ref: fdf020f1309bffde33554f5a13c7b3a1a3fb1891
dir: /sys/src/games/gb/cpu.c/
#include <u.h> #include <libc.h> #include <thread.h> #include "../eui.h" #include "dat.h" #include "fns.h" u8int r[8], ime; u16int pc, curpc, sp; int halt, trace; enum { FLAGC = 0x10, FLAGH = 0x20, FLAGN = 0x40, FLAGZ = 0x80 }; enum { rB, rC, rD, rE, rH, rL, rHL, rA, rF = rHL }; #define BC() (r[rB] << 8 | r[rC]) #define DE() (r[rD] << 8 | r[rE]) #define HL() (r[rH] << 8 | r[rL]) Var cpuvars[] = { ARR(r), VAR(ime), VAR(pc), VAR(curpc), VAR(sp), VAR(halt), {nil, 0, 0} }; static u8int fetch8(void) { return memread(pc++); } static u16int fetch16(void) { u16int u; u = memread(pc++); return u | memread(pc++) << 8; } static void push8(u8int u) { memwrite(--sp, u); } static void push16(u16int u) { memwrite(--sp, u >> 8); memwrite(--sp, u); } static u8int pop8(void) { return memread(sp++); } static u16int pop16(void) { u16int v; v = memread(sp++); return v | memread(sp++) << 8; } static u16int read16(u16int n) { return memread(n) | memread(n+1) << 8; } static void write16(u16int n, u16int v) { memwrite(n++, v); memwrite(n, v >> 8); } static int move(u8int dst, u8int src) { if(dst == rHL){ if(src == rHL){ halt = 1; return 4; } memwrite(HL(), r[src]); return 8; } if(src == rHL){ r[dst] = memread(HL()); return 8; } r[dst] = r[src]; return 4; } static int alu(u8int op, u8int n) { u8int v4; u8int u; u16int v; int t; switch(n){ case 8: u = fetch8(); t = 8; break; case rHL: u = memread(HL()); t = 8; break; default: u = r[n]; t = 4; } v4 = 0; switch(op){ default: v4 = (r[rA] & 0x0f) + (u & 0x0f); v = r[rA] + u; break; case 1: v4 = (r[rA] & 0x0f) + (u & 0x0f) + (r[rF] >> 4 & 1); v = r[rA] + u + (r[rF] >> 4 & 1); break; case 2: case 7: v4 = (r[rA] & 0x0f) + (~u & 0x0f) + 1; v = r[rA] + (u ^ 0xff) + 1; break; case 3: v4 = (r[rA] & 0x0f) + (~u & 0x0f) + (~r[rF] >> 4 & 1); v = r[rA] + (u ^ 0xff) + (~r[rF] >> 4 & 1); break; case 4: v = r[rA] & u; break; case 5: v = r[rA] ^ u; break; case 6: v = r[rA] | u; break; } r[rF] = 0; if((u8int)v == 0) r[rF] |= FLAGZ; if(op < 2){ if((v & 0x100) != 0) r[rF] |= FLAGC; if((v4 & 0x10) != 0) r[rF] |= FLAGH; }else if(op < 4 || op == 7){ r[rF] |= FLAGN; if((v & 0x100) == 0) r[rF] |= FLAGC; if((v4 & 0x10) == 0) r[rF] |= FLAGH; }else if(op == 4) r[rF] |= FLAGH; if(op != 7) r[rA] = v; return t; } static int branch(int cc, int t) { u16int v; v = (s8int)fetch8(); if(!cc) return t + 8; pc += v; return t + 12; } static u8int inc(u8int v) { r[rF] &= FLAGC; ++v; if(v == 0) r[rF] |= FLAGZ; if((v & 0xf) == 0) r[rF] |= FLAGH; return v; } static u8int dec(u8int v) { --v; r[rF] = r[rF] & FLAGC | FLAGN; if(v == 0) r[rF] |= FLAGZ; if((v & 0xf) == 0xf) r[rF] |= FLAGH; return v; } static int addhl(u16int u) { u32int v; r[rF] &= ~(FLAGN|FLAGC|FLAGH); v = HL() + u; if((v & 0x10000) != 0) r[rF] |= FLAGC; if((HL() & 0xfff) + (u & 0xfff) >= 