2;
                for(int i = 1; i <= arg3; i++) t = (t[-1]).AsStackAddr();
                PolyWord *constAddr = (PolyWord*)(pc+arg1+2); /* Get entry point. */
                *(--sp) = PolyWord::FromCodePtr(pc+6); /* Push return address to point after instruction. */
                *(--sp) = PolyWord::FromStackAddr(t); /* Push static link */
                pc = (*constAddr).AsCodePtr();
                break;
            }

        case INSTR_call_sl_X:
            {
                /* Get static link value. */
                PolyWord *t = sp+arg3;

                for(int u = 1; u <= arg4; u++) t = (t[-1]).AsStackAddr();

                PolyWord *constAddr = (PolyWord*)(pc+arg2+(arg1+4)*sizeof(PolyWord)+4); /* Get entry point. */
                *(--sp) = PolyWord::FromCodePtr(pc+8); /* Push return address to point after instruction. */
                *(--sp) = PolyWord::FromStackAddr(t); /* Push static link */
                pc = (*constAddr).AsCodePtr();
                break;
            }

        case INSTR_tail_3_b:
           tailCount = 3;
           tailPtr = sp + tailCount;
           sp = tailPtr + *pc;
           goto TAIL_CALL;

        case INSTR_tail_3_2:
           tailCount = 3;
           tailPtr = sp + tailCount;
           sp = tailPtr + 2;
           goto TAIL_CALL;

        case INSTR_tail_3_3:
           tailCount = 3;
           tailPtr = sp + tailCount;
           sp = tailPtr + 3;
           goto TAIL_CALL;

        case INSTR_tail_4_b:
           tailCount = 4;
           tailPtr = sp + tailCount;
           sp = tailPtr + *pc;
           goto TAIL_CALL;

        case INSTR_tail_b_b:
           tailCount = *pc;
           tailPtr = sp + tailCount;
           sp = tailPtr + pc[1];
           goto TAIL_CALL;

        case INSTR_tail:
           /* Tail recursive call. */
           /* Move items up the stack. */
           /* There may be an overlap if the function we are calling
              has more args than this one. */
           tailCount = arg1;
           tailPtr = sp + tailCount;
           sp = tailPtr + arg2;
           TAIL_CALL: /* For general case. */
           if (tailCount < 2) Crash("Invalid argument\n");
           for (; tailCount > 0; tailCount--) *(--sp) = *(--tailPtr);
           pc = (*sp++).AsCodePtr(); /* Pop the original return address. */
           li = INSTR_call_closure; /* If we have to re-execute. */
           /* And drop through. */

        case INSTR_call_closure: /* Closure call - may be machine code. */
        CALL_CLOSURE:  /* Jumped to from POLY_SYS_callcode */
            {
                PolyWord *t = (*sp).AsStackAddr(); /* Closure */
                PolyWord u = *t;   /* Get code address. (1st word of closure) */

                if (IS_INT(u)) { /* Closure address is io vector */
                    sp++; /* Remove closure. */
                    POLYSIGNED uu = UNTAGGED(u);
                    switch(uu) {

                    case POLY_SYS_callcode_tupled:
                        {
                            t = (*sp++).AsStackAddr();
                            PolyWord v = t[1]; /* Arguments. */
                            if (v != Zero) /* No args. */
                            {
                                PolyWord *vv = v.AsStackAddr();
                                POLYUNSIGNED u = v.AsObjPtr()->Length(); /* No. of args. */
                                for (; u > 0; u--) *(--sp) = *(vv++);
                            }
                            *(--sp) = t[0]; /* Push closure. */
                            goto CALL_CLOSURE;
                        }
 
                    case POLY_SYS_word_eq: 
                       u = *sp++;
                       *sp = u == *sp ? True : False;
                       break;

                    case POLY_SYS_word_neq:
                       u = *sp++;
                       *sp = u == *sp ? False : True;
                       break;

                    case POLY_SYS_word_geq:
                        u = *sp++; *sp = ((*sp).AsUnsigned() >= u.AsUnsigned())?True:False; break;

                    case POLY_SYS_word_leq:
                        u = *sp++; *sp = ((*sp).AsUnsigned() <= u.AsUnsigned())?True:False; break;

                    case POLY_SYS_word_gtr:
                        u = *sp++; *sp = ((*sp).AsUnsigned() > u.AsUnsigned())?True:False; break;

                    case POLY_SYS_word_lss:
                        u = *sp++; *sp = ((*sp).AsUnsigned() < u.AsUnsigned())?True:False; break;

                    case POLY_SYS_or_word:
                        u = *sp++; *sp = TAGGED(UNTAGGED(*sp) | UNTAGGED(u)); break; 

                    case POLY_SYS_and_word: 
                        u = *sp++; *sp = TAGGED(UNTAGGED(*sp) & UNTAGGED(u)); break; 

                    case POLY_SYS_not_bool:  *sp = (*sp == True) ? False : True; break; 

                    case POLY_SYS_string_length: 
                        /* Length is first word of string unless it is a
                           single character. */
                        if (IS_INT(*sp)) *sp = TAGGED(1);
                        else *sp = TAGGED(((PolyStringObject*)(*sp).AsObjPtr())->length);
                        break;

                    case POLY_SYS_touch_final:
                        *sp = TAGGED(0);
                        break;

                    case POLY_SYS_set_string_length: 
                        {
                            /* Store the length word of a string. */
                            POLYUNSIGNED len = UNTAGGED(*sp++);
                            ((PolyStringObject*)(*sp).AsObjPtr())->length = len;
                            *sp = Zero;
                            break; 
                        }

                    case POLY_SYS_mul_word:
                        u = *sp++; *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) * UNTAGGED_UNSIGNED(u)); break;

                    case POLY_SYS_plus_word: 
                        u = *sp++; *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) + UNTAGGED_UNSIGNED(u)); break;

                    case POLY_SYS_minus_word: 
                        u = *sp++; *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) - UNTAGGED_UNSIGNED(u)); break; 

                    case POLY_SYS_div_word:
                        {
                            POLYUNSIGNED u = UNTAGGED_UNSIGNED(*sp++);
                            if (u == 0)
                                raise_exception0(this, EXC_divide);
                            *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) / u); break;
                        }

                    case POLY_SYS_mod_word:
                        {
                            POLYUNSIGNED u = UNTAGGED_UNSIGNED(*sp++);
                            if (u == 0)
                                raise_exception0(this, EXC_divide);
                            // It's essential to use UNTAGGED_UNSIGNED here.
                            // The old version used UNTAGGED which uses an arithmetic shift
                            // and produces the wrong answer.
                            *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) % u);
                            break;
                        }

                    case POLY_SYS_xor_word:
                        {
                            PolyWord u = *sp++;
                            *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) ^ UNTAGGED_UNSIGNED(u));
                            break;
                        }

                    case POLY_SYS_shift_left_word: 
                        {
                            PolyWord u = *sp++;
                            if (UNTAGGED_UNSIGNED(u) > sizeof(PolyWord)*8)
                                *sp = Zero;
                            else
                                *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) << UNTAGGED_UNSIGNED(u));
                            break;
                        }

                    case POLY_SYS_shift_right_word:
                        {
                            PolyWord u = *sp++;
                            if (UNTAGGED_UNSIGNED(u) > sizeof(PolyWord)*8)
                                *sp = Zero;
                            else
                                *sp = TAGGED(UNTAGGED_UNSIGNED(*sp) >> UNTAGGED_UNSIGNED(u));
                            break;
                        }

                    case POLY_SYS_shift_right_arith_word:
                        {
                            PolyWord u = *sp++;
                            if (UNTAGGED_UNSIGNED(u) > sizeof(PolyWord)*8)
                            {
                                if (UNTAGGED(*sp) < 0)
                                    *sp = TAGGED(-1);
                                else *sp = Zero;
                            }
                            else
                            // Strictly speaking, C does not require that this uses
                            // arithmetic shifting so we really ought to set the
                            // high-order bits explicitly.
                                *sp = TAGGED(UNTAGGED(*sp) >> UNTAGGED(u));
                            break;
                        }

                    case POLY_SYS_load_byte:
                    case POLY_SYS_load_byte_immut:
                        {
                            POLYUNSIGNED u = UNTAGGED(*sp++);
                            *sp = TAGGED((*sp).AsCodePtr()[u]);
                            break; 
                        }

                    case POLY_SYS_load_word:
                    case POLY_SYS_load_word_immut:
                        {
                            POLYUNSIGNED u = UNTAGGED(*sp++);
                            *sp = (*sp).AsObjPtr()->Get(u);
                            break;
                        }

