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703 lines
22 KiB
C++
703 lines
22 KiB
C++
//
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// PerformImplementation.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/10/2023.
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// Copyright © 2023 Thomas Harte. All rights reserved.
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//
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#ifndef PerformImplementation_h
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#define PerformImplementation_h
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#include "../../../Numeric/Carry.hpp"
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#include "../../../Numeric/RegisterSizes.hpp"
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#include "../Interrupts.hpp"
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namespace InstructionSet::x86 {
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template <Model model, typename IntT, typename InstructionT, typename RegistersT, typename MemoryT>
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IntT *resolve(
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InstructionT &instruction,
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Source source,
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DataPointer pointer,
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RegistersT ®isters,
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MemoryT &memory,
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IntT *none = nullptr,
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IntT *immediate = nullptr
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);
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template <Model model, Source source, typename IntT, typename InstructionT, typename RegistersT, typename MemoryT>
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uint32_t address(
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InstructionT &instruction,
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DataPointer pointer,
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RegistersT ®isters,
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MemoryT &memory
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) {
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// TODO: non-word indexes and bases.
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if constexpr (source == Source::DirectAddress) {
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return instruction.offset();
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}
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uint32_t address;
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uint16_t zero = 0;
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address = *resolve<model, uint16_t>(instruction, pointer.index(), pointer, registers, memory, &zero);
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if constexpr (is_32bit(model)) {
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address <<= pointer.scale();
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}
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address += instruction.offset();
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if constexpr (source == Source::IndirectNoBase) {
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return address;
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}
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return address + *resolve<model, uint16_t>(instruction, pointer.base(), pointer, registers, memory);
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}
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template <Model model, typename IntT, typename InstructionT, typename RegistersT, typename MemoryT>
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IntT *resolve(
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InstructionT &instruction,
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Source source,
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DataPointer pointer,
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RegistersT ®isters,
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MemoryT &memory,
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IntT *none,
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IntT *immediate
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) {
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// Rules:
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//
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// * if this is a memory access, set target_address and break;
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// * otherwise return the appropriate value.
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uint32_t target_address;
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switch(source) {
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case Source::eAX:
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// Slightly contorted if chain here and below:
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//
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// (i) does the `constexpr` version of a `switch`; and
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// (i) ensures .eax() etc aren't called on @c registers for 16-bit processors, so they need not implement 32-bit storage.
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.eax(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.ax(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.al(); }
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else { return nullptr; }
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case Source::eCX:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.ecx(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.cx(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.cl(); }
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else { return nullptr; }
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case Source::eDX:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.edx(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.dx(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.dl(); }
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else if constexpr (std::is_same_v<IntT, uint32_t>) { return nullptr; }
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case Source::eBX:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.ebx(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.bx(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.bl(); }
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else if constexpr (std::is_same_v<IntT, uint32_t>) { return nullptr; }
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case Source::eSPorAH:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.esp(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.sp(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.ah(); }
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else { return nullptr; }
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case Source::eBPorCH:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.ebp(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.bp(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.ch(); }
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else { return nullptr; }
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case Source::eSIorDH:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.esi(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.si(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.dh(); }
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else { return nullptr; }
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case Source::eDIorBH:
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if constexpr (is_32bit(model) && std::is_same_v<IntT, uint32_t>) { return ®isters.edi(); }
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else if constexpr (std::is_same_v<IntT, uint16_t>) { return ®isters.di(); }
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else if constexpr (std::is_same_v<IntT, uint8_t>) { return ®isters.bh(); }
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else { return nullptr; }
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case Source::ES: if constexpr (std::is_same_v<IntT, uint16_t>) return ®isters.es(); else return nullptr;
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case Source::CS: if constexpr (std::is_same_v<IntT, uint16_t>) return ®isters.cs(); else return nullptr;
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case Source::SS: if constexpr (std::is_same_v<IntT, uint16_t>) return ®isters.ss(); else return nullptr;
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case Source::DS: if constexpr (std::is_same_v<IntT, uint16_t>) return ®isters.ds(); else return nullptr;
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// 16-bit models don't have FS and GS.
