8 u8int rA, rX, rY, rS, rP;
23 r |= memread(pc++) << 8;
30 memwrite(0x100 | rS--, v);
36 memwrite(0x100 | rS--, v >> 8);
37 memwrite(0x100 | rS--, v);
43 return memread(0x100 | ++rS);
51 v = memread(0x100 | ++rS);
52 v |= memread(0x100 | ++rS) << 8;
56 #define imm() fetch8()
57 #define zp() memread(fetch8())
58 #define zpX() memread(azpX(rX))
59 #define zpY() memread(azpX(rY))
60 #define abso() memread(fetch16())
61 #define absX() memread(aabsX(rX, 0))
62 #define absY() memread(aabsX(rY, 0))
63 #define indX() memread(aindX())
64 #define indY() memread(aindY(0))
77 aabsX(u8int a, int wr)
82 c = (u8int)v + a & 0x100;
110 a = memread(r++) + rY;
112 a += memread(r) << 8;
123 if((rP & FLAGD) != 0){
124 r = (rA & 0xf) + (d & 0xf) + (rP & FLAGC);
129 r += (rA & 0xf0) + (d & 0xf0);
131 r = rA + d + (rP & FLAGC);
132 rP &= ~(FLAGN | FLAGZ | FLAGV | FLAGC);
133 if((~(rA ^ d) & (rA ^ r)) & 0x80) rP |= FLAGV;
134 if((rP & FLAGD) != 0 && r > 0x9f)
136 if(r > 0xFF) rP |= FLAGC;
137 if(r & 0x80) rP |= FLAGN;
139 if(rA == 0) rP |= FLAGZ;
145 rP &= ~(FLAGN | FLAGZ);
146 if(d & 0x80) rP |= FLAGN;
147 if(d == 0) rP |= FLAGZ;
156 rP &= ~(FLAGN | FLAGZ | FLAGC);
159 if(v & 0x80) rP |= FLAGC;
161 if(v == 0) rP |= FLAGZ;
162 if(v & 0x80) rP |= FLAGN;
171 rP &= ~(FLAGN | FLAGZ | FLAGC);
176 if(v == 0) rP |= FLAGZ;
177 if(v & 0x80) rP |= FLAGN;
191 memread(pc & 0xff00 | npc & 0xff);
196 cmp(u8int a, u8int d)
198 rP &= ~(FLAGN | FLAGZ | FLAGC);
199 if(a == d) rP |= FLAGZ;
200 if(a >= d) rP |= FLAGC;
201 if((a - d) & 0x80) rP |= FLAGN;
211 memwrite(a, nz(v - 1));
233 rP &= ~(FLAGC | FLAGN | FLAGZ);
234 if(v & 0x80) rP |= FLAGC;
236 if(v & 0x80) rP |= FLAGN;
237 if(v == 0) rP |= FLAGZ;
249 rP &= ~(FLAGC | FLAGN | FLAGZ);
251 v = (v >> 1) | (b << 7);
252 if(v & 0x80) rP |= FLAGN;
253 if(v == 0) rP |= FLAGZ;
262 if((rP & FLAGD) != 0){
264 r = (rA & 0xf) + (d & 0xf) + (rP & FLAGC);
265 if(r < 0x10) r -= 0x06;
267 r += (rA & 0xf0) + (d & 0xf0);
269 r = rA + (u8int)~d + (rP & FLAGC);
270 rP &= ~(FLAGZ | FLAGV | FLAGC | FLAGN);
271 if(((rA ^ d) & (rA ^ r)) & 0x80) rP |= FLAGV;
272 if(r > 0xFF) rP |= FLAGC;
273 else if((rP & FLAGD) != 0)
276 if(rA == 0) rP |= FLAGZ;
277 if(rA & 0x80) rP |= FLAGN;
281 interrupt(int nmi, int brk)
285 push8(rP | 0x20 | (brk << 4));
286 pc = memread(0xFFFA | (!nmi << 2));
287 pc |= memread(0xFFFB | (!nmi << 2)) << 8;
304 print("%.4x %.2x | %.2x %.2x %.2x | %.2x %.2x | %3d %3d\n", curpc, op, rA, rX, rY, rS, rP, ppux-3, ppuy);
306 case 0x00: fetch8(); interrupt(0, 1); return;
307 case 0x01: nz(rA |= indX()); return;
308 case 0x05: nz(rA |= zp()); return;
309 case 0x06: asl(fetch8()); return;
310 case 0x08: memread(pc); push8(rP | 0x30); return;
311 case 0x09: nz(rA |= imm()); return;
313 rP &= ~(FLAGN | FLAGZ | FLAGC);
314 if(rA & 0x80) rP |= FLAGC;
316 if(rA == 0) rP |= FLAGZ;
317 if(rA & 0x80) rP |= FLAGN;
320 case 0x0D: nz(rA |= abso()); return;
321 case 0x0E: asl(fetch16()); return;
322 case 0x10: if((rP & FLAGN) == 0) branch(); else fetch8(); return;
323 case 0x11: nz(rA |= indY()); return;
324 case 0x15: nz(rA |= zpX()); return;
325 case 0x16: asl(azpX(rX)); return;
326 case 0x18: rP &= ~FLAGC; memread(pc); return;
327 case 0x19: nz(rA |= absY()); return;