                    case POLY_SYS_assign_byte: 
                        {
                            POLYUNSIGNED t = UNTAGGED(*sp++);
                            POLYUNSIGNED u = UNTAGGED(*sp++);
                            (*sp).AsCodePtr()[u] = (byte)t;
                            *sp = Zero;
                            break; 
                        }

                    case POLY_SYS_assign_word: 
                        {
                            PolyWord t = *sp++;
                            POLYUNSIGNED u = UNTAGGED(*sp++);
                            (*sp).AsStackAddr()[u] = t;
                            *sp = Zero;
                            break;
                        }

                    case POLY_SYS_lockseg:
                        {
                            PolyObject *obj = (*sp).AsObjPtr();
                            POLYUNSIGNED lengthW = obj->LengthWord();
                            /* Clear the mutable bit. */
                            obj->SetLengthWord(lengthW & ~_OBJ_MUTABLE_BIT);
                            *sp = Zero;
                            break;
                        }

                    case POLY_SYS_get_length: 
                        /* Return the length word. */
                        *sp = TAGGED((*sp).AsObjPtr()->Length());
                        break;

                    case POLY_SYS_is_short:
                        *sp = IS_INT(*sp) ? True : False; break;

                    case POLY_SYS_io_operation:
                        *sp = (PolyObject*)IoEntry((unsigned)UNTAGGED(*sp));
                        break;

                    case POLY_SYS_exception_trace_fn:
                        u = *sp; /* Function to call. */
                        *(--sp) = PolyWord::FromCodePtr(pc); /* Push a return address. */
                        *(--sp) = PolyWord::FromStackAddr(this->p_hr); /* Push old handler */
                        *(--sp) = SPECIAL_PC_TRACE_EX_FN; /* Marks exception trace. */
                        *(--sp) = Zero; /* Catch everything. */
                        this->p_hr = sp; /* Handler is here. */
                        pc = (SPECIAL_PC_TRACE_EX_RETURN).AsCodePtr(); /* Special return address. */
                        *(--sp) = Zero; /* Unit argument to the function. */
                        *(--sp) = u; /* Push the procedure. */
                        goto CALL_CLOSURE;

                    case POLY_SYS_is_big_endian: {
                        union { unsigned long wrd; char chrs[sizeof(unsigned long)]; } endian;
                        endian.wrd = 1;
                        *(--sp) = endian.chrs[0] == 0 ? True : False;
                        break;
                    }

                    case POLY_SYS_bytes_per_word:
                        *(--sp) = TAGGED(sizeof(PolyWord)); break;
 
                    case POLY_SYS_raisex:
                        goto RAISE_EXCEPTION;

                    case POLY_SYS_aplus:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            // If they're both short and no overflow.
                            if (IS_INT(x) && IS_INT(y))
                            {
                                POLYSIGNED t = UNTAGGED(x) + UNTAGGED(y);
                                if (t <= MAXTAGGED && t >= -MAXTAGGED-1)
                                {
                                    sp++;
                                    *sp = TAGGED(t);
                                    break;
                                }
                                else goto FullRTSCall;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_aminus:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            // If they're both short and no overflow.
                            if (IS_INT(x) && IS_INT(y))
                            {
                                POLYSIGNED t = UNTAGGED(y) - UNTAGGED(x);
                                if (t <= MAXTAGGED && t >= -MAXTAGGED-1)
                                {
                                    sp++;
                                    *sp = TAGGED(t);
                                    break;
                                }
                                else goto FullRTSCall;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_equala:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            // If either argument is short the values are only equal
                            // if the words contain the same bit pattern.
                            if (IS_INT(x) || IS_INT(y))
                            {
                                sp++;
                                *sp = y == x ? True : False;
                                break;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_int_geq:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            if (IS_INT(x) && IS_INT(y))
                            {
                                sp++;
                                *sp = UNTAGGED(y) >= UNTAGGED(x) ? True : False;
                                break;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_int_leq:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            if (IS_INT(x) && IS_INT(y))
                            {
                                sp++;
                                *sp = UNTAGGED(y) <= UNTAGGED(x) ? True : False;
                                break;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_int_gtr:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            if (IS_INT(x) && IS_INT(y))
                            {
                                sp++;
                                *sp = UNTAGGED(y) > UNTAGGED(x) ? True : False;
                                break;
                            }
                            else goto FullRTSCall;
                        }

                    case POLY_SYS_int_lss:
                        {
                            PolyWord x = sp[0];
                            PolyWord y = sp[1];
                            if (IS_INT(x) && IS_INT(y))
                            {
                                sp++;
                                *sp = UNTAGGED(y) < UNTAGGED(x) ? True : False;
                                break;
                            }
                            else goto FullRTSCall;
                        }

                    default:
                    FullRTSCall:
                        // For all the calls that aren't built in ...
                        /* Save the state so that the instruction can be retried if necessary. */
                        this->p_pc = pc; /* Pc value after instruction. */
                        this->p_lastInstr = li; /* Previous instruction. */
                        this->p_sp = sp-1; /* Include the closure address. */
                        return (int)uu;
                    }
                } /* End of system calls. */
                else {
                    sp--;
                    *sp = sp[1];      /* Move closure up. */
                    sp[1] = PolyWord::FromCodePtr(pc); /* Save return address. */
                    pc = u.AsCodePtr();    /* Get entry point. */
                }
            }
            break;

        case INSTR_return_w:
            returnCount = arg1; /* Get no. of args to remove. */

            RETURN: /* Common code for return. */
            {
                PolyWord result = *sp++; /* Result */
                sp++; /* Remove the link/closure */
                pc = (*sp++).AsCodePtr(); /* Return address */
                sp += returnCount; /* Add on number of args. */
                if (pc == (SPECIAL_PC_END_THREAD).AsCodePtr())
                    exitThread(this); // This thread is exiting.
                else if (pc == (SPECIAL_PC_TRACE_EX_RETURN).AsCodePtr())
                {
                    /* Return from a call to exception_trace when an exception
                       has not been raised. */
                    sp += 1;
                    this->p_hr = (sp[1]).AsStackAddr();
                    *sp = result;
                    returnCount = 1;
                    goto RETURN;
                }
                *(--sp) = result; /* Result */
            }
            break;

        case INSTR_return_b: returnCount = *pc; goto RETURN;
        case INSTR_return_0: returnCount = 0; goto RETURN;
        case INSTR_return_1: returnCount = 1; goto RETURN;
        case INSTR_return_2: returnCount = 2; goto RETURN;
        case INSTR_return_3: returnCount = 3; goto RETURN;

        case INSTR_pad: /* No-op */ break;

        case INSTR_raise_ex:
            {
            RAISE_EXCEPTION:
                PolyException *exn = (PolyException*)((*sp).AsObjPtr());
                this->p_exception_arg = exn; /* Get exception data */
                this->p_sp = sp; /* Save this in case of trace. */
                PolyWord *t = this->p_hr;  /* First handler */
                PolyWord *endStack = this->stack->top;
                // The legacy version pushes an identifier which is always zero.
                if (*t == Zero) t++;
                if (*t == SPECIAL_PC_TRACE_EX_FN)
                {
                    // New exception trace
                    *sp = PolyWord::FromCodePtr(pc); /* So that this function will be included. */
                    // exceptionToTraceException expects the new format of exception handling that is
                    // used in the X86 code-generator.  That does not push an exception id.
                    this->p_hr = t;
                    Handle marker = this->saveVec.mark();
                    try {
                        exceptionToTraceException(this,
                            this->saveVec.push(this->p_exception_arg));
                    }
                    catch (IOException &) {
                    }
                    this->saveVec.reset(marker);
                    // This will have reraised the exception by calling SetException
                    goto RESTART;
                }
                else if (*t == SPECIAL_PC_END_THREAD)
                    exitThread(this);  // Default handler for thread.
                this->p_pc = (*t).AsCodePtr();
                /* Now remove this handler. */
                sp = t;
                while ((t = (*sp).AsStackAddr()) < sp || t > endStack)
                    sp++;
                this->p_hr = t; /* Restore old handler */
                sp++; /* Remove that entry. */
                this->p_sp = sp;
                this->p_lastInstr = 256; /* Get the next instruction. */
                goto RESTART; /* Restart in case pc is persistent (??? Still relevant????). */
            }

        case INSTR_get_store_w:
            {
                storeWords = arg1+1;
                instrBytes = 2; // Number of bytes of arg of instruction

