| 1 | /* Decode a Game Genie code into an M68000 address/data pair. |
| 2 | * The Game Genie code is made of the characters |
| 3 | * ABCDEFGHJKLMNPRSTVWXYZ0123456789 (notice the missing I, O, Q and U). |
| 4 | * Where A = 00000, B = 00001, C = 00010, ... , on to 9 = 11111. |
| 5 | * |
| 6 | * These come out to a very scrambled bit pattern like this: |
| 7 | * (SCRA-MBLE is just an example) |
| 8 | * |
| 9 | * S C R A - M B L E |
| 10 | * 01111 00010 01110 00000 01011 00001 01010 00100 |
| 11 | * ijklm nopIJ KLMNO PABCD EFGHd efgha bcQRS TUVWX |
| 12 | * |
| 13 | * Our goal is to rearrange that to this: |
| 14 | * |
| 15 | * 0000 0101 1001 1100 0100 0100 : 1011 0000 0111 1000 |
| 16 | * ABCD EFGH IJKL MNOP QRST UVWX : abcd efgh ijkl mnop |
| 17 | * |
| 18 | * which in Hexadecimal is 059C44:B078. Simple, huh? ;) |
| 19 | * |
| 20 | * So, then, we dutifully change memory location 059C44 to B078! |
| 21 | * (of course, that's handled by a different source file :) |
| 22 | */ |
| 23 | |
| 24 | #include "pico_int.h" |
| 25 | #include "patch.h" |
| 26 | |
| 27 | struct patch |
| 28 | { |
| 29 | unsigned int addr; |
| 30 | unsigned short data; |
| 31 | unsigned char comp; |
| 32 | }; |
| 33 | |
| 34 | struct patch_inst *PicoPatches = NULL; |
| 35 | int PicoPatchCount = 0; |
| 36 | |
| 37 | static char genie_chars_md[] = "AaBbCcDdEeFfGgHhJjKkLlMmNnPpRrSsTtVvWwXxYyZz0O1I2233445566778899"; |
| 38 | |
| 39 | /* genie_decode |
| 40 | * This function converts a Game Genie code to an address:data pair. |
| 41 | * The code is given as an 8-character string, like "BJX0SA1C". It need not |
| 42 | * be null terminated, since only the first 8 characters are taken. It is |
| 43 | * assumed that the code is already made of valid characters, i.e. there are no |
| 44 | * Q's, U's, or symbols. If such a character is |
| 45 | * encountered, the function will return with a warning on stderr. |
| 46 | * |
| 47 | * The resulting address:data pair is returned in the struct patch pointed to |
| 48 | * by result. If an error results, both the address and data will be set to -1. |
| 49 | */ |
| 50 | |
| 51 | static void genie_decode_md(const char* code, struct patch* result) |
| 52 | { |
| 53 | int i = 0, n; |
| 54 | char* x; |
| 55 | |
| 56 | for(; i < 9; ++i) |
| 57 | { |
| 58 | /* Skip i=4; it's going to be the separating hyphen */ |
| 59 | if (i==4) continue; |
| 60 | |
| 61 | /* If strchr returns NULL, we were given a bad character */ |
| 62 | if(!(x = strchr(genie_chars_md, code[i]))) |
| 63 | { |
| 64 | result->addr = -1; result->data = -1; |
| 65 | return; |
| 66 | } |
| 67 | n = (x - genie_chars_md) >> 1; |
| 68 | /* Now, based on which character this is, fit it into the result */ |
| 69 | switch(i) |
| 70 | { |
| 71 | case 0: |
| 72 | /* ____ ____ ____ ____ ____ ____ : ____ ____ ABCD E___ */ |
| 73 | result->data |= n << 3; |
| 74 | break; |
| 75 | case 1: |
| 76 | /* ____ ____ DE__ ____ ____ ____ : ____ ____ ____ _ABC */ |
| 77 | result->data |= n >> 2; |
| 78 | result->addr |= (n & 3) << 14; |
| 79 | break; |
| 80 | case 2: |
| 81 | /* ____ ____ __AB CDE_ ____ ____ : ____ ____ ____ ____ */ |
| 82 | result->addr |= n << 9; |
| 83 | break; |
| 84 | case 3: |
| 85 | /* BCDE ____ ____ ___A ____ ____ : ____ ____ ____ ____ */ |
| 86 | result->addr |= (n & 0xF) << 20 | (n >> 4) << 8; |
