disasm.cpp

#include <vector>
#include <stdint.h>
#include <stdio.h>

static constexpr const char opcodes[] = 
	"brkoracoporatsboraaslora"
	"phporaaslphdtsboraaslora"
	"bploraoraoratrboraaslora"
	"clcorainctcstrboraaslora"
	"jsrandjslandbitandroland"
	"plpandrolpldbitandroland"
	"bmiandandandbitandroland"
	"secanddectscbitandroland"
	"rtieorwdmeormvpeorlsreor"
	"phaeorlsrphkjmpeorlsreor"
	"bvceoreoreormvneorlsreor"
	"clieorphytcdjmleorlsreor"
	"rtsadcperadcstzadcroradc"
	"plaadcrorrtljmpadcroradc"
	"bvsadcadcadcstzadcroradc"
	"seiadcplytdcjmpadcroradc"
	"brastabrlstastystastxsta"
	"deybittxaphbstystastxsta"
	"bccstastastastystastxsta"
	"tyastatxstxystzstastzsta"
	"ldyldaldxldaldyldaldxlda"
	"tayldataxplbldyldaldxlda"
	"bcsldaldaldaldyldaldxlda"
	"clvldatsxtyxldyldaldxlda"
	"cpycmprepcmpcpycmpdeccmp"
	"inycmpdexwaicpycmpdeccmp"
	"bnecmpcmpcmppeicmpdeccmp"
	"cldcmpphxstpjmlcmpdeccmp"
	"cpxsbcsepsbccpxsbcincsbc"
	"inxsbcnopxbacpxsbcincsbc"
	"beqsbcsbcsbcpeasbcincsbc"
	"sedsbcplxxcejsrsbcincsbc"
	;

static constexpr const int mImplied =      0x0000;
static constexpr const int mImmediate =    0x1000;
static constexpr const int mAbsolute =     0x2000;
static constexpr const int mAbsoluteI =    0x3000;
static constexpr const int mAbsoluteIL =   0x4000;
static constexpr const int mAbsoluteLong = 0x5000;
static constexpr const int mDP =           0x6000;
static constexpr const int mDPI =          0x7000;
static constexpr const int mDPIL =         0x8000;
static constexpr const int mRelative =     0x9000;
static constexpr const int mBlockMove =    0xa000;

static constexpr const int m_S =          0x0100;
static constexpr const int m_X =          0x0200;
static constexpr const int m_Y =          0x0400;

static constexpr const int m_M =          0x0020;
static constexpr const int m_I =          0x0010;

static constexpr const int modes[] =
{
	1 | mAbsolute,              // 00 brk #imm
	1 | mDPI | m_X,             // 01 ora (dp,x)
	1 | mAbsolute,              // 02 cop #imm
	1 | mDP | m_S,              // 03 ora ,s
	1 | mDP,                    // 04 tsb <dp
	1 | mDP,                    // 05 ora <dp
	1 | mDP,                    // 06 asl <dp
	1 | mDPIL,                  // 07 ora [dp]
	0 | mImplied,               // 08 php
	1 | mImmediate | m_M,       // 09 ora #imm
	0 | mImplied,               // 0a asl a
	0 | mImplied,               // 0b phd
	2 | mAbsolute,              // 0c tsb |abs
	2 | mAbsolute,              // 0d ora |abs
	2 | mAbsolute,              // 0e asl |abs
	3 | mAbsoluteLong,          // 0f ora >abs

	1 | mRelative,              // 10 bpl
	1 | mDPI | m_Y,             // 11 ora (dp),y
	1 | mDPI,                   // 12 ora (dp)
	1 | mDPI | m_S | m_Y,       // 13 ora ,s,y
	1 | mDP,                    // 14 trb <dp
	1 | mDP | m_X,              // 15 ora <dp,x
	1 | mDP | m_X,              // 16 asl <dp,x
	1 | mDPIL | m_Y,            // 17 ora [dp],y
	0 | mImplied,               // 18 clc
	2 | mAbsolute | m_Y,        // 19 ora |abs,y
	0 | mImplied,               // 1a inc a
	0 | mImplied,               // 1b tcs
	2 | mAbsolute,              // 1c trb |abs
	2 | mAbsolute | m_X,        // 1d ora |abs,x
	2 | mAbsolute | m_X,        // 1e asl |abs,x
	3 | mAbsoluteLong | m_X,    // 1f ora >abs,x
	