                GET_STORE: /* Common code for allocation. */
                this->allocPointer -= storeWords;
                if (this->allocPointer < this->allocLimit)
                {
                    this->allocPointer += storeWords;
                    this->p_sp = sp;
                    this->p_pc = pc;
                    this->p_lastInstr = li;
                    goto RESTART;
                }
                pc += instrBytes;
                storeWords--; // Remove the length word from the count
                *this->allocPointer = PolyWord::FromUnsigned(storeWords | _OBJ_MUTABLE_BIT); /* Allocation must be mutable! */
                PolyWord *t = this->allocPointer+1;
                for(; storeWords > 0; ) t[--storeWords] = PolyWord::FromUnsigned(0); /* Must initialise store! */
                *(--sp) = PolyWord::FromStackAddr(t);
                break;
                }

        case INSTR_get_store_2: storeWords = 2+1; instrBytes = 0; goto GET_STORE;
        case INSTR_get_store_3: storeWords = 3+1; instrBytes = 0; goto GET_STORE;
        case INSTR_get_store_4: storeWords = 4+1; instrBytes = 0; goto GET_STORE;
        case INSTR_get_store_b: storeWords = *pc+1; instrBytes = 1; goto GET_STORE;


        case INSTR_tuple_w:
            {
                storeWords = arg1+1; instrBytes = 2;

                TUPLE: /* Common code for tupling. */
                this->allocPointer -= storeWords;
                if (this->allocPointer < this->allocLimit) {
                    this->allocPointer += storeWords;
                    this->p_sp = sp;
                    this->p_pc = pc;
                    this->p_lastInstr = li;
                    goto RESTART;
                }
                pc += instrBytes;
                storeWords--; // Remove the length word from the count
                *this->allocPointer = PolyWord::FromUnsigned(storeWords);
                PolyWord *t = this->allocPointer+1;
                for(; storeWords > 0; ) t[--storeWords] = *sp++;
                *(--sp) = (PolyObject*)t;
                break;
            }

        case INSTR_tuple_2: storeWords = 2+1; instrBytes = 0; goto TUPLE;
        case INSTR_tuple_3: storeWords = 3+1; instrBytes = 0; goto TUPLE;
        case INSTR_tuple_4: storeWords = 4+1; instrBytes = 0; goto TUPLE;
        case INSTR_tuple_b: storeWords = *pc+1; instrBytes = 1; goto TUPLE;


        case INSTR_non_local:
            {
                PolyWord *t = sp+arg1;
                POLYSIGNED uu;
                for(uu = 1; uu <= arg2; uu++) t = (t[-1]).AsStackAddr();
                uu = arg3; /* Can be negative. */
                if (uu > 32767) uu -= 65536;
                *(--sp) = t[uu];
                pc += 6;
                break;
            }

        case INSTR_local_w:
            {
                PolyWord u = sp[arg1];
                *(--sp) = u;
                pc += 2;
                break;
            }

        case INSTR_indirect_w:
            *sp = (*sp).AsObjPtr()->Get(arg1); pc += 2; break;

        case INSTR_move_to_vec_w:
            {
                PolyWord u = *sp++;
                (*sp).AsObjPtr()->Set(arg1, u);
                pc += 2;
                break;
            }

        case INSTR_set_stack_val_w:
            {
                PolyWord u = *sp++;
                sp[arg1-1] = u;
                pc += 2;
                break;
            }

        case INSTR_reset_w: sp += arg1; pc += 2; break;

        case INSTR_reset_r_w:
            {
                PolyWord u = *sp;
                sp += arg1;
                *sp = u;
                pc += 2;
                break;
            }

        case INSTR_const_addr:
            *(--sp) = *(PolyWord*)(pc + arg1 + 2); pc += 2; break;

        case INSTR_const_addr_Xb:
            *(--sp) = (PolyWord::FromCodePtr(pc + (pc[0]+4)*sizeof(PolyWord) + pc[1] + pc[2]*256 + 3)).AsObjPtr()->Get(0);
            pc += 3;
            break;

        case INSTR_const_addr_Xw:
            *(--sp) = (PolyWord::FromCodePtr(pc + (arg1+4)*sizeof(PolyWord)+arg2 + 4)).AsObjPtr()->Get(0);
            pc += 4;
            break;

        case INSTR_const_int_w: *(--sp) = TAGGED(arg1); pc += 2; break;

        case INSTR_io_vec_entry:
            *(--sp) = (PolyObject*)IoEntry(*pc);
            pc += 1;
            break;

        case INSTR_const_nil: *(--sp) = Zero; break;

        case INSTR_jump_back: pc -= *pc + 1; break;

        case INSTR_jump_back16:
            pc -= arg1 + 1; break;

        case INSTR_lock:
            {
                PolyObject *obj = (*sp).AsObjPtr();
                obj->SetLengthWord(obj->LengthWord() & ~_OBJ_MUTABLE_BIT);
                break;
            }

        case INSTR_ldexc: *(--sp) = this->p_exception_arg; break;

        case INSTR_local_b: { PolyWord u = sp[*pc]; *(--sp) = u; pc += 1; break; }

        case INSTR_indirect_b:
            *sp = (*sp).AsObjPtr()->Get(*pc); pc += 1; break;

        case INSTR_move_to_vec_b:
            { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(*pc, u); pc += 1; break; }

        case INSTR_set_stack_val_b:
            { PolyWord u = *sp++; sp[*pc-1] = u; pc += 1; break; }

        case INSTR_reset_b: sp += *pc; pc += 1; break;

        case INSTR_reset_r_b:
            { PolyWord u = *sp; sp += *pc; *sp = u; pc += 1; break; }

        case INSTR_const_int_b: *(--sp) = TAGGED(*pc); pc += 1; break;

        case INSTR_local_0: { PolyWord u = sp[0]; *(--sp) = u; break; }
        case INSTR_local_1: { PolyWord u = sp[1]; *(--sp) = u; break; }
        case INSTR_local_2: { PolyWord u = sp[2]; *(--sp) = u; break; }
        case INSTR_local_3: { PolyWord u = sp[3]; *(--sp) = u; break; }
        case INSTR_local_4: { PolyWord u = sp[4]; *(--sp) = u; break; }
        case INSTR_local_5: { PolyWord u = sp[5]; *(--sp) = u; break; }
        case INSTR_local_6: { PolyWord u = sp[6]; *(--sp) = u; break; }
        case INSTR_local_7: { PolyWord u = sp[7]; *(--sp) = u; break; }
        case INSTR_local_8: { PolyWord u = sp[8]; *(--sp) = u; break; }
        case INSTR_local_9: { PolyWord u = sp[9]; *(--sp) = u; break; }
        case INSTR_local_10: { PolyWord u = sp[10]; *(--sp) = u; break; }
        case INSTR_local_11: { PolyWord u = sp[11]; *(--sp) = u; break; }

        case INSTR_indirect_0:
            if ((*sp) == PolyWord::FromStackAddr(IoEntry(55)))
                *sp = TAGGED(401); // We still seem to have some of the old AHL version number references.
            else *sp = (*sp).AsObjPtr()->Get(0); break;

        case INSTR_indirect_1:
            *sp = (*sp).AsObjPtr()->Get(1); break;

        case INSTR_indirect_2:
            *sp = (*sp).AsObjPtr()->Get(2); break;

        case INSTR_indirect_3:
            *sp = (*sp).AsObjPtr()->Get(3); break;

        case INSTR_indirect_4:
            *sp = (*sp).AsObjPtr()->Get(4); break;

        case INSTR_indirect_5:
            *sp = (*sp).AsObjPtr()->Get(5); break;

        case INSTR_const_0: *(--sp) = Zero; break;
        case INSTR_const_1: *(--sp) = TAGGED(1); break;
        case INSTR_const_2: *(--sp) = TAGGED(2); break;
        case INSTR_const_3: *(--sp) = TAGGED(3); break;
        case INSTR_const_4: *(--sp) = TAGGED(4); break;
        case INSTR_const_10: *(--sp) = TAGGED(10); break;


