mirror of
https://github.com/zoriya/ComSquare.git
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98 lines
2.3 KiB
C++
98 lines
2.3 KiB
C++
//
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// Created by anonymus-raccoon on 2/20/20.
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//
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#include <iostream>
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#include "../../Models/Int24.hpp"
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#include "../CPU.hpp"
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namespace ComSquare::CPU
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{
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int CPU::TSB(uint24_t valueAddr, AddressingMode mode)
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{
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uint16_t value = this->_bus->read(valueAddr);
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if (!this->_registers.p.m)
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value += this->_bus->read(valueAddr + 1) << 8u;
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value |= this->_registers.a;
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this->_bus->write(valueAddr, value);
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if (!this->_registers.p.m)
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this->_bus->write(valueAddr + 1, value >> 8u);
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this->_registers.p.z = value == 0;
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int cycles = 0;
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if (!this->_registers.p.m)
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cycles += 2;
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if (mode == DirectPage)
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cycles += this->_registers.dl != 0;
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return cycles;
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}
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int CPU::BIT(uint24_t valueAddr, AddressingMode mode)
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{
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unsigned negativeMask = this->_registers.p.m ? 0x80u : 0x8000u;
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unsigned value = this->_bus->read(valueAddr);
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if (!this->_registers.p.m)
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value += this->_bus->read(valueAddr + 1) << 8u;
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if (mode != ImmediateForA) {
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this->_registers.p.n = value & negativeMask;
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this->_registers.p.v = value & (negativeMask >> 1u);
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}
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this->_registers.p.z = (value & this->_registers.a) == 0;
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int cycles = !this->_registers.p.m;
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switch (mode) {
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case DirectPage:
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case DirectPageIndexedByX:
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cycles += this->_registers.dl != 0;
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break;
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case AbsoluteIndexedByX:
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cycles += this->_hasIndexCrossedPageBoundary;
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break;
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default:
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break;
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}
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return cycles;
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}
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int CPU::ASL(uint24_t valueAddr, AddressingMode mode)
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{
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unsigned highByte = this->_registers.p.m ? 0x80u : 0x8000u;
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if (mode == Implied) {
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this->_registers.a <<= 1u;
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this->_registers.p.n = this->_registers.a & highByte;
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this->_registers.p.z = this->_registers.a == 0;
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return 0;
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}
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uint16_t value = this->_bus->read(valueAddr);
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if (!this->_registers.p.m)
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value += this->_bus->read(valueAddr + 1) << 8u;
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this->_registers.p.c = value & highByte;
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value <<= 1u;
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this->_bus->write(valueAddr, value);
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if (!this->_registers.p.m)
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this->_bus->write(valueAddr + 1, value >> 8u);
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this->_registers.p.n = value & highByte;
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this->_registers.p.z = value == 0;
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int cycles = 2 * !this->_registers.p.m;
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switch (mode) {
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case DirectPage:
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case DirectPageIndexedByX:
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cycles += this->_registers.dl != 0;
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break;
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case AbsoluteIndexedByX:
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cycles += this->_hasIndexCrossedPageBoundary;
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break;
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default:
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break;
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}
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return cycles;
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}
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} |