	2 | mAbsolute,              // 20 jsr |abs
	1 | mDPI | m_X,             // 21 and (dp,x)
	3 | mAbsoluteLong,          // 22 jsl >abs
	1 | mDP | m_S,              // 23 and ,s
	1 | mDP,                    // 24 bit <dp
	1 | mDP,                    // 25 and <dp
	1 | mDP,                    // 26 rol <dp
	1 | mDPIL,                  // 27 and [dp]
	0 | mImplied,               // 28 plp
	1 | mImmediate | m_M,       // 29 and #imm
	0 | mImplied,               // 2a rol a
	0 | mImplied,               // 2b pld
	2 | mAbsolute,              // 2c bit |abs
	2 | mAbsolute,              // 2d and |abs
	2 | mAbsolute,              // 2e rol |abs
	3 | mAbsoluteLong,          // 2f and >abs
	
	1 | mRelative,              // 30 bmi 
	1 | mDPI | m_Y,             // 31 and (dp),y
	1 | mDPI,                   // 32 and (dp)
	1 | mDPI | m_S | m_Y,       // 33 and ,s,y
	1 | mDP | m_X,              // 34 bit dp,x
	1 | mDP | m_X,              // 35 and dp,x
	1 | mDP | m_X,              // 36 rol <dp,x
	1 | mDPIL | m_Y,            // 37 and [dp],y
	0 | mImplied,               // 38 sec
	2 | mAbsolute | m_Y,        // 39 and |abs,y
	0 | mImplied,               // 3a dec a
	0 | mImplied,               // 3b tsc
	2 | mAbsolute | m_X,        // 3c bits |abs,x
	2 | mAbsolute | m_X,        // 3d and |abs,x
	2 | mAbsolute | m_X,        // 3e rol |abs,x
	3 | mAbsoluteLong | m_X,    // 3f and >abs,x
	
	0 | mImplied,               // 40 rti
	1 | mDPI | m_X,             // 41 eor (dp,x)
	1 | mAbsolute,              // 42 wdm #imm
	1 | mDP | m_S,              // 43 eor ,s
	2 | mBlockMove,             // 44 mvp x,x
	1 | mDP,                    // 45 eor dp
	1 | mDP,                    // 46 lsr dp
	1 | mDPIL | m_Y,            // 47 eor [dp],y
	0 | mImplied,               // 48 pha
	1 | mImmediate | m_M,       // 49 eor #imm
	0 | mImplied,               // 4a lsr a
	0 | mImplied,               // 4b phk
	2 | mAbsolute,              // 4c jmp |abs
	2 | mAbsolute,              // 4d eor |abs
	2 | mAbsolute,              // 4e lsr |abs
	3 | mAbsoluteLong,          // 4f eor >abs      
	
	1 | mRelative,                  // 50 bvc
	1 | mDPI | m_Y,                 // 51 eor (dp),y
	1 | mDPI,                       // 52 eor (dp)
	1 | mDPI | m_S | m_Y,           // 53 eor ,s,y
	2 | mBlockMove,                 // 54 mvn x,x
	1 | mDP | m_X,                  // 55 eor dp,x
	1 | mDP | m_X,                  // 56 lsr dp,x
	1 | mDPIL | m_Y,                // 57 eor [dp],y
	0 | mImplied,                   // 58 cli
	2 | mAbsolute | m_Y,            // 59 eor |abs,y
	0 | mImplied,                   // 5a phy
	0 | mImplied,                   // 5b tcd
	3 | mAbsoluteLong,              // 5c jml >abs
	2 | mAbsolute | m_X,            // 5d eor |abs,x
	2 | mAbsolute | m_X,            // 5e lsr |abs,x
	3 | mAbsoluteLong | m_X,        // 5f eor >abs,x