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case Source::FS: if constexpr (is_32bit(model) && std::is_same_v<IntT, uint16_t>) return ®isters.fs(); else return nullptr;
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case Source::GS: if constexpr (is_32bit(model) && std::is_same_v<IntT, uint16_t>) return ®isters.gs(); else return nullptr;
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case Source::Immediate:
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*immediate = instruction.operand();
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return immediate;
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case Source::None: return none;
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case Source::Indirect:
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target_address = address<model, Source::Indirect, IntT>(instruction, pointer, registers, memory);
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break;
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case Source::IndirectNoBase:
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target_address = address<model, Source::IndirectNoBase, IntT>(instruction, pointer, registers, memory);
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break;
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case Source::DirectAddress:
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target_address = address<model, Source::DirectAddress, IntT>(instruction, pointer, registers, memory);
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break;
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}
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// If execution has reached here then a memory fetch is required.
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// Do it and exit.
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const Source segment = pointer.segment(instruction.segment_override());
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return &memory.template access<IntT>(segment, target_address);
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};
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namespace Primitive {
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//
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// BEGIN TEMPORARY COPY AND PASTE SECTION.
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//
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// The following are largely excised from the M68k PerformImplementation.hpp; if there proves to be no
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// reason further to specialise them, there'll be a factoring out. In some cases I've tightened the documentation.
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//
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/// @returns An int of type @c IntT with only the most-significant bit set.
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template <typename IntT> constexpr IntT top_bit() {
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static_assert(!std::numeric_limits<IntT>::is_signed);
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constexpr IntT max = std::numeric_limits<IntT>::max();
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return max - (max >> 1);
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}
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/// @returns The number of bits in @c IntT.
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template <typename IntT> constexpr int bit_size() {
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return sizeof(IntT) * 8;
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}
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/// @returns An int with the top bit indicating whether overflow occurred during the calculation of
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/// • @c lhs + @c rhs (if @c is_add is true); or
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/// • @c lhs - @c rhs (if @c is_add is false)
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/// and the result was @c result. All other bits will be clear.
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template <bool is_add, typename IntT>
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IntT overflow(IntT lhs, IntT rhs, IntT result) {
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const IntT output_changed = result ^ lhs;
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const IntT input_differed = lhs ^ rhs;
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if constexpr (is_add) {
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return top_bit<IntT>() & output_changed & ~input_differed;
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} else {
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return top_bit<IntT>() & output_changed & input_differed;
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}
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}
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// NOTE TO FUTURE SELF: the original 68k `overflow` treats lhs and rhs the other way
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// around, affecting subtractive overflow. Be careful.
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//
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// END COPY AND PASTE SECTION.
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//
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//
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// Comments below on intended functioning of each operation come from the 1997 edition of the
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// Intel Architecture Software Developer’s Manual; that year all such definitions still fitted within a
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// single volume, Volume 2.
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//
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// Order Number 243191; e.g. https://www.ardent-tool.com/CPU/docs/Intel/IA/243191-002.pdf
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//
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inline void aaa(CPU::RegisterPair16 &ax, Status &status) { // P. 313
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/*
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IF ((AL AND 0FH) > 9) OR (AF = 1)
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THEN
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AL ← (AL + 6);
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AH ← AH + 1;
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AF ← 1;
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CF ← 1;
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ELSE
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AF ← 0;
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CF ← 0;
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FI;
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AL ← AL AND 0FH;
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*/
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/*
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The AF and CF flags are set to 1 if the adjustment results in a decimal carry;
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otherwise they are cleared to 0. The OF, SF, ZF, and PF flags are undefined.
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*/
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if((ax.halves.low & 0x0f) > 9 || status.auxiliary_carry) {
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ax.halves.low += 6;
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++ax.halves.high;
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status.auxiliary_carry = status.carry = 1;
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} else {
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status.auxiliary_carry = status.carry = 0;
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}
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ax.halves.low &= 0x0f;
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}
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inline void aad(CPU::RegisterPair16 &ax, uint8_t imm, Status &status) {
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/*
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tempAL ← AL;
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tempAH ← AH;
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AL ← (tempAL + (tempAH * imm8)) AND FFH; (* imm8 is set to 0AH for the AAD mnemonic *)
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AH ← 0
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*/
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/*
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The SF, ZF, and PF flags are set according to the result;
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the OF, AF, and CF flags are undefined.