0x1000) r[rF] |= FLAGH; r[rL] = v; r[rH] = v >> 8; return 8; } static void adchl(u16int u) { u32int v, v4; v = HL() + u + (r[rF] & FLAGC); v4 = (HL() & 0xfff) + (u & 0xfff) + (r[rF] & FLAGC); r[rF] = 0; if((v & 0x10000) != 0) r[rF] |= FLAGC; if((v4 & 0x1000) != 0) r[rF] |= FLAGH; if((u16int)v == 0) r[rF] |= FLAGZ; r[rL] = v; r[rH] = v >> 8; } static void sbchl(u16int u) { u32int v, v4; v = HL() + (u16int)~u + (~r[rF] & FLAGC); v4 = (HL() & 0xfff) + (~u & 0xfff) + (~r[rF] & FLAGC); r[rF] = FLAGN; if((v & 0x10000) == 0) r[rF] |= FLAGC; if((v4 & 0x1000) == 0) r[rF] |= FLAGH; if((u16int)v == 0) r[rF] |= FLAGZ; r[rL] = v; r[rH] = v >> 8; } static int jump(int cc) { u16int v; v = fetch16(); if(!cc) return 12; pc = v; return 16; } static int call(u16int a, int cc) { if(!cc) return 12; push16(pc); pc = a; return cc < 0 ? 16 : 24; } static int bits(void) { u8int op, v, n, m, c; u16int a; int t; op = fetch8(); n = op & 7; m = op >> 3 & 7; a = HL(); if(n == 6){ v = memread(a); t = 16; }else{ v = r[n]; t = 8; } switch(op >> 6){ case 0: c = r[rF] >> 4 & 1; switch(m){ default: r[rF] = v >> 3 & 0x10; v = v << 1 | v >> 7; break; case 1: r[rF] = v << 4 & 0x10; v = v >> 1 | v << 7; break; case 2: r[rF] = v >> 3 & 0x10; v = v << 1 | c; break; case 3: r[rF] = v << 4 & 0x10; v = v >> 1 | c << 7; break; case 4: r[rF] = v >> 3 & 0x10; v = v << 1; break; case 5: r[rF] = v << 4 & 0x10; v = v & 0x80 | v >> 1; break; case 6: r[rF] = 0; v = v << 4 | v >> 4; break; case 7: r[rF] = v << 4 & 0x10; v >>= 1; break; } if(v == 0) r[rF] |= FLAGZ; break; case 1: r[rF] = r[rF] & ~(FLAGN|FLAGZ) | FLAGH; if((v & 1<<m) == 0) r[rF] |= FLAGZ; if(n == 6) t = 12; return t; case 2: v &= ~(1<<m); break; case 3: v |= (1<<m); } if(n == 6) memwrite(a, v); else r[n] = v; return t; } void reset(void) { r[rA] = 0x01; r[rF] = 0xb0; r[rC] = 0x13; r[rE] = 0xd8; r[rL] = 0x4d; r[rH] = 0x01; if((mode & COL) == COL) r[rA] = 0x11; sp = 0xfffe; pc = 0x100; } int step(void) { u8int op, v4; u16int v, w; s8int s; if(halt) if((reg[IF] & reg[IE]) != 0) halt = 0; else return 4; if((reg[IF] & reg[IE]) != 0 && ime != 0){ push16(pc); ime = 0; v4 = reg[IF] & reg[IE]; v4 &= -v4; reg[IF] &= ~v4; for(pc = 0x40; v4 != 1; pc += 8) v4 >>= 1; return 12; } curpc = pc; op = fetch8(); if(trace) print("%.4x %.2x AF %.2x%.2x BC %.2x%.2x DE %.2x%.2x HL %.2x%.2x SP %.4x\n", curpc, op, r[rA], r[rF], r[rB], r[rC], r[rD], r[rE], r[rH], r[rL], sp); switch(op >> 6){ case 1: return move(op >> 3 & 7, op & 7); case 2: return alu(op >> 3 & 7, op & 7); } switch(op){ case 0x00: return 4; case 0x10: if((mode & CGB) != 0 && (reg[KEY1] & 1) != 0){ reg[DIV] += divclock - clock >> 7 - ((mode & TURBO) != 0); divclock = clock; mode ^= TURBO; timertac(reg[TAC], 1); reg[KEY1] ^= 0x81; return 4; } print("STOP ignored (pc=%.4ux)\n", curpc); return 4; case 0x20: return branch((r[rF] & FLAGZ) == 0, 0); case 0x30: return