123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335 |
- /* Decode a Game Genie code into an M68000 address/data pair.
- * The Game Genie code is made of the characters
- * ABCDEFGHJKLMNPRSTVWXYZ0123456789 (notice the missing I, O, Q and U).
- * Where A = 00000, B = 00001, C = 00010, ... , on to 9 = 11111.
- *
- * These come out to a very scrambled bit pattern like this:
- * (SCRA-MBLE is just an example)
- *
- * S C R A - M B L E
- * 01111 00010 01110 00000 01011 00001 01010 00100
- * ijklm nopIJ KLMNO PABCD EFGHd efgha bcQRS TUVWX
- *
- * Our goal is to rearrange that to this:
- *
- * 0000 0101 1001 1100 0100 0100 : 1011 0000 0111 1000
- * ABCD EFGH IJKL MNOP QRST UVWX : abcd efgh ijkl mnop
- *
- * which in Hexadecimal is 059C44:B078. Simple, huh? ;)
- *
- * So, then, we dutifully change memory location 059C44 to B078!
- * (of course, that's handled by a different source file :)
- */
- #include "pico_int.h"
- #include "patch.h"
- struct patch
- {
- unsigned int addr;
- unsigned short data;
- };
- struct patch_inst *PicoPatches = NULL;
- int PicoPatchCount = 0;
- static char genie_chars[] = "AaBbCcDdEeFfGgHhJjKkLlMmNnPpRrSsTtVvWwXxYyZz0O1I2233445566778899";
- /* genie_decode
- * This function converts a Game Genie code to an address:data pair.
- * The code is given as an 8-character string, like "BJX0SA1C". It need not
- * be null terminated, since only the first 8 characters are taken. It is
- * assumed that the code is already made of valid characters, i.e. there are no
- * Q's, U's, or symbols. If such a character is
- * encountered, the function will return with a warning on stderr.
- *
- * The resulting address:data pair is returned in the struct patch pointed to
- * by result. If an error results, both the address and data will be set to -1.
- */
- static void genie_decode(const char* code, struct patch* result)
- {
- int i = 0, n;
- char* x;
- for(; i < 8; ++i)
- {
- /* If strchr returns NULL, we were given a bad character */
- if(!(x = strchr(genie_chars, code[i])))
- {
- result->addr = -1; result->data = -1;
- return;
- }
- n = (x - genie_chars) >> 1;
- /* Now, based on which character this is, fit it into the result */
- switch(i)
- {
- case 0:
- /* ____ ____ ____ ____ ____ ____ : ____ ____ ABCD E___ */
- result->data |= n << 3;
- break;
- case 1:
- /* ____ ____ DE__ ____ ____ ____ : ____ ____ ____ _ABC */
- result->data |= n >> 2;
- result->addr |= (n & 3) << 14;
- break;
- case 2:
- /* ____ ____ __AB CDE_ ____ ____ : ____ ____ ____ ____ */
- result->addr |= n << 9;
- break;
- case 3:
- /* BCDE ____ ____ ___A ____ ____ : ____ ____ ____ ____ */
- result->addr |= (n & 0xF) << 20 | (n >> 4) << 8;
- break;
- case 4:
- /* ____ ABCD ____ ____ ____ ____ : ___E ____ ____ ____ */
- result->data |= (n & 1) << 12;
- result->addr |= (n >> 1) << 16;
- break;
- case 5:
- /* ____ ____ ____ ____ ____ ____ : E___ ABCD ____ ____ */
- result->data |= (n & 1) << 15 | (n >> 1) << 8;
- break;
- case 6:
- /* ____ ____ ____ ____ CDE_ ____ : _AB_ ____ ____ ____ */
- result->data |= (n >> 3) << 13;
- result->addr |= (n & 7) << 5;
- break;
- case 7:
- /* ____ ____ ____ ____ ___A BCDE : ____ ____ ____ ____ */
- result->addr |= n;
- break;
- }
- /* Go around again */
- }
- return;
- }
- /* "Decode" an address/data pair into a structure. This is for "012345:ABCD"
- * type codes. You're more likely to find Genie codes circulating around, but
- * there's a chance you could come on to one of these. Which is nice, since
- * they're MUCH easier to implement ;) Once again, the input should be depunc-
- * tuated already. */
- static char hex_chars[] = "00112233445566778899AaBbCcDdEeFf";
- static void hex_decode(const char *code, struct patch *result)
- {
- char *x;
- int i;
- /* 6 digits for address */
- for(i = 0; i < 6; ++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->addr = (result->addr << 4) | ((x - hex_chars) >> 1);
- }
- /* 4 digits for data */
- for(i = 6; i < 10; ++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->data = (result->data << 4) | ((x - hex_chars) >> 1);
- }
- }
- /* THIS is the function you call from the MegaDrive or whatever. This figures
- * out whether it's a genie or hex code, depunctuates it, and calls the proper
- * decoder. */
- static void decode(const char* code, struct patch* result)
- {
- int len = strlen(code), i, j;
- char code_to_pass[16], *x;
- const char *ad, *da;
- int adl, dal;
- /* Initialize the result */
- result->addr = result->data = 0;
- /* Just assume 8 char long string to be Game Genie code */
- if (len == 8)
- {
- genie_decode(code, result);
- return;
- }
- /* If it's 9 chars long and the 5th is a hyphen, we have a Game Genie
- * code. */
- if(len == 9 && code[4] == '-')
- {
- /* Remove the hyphen and pass to genie_decode */
- code_to_pass[0] = code[0];
- code_to_pass[1] = code[1];
- code_to_pass[2] = code[2];
- code_to_pass[3] = code[3];
- code_to_pass[4] = code[5];
- code_to_pass[5] = code[6];
- code_to_pass[6] = code[7];
- code_to_pass[7] = code[8];
- code_to_pass[8] = '\0';
- genie_decode(code_to_pass, result);
- return;
- }
- /* Otherwise, we assume it's a hex code.