	0 | mImplied,                   // 60 rts
	1 | mDPI | m_X,                 // 61 adc (dp,x)
	2 | mRelative,                  // 62 per |abs
	1 | mDP | m_S,                  // 63 adc ,s
	1 | mDP,                        // 64 stz <dp
	1 | mDP,                        // 65 adc <dp
	1 | mDP,                        // 66 ror <dp
	1 | mDPIL,                      // 67 adc [dp]
	0 | mImplied,                   // 68 pla
	1 | mImmediate | m_M,           // 69 adc #imm
	0 | mImplied,                   // 6a ror a 
	0 | mImplied,                   // 6b rtl
	2 | mAbsoluteI,                 // 6c jmp (abs)
	2 | mAbsolute,                  // 6d adc |abs
	2 | mAbsolute,                  // 6e ror |abs
	3 | mAbsoluteLong,              // 6f adc >abs

	1 | mRelative,                  // 70 bvs
	1 | mDPI | m_Y,                 // 71 adc (dp),y
	1 | mDPI,                       // 72 adc (dp)
	1 | mDPI | m_S | m_Y,           // 73 adc ,s,y
	1 | mDP | m_X,                  // 74 stz dp,x
	1 | mDP | m_X,                  // 75 adc dp,x
	1 | mDP | m_X,                  // 76 ror dp,x
	1 | mDPIL | m_Y,                // 77 adc [dp],y
	0 | mImplied,                   // 78 sei
	2 | mAbsolute | m_Y,            // 79 adc |abs,y
	0 | mImplied,                   // 7a ply
	0 | mImplied,                   // 7b tdc
	2 | mAbsoluteI | m_X,           // 7c jmp (abs,x)
	2 | mAbsolute | m_X,            // 7d adc |abs,x
	2 | mAbsolute | m_X,            // 7e ror |abs,x
	3 | mAbsoluteLong | m_X,        // 7f adc >abs,x
	
	1 | mRelative,                  // 80 bra 
	1 | mDPI | m_X,                 // 81 sta (dp,x)
	2 | mRelative,                  // 82 brl |abs
	1 | mDP | m_S,                  // 83 sta ,s
	1 | mDP,                        // 84 sty <dp
	1 | mDP,                        // 85 sta <dp
	1 | mDP,                        // 86 stx <dp
	1 | mDPIL,                      // 87 sta [dp]
	0 | mImplied,                   // 88 dey
	1 | mImmediate | m_M,           // 89 bit #imm
	0 | mImplied,                   // 8a txa
	0 | mImplied,                   // 8b phb
	2 | mAbsolute,                  // 8c sty |abs
	2 | mAbsolute,                  // 8d sta |abs
	2 | mAbsolute,                  // 8e stx |abs
	3 | mAbsoluteLong,              // 8f sta >abs
	
	1 | mRelative,                  // 90 bcc
	1 | mDPI | m_Y,                 // 91 sta (dp),y
	1 | mDPI,                       // 92 sta (dp)
	1 | mDPI | m_S | m_Y,           // 93 sta ,s,y
	1 | mDP | m_X,                  // 94 sty dp,x
	1 | mDP | m_X,                  // 95 sta dp,x
	1 | mDP | m_Y,                  // 96 stx dp,y
	1 | mDPIL | m_Y,                // 97 sta [dp],y
	0 | mImplied,                   // 98 tya
	2 | mAbsolute | m_Y,            // 99 sta |abs,y
	0 | mImplied,                   // 9a txs
	0 | mImplied,                   // 9b txy
	2 | mAbsolute,                  // 9c stz |abs
	2 | mAbsolute | m_X,            // 9d sta |abs,x
	2 | mAbsolute | m_X,            // 9e stz |abs,x
	3 | mAbsoluteLong | m_X,        // 9f sta >abs,x
	
	1 | mImmediate | m_I,           // a0 ldy #imm
	1 | mDPI | m_X,                 // a1 lda (dp,x)
	1 | mImmediate | m_I,           // a2 ldx #imm
	1 | mDP | m_S,                  // a3 lda ,s
	1 | mDP,                        // a4 ldy <dp
	1 | mDP,                        // a5 lda <dp
	1 | mDP,                        // a6 ldx <dp
	1 | mDPIL,                      // a7 lda [dp]
	0 | mImplied,                   // a8 tay
	1 | mImmediate | m_M,           // a9 lda #imm
	0 | mImplied,                   // aa tax
	0 | mImplied,                   // ab plb
	2 | mAbsolute,                  // ac ldy |abs
	2 | mAbsolute,                  // ad lda |abs
	2 | mAbsolute,                  // ae ldx |abs
	3 | mAbsoluteLong,              // af lda >abs   
	
