533 lines
30 KiB
C++
533 lines
30 KiB
C++
#include "6502m.h"
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#include "mem.h"
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// P register Flags
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#define fC 0b00000001 // Carry
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#define fZ 0b00000010 // Zero
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#define fI 0b00000100 // Interrupt disable
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#define fD 0b00001000 // Decimal
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#define fB 0b00010000 // Interrupt type?
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#define f1 0b00100000 // -Unused-
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#define fV 0b01000000 // Overflow
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#define fN 0b10000000 // Negative
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namespace m6502
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{
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uint8_t interrupt_vector = 0xfe;
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uint8_t regs[13];
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uint8_t *_rA = ®s[0];
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uint8_t *_rX = ®s[1];
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uint8_t *_rY = ®s[2];
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uint8_t *_rS = ®s[3];
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uint8_t *_rP = ®s[4];
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uint8_t *_rPC_lo = ®s[5];
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uint8_t *_rPC_hi = ®s[6];
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uint16_t *_rPC = (uint16_t*)®s[5];
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uint8_t *_rB = ®s[7];
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uint8_t *_rT = ®s[8];
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uint8_t *_rI = ®s[9];
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uint8_t *_rAD_lo = ®s[10];
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uint8_t *_rAD_hi = ®s[11];
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uint16_t *_rAD = (uint16_t*)®s[10];
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uint8_t *_rTEMP_lo = ®s[12];
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uint8_t *_rTEMP_hi = ®s[13];
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uint16_t *_rTEMP = (uint16_t*)®s[12];
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#define rA (*_rA)
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#define rX (*_rX)
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#define rY (*_rY)
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#define rS (*_rS)
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#define rP (*_rP)
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#define rPC_lo (*_rPC_lo)
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#define rPC_hi (*_rPC_hi)
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#define rPC (*_rPC)
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#define rB (*_rB)
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#define rT (*_rT)
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#define rI (*_rI)
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#define rAD_lo (*_rAD_lo)
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#define rAD_hi (*_rAD_hi)
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#define rAD (*_rAD)
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#define rTEMP_lo (*_rTEMP_lo)
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#define rTEMP_hi (*_rTEMP_hi)
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#define rTEMP (*_rTEMP)
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uint8_t microcode[256];
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uint8_t microcode_pos = 0;
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uint8_t microcode_last = 0;
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enum microInstructions {
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miFetchOpcode,
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miFakeFetchOperand,
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miFetchOperandLo,
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miFetchOperandHi,
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miFetchOperandHiAndIndexX,
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miFetchOperandHiAndIndexY,
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miPushPCHi,
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miPushPCLo,
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miPushP,
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miPCLoInt,
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miPCHiInt,