        /* move_to_vec only occurs to newly allocated store so there is
           no problem with persistent store faults. */
        case INSTR_move_to_vec_0:  { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(0, u); break; }
        case INSTR_move_to_vec_1: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(1, u); break; }
        case INSTR_move_to_vec_2: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(2, u); break; }
        case INSTR_move_to_vec_3: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(3, u); break; }
        case INSTR_move_to_vec_4: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(4, u); break; }
        case INSTR_move_to_vec_5: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(5, u); break; }
        case INSTR_move_to_vec_6: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(6, u); break; }
        case INSTR_move_to_vec_7: { PolyWord u = *sp++; (*sp).AsObjPtr()->Set(7, u); break; }

        case INSTR_reset_r_1: { PolyWord u = *sp; sp += 1; *sp = u; break; }
        case INSTR_reset_r_2: { PolyWord u = *sp; sp += 2; *sp = u; break; }
        case INSTR_reset_r_3: { PolyWord u = *sp; sp += 3; *sp = u; break; }

        case INSTR_reset_1: sp += 1; break;
        case INSTR_reset_2: sp += 2; break;


        case INSTR_non_local_l_1:
            {
                POLYSIGNED uu = *pc;
                PolyWord u = (sp[uu >> 4]).AsStackAddr()[(uu & 0xf) - 6];
                *(--sp) = u;
                pc += 1;
                break;
            }

        case INSTR_non_local_l_2:
            {
                POLYSIGNED uu = *pc;
                PolyWord *t = sp[uu >> 4].AsStackAddr() -1;
                *(--sp) = (*t).AsStackAddr()[(uu & 0xf) - 6];
                pc += 1;
                break;
            }

        case INSTR_non_local_l_3:
            {
                POLYSIGNED uu = *pc;
                PolyWord *t = sp[uu >> 4].AsStackAddr() -1;
                t = (*t).AsStackAddr() - 1;
                *(--sp) = (*t).AsStackAddr()[(uu & 0xf) - 6];
                pc += 1; break;
            }

        case INSTR_call_sl_c: /* Static link call */
            {
                /* Get static link value. */
                POLYSIGNED uu = pc[2];
                PolyWord *t = sp + (uu >> 4) + 2;
                for(uu = uu & 0xf; uu > 0; uu--) t = t[-1].AsStackAddr();
                PolyWord u = PolyWord::FromCodePtr(pc+arg1+2); /* Get entry point. */
                *(--sp) = PolyWord::FromCodePtr(pc+3); /* Push return address to point after instruction. */
                *(--sp) = PolyWord::FromStackAddr(t); /* Push static link */
                pc = u.AsObjPtr()->Get(0).AsCodePtr();
                break;
            }

        case INSTR_call_sl_cX:
            {
                /* Get static link value. */
                POLYUNSIGNED uu = pc[3];
                PolyWord *t = sp + (uu >> 4) + 2;
                for(uu = uu & 0xf; uu > 0; uu--) t = t[-1].AsStackAddr();
                // This splits the offset into a number of words and a number of bytes
                // That's needed to try to make the code portable between 32 and 64 bit machines.
                PolyWord u = PolyWord::FromCodePtr(pc + (pc[0]+4)*sizeof(PolyWord) + pc[1] + pc[2]*256+3); /* Get entry point. */
                *(--sp) = PolyWord::FromCodePtr(pc+4); /* Push return address to point after instruction. */
                *(--sp) = PolyWord::FromStackAddr(t); /* Push static link */
                pc = u.AsObjPtr()->Get(0).AsCodePtr();
                break;
                }


        case INSTR_io_vec_233: *(--sp) = (PolyObject*)IoEntry(POLY_SYS_int_gtr); break;
        case INSTR_io_vec_236: *(--sp) = (PolyObject*)IoEntry(POLY_SYS_or_word); break;
        case INSTR_io_vec_251: *(--sp) = (PolyObject*)IoEntry(POLY_SYS_word_eq); break;
        case INSTR_io_vec_253: *(--sp) = (PolyObject*)IoEntry(POLY_SYS_load_word); break;
        case INSTR_io_vec_255: *(--sp) = (PolyObject*)IoEntry(POLY_SYS_assign_word); break;

        case INSTR_integer_equal:
            { PolyWord u = *sp++; *sp = (u == *sp)?True:False; break; }

        case INSTR_integer_leq:
            {
                POLYSIGNED uu = UNTAGGED(*sp++);
                *sp = (UNTAGGED(*sp) <= uu)?True:False;
                break;
            }

        case INSTR_integer_greater:
            {
                POLYSIGNED uu = UNTAGGED(*sp++);
                *sp = (UNTAGGED(*sp) > uu)?True:False; break; 
            }

        case INSTR_boolean_or:
            {
                PolyWord u = *sp++; if (u == True) *sp = True; break; 
            }

        case INSTR_word_equal:
            {
                PolyWord u = *sp++;
                if (u == *sp) *sp = True;
                else *sp = u == *sp ? True : False;
                break;
            }

        case INSTR_assign_word:
            {
                PolyWord u = *sp++;
                POLYUNSIGNED uu = UNTAGGED(*sp++);
                (*sp).AsObjPtr()->Set(uu, u);
                *sp = Zero;
                break;
            }

        case INSTR_container: /* Create a container. */
            {
                /* This is supposed to be on the stack but that causes problems in gencde
                   so we create a mutable segment on the heap. */
                storeWords = arg1+1;
                this->allocPointer -= storeWords;
                if (this->allocPointer < this->allocLimit) {
                    this->allocPointer += storeWords;
                    this->p_sp = sp;
                    this->p_pc = pc;
                    this->p_lastInstr = li;
                    goto RESTART;
                }
                storeWords--;
                PolyObject *t = (PolyObject*)(this->allocPointer+1);
                t->SetLengthWord(storeWords, F_MUTABLE_BIT);
                for(; storeWords > 0; ) t->Set(--storeWords, Zero);
                *(--sp) = t; /* Push the address of the container. */
                pc += 2;
                break;
            }

        case INSTR_set_container: /* Copy a tuple into a container. */
            {
                PolyWord u = *sp++; /* Pop the source tuple address. */
                for (POLYSIGNED uu = arg1; uu > 0; )
                {
                    uu--;
                    (*sp).AsObjPtr()->Set(uu, u.AsObjPtr()->Get(uu)); /* Copy the items. */
                }
                sp++;
                pc += 2;
                break;
            }

        case INSTR_tuple_container: /* Create a tuple from a container. */
            {
                storeWords = arg1+1;
                this->allocPointer -= storeWords;
                if (this->allocPointer < this->allocLimit) {
                    this->allocPointer += storeWords;
                    this->p_sp = sp;
                    this->p_pc = pc;
                    this->p_lastInstr = li;
                    goto RESTART;
                }
                storeWords--;
                PolyObject *t = (PolyObject *)(this->allocPointer+1);
                t->SetLengthWord(storeWords, 0);
                for(; storeWords > 0; )
                {
                    storeWords--;
                    t->Set(storeWords, (*sp).AsObjPtr()->Get(storeWords));
                }
                *sp = t;
                pc += 2;
                break;
            }

        default: Crash("Unknown instruction %x\n", li);

        } /* switch */
     } /* for */
     return 0;
} /* MD_switch_to_poly */

void IntTaskData::GCStack(ScanAddress *process)
{
    if (stack != 0)
    {
        StackSpace *stackSpace = stack;
        PolyWord *stackPtr = this->p_sp; // Save this BEFORE we update
        PolyWord *stackEnd = stackSpace->top;

        // Either this is TAGGED(0) indicating a retry or it's a code pointer.
        if (this->p_pc != TAGGED(0).AsCodePtr())
            this->p_pc = process->ScanStackAddress (PolyWord::FromCodePtr(this->p_pc), stackSpace, true).AsCodePtr();

        // Stack pointer and handler pointers
        this->p_sp =
            process->ScanStackAddress (PolyWord::FromStackAddr(this->p_sp), stackSpace, false).AsStackAddr();
        this->p_hr =
            process->ScanStackAddress (PolyWord::FromStackAddr(this->p_hr), stackSpace, false).AsStackAddr();

        // The exception arg if any
        this->p_exception_arg = process->ScanStackAddress(this->p_exception_arg, stackSpace, false);

        // Now the values on the stack.
        for (PolyWord *q = stackPtr; q < stackEnd; q++)
            *q = process->ScanStackAddress(*q, stackSpace, false);
     }
}

// Copy a stack
void IntTaskData::CopyStackFrame(StackObject *old_stack, POLYUNSIGNED old_length, StackObject *new_stack, POLYUNSIGNED new_length)
{
  /* Moves a stack, updating all references within the stack */
    PolyWord *old_base  = (PolyWord *)old_stack;
    PolyWord *new_base  = (PolyWord*)new_stack;
    PolyWord *old_top   = old_base + old_length;

    /* Calculate the offset of the new stack from the old. If the frame is
       being extended objects in the new frame will be further up the stack
       than in the old one. */

    POLYSIGNED offset = new_base - old_base + new_length - old_length;
    PolyWord *oldSp = this->p_sp;
    this->p_sp    = oldSp + offset;
    this->p_hr    = this->p_hr + offset;

    /* Skip the unused part of the stack. */

    POLYUNSIGNED i = oldSp - old_base;

    ASSERT (i <= old_length);

    i = old_length - i;

