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/*=============================================================================
Copyright (c) 2001-2011 Joel de Guzman
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#include "vm.hpp"
#if defined(_MSC_VER)
# pragma warning(disable: 4800) // forcing value to bool 'true' or 'false'
// (performance warning)
#endif
namespace client
{
int vmachine::execute(
std::vector<int> const& code
, std::vector<int>::const_iterator pc
, std::vector<int>::iterator frame_ptr
)
{
std::vector<int>::iterator stack_ptr = frame_ptr;
while (true)
{
switch (*pc++)
{
case op_neg:
stack_ptr[-1] = -stack_ptr[-1];
break;
case op_not:
stack_ptr[-1] = !bool(stack_ptr[-1]);
break;
case op_add:
--stack_ptr;
stack_ptr[-1] += stack_ptr[0];
break;
case op_sub:
--stack_ptr;
stack_ptr[-1] -= stack_ptr[0];
break;
case op_mul:
--stack_ptr;
stack_ptr[-1] *= stack_ptr[0];
break;
case op_div:
--stack_ptr;
stack_ptr[-1] /= stack_ptr[0];
break;
case op_eq:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] == stack_ptr[0]);
break;
case op_neq:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] != stack_ptr[0]);
break;
case op_lt:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] < stack_ptr[0]);
break;
case op_lte:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] <= stack_ptr[0]);
break;
case op_gt:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] > stack_ptr[0]);
break;
case op_gte:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1] >= stack_ptr[0]);
break;
case op_and:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1]) && bool(stack_ptr[0]);
break;
case op_or:
--stack_ptr;
stack_ptr[-1] = bool(stack_ptr[-1]) || bool(stack_ptr[0]);
break;
case op_load:
*stack_ptr++ = frame_ptr[*pc++];
break;
case op_store:
--stack_ptr;
frame_ptr[*pc++] = stack_ptr[0];
break;
case op_int:
*stack_ptr++ = *pc++;
break;
case op_true:
*stack_ptr++ = true;
break;
case op_false:
*stack_ptr++ = false;
break;
case op_jump:
pc += *pc;
break;
case op_jump_if:
if (!bool(stack_ptr[-1]))
pc += *pc;
else
++pc;
--stack_ptr;
break;
case op_stk_adj:
stack_ptr += *pc++;
break;
case op_call:
{
int nargs = *pc++;
int jump = *pc++;
// a function call is a recursive call to execute
int r = execute(
code
, code.begin() + jump
, stack_ptr - nargs
);
// cleanup after return from function
stack_ptr[-nargs] = r; // get return value
stack_ptr -= (nargs - 1); // the stack will now contain
// the return value
}
break;
case op_return:
return stack_ptr[-1];
}
}
}
}
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