123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521 |
- /* 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 "memory.h"
- #include "patch.h"
- #ifdef USE_LIBRETRO_VFS
- #include "file_stream_transforms.h"
- #endif
- struct patch
- {
- unsigned int addr;
- unsigned short data;
- unsigned char comp;
- };
- struct patch_inst *PicoPatches = NULL;
- int PicoPatchCount = 0;
- static char genie_chars_md[] = "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_md(const char* code, struct patch* result)
- {
- int i = 0, n;
- char* x;
- for(; i < 9; ++i)
- {
- /* Skip i=4; it's going to be the separating hyphen */
- if (i==4) continue;
- /* If strchr returns NULL, we were given a bad character */
- if(!(x = strchr(genie_chars_md, code[i])))
- {
- result->addr = -1; result->data = -1;
- return;
- }
- n = (x - genie_chars_md) >> 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 5:
- /* ____ ABCD ____ ____ ____ ____ : ___E ____ ____ ____ */
- result->data |= (n & 1) << 12;
- result->addr |= (n >> 1) << 16;
- break;
- case 6:
- /* ____ ____ ____ ____ ____ ____ : E___ ABCD ____ ____ */
- result->data |= (n & 1) << 15 | (n >> 1) << 8;
- break;
- case 7:
- /* ____ ____ ____ ____ CDE_ ____ : _AB_ ____ ____ ____ */
- result->data |= (n >> 3) << 13;
- result->addr |= (n & 7) << 5;
- break;
- case 8:
- /* ____ ____ ____ ____ ___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_md(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 = 7; i < 11; ++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- if (i==8) break;
- result->addr = result->data = -1;
- return;
- }
- result->data = (result->data << 4) | ((x - hex_chars) >> 1);
- }
- }
- void genie_decode_ms(const char *code, struct patch *result)
- {
- char *x;
- int i;
- /* 2 digits for data */
- for(i=0;i<2;++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->data = (result->data << 4) | ((x - hex_chars) >> 1);
- }
- /* 4 digits for address */
- for(i=2;i<7;++i)
- {
- /* 4th character is hyphen and can be skipped*/
- if (i==3) continue;
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->addr = (result->addr << 4) | ((x - hex_chars) >> 1);
- }
- /* Correct the address */
- result->addr = ((result->addr >> 4) | (result->addr << 12 & 0xF000)) ^ 0xF000;
- /* Optional: 3 digits for comp */
- if (code[7]=='-')
- {
- for(i=8;i<11;++i)
- {
- if (i==9) continue; /* 2nd character is ignored */
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->comp = (result->comp << 4) | ((x - hex_chars) >> 1);
- }
- /* Correct the comp */
- result->comp = ((result->comp >> 2) | ((result->comp << 6) & 0xC0)) ^ 0xBA;
- }
- }
- void ar_decode_ms(const char *code, struct patch *result){
- char *x;
- int i;
- /* 2 digits of padding*/
- /* 4 digits for address */
- for(i=2;i<7;++i)
- {
- /* 5th character is hyphen and can be skipped*/
- if (i==4) continue;
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->addr = (result->addr << 4) | ((x - hex_chars) >> 1);
- }
- /* 2 digits for data */
- for(i=7;i<9;++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->data = (result->data << 4) | ((x - hex_chars) >> 1);
- }
- }
- void fusion_ram_decode(const char *code, struct patch *result){
- char *x;
- int i;
- /* 4 digits for address */
- for(i=0;i<4;++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->addr = (result->addr << 4) | ((x - hex_chars) >> 1);
- }
- /* Skip the ':' */
- /* 2 digits for data */
- for(i=5;i<7;++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->data = (result->data << 4) | ((x - hex_chars) >> 1);
- }
- }
- void fusion_rom_decode(const char *code, struct patch *result){
- char *x;
- int i;
- /* 2 digits for comp */
- for(i=0;i<2;++i)
- {
- if(!(x = strchr(hex_chars, code[i])))
- {
- result->addr = result->data = -1;
- return;
- }
- result->comp = (result->comp << 4) | ((x - hex_chars) >> 1);
- }
- /* 4 digits for address */
- for(i=2;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);
- }
- /* 2 digits for data */
- for(i=7;i<9;++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. */
- void decode(const char* code, struct patch* result)
- {
- int len = strlen(code);
- /* Initialize the result */
- result->addr = result->data = result->comp = 0;
- if(!(PicoIn.AHW & PAHW_SMS))
- {
- //If Genesis
- //Game Genie
- if(len == 9 && code[4] == '-')
- {
- genie_decode_md(code, result);
- return;
- }
- //Master
- else if(len >=9 && code[6] == ':')
- {
- hex_decode_md(code, result);
- }
- else
- {
- goto bad_code;
- }
- } else {
- //If Master System
- //Genie
- if(len >= 7 && code[3] == '-')
- {
- genie_decode_ms(code, result);
- }
- //AR
- else if(len == 9 && code[4] == '-')
- {
- ar_decode_ms(code, result);
- }
- //Fusion RAM
- else if(len == 7 && code[4] == ':')
- {
- fusion_ram_decode(code, result);
- }
- //Fusion ROM
- else if(len == 9 && code[6] == ':')
- {
- fusion_rom_decode(code, result);
- }
- else
- {
- goto bad_code;
- }
- //Convert RAM address space to Genesis location.
- if (result->addr>=0xC000)
- result->addr= 0xFF0000 | (0x1FFF & result->addr);
- }
- return;
- bad_code:
- result->data = result->addr = -1;
- return;
- }
- 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;
- int addr;
- for (i = 0; i < PicoPatchCount; i++)
- {
- addr=PicoPatches[i].addr;
- addr &= ~1;
- if (addr < Pico.romsize)
- PicoPatches[i].data_old = *(u16 *)(Pico.rom + addr);
- else
- {
- if(!(PicoIn.AHW & PAHW_SMS))
- PicoPatches[i].data_old = (u16) m68k_read16(addr);
- else
- ;// wrong: PicoPatches[i].data_old = (unsigned char) PicoRead8_z80(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)
- {
- if (!(PicoIn.AHW & PAHW_SMS))
- *(u16 *)(Pico.rom + addr) = PicoPatches[i].data;
- else if (!PicoPatches[i].comp || PicoPatches[i].comp == *(char *)(Pico.rom + addr))
- *(char *)(Pico.rom + addr) = (char) 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)
- {
- if (!(PicoIn.AHW & PAHW_SMS))
- *(u16 *)(Pico.rom + addr) = PicoPatches[i].data_old;
- else
- *(char *)(Pico.rom + addr) = (char) PicoPatches[i].data_old;
- }
- }
- // fprintf(stderr, "patched %i: %06x:%04x\n", PicoPatches[i].active, addr,
- // *(u16 *)(Pico.rom + addr));
- }
- else
- {
- if (PicoPatches[i].active)
- {
- if (!(PicoIn.AHW & PAHW_SMS))
- m68k_write16(addr,PicoPatches[i].data);
- else
- ;// wrong: PicoWrite8_z80(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)
- {
- if (!(PicoIn.AHW & PAHW_SMS))
- m68k_write16(PicoPatches[i].addr,PicoPatches[i].data_old);
- else
- ;// wrong: PicoWrite8_z80(PicoPatches[i].addr,PicoPatches[i].data_old);
- }
- }
- }
- }
- }
|