| 87 | break; |
| 88 | case 5: |
| 89 | /* ____ ABCD ____ ____ ____ ____ : ___E ____ ____ ____ */ |
| 90 | result->data |= (n & 1) << 12; |
| 91 | result->addr |= (n >> 1) << 16; |
| 92 | break; |
| 93 | case 6: |
| 94 | /* ____ ____ ____ ____ ____ ____ : E___ ABCD ____ ____ */ |
| 95 | result->data |= (n & 1) << 15 | (n >> 1) << 8; |
| 96 | break; |
| 97 | case 7: |
| 98 | /* ____ ____ ____ ____ CDE_ ____ : _AB_ ____ ____ ____ */ |
| 99 | result->data |= (n >> 3) << 13; |
| 100 | result->addr |= (n & 7) << 5; |
| 101 | break; |
| 102 | case 8: |
| 103 | /* ____ ____ ____ ____ ___A BCDE : ____ ____ ____ ____ */ |
| 104 | result->addr |= n; |
| 105 | break; |
| 106 | } |
| 107 | /* Go around again */ |
| 108 | } |
| 109 | return; |
| 110 | } |
| 111 | |
| 112 | /* "Decode" an address/data pair into a structure. This is for "012345:ABCD" |
| 113 | * type codes. You're more likely to find Genie codes circulating around, but |
| 114 | * there's a chance you could come on to one of these. Which is nice, since |
| 115 | * they're MUCH easier to implement ;) Once again, the input should be depunc- |
| 116 | * tuated already. */ |
| 117 | |
| 118 | static char hex_chars[] = "00112233445566778899AaBbCcDdEeFf"; |
| 119 | |
| 120 | static void hex_decode_md(const char *code, struct patch *result) |
| 121 | { |
| 122 | char *x; |
| 123 | int i; |
| 124 | /* 6 digits for address */ |
| 125 | for(i = 0; i < 6; ++i) |
| 126 | { |
| 127 | if(!(x = strchr(hex_chars, code[i]))) |
| 128 | { |
| 129 | result->addr = result->data = -1; |
| 130 | return; |
| 131 | } |
| 132 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
| 133 | } |
| 134 | /* 4 digits for data */ |
| 135 | for(i = 7; i < 11; ++i) |
| 136 | { |
| 137 | if(!(x = strchr(hex_chars, code[i]))) |
| 138 | { |
| 139 | if (i==8) break; |
| 140 | result->addr = result->data = -1; |
| 141 | return; |
| 142 | } |
| 143 | result->data = (result->data << 4) | ((x - hex_chars) >> 1); |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | void genie_decode_ms(const char *code, struct patch *result) |
| 148 | { |
| 149 | char *x; |
| 150 | int i; |
| 151 | /* 2 digits for data */ |
| 152 | for(i=0;i<2;++i) |
| 153 | { |
| 154 | if(!(x = strchr(hex_chars, code[i]))) |
| 155 | { |
| 156 | result->addr = result->data = -1; |
| 157 | return; |
| 158 | } |
| 159 | result->data = (result->data << 4) | ((x - hex_chars) >> 1); |
| 160 | } |
| 161 | /* 4 digits for address */ |
| 162 | for(i=2;i<7;++i) |
| 163 | { |
| 164 | /* 4th character is hyphen and can be skipped*/ |
| 165 | if (i==3) continue; |
| 166 | if(!(x = strchr(hex_chars, code[i]))) |
| 167 | { |
| 168 | result->addr = result->data = -1; |
| 169 | return; |
| 170 | } |
| 171 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
| 172 | } |
| 173 | /* Correct the address */ |
| 174 | result->addr = ((result->addr >> 4) | (result->addr << 12 & 0xF000)) ^ 0xF000; |
| 175 | /* Optional: 3 digits for comp */ |
| 176 | printf("CHEAT: code[8]==%c\n",code[8]); |
| 177 | if (code[7]=='-'){ |
| 178 | for(i=8;i<11;++i) |
| 179 | { |
| 180 | if (i==9) continue; /* 2nd character is ignored */ |
| 181 | if(!(x = strchr(hex_chars, code[i]))) |
| 182 | { |
| 183 | result->addr = result->data = -1; |
| 184 | return; |
| 185 | } |