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miIndexX,
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miFetchAddressLo,
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miFetchAddressHi,
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miFetchAddressHiAndIndex,
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miReadAddress,
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miReadAddressAndSkip,
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miWriteRegister,
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miWriteAddress,
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miPushA,
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miFetchOperandAndCheckBranch,
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miCheckIfPageCrossed,
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miPullPCHi,
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miPullPCLo,
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miPullP,
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miPullA,
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miIncrementPC,
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miFetchAddressHiToPC,
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miIndexY,
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miNumMicroinstructions
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};
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uint8_t instructions[256][7] = {
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/* 0x00 BRK */ { miFetchOperandLo, miPushPCHi, miPushPCLo, miPushP, miPCLoInt, miPCHiInt, miFetchOpcode },
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/* 0x01 ORA X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0x02 --- */ { miFetchOpcode },
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/* 0x03 --- */ { miFetchOpcode },
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/* 0x04 --- */ { miFetchOpcode },
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/* 0x05 ORA zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0x06 ASL zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x07 --- */ { miFetchOpcode },
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/* 0x08 PHP */ { miFetchOperandLo, miPushP, miFetchOpcode },
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/* 0x09 ORA imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0x0A ASL A */ { miFakeFetchOperand, miFetchOpcode },
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/* 0x0B --- */ { miFetchOpcode },
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/* 0x0C --- */ { miFetchOpcode },
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/* 0x0D ORA abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0x0E ASL abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x0F --- */ { miFetchOpcode },
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/* 0x10 BPL */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0x11 ORA ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x12 --- */ { miFetchOpcode },
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/* 0x13 --- */ { miFetchOpcode },
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/* 0x14 --- */ { miFetchOpcode },
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/* 0x15 ORA zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0x16 ASL zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x17 --- */ { miFetchOpcode },
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/* 0x18 CLC */ { miFetchOperandLo, miFetchOpcode },
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/* 0x19 ORA abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x1A --- */ { miFetchOpcode },
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/* 0x1B --- */ { miFetchOpcode },
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/* 0x1C --- */ { miFetchOpcode },
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/* 0x1D ORA abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x1E ASL abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x1F --- */ { miFetchOpcode },
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/* 0x20 JSR abs */ { miFetchAddressLo, miFakeFetchOperand, miPushPCHi, miPushPCLo, miFetchAddressHi, miFetchOpcode },
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/* 0x21 AND X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0x22 --- */ { miFetchOpcode },
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/* 0x23 --- */ { miFetchOpcode },
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/* 0x24 BIT zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0x25 AND zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0x26 ROL zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x27 --- */ { miFetchOpcode },
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/* 0x28 PLP */ { miFetchOperandLo, miPushP, miFetchOpcode },