- * Find the colon so we know where address ends and data starts. If there's
- * no colon, then we haven't a code at all! */
- if(!(x = strchr(code, ':'))) goto bad_code;
- ad = code; da = x + 1; adl = x - code; dal = len - adl - 1;
- /* If a section is empty or too long, toss it */
- if(adl == 0 || adl > 6 || dal == 0 || dal > 4) goto bad_code;
- /* Pad the address with zeros, then fill it with the value */
- for(i = 0; i < (6 - adl); ++i) code_to_pass[i] = '0';
- for(j = 0; i < 6; ++i, ++j) code_to_pass[i] = ad[j];
- /* Do the same for data */
- for(i = 6; i < (10 - dal); ++i) code_to_pass[i] = '0';
- for(j = 0; i < 10; ++i, ++j) code_to_pass[i] = da[j];
- code_to_pass[10] = '\0';
- /* Decode and goodbye */
- hex_decode(code_to_pass, result);
- return;
- bad_code:
- /* AGH! Invalid code! */
- result->data = result->addr = -1;
- return;
- }
- unsigned int PicoRead16(unsigned int a);
- void PicoWrite16(unsigned int a, unsigned short d);
- void PicoPatchUnload(void)
- {
- if (PicoPatches != NULL)
- {
- free(PicoPatches);
- PicoPatches = NULL;
- }
- PicoPatchCount = 0;
- }
- int PicoPatchLoad(const char *fname)
- {
- FILE *f;
- char buff[256];
- struct patch pt;
- int array_len = 0;
- PicoPatchUnload();
- f = fopen(fname, "r");
- if (f == NULL)
- {
- return -1;
- }
- while (fgets(buff, sizeof(buff), f))
- {
- int llen, clen;
- llen = strlen(buff);
- for (clen = 0; clen < llen; clen++)
- if (isspace_(buff[clen]))
- break;
- buff[clen] = 0;
- if (clen > 11 || clen < 8)
- continue;
- decode(buff, &pt);
- if (pt.addr == (unsigned int)-1 || pt.data == (unsigned short)-1)
- continue;
- /* code was good, add it */
- if (array_len < PicoPatchCount + 1)
- {
- void *ptr;
- array_len *= 2;
- array_len++;
- ptr = realloc(PicoPatches, array_len * sizeof(PicoPatches[0]));
- if (ptr == NULL) break;
- PicoPatches = ptr;
- }
- strcpy(PicoPatches[PicoPatchCount].code, buff);
- /* strip */
- for (clen++; clen < llen; clen++)
- if (!isspace_(buff[clen]))
- break;
- for (llen--; llen > 0; llen--)
- if (!isspace_(buff[llen]))
- break;
- buff[llen+1] = 0;
- strncpy(PicoPatches[PicoPatchCount].name, buff + clen, 51);
- PicoPatches[PicoPatchCount].name[51] = 0;
- PicoPatches[PicoPatchCount].active = 0;
- PicoPatches[PicoPatchCount].addr = pt.addr;
- PicoPatches[PicoPatchCount].data = pt.data;
- PicoPatches[PicoPatchCount].data_old = 0;
- PicoPatchCount++;
- // fprintf(stderr, "loaded patch #%i: %06x:%04x \"%s\"\n", PicoPatchCount-1, pt.addr, pt.data,
- // PicoPatches[PicoPatchCount-1].name);
- }
- fclose(f);
- return 0;
- }
- /* to be called when the Rom is loaded and byteswapped */
- void PicoPatchPrepare(void)
- {
- int i;
- for (i = 0; i < PicoPatchCount; i++)
- {
- PicoPatches[i].addr &= ~1;
- if (PicoPatches[i].addr < Pico.romsize)
- PicoPatches[i].data_old = *(unsigned short *)(Pico.rom + PicoPatches[i].addr);
- if (strstr(PicoPatches[i].name, "AUTO"))
- PicoPatches[i].active = 1;
- }
- }
- void PicoPatchApply(void)
- {
- int i, u;
- unsigned int addr;
- for (i = 0; i < PicoPatchCount; i++)
- {
- addr = PicoPatches[i].addr;
- if (addr < Pico.romsize)
- {
- if (PicoPatches[i].active)
- *(unsigned short *)(Pico.rom + addr) = PicoPatches[i].data;
- else {
- // if current addr is not patched by older patch, write back original val
- for (u = 0; u < i; u++)
- if (PicoPatches[u].addr == addr) break;
- if (u == i)
- *(unsigned short *)(Pico.rom + addr) = PicoPatches[i].data_old;
- }
- // fprintf(stderr, "patched %i: %06x:%04x\n", PicoPatches[i].active, addr,
- // *(unsigned short *)(Pico.rom + addr));
- }
- else
- {
- /* TODO? */
- }
- }
- }
|