| 186 | result->comp = (result->comp << 4) | ((x - hex_chars) >> 1); |
| 187 | } |
| 188 | /* Correct the comp */ |
| 189 | result->comp = ((result->comp >> 2) | ((result->comp << 6) & 0xC0)) ^ 0xBA; |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | void ar_decode_ms(const char *code, struct patch *result){ |
| 194 | char *x; |
| 195 | int i; |
| 196 | /* 2 digits of padding*/ |
| 197 | /* 4 digits for address */ |
| 198 | for(i=2;i<7;++i) |
| 199 | { |
| 200 | /* 5th character is hyphen and can be skipped*/ |
| 201 | if (i==4) continue; |
| 202 | if(!(x = strchr(hex_chars, code[i]))) |
| 203 | { |
| 204 | result->addr = result->data = -1; |
| 205 | return; |
| 206 | } |
| 207 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
| 208 | } |
| 209 | /* 2 digits for data */ |
| 210 | for(i=7;i<9;++i) |
| 211 | { |
| 212 | if(!(x = strchr(hex_chars, code[i]))) |
| 213 | { |
| 214 | result->addr = result->data = -1; |
| 215 | return; |
| 216 | } |
| 217 | result->data = (result->data << 4) | ((x - hex_chars) >> 1); |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | void fusion_ram_decode(const char *code, struct patch *result){ |
| 222 | char *x; |
| 223 | int i; |
| 224 | /* 4 digits for address */ |
| 225 | for(i=0;i<4;++i) |
| 226 | { |
| 227 | if(!(x = strchr(hex_chars, code[i]))) |
| 228 | { |
| 229 | result->addr = result->data = -1; |
| 230 | return; |
| 231 | } |
| 232 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
| 233 | } |
| 234 | /* Skip the ':' */ |
| 235 | /* 2 digits for data */ |
| 236 | for(i=5;i<7;++i) |
| 237 | { |
| 238 | if(!(x = strchr(hex_chars, code[i]))) |
| 239 | { |
| 240 | result->addr = result->data = -1; |
| 241 | return; |
| 242 | } |
| 243 | result->data = (result->data << 4) | ((x - hex_chars) >> 1); |
| 244 | } |
| 245 | } |
| 246 | |
| 247 | void fusion_rom_decode(const char *code, struct patch *result){ |
| 248 | char *x; |
| 249 | int i; |
| 250 | /* 2 digits for comp */ |
| 251 | for(i=0;i<2;++i) |
| 252 | { |
| 253 | if(!(x = strchr(hex_chars, code[i]))) |
| 254 | { |
| 255 | result->addr = result->data = -1; |
| 256 | return; |
| 257 | } |
| 258 | result->comp = (result->comp << 4) | ((x - hex_chars) >> 1); |
| 259 | } |
| 260 | /* 4 digits for address */ |
| 261 | for(i=2;i<6;++i) |
| 262 | { |
| 263 | if(!(x = strchr(hex_chars, code[i]))) |
| 264 | { |
| 265 | result->addr = result->data = -1; |
| 266 | return; |
| 267 | } |
| 268 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
| 269 | } |
| 270 | /* 2 digits for data */ |
| 271 | for(i=7;i<9;++i) |
| 272 | { |
| 273 | if(!(x = strchr(hex_chars, code[i]))) |
| 274 | { |
| 275 | result->addr = result->data = -1; |
| 276 | return; |
| 277 | } |
| 278 | result->data = (result->data << 4) | ((x - hex_chars) >> 1); |
| 279 | } |
| 280 | } |
| 281 | |
| 282 | /* THIS is the function you call from the MegaDrive or whatever. This figures |
| 283 | * out whether it's a genie or hex code, depunctuates it, and calls the proper |
| 284 | * decoder. */ |
| 285 | void decode(const char* code, struct patch* result) |
| 286 | { |
| 287 | int len = strlen(code); |
| 288 | |
| 289 | /* Initialize the result */ |
| 290 | result->addr = result->data = result->comp = 0; |
| 291 | |
| 292 | if(!(PicoAHW & PAHW_SMS)) |
| 293 | { |
| 294 | //If Genesis |
| 295 | |
| 296 | //Game Genie |