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/* 0x29 AND imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0x2A ROL A */ { miFakeFetchOperand, miFetchOpcode },
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/* 0x2B --- */ { miFetchOpcode },
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/* 0x2C BIT abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0x2D AND abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0x2E ROL abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x2F --- */ { miFetchOpcode },
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/* 0x30 BMI */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0x31 AND ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x32 --- */ { miFetchOpcode },
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/* 0x33 --- */ { miFetchOpcode },
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/* 0x34 --- */ { miFetchOpcode },
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/* 0x35 AND zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0x36 ROL zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x37 --- */ { miFetchOpcode },
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/* 0x38 ESC */ { miFetchOperandLo, miFetchOpcode },
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/* 0x39 AND abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x3A --- */ { miFetchOpcode },
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/* 0x3B --- */ { miFetchOpcode },
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/* 0x3C --- */ { miFetchOpcode },
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/* 0x3D AND abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x3E ROL abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x3F --- */ { miFetchOpcode },
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/* 0x40 RTI */ { miFetchOperandLo, miFakeFetchOperand, miPullP, miPullPCLo, miPullPCHi, miFetchOpcode },
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/* 0x41 EOR X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0x42 --- */ { miFetchOpcode },
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/* 0x43 --- */ { miFetchOpcode },
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/* 0x44 --- */ { miFetchOpcode },
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/* 0x45 EOR zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0x46 LSR zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x47 --- */ { miFetchOpcode },
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/* 0x48 PHA */ { miFetchOperandLo, miPushA, miFetchOpcode },
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/* 0x49 EOR imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0x4A LSR A */ { miFakeFetchOperand, miFetchOpcode },
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/* 0x4B --- */ { miFetchOpcode },
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/* 0x4C JMP abs */ { miFetchAddressLo, miFetchAddressHi, miFetchOpcode },
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/* 0x4D EOR abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0x4E LSR abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x4F --- */ { miFetchOpcode },
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/* 0x50 BVC */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0x51 EOR ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x52 --- */ { miFetchOpcode },
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/* 0x53 --- */ { miFetchOpcode },
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/* 0x54 --- */ { miFetchOpcode },
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/* 0x55 EOR zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0x56 LSR zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x57 --- */ { miFetchOpcode },
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/* 0x58 CLI */ { miFetchOperandLo, miFetchOpcode },
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/* 0x59 EOR abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x5A --- */ { miFetchOpcode },
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/* 0x5B --- */ { miFetchOpcode },
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/* 0x5C --- */ { miFetchOpcode },
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/* 0x5D EOR abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x5E LSR abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x5F --- */ { miFetchOpcode },
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/* 0x60 RTS */ { miFetchOperandLo, miFakeFetchOperand, miPullPCLo, miPullPCHi, miIncrementPC, miFetchOpcode },
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/* 0x61 ADC X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0x62 --- */ { miFetchOpcode },
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/* 0x63 --- */ { miFetchOpcode },
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/* 0x64 --- */ { miFetchOpcode },