    PolyWord *old = oldSp;
    PolyWord *newp= this->p_sp;

    while (i--)
    {
//        ASSERT(old >= old_base && old < old_base+old_length);
//        ASSERT(newp >= new_base && newp < new_base+new_length);
        PolyWord old_word = *old++;
        if (old_word.IsTagged() || old_word.AsStackAddr() < old_base || old_word.AsStackAddr() >= old_top)
            *newp++ = old_word;
        else
            *newp++ = PolyWord::FromStackAddr(old_word.AsStackAddr() + offset);
    }
    ASSERT(old == ((PolyWord*)old_stack)+old_length);
    ASSERT(newp == ((PolyWord*)new_stack)+new_length);
}


static void CallIO0(IntTaskData *taskData, Handle(*ioFun)(TaskData *))
{
    Handle result = (*ioFun)(taskData);
    *(taskData->p_sp) = result->Word();
    taskData->p_lastInstr = 256; /* Take next instruction. */
}

static void CallIO1(IntTaskData *taskData, Handle(*ioFun)(TaskData *, Handle))
{
    Handle funarg = taskData->saveVec.push(taskData->p_sp[1]);
    Handle result = (*ioFun)(taskData, funarg);
    *(++taskData->p_sp) = result->Word();
    taskData->p_lastInstr = 256; /* Take next instruction. */
}

static void CallIO2(IntTaskData *taskData, Handle(*ioFun)(TaskData *, Handle, Handle))
{
    Handle funarg1 = taskData->saveVec.push(taskData->p_sp[1]);
    Handle funarg2 = taskData->saveVec.push(taskData->p_sp[2]);
    Handle result = (*ioFun)(taskData, funarg1, funarg2);
    taskData->p_sp += 2;
    *(taskData->p_sp) = DEREFWORD(result);
    taskData->p_lastInstr = 256; /* Take next instruction. */
}

static void CallIO3(IntTaskData *taskData, Handle(*ioFun)(TaskData *, Handle, Handle, Handle))
{
    Handle funarg1 = taskData->saveVec.push(taskData->p_sp[1]);
    Handle funarg2 = taskData->saveVec.push(taskData->p_sp[2]);
    Handle funarg3 = taskData->saveVec.push(taskData->p_sp[3]);
    Handle result = (*ioFun)(taskData, funarg1, funarg2, funarg3);
    taskData->p_sp += 3;
    *(taskData->p_sp) = DEREFWORD(result);
    taskData->p_lastInstr = 256; /* Take next instruction. */
}

static void CallIO4(IntTaskData *taskData, Handle(*ioFun)(TaskData *, Handle, Handle, Handle, Handle))
{
    Handle funarg1 = taskData->saveVec.push(taskData->p_sp[1]);
    Handle funarg2 = taskData->saveVec.push(taskData->p_sp[2]);
    Handle funarg3 = taskData->saveVec.push(taskData->p_sp[3]);
    Handle funarg4 = taskData->saveVec.push(taskData->p_sp[4]);
    Handle result = (*ioFun)(taskData, funarg1, funarg2, funarg3, funarg4);
    taskData->p_sp += 4;
    *(taskData->p_sp) = DEREFWORD(result);
    taskData->p_lastInstr = 256;
}

static void CallIO5(IntTaskData *taskData, Handle(*ioFun)(TaskData *, Handle, Handle, Handle, Handle, Handle))
{
    Handle funarg1 = taskData->saveVec.push(taskData->p_sp[1]);
    Handle funarg2 = taskData->saveVec.push(taskData->p_sp[2]);
    Handle funarg3 = taskData->saveVec.push(taskData->p_sp[3]);
    Handle funarg4 = taskData->saveVec.push(taskData->p_sp[4]);
    Handle funarg5 = taskData->saveVec.push(taskData->p_sp[5]);
    Handle result = (*ioFun)(taskData, funarg1, funarg2, funarg3, funarg4, funarg5);
    taskData->p_sp += 5;
    *(taskData->p_sp) = DEREFWORD(result);
    taskData->p_lastInstr = 256; /* Take next instruction. */
}

Handle IntTaskData::EnterPolyCode()
/* Called from "main" to enter the code. */
{
    Handle hOriginal = this->saveVec.mark(); // Set this up for the IO calls.
    while (1)
    {
        this->saveVec.reset(hOriginal); // Remove old RTS arguments and results.

        // Run the ML code and return with the function to call.
        this->inML = true;
        int ioFunction = SwitchToPoly();
        this->inML = false;

        if ((debugOptions & DEBUG_RTSCALLS))
            IncrementRTSCallCount(ioFunction);

        try {
            switch (ioFunction)
            {
            case -1:
                // We've been interrupted.  This usually involves simulating a
                // stack overflow so we could come here because of a genuine
                // stack overflow.
                // Previously this code was executed on every RTS call but there
                // were problems on Mac OS X at least with contention on schedLock.
                this->pendingInterrupt = false; // Clear this before we handle these
                // Process any asynchronous events i.e. interrupts or kill
                processes->ProcessAsynchRequests(this);
                // Release and re-acquire use of the ML memory to allow another thread
                // to GC.
                processes->ThreadReleaseMLMemory(this);
                processes->ThreadUseMLMemory(this);
                break;

            case -2: // A callback has returned.
                ASSERT(0); // Callbacks aren't implemented

            case POLY_SYS_exit:
                CallIO1(this, &finishc);
                break;

            case POLY_SYS_alloc_store:
                CallIO3(this, &alloc_store_long_c);
                break;

            case POLY_SYS_alloc_uninit:
                CallIO2(this, &alloc_uninit_c);
                break;

            case POLY_SYS_chdir:
                CallIO1(this, &change_dirc);
                break;

            case POLY_SYS_get_flags:
                CallIO1(this, &get_flags_c);
                break;

            case POLY_SYS_str_compare:
                CallIO2(this, compareStrings);
                break;

            case POLY_SYS_teststrgtr:
                CallIO2(this, &testStringGreater);
                break;

            case POLY_SYS_teststrlss:
                CallIO2(this, &testStringLess);
                break;

            case POLY_SYS_teststrgeq:
                CallIO2(this, &testStringGreaterOrEqual);
                break;

            case POLY_SYS_teststrleq:
                CallIO2(this, &testStringLessOrEqual);
                break;

            case POLY_SYS_profiler:
                CallIO1(this, &profilerc);
                break;

            case POLY_SYS_quotrem:
                CallIO3(this, &quot_rem_c);
                break;

            case POLY_SYS_aplus:
                CallIO2(this, &add_longc);
                break;

            case POLY_SYS_aminus:
                CallIO2(this, &sub_longc);
                break;

            case POLY_SYS_amul:
                CallIO2(this, &mult_longc);
                break;

            case POLY_SYS_adiv:
                CallIO2(this, &div_longc);
                break;

            case POLY_SYS_amod:
                CallIO2(this, &rem_longc);
                break;

            case POLY_SYS_aneg:
                CallIO1(this, &neg_longc);
                break;

            case POLY_SYS_equala:
                CallIO2(this, &equal_longc);
                break;

            case POLY_SYS_ora:
                CallIO2(this, &or_longc);
                break;

            case POLY_SYS_anda:
                CallIO2(this, &and_longc);
                break;

            case POLY_SYS_xora:
                CallIO2(this, &xor_longc);
                break;

            case POLY_SYS_Real_str:
                CallIO3(this, &Real_strc);
                break;

            case POLY_SYS_Real_geq:
                CallIO2(this, &Real_geqc);
                break;

            case POLY_SYS_Real_leq:
                CallIO2(this, &Real_leqc);
                break;

            case POLY_SYS_Real_gtr:
                CallIO2(this, &Real_gtrc);
                break;

            case POLY_SYS_Real_lss:
                CallIO2(this, &Real_lssc);
                break;

            case POLY_SYS_Real_eq:
                CallIO2(this, &Real_eqc);
                break;

            case POLY_SYS_Real_neq:
                CallIO2(this, &Real_neqc);
                break;

            case POLY_SYS_Real_Dispatch:
                CallIO2(this, &Real_dispatchc);
                break;

            case POLY_SYS_Add_real:
                CallIO2(this, &Real_addc);
                break;

            case POLY_SYS_Sub_real:
                CallIO2(this, &Real_subc);
                break;

            case POLY_SYS_Mul_real:
                CallIO2(this, &Real_mulc);
                break;

            case POLY_SYS_Div_real:
                CallIO2(this, &Real_divc);
                break;

            case POLY_SYS_Abs_real:
                CallIO1(this, &Real_absc);
                break;

            case POLY_SYS_Neg_real:
                CallIO1(this, &Real_negc);
                break;

            case POLY_SYS_conv_real:
                CallIO1(this, &Real_convc);
                break;

            case POLY_SYS_real_to_int:
                CallIO1(this, &Real_intc);
                break;

            case POLY_SYS_int_to_real:
                CallIO1(this, &Real_floatc);
                break;

            case POLY_SYS_sqrt_real:
                CallIO1(this, &Real_sqrtc);
                break;

            case POLY_SYS_sin_real:
                CallIO1(this, &Real_sinc);
                break;

            case POLY_SYS_cos_real:
                CallIO1(this, &Real_cosc);
                break;

            case POLY_SYS_arctan_real:
                CallIO1(this, &Real_arctanc);
                break;

            case POLY_SYS_exp_real:
                CallIO1(this, &Real_expc);
                break;

            case POLY_SYS_ln_real:
                CallIO1(this, &Real_lnc);
                break;

            case POLY_SYS_atomic_reset:
                CallIO1(this, &ProcessAtomicReset);
                break;

            case POLY_SYS_atomic_incr:
                CallIO1(this, &ProcessAtomicIncrement);
                break;

            case POLY_SYS_atomic_decr:
                CallIO1(this, &ProcessAtomicDecrement);
                break;

            case POLY_SYS_thread_self:
                CallIO0(this, &ThreadSelf);
                break;

            case POLY_SYS_thread_dispatch:
                CallIO2(this, &ThreadDispatch);
                break;

            case POLY_SYS_int_geq:
                CallIO2(this, &ge_longc);
                break;

            case POLY_SYS_int_leq:
                CallIO2(this, &le_longc);
                break;

            case POLY_SYS_int_gtr:
                CallIO2(this, &gt_longc);
                break;

            case POLY_SYS_int_lss:
                CallIO2(this, &ls_longc);
                break;

