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