328 case 0x1D: nz(rA |= absX()); return;
329 case 0x1E: asl(aabsX(rX, 1)); return;
330 case 0x20: v = fetch8(); memread(rS|0x100); push16(pc); pc = fetch8() << 8 | v; return;
331 case 0x21: nz(rA &= indX()); return;
333 a = memread(fetch8());
334 rP &= ~(FLAGN | FLAGZ | FLAGV);
336 if((a & rA) == 0) rP |= FLAGZ;
338 case 0x25: nz(rA &= zp()); return;
339 case 0x26: rol(fetch8()); return;
340 case 0x28: memread(pc); memread(0x100|rS); rP = pop8() & 0xcf; return;
341 case 0x29: nz(rA &= imm()); return;
344 rP &= ~(FLAGC | FLAGZ | FLAGN);
345 if(rA & 0x80) rP |= FLAGC;
347 if(rA & 0x80) rP |= FLAGN;
348 if(rA == 0) rP |= FLAGZ;
352 a = memread(fetch16());
353 rP &= ~(FLAGN | FLAGZ | FLAGV);
355 if((a & rA) == 0) rP |= FLAGZ;
357 case 0x2D: nz(rA &= abso()); return;
358 case 0x2E: rol(fetch16()); return;
359 case 0x30: if((rP & FLAGN) != 0) branch(); else fetch8(); return;
360 case 0x31: nz(rA &= indY()); return;
361 case 0x35: nz(rA &= zpX()); return;
362 case 0x36: rol(azpX(rX)); return;
363 case 0x38: rP |= FLAGC; memread(pc); return;
364 case 0x39: nz(rA &= absY()); return;
365 case 0x3E: rol(aabsX(rX, 1)); return;
366 case 0x3D: nz(rA &= absX()); return;
367 case 0x40: fetch8(); memread(rS|0x100); rP = pop8() & 0xcf; pc = pop16(); return;
368 case 0x41: nz(rA ^= indX()); return;
369 case 0x45: nz(rA ^= zp()); return;
370 case 0x46: lsr(fetch8()); return;
371 case 0x48: memread(pc); push8(rA); return;
372 case 0x49: nz(rA ^= imm()); return;
374 rP &= ~(FLAGN | FLAGZ | FLAGC);
377 if(rA == 0) rP |= FLAGZ;
378 if(rA & 0x80) rP |= FLAGN;
381 case 0x4C: pc = fetch16(); return;
382 case 0x4D: nz(rA ^= abso()); return;
383 case 0x4E: lsr(fetch16()); return;
384 case 0x51: nz(rA ^= indY()); return;
385 case 0x56: lsr(azpX(rX)); return;
386 case 0x58: rP &= ~FLAGI; memread(pc); return;
387 case 0x50: if((rP & FLAGV) == 0) branch(); else fetch8(); return;
388 case 0x55: nz(rA ^= zpX()); return;
389 case 0x59: nz(rA ^= absY()); return;
390 case 0x5D: nz(rA ^= absX()); return;
391 case 0x5E: lsr(aabsX(rX, 1)); return;
392 case 0x60: fetch8(); memread(rS | 0x100); pc = pop16(); fetch8(); return;
393 case 0x61: adc(indX()); return;
394 case 0x65: adc(zp()); return;
395 case 0x66: ror(fetch8()); return;
396 case 0x68: memread(pc); memread(0x100|rS); nz(rA = pop8()); return;
397 case 0x69: adc(imm()); return;
400 rP &= ~(FLAGC | FLAGN | FLAGZ);
402 rA = (rA >> 1) | (a << 7);
403 if(rA & 0x80) rP |= FLAGN;
404 if(rA == 0) rP |= FLAGZ;
407 case 0x6C: v = fetch16(); pc = memread(v) | (memread((v & 0xFF00) | (u8int)(v+1)) << 8); return;
408 case 0x6D: adc(abso()); return;
409 case 0x6E: ror(fetch16()); return;
410 case 0x70: if((rP & FLAGV) != 0) branch(); else fetch8(); return;
411 case 0x71: adc(indY()); return;
412 case 0x75: adc(zpX()); return;
413 case 0x76: ror(azpX(rX)); return;
414 case 0x78: rP |= FLAGI; memread(pc); return;
415 case 0x79: adc(absY()); return;
416 case 0x7D: adc(absX()); return;
417 case 0x7E: ror(aabsX(rX, 1)); return;
418 case 0x81: memwrite(aindX(), rA); return;
419 case 0x84: memwrite(fetch8(), rY); return;
420 case 0x85: memwrite(fetch8(), rA); return;
421 case 0x86: memwrite(fetch8(), rX); return;
422 case 0x88: nz(--rY); memread(pc); return;