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*/
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ax.halves.low = ax.halves.low + (ax.halves.high * imm);
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ax.halves.high = 0;
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status.sign = ax.halves.low & 0x80;
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status.parity = status.zero = ax.halves.low;
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}
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template <typename FlowControllerT>
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inline void aam(CPU::RegisterPair16 &ax, uint8_t imm, Status &status, FlowControllerT &flow_controller) {
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/*
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tempAL ← AL;
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AH ← tempAL / imm8; (* imm8 is set to 0AH for the AAD mnemonic *)
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AL ← tempAL MOD imm8;
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*/
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/*
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The SF, ZF, and PF flags are set according to the result.
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The OF, AF, and CF flags are undefined.
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*/
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/*
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If ... an immediate value of 0 is used, it will cause a #DE (divide error) exception.
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*/
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if(!imm) {
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flow_controller.interrupt(Interrupt::DivideByZero);
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return;
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}
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ax.halves.high = ax.halves.low / imm;
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ax.halves.low = ax.halves.low % imm;
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status.sign = ax.halves.low & 0x80;
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status.parity = status.zero = ax.halves.low;
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}
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inline void aas(CPU::RegisterPair16 &ax, Status &status) {
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/*
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IF ((AL AND 0FH) > 9) OR (AF = 1)
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THEN
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AL ← AL – 6;
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AH ← AH – 1;
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AF ← 1;
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CF ← 1;
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ELSE
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CF ← 0;
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AF ← 0;
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FI;
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AL ← AL AND 0FH;
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*/
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/*
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The AF and CF flags are set to 1 if there is a decimal borrow;
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otherwise, they are cleared to 0. The OF, SF, ZF, and PF flags are undefined.
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*/
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if((ax.halves.low & 0x0f) > 9 || status.auxiliary_carry) {
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ax.halves.low -= 6;
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--ax.halves.high;
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status.auxiliary_carry = status.carry = 1;
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} else {
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status.auxiliary_carry = status.carry = 0;
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}
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ax.halves.low &= 0x0f;
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}
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inline void daa(uint8_t &al, Status &status) {
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/*
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(as modified by https://www.felixcloutier.com/x86/daa ...)
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old_AL ← AL;
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old_CF ← CF;
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CF ← 0;
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IF (((AL AND 0FH) > 9) or AF = 1)
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THEN
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AL ← AL + 6;
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CF ← old_CF OR CarryFromLastAddition; (* CF OR carry from AL ← AL + 6 *)
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AF ← 1;
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ELSE
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AF ← 0;
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FI;
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IF ((old_AL > 99H) or old_CF = 1)
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THEN
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AL ← AL + 60H;
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CF ← 1;
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ELSE
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CF ← 0;
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FI;
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*/
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/*
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The CF and AF flags are set if the adjustment of the value results in a
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decimal carry in either digit of the result (see the “Operation” section above).
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The SF, ZF, and PF flags are set according to the result. The OF flag is undefined.
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*/
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const uint8_t old_al = al;
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const auto old_carry = status.carry;
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status.carry = 0;
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if((al & 0x0f) > 0x09 || status.auxiliary_carry) {
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status.carry = old_carry | (al > 0xf9);
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al += 0x06;
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status.auxiliary_carry = 1;
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} else {
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status.auxiliary_carry = 0;
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}
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if(old_al > 0x99 || old_carry) {
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al += 0x60;
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status.carry = 1;
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} else {
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status.carry = 0;
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}
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status.sign = al & 0x80;
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status.zero = status.parity = al;
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}
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inline void das(uint8_t &al, Status &status) {
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/*
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(as modified by https://www.felixcloutier.com/x86/daa ...)
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old_AL ← AL;
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old_CF ← CF;
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CF ← 0;
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IF (((AL AND 0FH) > 9) or AF = 1)
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THEN
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AL ← AL - 6;
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CF ← old_CF OR CarryFromLastAddition; (* CF OR borrow from AL ← AL - 6 *)
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AF ← 1;
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ELSE
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AF ← 0;
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FI;
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IF ((old_AL > 99H) or old_CF = 1)
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THEN
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AL ← AL - 60H;
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CF ← 1;
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ELSE
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CF ← 0;
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FI;
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*/
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/*
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The CF and AF flags are set if the adjustment of the value results in a
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decimal carry in either digit of the result (see the “Operation” section above).