            // ObjSize and ShowSize are now in the poly_specific functions and
            // probably should be removed from here.
            case POLY_SYS_objsize:
                CallIO1(this, &ObjSize);
                break;

            case POLY_SYS_showsize:
                CallIO1(this, &ShowSize);
                break;

            case POLY_SYS_timing_dispatch:
                CallIO2(this, &timing_dispatch_c);
                break;

            case POLY_SYS_XWindows:
                CallIO1(this, &XWindows_c);
                break;

            case POLY_SYS_full_gc:
                CallIO0(this, &full_gc_c);
                break;

            case POLY_SYS_stack_trace:
                CallIO0(this, & stack_trace_c);
                break;

            case POLY_SYS_foreign_dispatch:
                CallIO2(this, &foreign_dispatch_c);
                break;

            case POLY_SYS_ffi:
                CallIO2(this, &poly_ffi);
                break;

            case POLY_SYS_process_env: CallIO2(this, &process_env_dispatch_c); break;

            case POLY_SYS_shrink_stack:
                CallIO1(this, &shrink_stack_c);
                break;

            case POLY_SYS_code_flags:
                CallIO2(this, &CodeSegmentFlags);
                break;

            case POLY_SYS_get_first_long_word:
            case POLY_SYS_int_to_word:
                // POLY_SYS_int_to_word has generally been replaced by POLY_SYS_get_first_long_word.
                // The reason is that POLY_SYS_int_to_word may be applied to either a long or
                // a short argument whereas POLY_SYS_get_first_long_word must be applied to a
                // long argument and can be implemented very easily in the code-generator, at
                // least on a little-endian machine.
                CallIO1(this, &int_to_word_c);
                break;

            case POLY_SYS_poly_specific:
                CallIO2(this, &poly_dispatch_c);
                break;

            case POLY_SYS_bytevec_eq:
                CallIO5(this, &testBytesEqual);
                break;

            case POLY_SYS_cmem_load_8:
                CallIO3(this, &cmem_load_8);
                break;

            case POLY_SYS_cmem_load_16:
                CallIO3(this, &cmem_load_16);
                break;

            case POLY_SYS_cmem_load_32:
                CallIO3(this, &cmem_load_32);
                break;

            case POLY_SYS_cmem_load_float:
                CallIO3(this, &cmem_load_float);
                break;

            case POLY_SYS_cmem_load_double:
                CallIO3(this, &cmem_load_double);
                break;

            case POLY_SYS_cmem_store_8:
                CallIO4(this, &cmem_store_8);
                break;

            case POLY_SYS_cmem_store_16:
                CallIO4(this, &cmem_store_16);
                break;

            case POLY_SYS_cmem_store_32:
                CallIO4(this, &cmem_store_32);
                break;

#if (SIZEOF_VOIDP == 8)
            case POLY_SYS_cmem_load_64:
                CallIO3(this, &cmem_load_64);
                break;

            case POLY_SYS_cmem_store_64:
                CallIO4(this, &cmem_store_64);
                break;
#endif

            case POLY_SYS_cmem_store_float:
                CallIO4(this, &cmem_store_float);
                break;

            case POLY_SYS_cmem_store_double:
                CallIO4(this, &cmem_store_double);
                break;

//            case POLY_SYS_set_code_constant: // Not used in the interpreter
//                CallIO4(this, &set_code_constant);
//                break;

            case POLY_SYS_move_bytes:
            case POLY_SYS_move_bytes_overlap:
                CallIO5(this, &move_bytes_long_c);
                break;

            case POLY_SYS_move_words:
            case POLY_SYS_move_words_overlap:
                CallIO5(this, &move_words_long_c);
                break;

            case POLY_SYS_io_dispatch:
                CallIO3(this, &IO_dispatch_c);
                break;

            case POLY_SYS_network:
                CallIO2(this, &Net_dispatch_c);
                break;

            case POLY_SYS_os_specific:
                CallIO2(this, &OS_spec_dispatch_c);
                break;

            case POLY_SYS_signal_handler:
                CallIO2(this, &Sig_dispatch_c);
                break;

            case POLY_SYS_kill_self:
                CallIO0(this, exitThread);
                break;

            case POLY_SYS_eq_longword:
                CallIO2(this, &eqLongWord);
                break;

            case POLY_SYS_neq_longword:
                CallIO2(this, &neqLongWord);
                break;

            case POLY_SYS_geq_longword:
                CallIO2(this, &geqLongWord);
                break;

            case POLY_SYS_leq_longword:
                CallIO2(this, &leqLongWord);
                break;

            case POLY_SYS_gt_longword:
                CallIO2(this, &gtLongWord);
                break;

            case POLY_SYS_lt_longword:
                CallIO2(this, &ltLongWord);
                break;

            case POLY_SYS_plus_longword:
                CallIO2(this, &plusLongWord);
                break;

            case POLY_SYS_minus_longword:
                CallIO2(this, &minusLongWord);
                break;

            case POLY_SYS_mul_longword:
                CallIO2(this, &mulLongWord);
                break;

            case POLY_SYS_div_longword:
                CallIO2(this, &divLongWord);
                break;

            case POLY_SYS_mod_longword:
                CallIO2(this, &modLongWord);
                break;

            case POLY_SYS_andb_longword:
                CallIO2(this, &andbLongWord);
                break;

            case POLY_SYS_orb_longword:
                CallIO2(this, &orbLongWord);
                break;

            case POLY_SYS_xorb_longword:
                CallIO2(this, &xorbLongWord);
                break;

            case POLY_SYS_shift_left_longword:
                CallIO2(this, &shiftLeftLongWord);
                break;

            case POLY_SYS_shift_right_longword:
                CallIO2(this, &shiftRightLongWord);
                break;

            case POLY_SYS_shift_right_arith_longword:
                CallIO2(this, &shiftRightArithLongWord);
                break;

            case POLY_SYS_longword_to_tagged:
                CallIO1(this, &longWordToTagged);
                break;

            case POLY_SYS_signed_to_longword:
                CallIO1(this, &signedToLongWord);
                break;

            case POLY_SYS_unsigned_to_longword:
                CallIO1(this, &unsignedToLongWord);
                break;

            case POLY_SYS_give_ex_trace_fn:
                CallIO1(this, exceptionToTraceException);
                break;

            default:
                Crash("Unknown io operation %d\n", ioFunction);
            }
        }
        catch (IOException &) {
        }