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/* 0x65 ADC zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0x66 ROR zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x67 --- */ { miFetchOpcode },
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/* 0x68 PLA */ { miFetchOperandLo, miFakeFetchOperand, miPullA, miFetchOpcode },
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/* 0x69 ADC imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0x6A ROR A */ { miFakeFetchOperand, miFetchOpcode },
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/* 0x6B --- */ { miFetchOpcode },
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/* 0x6C JMP ind */ { miFetchOperandLo, miFetchOperandHi, miFetchAddressLo, miFetchAddressHiToPC, miFetchOpcode },
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/* 0x6D ADC abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0x6E ROR abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x6F --- */ { miFetchOpcode },
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/* 0x70 BVS */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0x71 ADC ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x72 --- */ { miFetchOpcode },
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/* 0x73 --- */ { miFetchOpcode },
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/* 0x74 --- */ { miFetchOpcode },
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/* 0x75 ADC zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0x76 ROR zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x77 --- */ { miFetchOpcode },
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/* 0x78 SEI */ { miFetchOperandLo, miFetchOpcode },
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/* 0x79 ADC abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x7A --- */ { miFetchOpcode },
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/* 0x7B --- */ { miFetchOpcode },
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/* 0x7C --- */ { miFetchOpcode },
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/* 0x7D ADC abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0x7E ROR abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0x7F --- */ { miFetchOpcode },
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/* 0x80 --- */ { miFetchOpcode },
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/* 0x81 STA X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miWriteRegister, miFetchOpcode },
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/* 0x82 --- */ { miFetchOpcode },
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/* 0x83 --- */ { miFetchOpcode },
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/* 0x84 STY zpg */ { miFetchOperandLo, miWriteRegister, miFetchOpcode },
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/* 0x85 STA zpg */ { miFetchOperandLo, miWriteRegister, miFetchOpcode },
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/* 0x86 STX zpg */ { miFetchOperandLo, miWriteRegister, miFetchOpcode },
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/* 0x87 --- */ { miFetchOpcode },
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/* 0x88 DEY */ { miFetchOperandLo, miFetchOpcode },
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/* 0x89 --- */ { miFetchOpcode },
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/* 0x8A TXA */ { miFetchOperandLo, miFetchOpcode },
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/* 0x8B --- */ { miFetchOpcode },
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/* 0x8C STY abs */ { miFetchOperandLo, miFetchOperandHi, miWriteRegister, miFetchOpcode },
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/* 0x8D STA abs */ { miFetchOperandLo, miFetchOperandHi, miWriteRegister, miFetchOpcode },
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/* 0x8E STX abs */ { miFetchOperandLo, miFetchOperandHi, miWriteRegister, miFetchOpcode },
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/* 0x8F --- */ { miFetchOpcode },
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/* 0x90 BCC */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0x91 STA ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddress, miWriteRegister, miFetchOpcode },
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/* 0x92 --- */ { miFetchOpcode },
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/* 0x93 --- */ { miFetchOpcode },
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/* 0x94 STY zpg,X */ { miFetchOperandLo, miIndexX, miWriteRegister, miFetchOpcode },
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/* 0x95 STA zpg,X */ { miFetchOperandLo, miIndexX, miWriteRegister, miFetchOpcode },
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/* 0x96 STX zpg,X */ { miFetchOperandLo, miIndexX, miWriteRegister, miFetchOpcode },
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/* 0x97 --- */ { miFetchOpcode },
