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Implement Missing JMP and LDA Instructions

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Palindromic Bread Loaf
2025-07-23 20:46:53 -04:00
parent 1f9051a60d
commit 211e243fc5
2 changed files with 125 additions and 15 deletions
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135
src/cpu.cpp
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@@ -407,10 +407,11 @@ void CPU::ExecuteInstruction() {
case 0x53: EOR_StackRelativeIndirectY(); break; // EOR ($nn,S),Y
// JMP - Jump to an Address
case 0x4C: JMP_Absolute(); break; // JMP $nnnn
case 0x6C: JMP_AbsoluteIndirect(); break; // JMP ($nnnn)
case 0x5C: JMP_AbsoluteLong(); break; // JMP $nnnnnn
case 0x7C: JMP_AbsoluteIndirectX(); break; // JMP ($nnnn,X)
case 0x4C: JMP_Absolute(); break; // JMP $nnnn
case 0x6C: JMP_AbsoluteIndirect(); break; // JMP ($nnnn)
case 0x5C: JMP_AbsoluteLong(); break; // JMP $nnnnnn
case 0x7C: JMP_AbsoluteIndirectX(); break; // JMP ($nnnn,X)
case 0xDC: JMP_AbsoluteIndirectLong(); break; // JMP [addr]
// Subroutine instructions
case 0x20: JSR_Absolute(); break; // JSR $nnnn
@@ -436,17 +437,21 @@ void CPU::ExecuteInstruction() {
case 0xEA: NOP(); break; //NOP
// LDA - Load Accumulator
case 0xA9: LDA_Immediate(); break; // LDA #$nn or #$nnnn
case 0xAD: LDA_Absolute(); break; // LDA $nnnn
case 0xBD: LDA_AbsoluteX(); break; // LDA $nnnn,X
case 0xB9: LDA_AbsoluteY(); break; // LDA $nnnn,Y
case 0xA5: LDA_DirectPage(); break; // LDA $nn
case 0xB5: LDA_DirectPageX(); break; // LDA $nn,X
case 0xB2: LDA_IndirectDirectPage(); break; // LDA ($nn)
case 0xB1: LDA_IndirectDirectPageY(); break; // LDA ($nn),Y
case 0xA1: LDA_DirectPageIndirectX(); break; // LDA ($nn,X)
case 0xAF: LDA_Long(); break; // LDA $nnnnnn
case 0xBF: LDA_LongX(); break; // LDA $nnnnnn,X
case 0xA9: LDA_Immediate(); break; // LDA #$nn or #$nnnn
case 0xAD: LDA_Absolute(); break; // LDA $nnnn
case 0xBD: LDA_AbsoluteX(); break; // LDA $nnnn,X
case 0xB9: LDA_AbsoluteY(); break; // LDA $nnnn,Y
case 0xA5: LDA_DirectPage(); break; // LDA $nn
case 0xB5: LDA_DirectPageX(); break; // LDA $nn,X
case 0xB2: LDA_IndirectDirectPage(); break; // LDA ($nn)
case 0xB1: LDA_IndirectDirectPageY(); break; // LDA ($nn),Y
case 0xA1: LDA_DirectPageIndirectX(); break; // LDA ($nn,X)
case 0xAF: LDA_Long(); break; // LDA $nnnnnn
case 0xBF: LDA_LongX(); break; // LDA $nnnnnn,X
case 0xA3: LDA_StackRelative(); break; // LDA sr,S
case 0xA7: LDA_IndirectDirectPageLong(); break; // LDA [dp]
case 0xB3: LDA_StackRelativeIndirectY(); break; // LDA (sr,S),Y
case 0xB7: LDA_IndirectDirectPageLongY(); break; // LDA [dp],Y
// LDX - Load X Register
case 0xA2: LDX_Immediate(); break; // LDX #$nn or LDX #$nnnn
@@ -3223,4 +3228,104 @@ void CPU::EOR_StackRelativeIndirectY() {
UpdateNZ16(A);
cycles += 8;
}
}
void CPU::JMP_AbsoluteIndirectLong() {
const uint16_t pointer_address = ReadWord(PC);
PC += 2;
const uint32_t target_address = ReadByte(pointer_address) |
(ReadByte(pointer_address + 1) << 8) |
(ReadByte(pointer_address + 2) << 16);
PC = target_address & 0xFFFF;
PB = (target_address >> 16) & 0xFF;
cycles += 6;
}
void CPU::LDA_StackRelative() {
const uint8_t offset = ReadByte(PC++);
const uint32_t address = SP + offset;
if (P & FLAG_M) { // 8-bit mode
const uint8_t value = ReadByte(address);
A = (A & 0xFF00) | value;
UpdateNZ8(value);
cycles += 4;
} else { // 16-bit mode
const uint16_t value = ReadWord(address);
A = value;
UpdateNZ16(value);
cycles += 5;
}
}
void CPU::LDA_IndirectDirectPageLong() {
const uint8_t offset = ReadByte(PC++);
const uint32_t pointer_address = D + offset;
const uint32_t full_address = ReadByte(pointer_address) |
(ReadByte(pointer_address + 1) << 8) |
(ReadByte(pointer_address + 2) << 16);
if (P & FLAG_M) { // 8-bit mode
const uint8_t value = ReadByte(full_address);
A = (A & 0xFF00) | value;
UpdateNZ8(value);
cycles += 6;
if (D & 0xFF) cycles++;
} else { // 16-bit mode
const uint16_t value = ReadWord(full_address);
A = value;
UpdateNZ16(value);
cycles += 7;
if (D & 0xFF) cycles++;
}
}
void CPU::LDA_StackRelativeIndirectY() {
const uint8_t offset = ReadByte(PC++);
const uint32_t pointer_address = SP + offset;
const uint16_t base_address = ReadWord(pointer_address);
const uint32_t full_address = (DB << 16) | (base_address + Y);
if (P & FLAG_M) { // 8-bit mode
const uint8_t value = ReadByte(full_address);
A = (A & 0xFF00) | value;
UpdateNZ8(value);
cycles += 7;
} else { // 16-bit mode
const uint16_t value = ReadWord(full_address);
A = value;
UpdateNZ16(value);
cycles += 8;
}
}
void CPU::LDA_IndirectDirectPageLongY() {
const uint8_t offset = ReadByte(PC++);
const uint32_t pointer_address = D + offset;
const uint32_t base_address = ReadByte(pointer_address) |
(ReadByte(pointer_address + 1) << 8) |
(ReadByte(pointer_address + 2) << 16);
const uint32_t full_address = base_address + Y;
if (P & FLAG_M) { // 8-bit mode
const uint8_t value = ReadByte(full_address);
A = (A & 0xFF00) | value;
UpdateNZ8(value);
cycles += 6;
if (D & 0xFF) cycles++;
} else { // 16-bit mode
const uint16_t value = ReadWord(full_address);
A = value;
UpdateNZ16(value);
cycles += 7;
if (D & 0xFF) cycles++;
}
}