    }
}

void Interpreter::InitInterfaceVector(void)
{
    add_word_to_io_area(POLY_SYS_exit, TAGGED(POLY_SYS_exit));
    add_word_to_io_area(POLY_SYS_chdir, TAGGED(POLY_SYS_chdir));
    add_word_to_io_area(POLY_SYS_alloc_store, TAGGED(POLY_SYS_alloc_store));
    add_word_to_io_area(POLY_SYS_alloc_uninit, TAGGED(POLY_SYS_alloc_uninit));
    add_word_to_io_area(POLY_SYS_raisex, TAGGED(POLY_SYS_raisex));
    add_word_to_io_area(POLY_SYS_get_length, TAGGED(POLY_SYS_get_length));
    add_word_to_io_area(POLY_SYS_get_flags, TAGGED(POLY_SYS_get_flags));
    add_word_to_io_area(POLY_SYS_str_compare, TAGGED(POLY_SYS_str_compare));
    add_word_to_io_area(POLY_SYS_teststrgtr, TAGGED(POLY_SYS_teststrgtr));
    add_word_to_io_area(POLY_SYS_teststrlss, TAGGED(POLY_SYS_teststrlss));
    add_word_to_io_area(POLY_SYS_teststrgeq, TAGGED(POLY_SYS_teststrgeq));
    add_word_to_io_area(POLY_SYS_teststrleq, TAGGED(POLY_SYS_teststrleq));
    add_word_to_io_area(POLY_SYS_exception_trace_fn, TAGGED(POLY_SYS_exception_trace_fn));
    add_word_to_io_area(POLY_SYS_lockseg, TAGGED(POLY_SYS_lockseg));
    add_word_to_io_area(POLY_SYS_network, TAGGED(POLY_SYS_network));
    add_word_to_io_area(POLY_SYS_os_specific, TAGGED(POLY_SYS_os_specific));
    add_word_to_io_area(POLY_SYS_eq_longword, TAGGED(POLY_SYS_eq_longword));
    add_word_to_io_area(POLY_SYS_neq_longword, TAGGED(POLY_SYS_neq_longword));
    add_word_to_io_area(POLY_SYS_geq_longword, TAGGED(POLY_SYS_geq_longword));
    add_word_to_io_area(POLY_SYS_leq_longword, TAGGED(POLY_SYS_leq_longword));
    add_word_to_io_area(POLY_SYS_gt_longword, TAGGED(POLY_SYS_gt_longword));
    add_word_to_io_area(POLY_SYS_lt_longword, TAGGED(POLY_SYS_lt_longword));
    add_word_to_io_area(POLY_SYS_io_dispatch, TAGGED(POLY_SYS_io_dispatch));
    add_word_to_io_area(POLY_SYS_signal_handler, TAGGED(POLY_SYS_signal_handler));
    add_word_to_io_area(POLY_SYS_atomic_reset, TAGGED(POLY_SYS_atomic_reset));
    add_word_to_io_area(POLY_SYS_atomic_incr, TAGGED(POLY_SYS_atomic_incr));
    add_word_to_io_area(POLY_SYS_atomic_decr, TAGGED(POLY_SYS_atomic_decr));
    add_word_to_io_area(POLY_SYS_thread_self, TAGGED(POLY_SYS_thread_self));
    add_word_to_io_area(POLY_SYS_thread_dispatch, TAGGED(POLY_SYS_thread_dispatch));
    add_word_to_io_area(POLY_SYS_plus_longword, TAGGED(POLY_SYS_plus_longword));
    add_word_to_io_area(POLY_SYS_minus_longword, TAGGED(POLY_SYS_minus_longword));
    add_word_to_io_area(POLY_SYS_mul_longword, TAGGED(POLY_SYS_mul_longword));
    add_word_to_io_area(POLY_SYS_div_longword, TAGGED(POLY_SYS_div_longword));
    add_word_to_io_area(POLY_SYS_mod_longword, TAGGED(POLY_SYS_mod_longword));
    add_word_to_io_area(POLY_SYS_andb_longword, TAGGED(POLY_SYS_andb_longword));
    add_word_to_io_area(POLY_SYS_orb_longword, TAGGED(POLY_SYS_orb_longword));
    add_word_to_io_area(POLY_SYS_xorb_longword, TAGGED(POLY_SYS_xorb_longword));
    add_word_to_io_area(POLY_SYS_kill_self, TAGGED(POLY_SYS_kill_self));
    add_word_to_io_area(POLY_SYS_shift_left_longword, TAGGED(POLY_SYS_shift_left_longword));
    add_word_to_io_area(POLY_SYS_shift_right_longword, TAGGED(POLY_SYS_shift_right_longword));
    add_word_to_io_area(POLY_SYS_shift_right_arith_longword, TAGGED(POLY_SYS_shift_right_arith_longword));
    add_word_to_io_area(POLY_SYS_profiler, TAGGED(POLY_SYS_profiler));
    add_word_to_io_area(POLY_SYS_longword_to_tagged, TAGGED(POLY_SYS_longword_to_tagged));
    add_word_to_io_area(POLY_SYS_signed_to_longword, TAGGED(POLY_SYS_signed_to_longword));
    add_word_to_io_area(POLY_SYS_unsigned_to_longword, TAGGED(POLY_SYS_unsigned_to_longword));
    add_word_to_io_area(POLY_SYS_full_gc, TAGGED(POLY_SYS_full_gc));
    add_word_to_io_area(POLY_SYS_stack_trace, TAGGED(POLY_SYS_stack_trace));
    add_word_to_io_area(POLY_SYS_timing_dispatch, TAGGED(POLY_SYS_timing_dispatch));
    add_word_to_io_area(POLY_SYS_objsize, TAGGED(POLY_SYS_objsize));
    add_word_to_io_area(POLY_SYS_showsize, TAGGED(POLY_SYS_showsize));
    add_word_to_io_area(POLY_SYS_quotrem, TAGGED(POLY_SYS_quotrem));
    add_word_to_io_area(POLY_SYS_is_short, TAGGED(POLY_SYS_is_short));
    add_word_to_io_area(POLY_SYS_aplus, TAGGED(POLY_SYS_aplus));
    add_word_to_io_area(POLY_SYS_aminus, TAGGED(POLY_SYS_aminus));
    add_word_to_io_area(POLY_SYS_amul, TAGGED(POLY_SYS_amul));
    add_word_to_io_area(POLY_SYS_adiv, TAGGED(POLY_SYS_adiv));
    add_word_to_io_area(POLY_SYS_amod, TAGGED(POLY_SYS_amod));
    add_word_to_io_area(POLY_SYS_aneg, TAGGED(POLY_SYS_aneg));
    add_word_to_io_area(POLY_SYS_xora, TAGGED(POLY_SYS_xora));
    add_word_to_io_area(POLY_SYS_equala, TAGGED(POLY_SYS_equala));
    add_word_to_io_area(POLY_SYS_ora, TAGGED(POLY_SYS_ora));
    add_word_to_io_area(POLY_SYS_anda, TAGGED(POLY_SYS_anda));
    add_word_to_io_area(POLY_SYS_Real_str, TAGGED(POLY_SYS_Real_str));
    add_word_to_io_area(POLY_SYS_Real_geq, TAGGED(POLY_SYS_Real_geq));
    add_word_to_io_area(POLY_SYS_Real_leq, TAGGED(POLY_SYS_Real_leq));
    add_word_to_io_area(POLY_SYS_Real_gtr, TAGGED(POLY_SYS_Real_gtr));
    add_word_to_io_area(POLY_SYS_Real_lss, TAGGED(POLY_SYS_Real_lss));
    add_word_to_io_area(POLY_SYS_Real_eq, TAGGED(POLY_SYS_Real_eq));
    add_word_to_io_area(POLY_SYS_Real_neq, TAGGED(POLY_SYS_Real_neq));
    add_word_to_io_area(POLY_SYS_Real_Dispatch, TAGGED(POLY_SYS_Real_Dispatch));
    add_word_to_io_area(POLY_SYS_Add_real, TAGGED(POLY_SYS_Add_real));
    add_word_to_io_area(POLY_SYS_Sub_real, TAGGED(POLY_SYS_Sub_real));
    add_word_to_io_area(POLY_SYS_Mul_real, TAGGED(POLY_SYS_Mul_real));
    add_word_to_io_area(POLY_SYS_Div_real, TAGGED(POLY_SYS_Div_real));
    add_word_to_io_area(POLY_SYS_Abs_real, TAGGED(POLY_SYS_Abs_real));
    add_word_to_io_area(POLY_SYS_Neg_real, TAGGED(POLY_SYS_Neg_real));
    add_word_to_io_area(POLY_SYS_conv_real, TAGGED(POLY_SYS_conv_real));
    add_word_to_io_area(POLY_SYS_real_to_int, TAGGED(POLY_SYS_real_to_int));
    add_word_to_io_area(POLY_SYS_int_to_real, TAGGED(POLY_SYS_int_to_real));
    add_word_to_io_area(POLY_SYS_sqrt_real, TAGGED(POLY_SYS_sqrt_real));
    add_word_to_io_area(POLY_SYS_sin_real, TAGGED(POLY_SYS_sin_real));
    add_word_to_io_area(POLY_SYS_cos_real, TAGGED(POLY_SYS_cos_real));
    add_word_to_io_area(POLY_SYS_arctan_real, TAGGED(POLY_SYS_arctan_real));
    add_word_to_io_area(POLY_SYS_exp_real, TAGGED(POLY_SYS_exp_real));
    add_word_to_io_area(POLY_SYS_ln_real, TAGGED(POLY_SYS_ln_real));
    add_word_to_io_area(POLY_SYS_process_env, TAGGED(POLY_SYS_process_env));
    add_word_to_io_area(POLY_SYS_set_string_length, TAGGED(POLY_SYS_set_string_length));
    add_word_to_io_area(POLY_SYS_get_first_long_word, TAGGED(POLY_SYS_get_first_long_word));
    add_word_to_io_area(POLY_SYS_poly_specific, TAGGED(POLY_SYS_poly_specific));
    add_word_to_io_area(POLY_SYS_bytevec_eq, TAGGED(POLY_SYS_bytevec_eq));
    add_word_to_io_area(POLY_SYS_cmem_load_8, TAGGED(POLY_SYS_cmem_load_8));
    add_word_to_io_area(POLY_SYS_cmem_load_16, TAGGED(POLY_SYS_cmem_load_16));
    add_word_to_io_area(POLY_SYS_cmem_load_32, TAGGED(POLY_SYS_cmem_load_32));
    add_word_to_io_area(POLY_SYS_cmem_load_64, TAGGED(POLY_SYS_cmem_load_64));
    add_word_to_io_area(POLY_SYS_cmem_load_float, TAGGED(POLY_SYS_cmem_load_float));
    add_word_to_io_area(POLY_SYS_cmem_load_double, TAGGED(POLY_SYS_cmem_load_double));
    add_word_to_io_area(POLY_SYS_cmem_store_8, TAGGED(POLY_SYS_cmem_store_8));
    add_word_to_io_area(POLY_SYS_cmem_store_16, TAGGED(POLY_SYS_cmem_store_16));
    add_word_to_io_area(POLY_SYS_cmem_store_32, TAGGED(POLY_SYS_cmem_store_32));
    add_word_to_io_area(POLY_SYS_cmem_store_64, TAGGED(POLY_SYS_cmem_store_64));
    add_word_to_io_area(POLY_SYS_cmem_store_float, TAGGED(POLY_SYS_cmem_store_float));
    add_word_to_io_area(POLY_SYS_cmem_store_double, TAGGED(POLY_SYS_cmem_store_double));
    add_word_to_io_area(POLY_SYS_io_operation, TAGGED(POLY_SYS_io_operation));
    add_word_to_io_area(POLY_SYS_ffi, TAGGED(POLY_SYS_ffi));
    add_word_to_io_area(POLY_SYS_move_words_overlap, TAGGED(POLY_SYS_move_words_overlap));
    add_word_to_io_area(POLY_SYS_set_code_constant, TAGGED(POLY_SYS_set_code_constant));
    add_word_to_io_area(POLY_SYS_move_words, TAGGED(POLY_SYS_move_words));
    add_word_to_io_area(POLY_SYS_shift_right_arith_word, TAGGED(POLY_SYS_shift_right_arith_word));
    add_word_to_io_area(POLY_SYS_int_to_word, TAGGED(POLY_SYS_int_to_word));
    add_word_to_io_area(POLY_SYS_move_bytes, TAGGED(POLY_SYS_move_bytes));
    add_word_to_io_area(POLY_SYS_move_bytes_overlap, TAGGED(POLY_SYS_move_bytes_overlap));
    add_word_to_io_area(POLY_SYS_code_flags, TAGGED(POLY_SYS_code_flags));
    add_word_to_io_area(POLY_SYS_shrink_stack, TAGGED(POLY_SYS_shrink_stack));
    add_word_to_io_area(POLY_SYS_callcode_tupled, TAGGED(POLY_SYS_callcode_tupled));
    add_word_to_io_area(POLY_SYS_foreign_dispatch, TAGGED(POLY_SYS_foreign_dispatch));
    add_word_to_io_area(POLY_SYS_XWindows, TAGGED(POLY_SYS_XWindows));
    add_word_to_io_area(POLY_SYS_is_big_endian, TAGGED(POLY_SYS_is_big_endian));
    add_word_to_io_area(POLY_SYS_bytes_per_word, TAGGED(POLY_SYS_bytes_per_word));
    add_word_to_io_area(POLY_SYS_offset_address, TAGGED(POLY_SYS_offset_address));
    add_word_to_io_area(POLY_SYS_shift_right_word, TAGGED(POLY_SYS_shift_right_word));
    add_word_to_io_area(POLY_SYS_word_neq, TAGGED(POLY_SYS_word_neq));
    add_word_to_io_area(POLY_SYS_not_bool, TAGGED(POLY_SYS_not_bool));
    add_word_to_io_area(POLY_SYS_string_length, TAGGED(POLY_SYS_string_length));
    add_word_to_io_area(POLY_SYS_touch_final, TAGGED(POLY_SYS_touch_final));
    add_word_to_io_area(POLY_SYS_int_geq, TAGGED(POLY_SYS_int_geq));
    add_word_to_io_area(POLY_SYS_int_leq, TAGGED(POLY_SYS_int_leq));
    add_word_to_io_area(POLY_SYS_int_gtr, TAGGED(POLY_SYS_int_gtr));
    add_word_to_io_area(POLY_SYS_int_lss, TAGGED(POLY_SYS_int_lss));
    add_word_to_io_area(POLY_SYS_load_byte_immut, TAGGED(POLY_SYS_load_byte_immut));
    add_word_to_io_area(POLY_SYS_load_word_immut, TAGGED(POLY_SYS_load_word_immut));
    add_word_to_io_area(POLY_SYS_mul_word, TAGGED(POLY_SYS_mul_word));
    add_word_to_io_area(POLY_SYS_plus_word, TAGGED(POLY_SYS_plus_word));
    add_word_to_io_area(POLY_SYS_minus_word, TAGGED(POLY_SYS_minus_word));
    add_word_to_io_area(POLY_SYS_div_word, TAGGED(POLY_SYS_div_word));
    add_word_to_io_area(POLY_SYS_or_word, TAGGED(POLY_SYS_or_word));
    add_word_to_io_area(POLY_SYS_and_word, TAGGED(POLY_SYS_and_word));
    add_word_to_io_area(POLY_SYS_xor_word, TAGGED(POLY_SYS_xor_word));
    add_word_to_io_area(POLY_SYS_shift_left_word, TAGGED(POLY_SYS_shift_left_word));
    add_word_to_io_area(POLY_SYS_mod_word, TAGGED(POLY_SYS_mod_word));
    add_word_to_io_area(POLY_SYS_word_geq, TAGGED(POLY_SYS_word_geq));
    add_word_to_io_area(POLY_SYS_word_leq, TAGGED(POLY_SYS_word_leq));
    add_word_to_io_area(POLY_SYS_word_gtr, TAGGED(POLY_SYS_word_gtr));
    add_word_to_io_area(POLY_SYS_word_lss, TAGGED(POLY_SYS_word_lss));
    add_word_to_io_area(POLY_SYS_word_eq, TAGGED(POLY_SYS_word_eq));
    add_word_to_io_area(POLY_SYS_load_byte, TAGGED(POLY_SYS_load_byte));
    add_word_to_io_area(POLY_SYS_load_word, TAGGED(POLY_SYS_load_word));
    add_word_to_io_area(POLY_SYS_assign_byte, TAGGED(POLY_SYS_assign_byte));
    add_word_to_io_area(POLY_SYS_assign_word, TAGGED(POLY_SYS_assign_word));
}

