EightBit/inc/IntelProcessor.h

120 lines
2.4 KiB
C
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#pragma once
#include "Processor.h"
namespace EightBit {
class IntelProcessor : public Processor
{
public:
register16_t& MEMPTR() { return m_memptr; }
virtual void initialise();
protected:
IntelProcessor(Memory& memory);
std::array<bool, 8> m_halfCarryTableAdd = { { false, false, true, false, true, false, true, true } };
std::array<bool, 8> m_halfCarryTableSub = { { false, true, true, true, false, false, false, true } };
int buildHalfCarryIndex(uint8_t before, uint8_t value, int calculation) {
return ((before & 0x88) >> 1) | ((value & 0x88) >> 2) | ((calculation & 0x88) >> 3);
}
bool calculateHalfCarryAdd(uint8_t before, uint8_t value, int calculation) {
auto index = buildHalfCarryIndex(before, value, calculation);
return m_halfCarryTableAdd[index & Mask3];
}
bool calculateHalfCarrySub(uint8_t before, uint8_t value, int calculation) {
auto index = buildHalfCarryIndex(before, value, calculation);
return m_halfCarryTableSub[index & Mask3];
}
void push(uint8_t value);
void pushWord(register16_t value);
uint8_t pop();
void popWord(register16_t& output);
void fetchWord() {
Processor::fetchWord(MEMPTR());
}
//
uint8_t& memptrReference() {
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m_memory.ADDRESS() = MEMPTR();
MEMPTR().word++;
return m_memory.reference();
}
void getWordViaMemptr(register16_t& value) {
value.low = memptrReference();
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m_memory.ADDRESS().word++;
value.high = m_memory.reference();
}
void setWordViaMemptr(register16_t value) {
memptrReference() = value.low;
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m_memory.ADDRESS().word++;
m_memory.reference() = value.high;
}
//
void jump() {
pc = MEMPTR();
}
void call() {
pushWord(pc);
jump();
}
void restart(uint8_t address) {
MEMPTR().low = address;
MEMPTR().high = 0;
call();
}
bool callConditional(int condition) {
fetchWord();
if (condition)
call();
return condition != 0;
}
bool jumpConditional(int conditional) {
fetchWord();
if (conditional)
jump();
return conditional != 0;
}
void ret() {
popWord(MEMPTR());
jump();
}
bool returnConditional(int condition) {
if (condition)
ret();
return condition != 0;
}
void jr(int8_t offset) {
MEMPTR().word = pc.word + offset;
jump();
}
bool jrConditional(int conditional) {
auto offset = fetchByte();
if (conditional)
jr(offset);
return conditional != 0;
}
private:
register16_t m_memptr;
};
}