| 297 | if(len == 9 && code[4] == '-') |
| 298 | { |
| 299 | genie_decode_md(code, result); |
| 300 | return; |
| 301 | } |
| 302 | |
| 303 | //Master |
| 304 | else if(len >=9 && code[6] == ':') |
| 305 | { |
| 306 | hex_decode_md(code, result); |
| 307 | } |
| 308 | |
| 309 | else |
| 310 | { |
| 311 | goto bad_code; |
| 312 | } |
| 313 | } else { |
| 314 | //If Master System |
| 315 | |
| 316 | //Genie |
| 317 | if(len >= 7 && code[3] == '-') |
| 318 | { |
| 319 | genie_decode_ms(code, result); |
| 320 | } |
| 321 | |
| 322 | //AR |
| 323 | else if(len == 9 && code[4] == '-') |
| 324 | { |
| 325 | ar_decode_ms(code, result); |
| 326 | } |
| 327 | |
| 328 | //Fusion RAM |
| 329 | else if(len == 7 && code[4] == ':') |
| 330 | { |
| 331 | fusion_ram_decode(code, result); |
| 332 | } |
| 333 | |
| 334 | //Fusion ROM |
| 335 | else if(len == 9 && code[6] == ':') |
| 336 | { |
| 337 | fusion_rom_decode(code, result); |
| 338 | } |
| 339 | |
| 340 | else |
| 341 | { |
| 342 | goto bad_code; |
| 343 | } |
| 344 | |
| 345 | //Convert RAM address space to Genesis location. |
| 346 | if (result->addr>=0xC000) |
| 347 | result->addr= 0xFF0000 | (0x1FFF & result->addr); |
| 348 | } |
| 349 | |
| 350 | return; |
| 351 | |
| 352 | bad_code: |
| 353 | result->data = result->addr = -1; |
| 354 | return; |
| 355 | } |
| 356 | |
| 357 | |
| 358 | |
| 359 | unsigned int PicoRead16(unsigned int a); |
| 360 | void PicoWrite16(unsigned int a, unsigned short d); |
| 361 | extern unsigned short m68k_read16(unsigned int a); |
| 362 | extern void m68k_write16(unsigned int a, unsigned short d); |
| 363 | extern char PicoRead8_z80(unsigned short a); |
| 364 | extern void PicoWrite8_z80(unsigned short a, char d); |
| 365 | |
| 366 | void PicoPatchUnload(void) |
| 367 | { |
| 368 | if (PicoPatches != NULL) |
| 369 | { |
| 370 | free(PicoPatches); |
| 371 | PicoPatches = NULL; |
| 372 | } |
| 373 | PicoPatchCount = 0; |
| 374 | } |
| 375 | |
| 376 | int PicoPatchLoad(const char *fname) |
| 377 | { |
| 378 | FILE *f; |
| 379 | char buff[256]; |
| 380 | struct patch pt; |
| 381 | int array_len = 0; |
| 382 | |
| 383 | PicoPatchUnload(); |
| 384 | |
| 385 | f = fopen(fname, "r"); |
| 386 | if (f == NULL) |
| 387 | { |
| 388 | return -1; |
| 389 | } |
| 390 | |
| 391 | while (fgets(buff, sizeof(buff), f)) |
| 392 | { |
| 393 | int llen, clen; |
| 394 | |
| 395 | llen = strlen(buff); |
| 396 | for (clen = 0; clen < llen; clen++) |
| 397 | if (isspace_(buff[clen])) |
| 398 | break; |
| 399 | buff[clen] = 0; |
| 400 | |
| 401 | if (clen > 11 || clen < 8) |
| 402 | continue; |
| 403 | |
| 404 | decode(buff, &pt); |
| 405 | if (pt.addr == (unsigned int)-1 || pt.data == (unsigned short)-1) |
| 406 | continue; |
| 407 | |
| 408 | /* code was good, add it */ |
| 409 | if (array_len < PicoPatchCount + 1) |
| 410 | { |
| 411 | void *ptr; |
| 412 | array_len *= 2; |
| 413 | array_len++; |
| 414 | ptr = realloc(PicoPatches, array_len * sizeof(PicoPatches[0])); |
| 415 | if (ptr == NULL) break; |
| 416 | PicoPatches = ptr; |
| 417 | } |
| 418 | strcpy(PicoPatches[PicoPatchCount].code, buff); |
| 419 | /* strip */ |
| 420 | for (clen++; clen < llen; clen++) |
| 421 | if (!isspace_(buff[clen])) |
| 422 | break; |
| 423 | for (llen--; llen > 0; llen--) |
| 424 | if (!isspace_(buff[llen])) |