// As far as possible we want locking and unlocking an ML mutex to be fast so
// we try to implement the code in the assembly code using appropriate
// interlocked instructions.  That does mean that if we need to lock and
// unlock an ML mutex in this code we have to use the same, machine-dependent,
// code to do it.  These are defaults that are used where there is no
// machine-specific code.

// Increment the value contained in the first word of the mutex.
// On most platforms this code will be done with a piece of assembly code.
static PLock mutexLock;

Handle IntTaskData::AtomicIncrement(Handle mutexp)
{
    PLocker l(&mutexLock);
    PolyObject *p = DEREFHANDLE(mutexp);
    // A thread can only call this once so the values will be short
    PolyWord newValue = TAGGED(UNTAGGED(p->Get(0))+1);
    p->Set(0, newValue);
    return this->saveVec.push(newValue);
}

// Decrement the value contained in the first word of the mutex.
Handle IntTaskData::AtomicDecrement(Handle mutexp)
{
    PLocker l(&mutexLock);
    PolyObject *p = DEREFHANDLE(mutexp);
    PolyWord newValue = TAGGED(UNTAGGED(p->Get(0))-1);
    p->Set(0, newValue);
    return this->saveVec.push(newValue);
}

// Release a mutex.  We need to lock the mutex to ensure we don't
// reset it in the time between one of atomic operations reading
// and writing the mutex.
void IntTaskData::AtomicReset(Handle mutexp)
{
    PLocker l(&mutexLock);
    DEREFHANDLE(mutexp)->Set(0, TAGGED(1)); // Set this to released.
}

static Interpreter interpreterObject;

MachineDependent *machineDependent = &interpreterObject;