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The SF, ZF, and PF flags are set according to the result. The OF flag is undefined.
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*/
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const uint8_t old_al = al;
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const auto old_carry = status.carry;
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status.carry = 0;
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if((al & 0x0f) > 0x09 || status.auxiliary_carry) {
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status.carry = old_carry | (al < 0x06);
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al -= 0x06;
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status.auxiliary_carry = 1;
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} else {
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status.auxiliary_carry = 0;
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}
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if(old_al > 0x99 || old_carry) {
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al -= 0x60;
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status.carry = 1;
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} else {
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status.carry = 0;
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}
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status.sign = al & 0x80;
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status.zero = status.parity = al;
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}
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template <typename IntT>
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void adc(IntT &destination, IntT source, Status &status) {
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/*
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DEST ← DEST + SRC + CF;
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*/
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/*
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The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
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*/
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const IntT result = destination + source + status.carry_bit<IntT>();
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status.carry = Numeric::carried_out<true, bit_size<IntT>() - 1>(destination, source, result);
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status.auxiliary_carry = Numeric::carried_in<true, 4>(destination, source, result);
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status.sign = result & top_bit<IntT>();
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status.zero = status.parity = result;
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status.overflow = overflow<true, IntT>(destination, source, result);
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destination = result;
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}
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template <typename IntT>
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void add(IntT &destination, IntT source, Status &status) {
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/*
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DEST ← DEST + SRC;
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*/
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/*
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The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
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*/
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const IntT result = destination + source;
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status.carry = Numeric::carried_out<true, bit_size<IntT>() - 1>(destination, source, result);
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status.auxiliary_carry = Numeric::carried_in<true, 4>(destination, source, result);
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status.sign = result & top_bit<IntT>();
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status.zero = status.parity = result;
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status.overflow = overflow<true, IntT>(destination, source, result);
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destination = result;
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}
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template <typename IntT>
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void sbb(IntT &destination, IntT source, Status &status) {
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/*
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DEST ← DEST - (SRC + CF);
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*/
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/*
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The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
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*/
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const IntT result = destination - source - status.carry_bit<IntT>();
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status.carry = Numeric::carried_out<false, bit_size<IntT>() - 1>(destination, source, result);
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status.auxiliary_carry = Numeric::carried_in<false, 4>(destination, source, result);
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status.sign = result & top_bit<IntT>();
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status.zero = status.parity = result;
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status.overflow = overflow<false, IntT>(destination, source, result);
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destination = result;
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}
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template <typename IntT>
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void sub(IntT &destination, IntT source, Status &status) {
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/*
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DEST ← DEST - SRC;
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*/
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/*
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The OF, SF, ZF, AF, CF, and PF flags are set according to the result.
|
||
*/
|
||
const IntT result = destination - source;
|
||
|
||
status.carry = Numeric::carried_out<false, bit_size<IntT>() - 1>(destination, source, result);
|
||
status.auxiliary_carry = Numeric::carried_in<false, 4>(destination, source, result);
|
||
status.sign = result & top_bit<IntT>();
|
||
status.zero = status.parity = result;
|
||
status.overflow = overflow<false, IntT>(destination, source, result);
|
||
|
||
destination = result;
|
||
}
|
||
|
||
template <typename IntT>
|
||
void and_(IntT &destination, IntT source, Status &status) {
|
||
/*
|
||
DEST ← DEST AND SRC;
|
||
*/
|
||
/*
|
||
The OF and CF flags are cleared; the SF, ZF, and PF flags are set according to the result.
|
||
The state of the AF flag is undefined.
|
||
*/
|
||
destination &= source;
|
||
|
||
status.overflow = 0;
|
||
status.carry = 0;
|
||
status.sign = destination & top_bit<IntT>();
|
||
status.zero = status.parity = destination;
|
||
}
|
||
|
||
template <typename IntT, typename RegistersT, typename FlowControllerT>
|
||
inline void call_relative(IntT offset, RegistersT ®isters, FlowControllerT &flow_controller) {
|
||
flow_controller.call(registers.ip() + offset);
|
||
}
|
||
|
||
template <typename IntT, typename FlowControllerT>
|
||
inline void call_absolute(IntT target, FlowControllerT &flow_controller) {
|
||
flow_controller.call(target);
|
||
}
|
||
|
||
template <Model model, typename InstructionT, typename FlowControllerT, typename RegistersT, typename MemoryT>
|
||
void call_far(InstructionT &instruction,
|
||
FlowControllerT &flow_controller,
|
||
RegistersT ®isters,
|
||
MemoryT &memory) {
|
||
|
||
// TODO: eliminate 16-bit assumption below.
