b67ef287 |
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 | |
efcba75f |
24 | #include "pico_int.h" |
25 | #include "patch.h" |
b67ef287 |
26 | |
27 | struct patch |
28 | { |
5c4adfba |
29 | unsigned int addr; |
30 | unsigned short data; |
31 | unsigned char comp; |
b67ef287 |
32 | }; |
33 | |
34 | struct patch_inst *PicoPatches = NULL; |
35 | int PicoPatchCount = 0; |
36 | |
fa55ee51 |
37 | static char genie_chars_md[] = "AaBbCcDdEeFfGgHhJjKkLlMmNnPpRrSsTtVvWwXxYyZz0O1I2233445566778899"; |
b67ef287 |
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 | |
fa55ee51 |
51 | static void genie_decode_md(const char* code, struct patch* result) |
b67ef287 |
52 | { |
53 | int i = 0, n; |
54 | char* x; |
55 | |
fa55ee51 |
56 | for(; i < 9; ++i) |
b67ef287 |
57 | { |
fa55ee51 |
58 | /* Skip i=4; it's going to be the separating hyphen */ |
59 | if (i==4) continue; |
60 | |
b67ef287 |
61 | /* If strchr returns NULL, we were given a bad character */ |
fa55ee51 |
62 | if(!(x = strchr(genie_chars_md, code[i]))) |
b67ef287 |
63 | { |
64 | result->addr = -1; result->data = -1; |
65 | return; |
66 | } |
fa55ee51 |
67 | n = (x - genie_chars_md) >> 1; |
b67ef287 |
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; |
fa55ee51 |
88 | case 5: |
b67ef287 |
89 | /* ____ ABCD ____ ____ ____ ____ : ___E ____ ____ ____ */ |
90 | result->data |= (n & 1) << 12; |
91 | result->addr |= (n >> 1) << 16; |
92 | break; |
fa55ee51 |
93 | case 6: |
b67ef287 |
94 | /* ____ ____ ____ ____ ____ ____ : E___ ABCD ____ ____ */ |
95 | result->data |= (n & 1) << 15 | (n >> 1) << 8; |
96 | break; |
fa55ee51 |
97 | case 7: |
b67ef287 |
98 | /* ____ ____ ____ ____ CDE_ ____ : _AB_ ____ ____ ____ */ |
99 | result->data |= (n >> 3) << 13; |
100 | result->addr |= (n & 7) << 5; |
101 | break; |
fa55ee51 |
102 | case 8: |
b67ef287 |
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 | |
fa55ee51 |
120 | static void hex_decode_md(const char *code, struct patch *result) |
b67ef287 |
121 | { |
122 | char *x; |
123 | int i; |
124 | /* 6 digits for address */ |
125 | for(i = 0; i < 6; ++i) |
fa55ee51 |
126 | { |
127 | if(!(x = strchr(hex_chars, code[i]))) |
b67ef287 |
128 | { |
fa55ee51 |
129 | result->addr = result->data = -1; |
130 | return; |
b67ef287 |
131 | } |
fa55ee51 |
132 | result->addr = (result->addr << 4) | ((x - hex_chars) >> 1); |
133 | } |
b67ef287 |
134 | /* 4 digits for data */ |
fa55ee51 |
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 */ |
5c4adfba |
176 | printf("CHEAT: code[8]==%c\n",code[8]); |
177 | if (code[7]=='-'){ |
fa55ee51 |
178 | for(i=8;i<11;++i) |
b67ef287 |
179 | { |
fa55ee51 |
180 | if (i==9) continue; /* 2nd character is ignored */ |
b67ef287 |
181 | if(!(x = strchr(hex_chars, code[i]))) |
182 | { |
5c4adfba |
183 | result->addr = result->data = -1; |
184 | return; |
b67ef287 |
185 | } |
fa55ee51 |
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; |
b67ef287 |
257 | } |
fa55ee51 |
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 | } |
b67ef287 |
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. */ |
20563b60 |
285 | void decode(const char* code, struct patch* result) |
b67ef287 |
286 | { |
fa55ee51 |
287 | int len = strlen(code); |
b67ef287 |
288 | |