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/* 0x98 TYA */ { miFetchOperandLo, miFetchOpcode },
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/* 0x99 STA abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddress, miWriteRegister, miFetchOpcode },
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/* 0x9A TXS */ { miFetchOperandLo, miFetchOpcode },
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/* 0x9B --- */ { miFetchOpcode },
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/* 0x9C --- */ { miFetchOpcode },
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/* 0x9D STA abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miWriteRegister, miFetchOpcode },
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/* 0x9E --- */ { miFetchOpcode },
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/* 0x9F --- */ { miFetchOpcode },
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/* 0xA0 LDY imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0xA1 LDA X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0xA2 LDX imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0xA3 --- */ { miFetchOpcode },
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/* 0xA4 LDY zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0xA5 LDA zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0xA6 LDX zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0xA7 --- */ { miFetchOpcode },
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/* 0xA8 TAY */ { miFetchOperandLo, miFetchOpcode },
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/* 0xA9 LDA imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0xAA TAX */ { miFetchOperandLo, miFetchOpcode },
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/* 0xAB --- */ { miFetchOpcode },
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/* 0xAC LDY abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0xAD LDA abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0xAE LDX abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0xAF --- */ { miFetchOpcode },
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/* 0xB0 BCS */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
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/* 0xB1 LDA ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0xB2 --- */ { miFetchOpcode },
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/* 0xB3 --- */ { miFetchOpcode },
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/* 0xB4 LDY zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0xB5 LDA zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
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/* 0xB6 LDX zpg,Y */ { miFetchOperandLo, miIndexY, miReadAddress, miFetchOpcode },
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/* 0xB7 --- */ { miFetchOpcode },
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/* 0xB8 CLV */ { miFetchOperandLo, miFetchOpcode },
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/* 0xB9 LDA abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0xBA TSX */ { miFetchOperandLo, miFetchOpcode },
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/* 0xBB --- */ { miFetchOpcode },
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/* 0xBC LDY abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0xBD LDA abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0xBE LDX abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
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/* 0xBF --- */ { miFetchOpcode },
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/* 0xC0 CPY, imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0xC1 CMP X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
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/* 0xC2 --- */ { miFetchOpcode },
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/* 0xC3 --- */ { miFetchOpcode },
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/* 0xC4 CPY zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0xC5 CMP zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
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/* 0xC6 DEC zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
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/* 0xC7 --- */ { miFetchOpcode },
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/* 0xC8 INY */ { miFetchOperandLo, miFetchOpcode },
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/* 0xC9 CMP imm */ { miFetchOperandLo, miFetchOpcode },
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/* 0xCA DEX */ { miFetchOperandLo, miFetchOpcode },
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/* 0xCB --- */ { miFetchOpcode },
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/* 0xCC CPY abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
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/* 0xCD CMP abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
|
|
