md-joe.cpp

   1 // DGen/SDL v1.15+
   2
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6 #include "md.h"
   7 #include "decode.h"
   8
   9 // These are my (Joe's) functions added to the md class.
  10
  11 // This takes a comma or whitespace-separated list of Game Genie and/or hex
  12 // codes to patch the ROM with.
  13 void md::patch(const char *list)
  14 {
  15   static const char delims[] = " \t\n,";
  16   char *worklist, *tok;
  17   struct patch p;
  18
  19   // Copy the given list to a working list so we can strtok it
  20   worklist = (char*)malloc(strlen(list)+1);
  21   strcpy(worklist, list);
  22
  23   for(tok = strtok(worklist, delims); tok; tok = strtok(NULL, delims))
  24     {
  25       // If it's empty, toss it
  26       if(*tok == '\0') continue;
  27       // Decode it
  28       decode(tok, &p);
  29       // Discard it if it was bad code
  30       if((signed)p.addr == -1) {
  31         printf("Bad patch \"%s\"\n", tok);
  32         continue;
  33       }
  34       // Put it into the ROM (remember byteswapping)
  35       printf("Patch \"%s\" -> %06X:%04X\n", tok, p.addr, p.data);
  36       rom[p.addr] = (char)(p.data & 0xFF);
  37       rom[p.addr+1] = (char)((p.data & 0xFF00) >> 8);
  38     }
  39   // Done!
  40   free(worklist);
  41   return;
  42 }
  43
  44 // Get/put saveram from/to FILE*'s
  45 void md::get_save_ram(FILE *from)
  46 {
  47   // Pretty simple, just read the saveram raw
  48   fread((void*)saveram, 1, save_len, from);
  49 }
  50
  51 void md::put_save_ram(FILE *into)
  52 {
  53   // Just the opposite of the above :)
  54   fwrite((void*)saveram, 1, save_len, into);
  55 }
  56
  57 // Dave: This is my code, but I thought it belonged here
  58 // Joe: Thanks Dave! No problem ;)
  59 static unsigned short calculate_checksum(unsigned char *rom,int len)
  60 {
  61   unsigned short checksum=0;
  62   int i;
  63   for (i=512;i<=(len-2);i+=2)
  64   {
  65     checksum+=(rom[i+1]<<8);
  66     checksum+=rom[i+0];
  67   }
  68   return checksum;
  69 }
  70
  71 void md::fix_rom_checksum()
  72 {
  73   unsigned short cs; cs=calculate_checksum(rom,romlen);
  74   if (romlen>=0x190) { rom[0x18f]=cs>>8; rom[0x18e]=cs&255; }
  75 }
  76