branch((r[rF] & FLAGC) == 0, 0); case 0x01: r[rC] = fetch8(); r[rB] = fetch8(); return 12; case 0x11: r[rE] = fetch8(); r[rD] = fetch8(); return 12; case 0x21: r[rL] = fetch8(); r[rH] = fetch8(); return 12; case 0x31: sp = fetch16(); return 12; case 0x02: memwrite(BC(), r[rA]); return 8; case 0x12: memwrite(DE(), r[rA]); return 8; case 0x22: memwrite(HL(), r[rA]); if(++r[rL] == 0) r[rH]++; return 8; case 0x32: memwrite(HL(), r[rA]); if(r[rL]-- == 0) r[rH]--; return 8; case 0x03: if(++r[rC] == 0) r[rB]++; return 8; case 0x13: if(++r[rE] == 0) r[rD]++; return 8; case 0x23: if(++r[rL] == 0) r[rH]++; return 8; case 0x33: sp++; return 8; case 0x04: inc(r[rB]++); return 4; case 0x14: inc(r[rD]++); return 4; case 0x24: inc(r[rH]++); return 4; case 0x34: memwrite(HL(), inc(memread(HL()))); return 12; case 0x05: dec(r[rB]--); return 4; case 0x15: dec(r[rD]--); return 4; case 0x25: dec(r[rH]--); return 4; case 0x35: memwrite(HL(), dec(memread(HL()))); return 12; case 0x06: r[rB] = fetch8(); return 8; case 0x16: r[rD] = fetch8(); return 8; case 0x26: r[rH] = fetch8(); return 8; case 0x36: memwrite(HL(), fetch8()); return 12; case 0x07: r[rF] = r[rA] >> 3 & 0x10; r[rA] = r[rA] << 1 | r[rA] >> 7; return 4; case 0x17: v = r[rF] >> 4 & 1; r[rF] = r[rA] >> 3 & 0x10; r[rA] = r[rA] << 1 | v; return 4; case 0x27: if(r[rA] > 0x99 && (r[rF] & FLAGN) == 0 || (r[rF] & FLAGC) != 0){ r[rF] |= FLAGC; v = 0x60; }else{ r[rF] &= ~FLAGC; v = 0; } if((r[rA] & 0xf) > 9 && (r[rF] & FLAGN) == 0 || (r[rF] & FLAGH) != 0) v |= 6; if((r[rF] & FLAGN) != 0) r[rA] -= v; else r[rA] += v; r[rF] &= ~(FLAGZ|FLAGH); if(r[rA] == 0) r[rF] |= FLAGZ; return 4; case 0x37: r[rF] = r[rF] & ~(FLAGN | FLAGH) | FLAGC; return 4; case 0x08: write16(fetch16(), sp); return 20; case 0x18: return branch(1, 0); case 0x28: return branch((r[rF] & FLAGZ) != 0, 0); case 0x38: return branch((r[rF] & FLAGC) != 0, 0); case 0x09: return addhl(BC()); case 0x19: return addhl(DE()); case 0x29: return addhl(HL()); case 0x39: return addhl(sp); case 0x0a: r[rA] = memread(BC()); return 8; case 0x1a: r[rA] = memread(DE()); return 8; case 0x2a: r[rA] = memread(HL()); if(++r[rL] == 0) r[rH]++; return 8; case 0x3a: r[rA] = memread(HL()); if(r[rL]-- == 0) r[rH]--; return 8; case 0x0b: if(r[rC]-- == 0) r[rB]--; return 8; case 0x1b: if(r[rE]-- == 0) r[rD]--; return 8; case 0x2b: if(r[rL]-- == 0) r[rH]--; return 8; case 0x3b: sp--; return 8; case 0x0c: inc(r[rC]++); return 4; case 0x1c: inc(r[rE]++); return 4; case 0x2c: inc(r[rL]++); return 4; case 0x3c: inc(r[rA]++); return 4; case 0x0d: dec(r[rC]--); return 4; case 0x1d: dec(r[rE]--); return 4; case 0x2d: dec(r[rL]--); return 4; case 0x3d: dec(r[rA]--); return 4; case 0x0e: r[rC] = fetch8(); return 8; case 0x1e: r[rE] = fetch8(); return 8; case 0x2e: r[rL] = fetch8(); return 8; case 0x3e: r[rA] = fetch8(); return 8; case 0x0f: r[rF] = r[rA] << 