/* 0xCE DEC abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xCF --- */ { miFetchOpcode },
|
|
|
|
/* 0xD0 BNE */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
|
|
/* 0xD1 CMP ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xD2 --- */ { miFetchOpcode },
|
|
/* 0xD3 --- */ { miFetchOpcode },
|
|
/* 0xD4 --- */ { miFetchOpcode },
|
|
/* 0xD5 CMP zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
|
|
/* 0xD6 DEC zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xD7 --- */ { miFetchOpcode },
|
|
/* 0xD8 CLD */ { miFetchOperandLo, miFetchOpcode },
|
|
/* 0xD9 CMP abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xDA --- */ { miFetchOpcode },
|
|
/* 0xDB --- */ { miFetchOpcode },
|
|
/* 0xDC --- */ { miFetchOpcode },
|
|
/* 0xDD CMP abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xDE DEC abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xDF --- */ { miFetchOpcode },
|
|
|
|
/* 0xE0 CPX, imm */ { miFetchOperandLo, miFetchOpcode },
|
|
/* 0xE1 SBC X,ind */ { miFetchOperandLo, miIndexX, miFetchAddressLo, miFetchAddressHi, miReadAddress, miFetchOpcode },
|
|
/* 0xE2 --- */ { miFetchOpcode },
|
|
/* 0xE3 --- */ { miFetchOpcode },
|
|
/* 0xE4 CPX zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
|
|
/* 0xE5 SBC zpg */ { miFetchOperandLo, miReadAddress, miFetchOpcode },
|
|
/* 0xE6 INC zpg */ { miFetchOperandLo, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xE7 --- */ { miFetchOpcode },
|
|
/* 0xE8 INX */ { miFetchOperandLo, miFetchOpcode },
|
|
/* 0xE9 SBC imm */ { miFetchOperandLo, miFetchOpcode },
|
|
/* 0xEA NOP */ { miFetchOpcode },
|
|
/* 0xEB --- */ { miFetchOpcode },
|
|
/* 0xEC CPX abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
|
|
/* 0xED SBC abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miFetchOpcode },
|
|
/* 0xEE INC abs */ { miFetchOperandLo, miFetchOperandHi, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xEF --- */ { miFetchOpcode },
|
|
|
|
/* 0xF0 BEQ */ { miFetchOperandAndCheckBranch, miCheckIfPageCrossed, miFakeFetchOperand, miFetchOpcode },
|
|
/* 0xF1 SBC ind,Y */ { miFetchOperandLo, miFetchAddressLo, miFetchAddressHiAndIndex, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xF2 --- */ { miFetchOpcode },
|
|
/* 0xF3 --- */ { miFetchOpcode },
|
|
/* 0xF4 --- */ { miFetchOpcode },
|
|
/* 0xF5 SBC zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miFetchOpcode },
|
|
/* 0xF6 INC zpg,X */ { miFetchOperandLo, miIndexX, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xF7 --- */ { miFetchOpcode },
|
|
/* 0xF8 SED */ { miFetchOperandLo, miFetchOpcode },
|
|
/* 0xF9 SBC abs,Y */ { miFetchOperandLo, miFetchOperandHiAndIndexY, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xFA --- */ { miFetchOpcode },
|
|
/* 0xFB --- */ { miFetchOpcode },
|
|
/* 0xFC --- */ { miFetchOpcode },
|
|
/* 0xFD SBC abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddressAndSkip, miReadAddress, miFetchOpcode },
|
|
/* 0xFE INC abs,X */ { miFetchOperandLo, miFetchOperandHiAndIndexX, miReadAddress, miReadAddress, miWriteAddress, miWriteAddress, miFetchOpcode },
|
|
/* 0xFF --- */ { miFetchOpcode },
|
|
};
|
|
|
|
void SetFlags(uint8_t flags)
|
|
{
|
|
if (flags&fC) rP = ( rP & ~fC ) | ( rTEMP_hi & fC );
|
|
if (flags&fN) rP = ( rP & ~fN ) | ( rTEMP_lo & fN );
|
|
if (flags&fZ) rP = ( rTEMP_lo ? rP & ~fZ : rP | fZ );
|
|
if (flags&fV) rP = ( (rTEMP_lo ^ rA) & (rTEMP_lo ^ rB) & 0x80 ) ? rP | fV : rP & ~fV;
|
|
}
|
|
|
|
void DoOpcodeWork()
|
|
{
|
|
if (rI==0xCA) { rX--; rB = rX; SetFlags(fN|fZ); return; } /* DEX */
|
|
if (rI==0x88) { rY--; rB = rY; SetFlags(fN|fZ); return; } /* DEY */
|
|
if (rI==0xE8) { rX++; rB = rX; SetFlags(fN|fZ); return; } /* INX */
|
|
if (rI==0xC8) { rY++; rB = rY; SetFlags(fN|fZ); return; } /* INY */
|
|
|
|
if (rI==0xA8) { rY = rA; rB = rY; SetFlags(fN|fZ); return; } /* TAY */
|
|
if (rI==0x98) { rA = rY; rB = rA; SetFlags(fN|fZ); return; } /* TYA */
|
|
if (rI==0xAA) { rX = rA; rB = rX; SetFlags(fN|fZ); return; } /* TAX */
|
|
if (rI==0x8A) { rA = rX; rB = rA; SetFlags(fN|fZ); return; } /* TXA */
|
|
if (rI==0xBA) { rX = rS; rB = rX; SetFlags(fN|fZ); return; } /* TSX */
|
|
if (rI==0x9A) { rS = rX; rB = rS; SetFlags(fN|fZ); return; } /* TXS */
|
|
|
|
switch (rI&0x03) {
|
|
case 0: /* Clear/set flags*/
|
|
if ( (rI&0x1c)==0x18 ) {
|
|
switch (rI>>5) {
|
|
case 0: rP &= ~fC; break;
|
|
case 1: rP |= fC; break;
|
|
case 2: rP &= ~fI; break;
|
|
case 3: rP |= fI; break;
|
|
case 5: rP &= ~fV; break;
|
|
case 6: rP &= ~fD; break;
|
|
case 7: rP |= fD; break;
|
|
}
|
|
} else if ( ((rI>>5)==5) && (rI!=0xB0) ) {
|
|
/* LDY */ rTEMP_lo = rB; SetFlags(fN|fZ); rY = rTEMP_lo; break;
|
|
} else if ( ((rI&0xD3)==0xC0) && (((rI>>2)&3)!=2) ) {
|
|
if ( (rI&0xf0)==0xC0 ) {
|
|
/* CPY */ rTEMP = rY + ~rB; SetFlags(fN|fZ|fC); break;
|
|
} else {
|
|
/* CPX */ rTEMP = rX + ~rB; SetFlags(fN|fZ|fC); break;
|
|
}
|
|
}
|
|
break;
|
|
case 1: /* ALU */
|
|
switch ((rI>>5)&0x07) {