| 425 | break; |
| 426 | buff[llen+1] = 0; |
| 427 | strncpy(PicoPatches[PicoPatchCount].name, buff + clen, 51); |
| 428 | PicoPatches[PicoPatchCount].name[51] = 0; |
| 429 | PicoPatches[PicoPatchCount].active = 0; |
| 430 | PicoPatches[PicoPatchCount].addr = pt.addr; |
| 431 | PicoPatches[PicoPatchCount].data = pt.data; |
| 432 | PicoPatches[PicoPatchCount].data_old = 0; |
| 433 | PicoPatchCount++; |
| 434 | // fprintf(stderr, "loaded patch #%i: %06x:%04x \"%s\"\n", PicoPatchCount-1, pt.addr, pt.data, |
| 435 | // PicoPatches[PicoPatchCount-1].name); |
| 436 | } |
| 437 | fclose(f); |
| 438 | |
| 439 | return 0; |
| 440 | } |
| 441 | |
| 442 | /* to be called when the Rom is loaded and byteswapped */ |
| 443 | void PicoPatchPrepare(void) |
| 444 | { |
| 445 | int i; |
| 446 | int addr; |
| 447 | |
| 448 | for (i = 0; i < PicoPatchCount; i++) |
| 449 | { |
| 450 | addr=PicoPatches[i].addr; |
| 451 | addr &= ~1; |
| 452 | if (addr < Pico.romsize) |
| 453 | PicoPatches[i].data_old = *(unsigned short *)(Pico.rom + addr); |
| 454 | else |
| 455 | { |
| 456 | if(!(PicoAHW & PAHW_SMS)) |
| 457 | PicoPatches[i].data_old = (unsigned short) m68k_read16(addr); |
| 458 | else |
| 459 | PicoPatches[i].data_old = (unsigned char) PicoRead8_z80(addr); |
| 460 | } |
| 461 | if (strstr(PicoPatches[i].name, "AUTO")) |
| 462 | PicoPatches[i].active = 1; |
| 463 | } |
| 464 | } |
| 465 | |
| 466 | void PicoPatchApply(void) |
| 467 | { |
| 468 | int i, u; |
| 469 | unsigned int addr; |
| 470 | |
| 471 | for (i = 0; i < PicoPatchCount; i++) |
| 472 | { |
| 473 | addr = PicoPatches[i].addr; |
| 474 | |
| 475 | if (addr < Pico.romsize) |
| 476 | { |
| 477 | if (PicoPatches[i].active) |
| 478 | { |
| 479 | if (!(PicoAHW & PAHW_SMS)) |
| 480 | *(unsigned short *)(Pico.rom + addr) = PicoPatches[i].data; |
| 481 | else if (!PicoPatches[i].comp || PicoPatches[i].comp == *(char *)(Pico.rom + addr)) |
| 482 | *(char *)(Pico.rom + addr) = (char) PicoPatches[i].data; |
| 483 | } |
| 484 | else |
| 485 | { |
| 486 | // if current addr is not patched by older patch, write back original val |
| 487 | for (u = 0; u < i; u++) |
| 488 | if (PicoPatches[u].addr == addr) break; |
| 489 | if (u == i) |
| 490 | { |
| 491 | if (!(PicoAHW & PAHW_SMS)) |
| 492 | *(unsigned short *)(Pico.rom + addr) = PicoPatches[i].data_old; |
| 493 | else |
| 494 | *(char *)(Pico.rom + addr) = (char) PicoPatches[i].data_old; |
| 495 | } |
| 496 | } |
| 497 | // fprintf(stderr, "patched %i: %06x:%04x\n", PicoPatches[i].active, addr, |
| 498 | // *(unsigned short *)(Pico.rom + addr)); |
| 499 | } |
| 500 | else |
| 501 | { |
| 502 | if (PicoPatches[i].active) |
| 503 | { |
| 504 | if (!(PicoAHW & PAHW_SMS)) |
| 505 | m68k_write16(addr,PicoPatches[i].data); |
| 506 | else |
| 507 | PicoWrite8_z80(addr,PicoPatches[i].data); |
| 508 | } |
| 509 | else |
| 510 | { |
| 511 | // if current addr is not patched by older patch, write back original val |
| 512 | for (u = 0; u < i; u++) |
| 513 | if (PicoPatches[u].addr == addr) break; |
| 514 | if (u == i) |
| 515 | { |
| 516 | if (!(PicoAHW & PAHW_SMS)) |
| 517 | m68k_write16(PicoPatches[i].addr,PicoPatches[i].data_old); |
| 518 | else |
| 519 | PicoWrite8_z80(PicoPatches[i].addr,PicoPatches[i].data_old); |
| 520 | } |
| 521 | } |
| 522 | } |
| 523 | } |
| 524 | } |
| 525 | |