--- /dev/null
+/* 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 <stdio.h>
+//#include <string.h>
+#include <ctype.h>
+
+#include "PicoInt.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 short 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;
+ PicoPatches[i].data_old = PicoRead16(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
+ {
+ /* RAM or some other weird patch */
+ if (PicoPatches[i].active)
+ PicoWrite16(addr, PicoPatches[i].data);
+ }
+ }
+}
+
notaz.gp2x.de / picodrive.git / blobdiff