|
|
case 0: /* ORA */ rTEMP_lo = rA | rB; SetFlags(fN|fZ); rA = rTEMP_lo; break;
|
|
case 1: /* AND */ rTEMP_lo = rA & rB; SetFlags(fN|fZ); rA = rTEMP_lo; break;
|
|
case 2: /* EOR */ rTEMP_lo = rA ^ rB; SetFlags(fN|fZ); rA = rTEMP_lo; break;
|
|
case 3: /* ADC */ rTEMP = rA + rB + fC; SetFlags(fN|fV|fZ|fC); rA = rTEMP_lo; break;
|
|
case 5: /* LDA */ rTEMP_lo = rB; SetFlags(fN|fZ); rA = rTEMP_lo; break;
|
|
case 6: /* CMP */ rTEMP = rA + ~rB; SetFlags(fN|fZ|fC); break;
|
|
case 7: /* SBC */ rTEMP = rA + ~rB + fC; SetFlags(fN|fV|fZ|fC); rA = rTEMP_lo; break;
|
|
};
|
|
if ( (rI==0x24) || (rI==0x2C) ) /* BIT */ { rTEMP_lo = rA & rB; rP = (rP&~(fN|fV)) | (rB&(fN|fV)); SetFlags(fZ); }
|
|
break;
|
|
case 2:
|
|
if ( ((rI>>5)==5) ) {
|
|
/* LDX */ rTEMP_lo = rB; SetFlags(fN|fZ); rX = rTEMP_lo; break;
|
|
}
|
|
break;
|
|
|
|
};
|
|
}
|
|
|
|
void DoRMW()
|
|
{
|
|
switch (rI&0x03) {
|
|
case 2: /* RMW */
|
|
if ((rI & 0xF)==0xA) rB = rA;
|
|
switch ((rI>>5)&0x07) {
|
|
case 0: /* ASL */ rP = ( rP & ~fC ) | ( (rB & 0x80)>>7 ); rB = rB << 1; SetFlags(fN|fZ); break;
|
|
case 1: /* ROL */ rT = rP & fC; rP = ( rP & ~fC ) | ( (rB & 0x80)>>7 ); rB = (rB << 1) | rT; SetFlags(fN|fZ); break;
|
|
case 2: /* LSR */ rP = ( rP & ~fC ) | ( (rB & fC) ); rB = rB >> 1; SetFlags(fN|fZ); break;
|
|
case 3: /* ROR */ rT = (rP & fC) << 7; rP = ( rP & ~fC ) | ( (rB & fC) ); rB = (rB >> 1) | rT; SetFlags(fN|fZ); break;
|
|
case 6: /* DEC */ rB--; SetFlags(fN|fZ); break;
|
|
case 7: /* INC */ rB++; SetFlags(fN|fZ); break;
|
|
};
|
|
if ((rI & 0xF)==0xA) rA = rB;
|
|
break;
|
|
};
|
|
}
|
|
|
|
bool BranchCondition()
|
|
{
|
|
const uint8_t flags[4] = {fN, fV, fC, fZ};
|
|
const uint8_t flag = flags[rI>>6];
|
|
const bool condition = (rI>>5)&1;
|
|
return (rP & flag) == condition;
|
|
}
|
|
|
|
void InsertFetchOpcode()
|
|
{
|
|
microcode[microcode_pos] = miFetchOpcode;
|
|
microcode_last = microcode_pos+1;
|
|
}
|
|
|
|
void FetchOpcode()
|
|
{
|
|
DoOpcodeWork();
|
|
rI = mem::read(rPC++);
|
|
int i=0; do { microcode[microcode_last++] = instructions[rI][i++]; } while (instructions[rI][i-1] != miFetchOpcode);
|
|
}
|
|
|
|
void FakeFetchOperand() { rAD_lo = mem::read(rPC); }
|
|
void FetchOperandLo() { rTEMP = rAD_lo = rB = mem::read(rPC++); }
|
|
void FetchOperandHi() { rAD_hi = mem::read(rPC++); }
|
|
void FetchOperandHiAndIndexX() { rAD_hi = mem::read(rPC++); rTEMP = rAD_lo + rX; rAD_lo = rTEMP_lo; }
|
|
void FetchOperandHiAndIndexY() { rAD_hi = mem::read(rPC++); rTEMP = rAD_lo + rY; rAD_lo = rTEMP_lo; }
|
|
|
|
void PushPCHi() { mem::write(0x0100+(rS--), rPC_hi); }
|
|
void PushPCLo() { mem::write(0x0100+(rS--), rPC_lo); }
|
|
void PushP() { mem::write(0x0100+(rS--), rP|f1|fB); rP |= fI; }
|
|
void PCLoInt() { rPC_lo = mem::read(0xff00+interrupt_vector); }
|
|
void PCHiInt() { rPC_hi = mem::read(0xff00+interrupt_vector+1); }
|
|
|
|
void IndexX() { rB = mem::read(rAD); rAD_lo += rX; }
|
|
void FetchAddressLo() { rT = mem::read(rAD++); }
|
|
void FetchAddressHi() { rAD_hi = mem::read(rAD); rAD_lo = rT; }
|
|
void FetchAddressHiAndIndex() { rAD_hi = mem::read(rAD); rTEMP = rAD_lo + rY; rAD_lo = rTEMP_lo; }
|
|
void ReadAddress() { rB = mem::read(rAD); rAD_hi += rTEMP_hi; }
|
|
|
|
void ReadAddressAndSkip() { rB = mem::read(rAD); rAD_hi += rTEMP_hi; if (rTEMP_hi) InsertFetchOpcode(); }
|
|
void WriteRegister() { mem::write(rAD, (rI&3)==1 ? rA : (rI&3)==2 ? rX : rY ); }
|
|
void WriteAddress() { mem::write(rAD, rB); DoRMW(); }
|
|
void PushA() { mem::write(0x0100+(rS--), rA); }
|
|
void FetchOperandAndCheckBranch() { FetchOperandLo(); if (!BranchCondition()) InsertFetchOpcode(); else { rT = rPC_hi; rPC = rPC + (int8_t)rB; } }
|
|
|
|
void CheckIfPageCrossed() { FakeFetchOperand(); if (rPC_hi == rT) InsertFetchOpcode(); }
|
|
void PullPCHi() { rPC_hi = mem::read(0x0100+(++rS)); }
|
|
void PullPCLo() { rPC_lo = mem::read(0x0100+(++rS)); }
|
|
void PullP() { rP = mem::read(0x0100+(++rS)); }
|
|
void PullA() { rA = mem::read(0x0100+(++rS)); }
|
|
|
|
void IncrementPC() { rPC++; }
|
|
void FetchAddressHiToPC() { rPC_hi = mem::read(rAD); rPC_lo = rT; }
|
|
void IndexY() { rB = mem::read(rAD); rAD_lo += rY; }
|
|
|
|
void (*microinstructions[miNumMicroinstructions])(void) {
|
|
FetchOpcode, FakeFetchOperand, FetchOperandLo, FetchOperandHi, FetchOperandHiAndIndexX, FetchOperandHiAndIndexY,
|
|
PushPCHi, PushPCLo, PushP, PCLoInt, PCHiInt,
|
|
IndexX, FetchAddressLo, FetchAddressHi, FetchAddressHiAndIndex, ReadAddress,
|
|
ReadAddressAndSkip, WriteRegister, WriteAddress, PushA, FetchOperandAndCheckBranch,
|
|
CheckIfPageCrossed, PullPCHi, PullPCLo, PullP, PullA,
|
|
IncrementPC, FetchAddressHiToPC, IndexY };
|
|
|
|
void reset()
|
|
{
|
|
|
|
}
|
|
|
|
void interrupt(uint8_t type)
|
|
{
|
|
interrupt_vector = type;
|
|
}
|
|
|
|
void tick()
|
|
{
|
|
uint8_t m_inst = microcode[microcode_pos++];
|
|
microinstructions[m_inst]();
|
|
}
|
|
|
|
}
|