4 & 0x10; r[rA] = r[rA] >> 1 | r[rA] << 7; return 4; case 0x1f: v = r[rF] << 3 & 0x80; r[rF] = r[rA] << 4 & 0x10; r[rA] = r[rA] >> 1 | v; return 4; case 0x2f: r[rF] |= FLAGN|FLAGH; r[rA] ^= 0xff; return 4; case 0x3f: r[rF] = r[rF] & ~(FLAGN|FLAGH) ^ FLAGC; return 4; case 0xc0: if((r[rF] & FLAGZ) == 0) {pc = pop16(); return 20;} return 8; case 0xd0: if((r[rF] & FLAGC) == 0) {pc = pop16(); return 20;} return 8; case 0xe0: memwrite(0xff00 | fetch8(), r[rA]); return 12; case 0xf0: r[rA] = memread(0xff00 | fetch8()); return 12; case 0xc1: r[rC] = pop8(); r[rB] = pop8(); return 12; case 0xd1: r[rE] = pop8(); r[rD] = pop8(); return 12; case 0xe1: r[rL] = pop8(); r[rH] = pop8(); return 12; case 0xf1: r[rF] = pop8() & 0xf0; r[rA] = pop8(); return 12; case 0xc2: return jump((r[rF] & FLAGZ) == 0); case 0xd2: return jump((r[rF] & FLAGC) == 0); case 0xe2: memwrite(0xff00 | r[rC], r[rA]); return 8; case 0xf2: r[rA] = memread(0xff00 | r[rC]); return 8; case 0xc3: return jump(1); case 0xf3: ime = 0; return 4; case 0xc4: return call(fetch16(), (r[rF] & FLAGZ) == 0); case 0xd4: return call(fetch16(), (r[rF] & FLAGC) == 0); case 0xc5: push8(r[rB]); push8(r[rC]); return 16; case 0xd5: push8(r[rD]); push8(r[rE]); return 16; case 0xe5: push8(r[rH]); push8(r[rL]); return 16; case 0xf5: push8(r[rA]); push8(r[rF]); return 16; case 0xc6: return alu(0, 8); case 0xd6: return alu(2, 8); case 0xe6: return alu(4, 8); case 0xf6: return alu(6, 8); case 0xc7: return call(0x00, -1); case 0xd7: return call(0x10, -1); case 0xe7: return call(0x20, -1); case 0xf7: return call(0x30, -1); case 0xc8: if((r[rF] & FLAGZ) != 0) {pc = pop16(); return 20;} return 8; case 0xd8: if((r[rF] & FLAGC) != 0) {pc = pop16(); return 20;} return 8; case 0xe8: case 0xf8: s = fetch8(); v = sp + s; v4 = (sp & 0xf) + (s & 0xf); w = (sp & 0xff) + (s & 0xff); r[rF] = 0; if(v4 >= 0x10) r[rF] |= FLAGH; if(w >= 0x100) r[rF] |= FLAGC; if(op == 0xe8){ sp = v; return 16; }else{ r[rL] = v; r[rH] = v >> 8; return 12; } case 0xc9: pc = pop16(); return 16; case 0xd9: pc = pop16(); ime = 1; return 16; case 0xe9: pc = HL(); return 4; case 0xf9: sp = HL(); return 8; case 0xca: return jump((r[rF] & FLAGZ) != 0); case 0xda: return jump((r[rF] & FLAGC) != 0); case 0xea: memwrite(fetch16(), r[rA]); return 16; case 0xfa: r[rA] = memread(fetch16()); return 16; case 0xcb: return bits(); case 0xfb: ime = 1; return 4; case 0xcc: return call(fetch16(), (r[rF] & FLAGZ) != 0); case 0xdc: return call(fetch16(), (r[rF] & FLAGC) != 0); case 0xcd: return call(fetch16(), 1); case 0xce: return alu(1, 8); case 0xde: return alu(3, 8); case 0xee: return alu(5, 8); case 0xfe: return alu(7, 8); case 0xcf: return call(0x08, -1); case 0xdf: return call(0x18, -1); case 0xef: return call(0x28, -1); case 0xff: return call(0x38, -1); } sysfatal("undefined opcode %#.2x at pc=%#.4x", op, curpc); return 0; }