	1 | mRelative,                  // b0 bcs
	1 | mDPI | m_Y,                 // b1 lda (dp),y
	1 | mDPI,                       // b2 lda (dp)
	1 | mDPI | m_S | m_Y,           // b3 lda ,s,y
	1 | mDP | m_X,                  // b4 ldy <dp,x
	1 | mDP | m_X,                  // b5 lda <dp,x
	1 | mDP | m_Y,                  // b6 ldx <dp,y
	1 | mDPIL | m_Y,                // b7 lda [dp],y
	0 | mImplied,                   // b8 clv
	2 | mAbsolute | m_Y,            // b9 lda |abs,y
	0 | mImplied,                   // ba tsx
	0 | mImplied,                   // bb tyx
	2 | mAbsolute | m_X,            // bc ldy |abs,x
	2 | mAbsolute | m_X,            // bd lda |abs,x
	2 | mAbsolute | m_Y,            // be ldx |abs,y
	3 | mAbsoluteLong | m_X,        // bf lda >abs,x
	
	1 | mImmediate | m_I,           // c0 cpy #imm
	1 | mDPI | m_X,                 // c1 cmp (dp,x)
	1 | mImmediate,                 // c2 rep #
	1 | mDP | m_S,                  // c3 cmp ,s
	1 | mDP,                        // c4 cpy <dp
	1 | mDP,                        // c5 cmp <dp
	1 | mDP,                        // c6 dec <dp
	1 | mDPIL,                      // c7 cmp [dp]
	0 | mImplied,                   // c8 iny
	1 | mImmediate | m_M,           // c9 cmp #imm
	0 | mImplied,                   // ca dex
	0 | mImplied,                   // cb WAI
	2 | mAbsolute,                  // cc cpy |abs
	2 | mAbsolute,                  // cd cmp |abs
	2 | mAbsolute,                  // ce dec |abs
	3 | mAbsoluteLong,              // cf cmp >abs
	
	1 | mRelative,                  // d0 bne
	1 | mDPI | m_Y,                 // d1 cmp (dp),y
	1 | mDPI,                       // d2 cmp (dp)
	1 | mDPI | m_S | m_Y,           // d3 cmp ,s,y
	1 | mDPI,                       // d4 pei (dp)
	1 | mDP | m_X,                  // d5 cmp dp,x
	1 | mDP | m_X,                  // d6 dec dp,x
	1 | mDPIL | m_Y,                // d7 cmp [dp],y
	0 | mImplied,                   // d8 cld
	2 | mAbsolute | m_Y,            // d9 cmp |abs,y
	0 | mImplied,                   // da phx
	0 | mImplied,                   // db stp
	2 | mAbsoluteIL,                // dc jml [abs]
	2 | mAbsolute | m_X,            // dd cmp |abs,x
	2 | mAbsolute | m_X,            // de dec |abs,x
	3 | mAbsoluteLong | m_X,        // df cmp >abs,x
	
	1 | mImmediate | m_I,           // e0 cpx #imm
	1 | mDPI | m_X,                 // e1 sbc (dp,x)
	1 | mImmediate,                 // e2 sep #imm
	1 | mDP | m_S,                  // e3 sbc ,s
	1 | mDP,                        // e4 cpx <dp
	1 | mDP,                        // e5 sbc <dp
	1 | mDP,                        // e6 inc <dp
	1 | mDPIL,                      // e7 sbc [dp]
	0 | mImplied,                   // e8 inx
	1 | mImmediate| m_M,            // e9 sbc #imm
	0 | mImplied,                   // ea nop
	0 | mImplied,                   // eb xba
	2 | mAbsolute,                  // ec cpx |abs
	2 | mAbsolute,                  // ed abc |abs
	2 | mAbsolute,                  // ee inc |abs
	3 | mAbsoluteLong,              // ef sbc >abs
	