423 case 0x8A: nz(rA = rX); memread(pc); return;
424 case 0x8C: memwrite(fetch16(), rY); return;
425 case 0x8D: memwrite(fetch16(), rA); return;
426 case 0x8E: memwrite(fetch16(), rX); return;
427 case 0x90: if((rP & FLAGC) == 0) branch(); else fetch8(); return;
428 case 0x91: memwrite(aindY(1), rA); return;
429 case 0x94: memwrite(azpX(rX), rY); return;
430 case 0x95: memwrite(azpX(rX), rA); return;
431 case 0x96: memwrite(azpX(rY), rX); return;
432 case 0x98: nz(rA = rY); memread(pc); return;
433 case 0x99: memwrite(aabsX(rY, 1), rA); return;
434 case 0x9A: rS = rX; memread(pc); return;
435 case 0x9D: memwrite(aabsX(rX, 1), rA); return;
436 case 0xA0: nz(rY = imm()); return;
437 case 0xA1: nz(rA = indX()); return;
438 case 0xA2: nz(rX = imm()); return;
439 case 0xA4: nz(rY = zp()); return;
440 case 0xA5: nz(rA = zp()); return;
441 case 0xA6: nz(rX = zp()); return;
442 case 0xA8: nz(rY = rA); memread(pc); return;
443 case 0xA9: nz(rA = imm()); return;
444 case 0xAA: nz(rX = rA); memread(pc); return;
445 case 0xAC: nz(rY = abso()); return;
446 case 0xAE: nz(rX = abso()); return;
447 case 0xAD: nz(rA = abso()); return;
448 case 0xB0: if((rP & FLAGC) != 0) branch(); else fetch8(); return;
449 case 0xB1: nz(rA = indY()); return;
450 case 0xB4: nz(rY = zpX()); return;
451 case 0xB5: nz(rA = zpX()); return;
452 case 0xB6: nz(rX = zpY()); return;
453 case 0xB8: rP &= ~FLAGV; memread(pc); return;
454 case 0xB9: nz(rA = absY()); return;
455 case 0xBA: nz(rX = rS); memread(pc); return;
456 case 0xBC: nz(rY = absX()); return;
457 case 0xBD: nz(rA = absX()); return;
458 case 0xBE: nz(rX = absY()); return;
459 case 0xC1: cmp(rA, indX()); return;
460 case 0xC5: cmp(rA, zp()); return;
461 case 0xC9: cmp(rA, imm()); return;
462 case 0xCD: cmp(rA, abso()); return;
463 case 0xD0: if((rP & FLAGZ) == 0) branch(); else fetch8(); return;
464 case 0xD1: cmp(rA, indY()); return;
465 case 0xD5: cmp(rA, zpX()); return;
466 case 0xD8: rP &= ~FLAGD; memread(pc); return;
467 case 0xD9: cmp(rA, absY()); return;
468 case 0xDD: cmp(rA, absX()); return;
469 case 0xC0: cmp(rY, imm()); return;
470 case 0xC4: cmp(rY, zp()); return;
471 case 0xC6: dec(fetch8()); return;
472 case 0xC8: nz(++rY); memread(pc); return;
473 case 0xCA: nz(--rX); memread(pc); return;
474 case 0xCC: cmp(rY, abso()); return;
475 case 0xCE: dec(fetch16()); return;
476 case 0xD6: dec(azpX(rX)); return;
477 case 0xDE: dec(aabsX(rX, 1)); return;
478 case 0xE0: cmp(rX, imm()); return;
479 case 0xE1: sbc(indX()); return;
480 case 0xE4: cmp(rX, zp()); return;
481 case 0xE5: sbc(zp()); return;
482 case 0xE6: inc(fetch8()); return;
483 case 0xE8: nz(++rX); memread(pc); return;
484 case 0xE9: sbc(imm()); return;
485 case 0xEA: memread(pc); return;
486 case 0xEC: cmp(rX, abso()); return;
487 case 0xED: sbc(abso()); return;
488 case 0xEE: inc(fetch16()); return;
489 case 0xF0: if((rP & FLAGZ) != 0) branch(); else fetch8(); return;
490 case 0xF1: sbc(indY()); return;
491 case 0xF5: sbc(zpX()); return;
492 case 0xF6: inc(azpX(rX)); return;
493 case 0xF8: rP |= FLAGD; memread(pc); return;
494 case 0xF9: sbc(absY()); return;
495 case 0xFD: sbc(absX()); return;
496 case 0xFE: inc(aabsX(rX, 1)); return;
498 fprint(2, "undefined %#x (pc %#x)\n", op, curpc);