289 | /* Initialize the result */ |
fa55ee51 |
290 | result->addr = result->data = result->comp = 0; |
b67ef287 |
291 | |
fa55ee51 |
292 | if(!(PicoAHW & PAHW_SMS)) |
b67ef287 |
293 | { |
fa55ee51 |
294 | //If Genesis |
b67ef287 |
295 | |
fa55ee51 |
296 | //Game Genie |
b67ef287 |
297 | if(len == 9 && code[4] == '-') |
298 | { |
fa55ee51 |
299 | genie_decode_md(code, result); |
b67ef287 |
300 | return; |
301 | } |
302 | |
fa55ee51 |
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 |
b67ef287 |
315 | |
fa55ee51 |
316 | //Genie |
ba47d3df |
317 | if(len >= 7 && code[3] == '-') |
fa55ee51 |
318 | { |
319 | genie_decode_ms(code, result); |
320 | } |
b67ef287 |
321 | |
fa55ee51 |
322 | //AR |
323 | else if(len == 9 && code[4] == '-') |
324 | { |
325 | ar_decode_ms(code, result); |
326 | } |
b67ef287 |
327 | |
fa55ee51 |
328 | //Fusion RAM |
329 | else if(len == 7 && code[4] == ':') |
330 | { |
331 | fusion_ram_decode(code, result); |
332 | } |
b67ef287 |
333 | |
fa55ee51 |
334 | //Fusion ROM |
335 | else if(len == 9 && code[6] == ':') |
336 | { |
337 | fusion_rom_decode(code, result); |
338 | } |
b67ef287 |
339 | |
fa55ee51 |
340 | else |
341 | { |
342 | goto bad_code; |
343 | } |
b67ef287 |
344 | |
fa55ee51 |
345 | //Convert RAM address space to Genesis location. |
346 | if (result->addr>=0xC000) |
347 | result->addr= 0xFF0000 | (0x1FFF & result->addr); |
348 | } |
b67ef287 |
349 | |
fa55ee51 |
350 | return; |
351 | |
352 | bad_code: |
b67ef287 |
353 | result->data = result->addr = -1; |
354 | return; |
355 | } |
356 | |
357 | |
358 | |
eff55556 |
359 | unsigned int PicoRead16(unsigned int a); |
b67ef287 |
360 | void PicoWrite16(unsigned int a, unsigned short d); |
daae6156 |
361 | extern unsigned short m68k_read16(unsigned int a); |
fa55ee51 |
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); |
b67ef287 |
365 | |
366 | void PicoPatchUnload(void) |
367 | { |
5c4adfba |
368 | if (PicoPatches != NULL) |
369 | { |
370 | free(PicoPatches); |
371 | PicoPatches = NULL; |
372 | } |
373 | PicoPatchCount = 0; |
b67ef287 |
374 | } |
375 | |
376 | int PicoPatchLoad(const char *fname) |
377 | { |
5c4adfba |
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; |
b67ef287 |
440 | } |
441 | |
442 | /* to be called when the Rom is loaded and byteswapped */ |
443 | void PicoPatchPrepare(void) |
444 | { |
5c4adfba |
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); |
fa55ee51 |
454 | else |
5c4adfba |
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 | } |
b67ef287 |
464 | } |
465 | |
466 | void PicoPatchApply(void) |
467 | { |
5c4adfba |
468 | int i, u; |
469 | unsigned int addr; |
fa55ee51 |
470 | |
5c4adfba |
471 | for (i = 0; i < PicoPatchCount; i++) |
472 | { |
473 | addr = PicoPatches[i].addr; |
b67ef287 |
474 | |
5c4adfba |
475 | if (addr < Pico.romsize) |
fa55ee51 |
476 | { |
5c4adfba |
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 | } |
fa55ee51 |
497 | // fprintf(stderr, "patched %i: %06x:%04x\n", PicoPatches[i].active, addr, |
5c4adfba |
498 | // *(unsigned short *)(Pico.rom + addr)); |
fa55ee51 |
499 | } |
500 | else |
501 | { |
5c4adfba |
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 | } |
fa55ee51 |
522 | } |
5c4adfba |
523 | } |
b67ef287 |
524 | } |
525 | |