|
||
uint16_t source_address = 0;
|
||
auto pointer = instruction.destination();
|
||
switch(pointer.template source<false>()) {
|
||
default:
|
||
case Source::Immediate: flow_controller.call(instruction.segment(), instruction.offset()); return;
|
||
|
||
case Source::Indirect:
|
||
source_address = address<model, Source::Indirect, uint16_t>(instruction, pointer, registers, memory);
|
||
break;
|
||
case Source::IndirectNoBase:
|
||
source_address = address<model, Source::IndirectNoBase, uint16_t>(instruction, pointer, registers, memory);
|
||
break;
|
||
case Source::DirectAddress:
|
||
source_address = address<model, Source::DirectAddress, uint16_t>(instruction, pointer, registers, memory);
|
||
break;
|
||
}
|
||
|
||
const Source source_segment = pointer.segment(instruction.segment_override());
|
||
|
||
const uint16_t offset = memory.template access<uint16_t>(source_segment, source_address);
|
||
source_address += 2;
|
||
const uint16_t segment = memory.template access<uint16_t>(source_segment, source_address);
|
||
flow_controller.call(segment, offset);
|
||
}
|
||
|
||
template <typename IntT>
|
||
void cbw(IntT &ax) {
|
||
constexpr IntT test_bit = 1 << (sizeof(IntT) * 4 - 1);
|
||
constexpr IntT low_half = (1 << (sizeof(IntT) * 4)) - 1;
|
||
|
||
if(ax & test_bit) {
|
||
ax |= ~low_half;
|
||
} else {
|
||
ax &= low_half;
|
||
}
|
||
}
|
||
|
||
template <typename IntT>
|
||
void cwd(IntT &dx, IntT ax) {
|
||
dx = ax & top_bit<IntT>() ? IntT(~0) : IntT(0);
|
||
}
|
||
|
||
inline void clc(Status &status) { status.carry = 0; }
|
||
inline void cld(Status &status) { status.direction = 0; }
|
||
inline void cli(Status &status) { status.interrupt = 0; } // TODO: quite a bit more in protected mode.
|
||
inline void cmc(Status &status) { status.carry = !status.carry; }
|
||
|
||
}
|
||
|
||
template <
|
||
Model model,
|
||
DataSize data_size,
|
||
typename InstructionT,
|
||
typename FlowControllerT,
|
||
typename RegistersT,
|
||
typename MemoryT,
|
||
typename IOT
|
||
> void perform(
|
||
const InstructionT &instruction,
|
||
Status &status,
|
||
FlowControllerT &flow_controller,
|
||
RegistersT ®isters,
|
||
MemoryT &memory,
|
||
[[maybe_unused]] IOT &io
|
||
) {
|
||
using IntT = typename DataSizeType<data_size>::type;
|
||
using AddressT = typename AddressT<is_32bit(model)>::type;
|
||
|
||
// Establish source() and destination() shorthand to fetch data if necessary.
|
||
IntT immediate;
|
||
auto source = [&]() -> IntT& {
|
||
return *resolve<model, IntT>(
|
||
instruction,
|
||
instruction.source().template source<false>(),
|
||
instruction.source(),
|
||
registers,
|
||
memory,
|
||
nullptr,
|
||
&immediate);
|
||
};
|
||
auto destination = [&]() -> IntT& {
|
||
return *resolve<model, IntT>(
|
||
instruction,
|
||
instruction.destination().template source<false>(),
|
||
instruction.destination(),
|
||
registers,
|
||
memory,
|
||
nullptr,
|
||
&immediate);
|
||
};
|
||
|
||
// Guide to the below:
|
||
//
|
||
// * use hard-coded register names where appropriate;
|
||
// * return directly if there is definitely no possible write back to RAM;
|
||
// * otherwise use the source() and destination() lambdas, and break in order to allow a writeback if necessary.
