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/* yForth? - Written by Luca Padovani (C) 1996/97
* ------------------------------------------------------------------------
* This software is FreeWare as long as it comes with this header in each
* source file, anyway you can use it or any part of it whatever
* you want. It comes without any warranty, so use it at your own risk.
* ------------------------------------------------------------------------
* Module name: vm.c
* Abstract: The Virtual Machine on which is based the whole
* forth interpreter.
*/
#include <stdio.h>
#include <signal.h>
#include "yforth.h"
#include "core.h"
/* "ip" is the Instruction Pointer of the Virtual Machine. "ip" points to
* an array of "pfp", which stands for "primitive function pointer",
* in other words an array of pointers to primitive functions.
* Roughly speaking, primitive functions are the valid instructions of
* the Virtual Machine.
*/
pfp *ip; /* Instruction Pointer */
Cell *sp, *sp_top, *sp_base; /* various stack pointers... */
Cell *rp, *rp_top, *rp_base;
Real *fp, *fp_top, *fp_base;
Cell *bp;
#ifdef DCELL_MEM
static union double_cell dcell; /* Used for double-cell transfer */
#endif
/* stacks_recovery: called when an exception occurs, it sets all stack
* ptrs to their original value.
*/
void
stacks_recovery (void)
{
sp = sp_top;
rp = rp_top;
fp = fp_top;
}
/* If double-cell transfer is realized with memory-copying, the following
* auxiliary procedures are needed
*/
#ifdef DCELL_MEM
DCell
get_dcell (Cell * ptr)
{
dcell.d2.high = *ptr;
dcell.d2.low = *(ptr + 1);
return (dcell.d1);
}
void
put_dcell (Cell * ptr, DCell d)
{
dcell.d1 = d;
*ptr = dcell.d2.high;
*(ptr + 1) = dcell.d2.low;
}
#endif
/* sig_fpe_handler: signal handler for math exceptions */
void
sig_fpe_handler (int sig)
{
signal (SIGFPE, sig_fpe_handler);
_error = E_FPE;
_view_error_msg();
longjmp(warm_start_jump, 1);
}
/* sig_segv_handler: signal handler for segmentation violation */
void
sig_segv_handler (int sig)
{
signal (SIGSEGV, sig_segv_handler);
_error = E_SEGV;
_view_error_msg();
longjmp(warm_start_jump, 1);
}
/* init_signal: initialize signal handlers */
void
init_signals ()
{
signal (SIGFPE, sig_fpe_handler);
signal (SIGSEGV, sig_segv_handler);
}
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