	1 | mRelative,                  // f0 beq
	1 | mDPI | m_Y,                 // f1 sbc (dp),y
	1 | mDPI,                       // f2 sbc (dp)
	1 | mDPI | m_S | m_Y,           // f3 sbc ,s,y
	2 | mAbsolute,                  // f4 pea |abs
	1 | mDP | m_X,                  // f5 sbc dp,x
	1 | mDP | m_X,                  // f6 inc dp,x
	1 | mDPIL | m_Y,                // f7 sbc [dp],y
	0 | mImplied,                   // f8 sed
	2 | mAbsolute | m_Y,            // f9 sbc |abs,y
	0 | mImplied,                   // fa plx
	0 | mImplied,                   // fb xce
	2 | mAbsoluteI,                 // fc jsr (abs)
	2 | mAbsolute | m_X,            // fd sbc |abs,x
	2 | mAbsolute | m_X,            // fe inc |abs,x
	3 | mAbsoluteLong | m_X,        // ff sbc >abs,x      

};

unsigned init_flags(bool longM, bool longX) {
	unsigned flags = 0;
	if (longM) flags |= m_M;
	if (longX) flags |= m_I;
	return flags;
}


void dump(const std::vector<uint8_t> &data, unsigned &pc) {

	int count = 0;
	for (auto &x : data) {
		if (count == 0) printf("\tbyte\t");
		else printf(", ");
		printf("$%02x", x);
		++count;
		++pc;
		if (count == 8) { printf("\n"); count = 0; }
	}
	if (count) printf("\n");
}

void disasm(const std::vector<uint8_t> &data, unsigned &flags, unsigned &pc) {
	int i = 0;
	for (; i < data.size(); ) {
		uint8_t op = data[i];
		int attr = modes[op];
		int size = attr & 0x0f;

		// check if size increase for m/x bits.
		if (attr & flags & m_I) size++;
		if (attr & flags & m_M) size++;

		if (i + size + 1 > data.size())
			break;

		++i;

		printf("\t%.3s", &opcodes[op * 3]);

		switch(attr & 0xf000) {
			case mImmediate: printf("\t#"); break;
			case mDP: printf("\t<"); break;
			case mDPI: printf("\t(<"); break;
			case mDPIL: printf("\t[<"); break;

			case mRelative:
			case mBlockMove:
				printf("\t"); break;

			// cop, brk are treated as absolute.
			case mAbsolute: 
				if (size == 1) printf("\t");
				else printf("\t|");
				break;
			case mAbsoluteLong: printf("\t>"); break;
			case mAbsoluteI: printf("\t("); break;
		}


		uint32_t arg = 0;
		for (int j = 0; j < size; ++j) {
			arg |= (data[i++] << (8 * j));
		}

		// todo -- relative, block mode.
		switch (size) {
			case 0: break;
			case 1: printf("$%02x", arg); break;
			case 2: printf("$%04x", arg); break;
			case 3: printf("$%06x", arg); break;
		}

		switch(attr & 0x0f00) {
			case m_X: printf(",x"); break;
			case m_Y: if (!(attr & (mDPI|mDPIL))) printf(",y"); break;
			case m_S:
			case m_S | m_Y:
				printf(",s"); break;
		}

		switch(attr & 0xf000) {
			case mAbsoluteI:
			case mDPI:
				printf(")"); break;
			case mAbsoluteIL:
			case mDPIL:
				printf("]"); break;
		}

		// (xxx,s),y
		// (xxx),y
		// [xxx],y
		switch(attr & 0x0f00) {
			case m_Y: if (attr & (mDPI|mDPIL)) printf(",y"); break;
			case m_S | m_Y:
				printf(",y"); break;
		}		

		switch(op) {
			case 0xc2: // REP
				flags |= (arg & 0x30);
				break;
				//if (arg & 0x10) flags |= m_I;
				//if (arg & 0x20) flags |= m_M;
				break;
			case 0xe2: // SEP
				flags &= ~(arg & 0x30);
				//if (arg & 0x10) flags &= ~m_I;
				//if (arg & 0x20) flags &= ~m_M;
				break;
		}

		printf("\n");
		pc += size + 1;
	}
	// any remaining data...
	while (i < data.size()) {
		printf("\tbyte\t$%02x\n", data[i]);
		++i;
		++pc;
	}
}