|
||
switch(instruction.operation) {
|
||
default:
|
||
assert(false);
|
||
|
||
case Operation::AAA: Primitive::aaa(registers.axp(), status); return;
|
||
case Operation::AAD: Primitive::aad(registers.axp(), instruction.operand(), status); return;
|
||
case Operation::AAM: Primitive::aam(registers.axp(), instruction.operand(), status, flow_controller); return;
|
||
case Operation::AAS: Primitive::aas(registers.axp(), status); return;
|
||
case Operation::DAA: Primitive::daa(registers.al(), status); return;
|
||
case Operation::DAS: Primitive::das(registers.al(), status); return;
|
||
|
||
case Operation::CBW:
|
||
if constexpr (data_size == DataSize::Word) {
|
||
Primitive::cbw(registers.ax());
|
||
} else if constexpr (is_32bit(model) && data_size == DataSize::DWord) {
|
||
Primitive::cbw(registers.eax());
|
||
}
|
||
return;
|
||
case Operation::CWD:
|
||
if constexpr (data_size == DataSize::Word) {
|
||
Primitive::cwd(registers.dx(), registers.ax());
|
||
} else if constexpr (is_32bit(model) && data_size == DataSize::DWord) {
|
||
Primitive::cwd(registers.edx(), registers.eax());
|
||
}
|
||
return;
|
||
|
||
case Operation::ESC:
|
||
case Operation::NOP: return;
|
||
|
||
case Operation::HLT: flow_controller.halt(); return;
|
||
case Operation::WAIT: flow_controller.wait(); return;
|
||
|
||
case Operation::ADC: Primitive::adc(destination(), source(), status); break;
|
||
case Operation::ADD: Primitive::add(destination(), source(), status); break;
|
||
case Operation::SBB: Primitive::sbb(destination(), source(), status); break;
|
||
case Operation::SUB: Primitive::sub(destination(), source(), status); break;
|
||
|
||
case Operation::AND: Primitive::and_(destination(), source(), status); break;
|
||
|
||
case Operation::CALLrel:
|
||
Primitive::call_relative(instruction.displacement(), registers, flow_controller);
|
||
return;
|
||
case Operation::CALLabs:
|
||
Primitive::call_absolute(destination(), flow_controller);
|
||
return;
|
||
case Operation::CALLfar:
|
||
Primitive::call_far<model>(instruction, flow_controller, registers, memory);
|
||
return;
|
||
|
||
case Operation::CLC: Primitive::clc(status); return;
|
||
case Operation::CLD: Primitive::cld(status); return;
|
||
case Operation::CLI: Primitive::cli(status); return;
|
||
case Operation::CMC: Primitive::cmc(status); return;
|
||
}
|
||
|
||
// Write to memory if required to complete this operation.
|
||
memory.template write_back<IntT>();
|
||
}
|
||
|
||
template <
|
||
Model model,
|
||
typename InstructionT,
|
||
typename FlowControllerT,
|
||
typename RegistersT,
|
||
typename MemoryT,
|
||
typename IOT
|
||
> void perform(
|
||
const InstructionT &instruction,
|
||
Status &status,
|
||
FlowControllerT &flow_controller,
|
||
RegistersT ®isters,
|
||
MemoryT &memory,
|
||
IOT &io
|
||
) {
|
||
// Dispatch to a function just like this that is specialised on data size.
|
||
// Fetching will occur in that specialised function, per the overlapping
|
||
// meaning of register names.
|
||
switch(instruction.operation_size()) {
|
||
case DataSize::Byte:
|
||
perform<model, DataSize::Byte>(instruction, status, flow_controller, registers, memory, io);
|
||
break;
|
||
case DataSize::Word:
|
||
perform<model, DataSize::Word>(instruction, status, flow_controller, registers, memory, io);
|
||
break;
|
||
case DataSize::DWord:
|
||
perform<model, DataSize::DWord>(instruction, status, flow_controller, registers, memory, io);
|
||
break;
|
||
case DataSize::None:
|
||
perform<model, DataSize::None>(instruction, status, flow_controller, registers, memory, io);
|
||
break;
|
||
}
|
||
}
|
||
|
||
}
|
||
|
||
#endif /* PerformImplementation_h */
|