Add cheat decoding code for multiple formats.

libretro · Mar 26, 2017 · da026a5 · da026a5
1 parent e808994
commit da026a5
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Showing 2 changed files with 144 additions and 3 deletions.
diff --git a/gb/cheat/cheat.cpp b/gb/cheat/cheat.cpp
@@ -27,6 +27,14 @@ optional<unsigned> Cheat::find(unsigned addr, unsigned comp) {
 }
 
 bool Cheat::decode(const char *part, unsigned &addr, unsigned &comp, unsigned &data) {
+  /* Code Types
+   * RAW:
+   *   AAAA:DD
+   * Game Genie: http://gamehacking.org/library/114
+   * GameShark: 0BDDAAAA - Byteswapped Address, bank+1
+   * Codebreaker: 0BAAAA-DD
+   * Xploder: Unknown
+   */
   std::cerr << "[bsnes]: Decoding cheats not implemented." << std::endl;
   return false;
 }

diff --git a/sfc/cheat/cheat.cpp b/sfc/cheat/cheat.cpp
@@ -1,5 +1,6 @@
 #include <sfc/sfc.hpp>
 #include <iostream>
+#include <cstdlib>
 
 #define CHEAT_CPP
 namespace SuperFamicom {
@@ -30,13 +31,145 @@ optional<unsigned> Cheat::find(unsigned addr, unsigned comp) {
   return false;
 }
 
+static char genie_replace(char input){
+  switch (input){
+    case '0':
+      return '4';
+    case '1':
+      return '6';
+    case '2':
+      return 'D';
+    case '3':
+      return 'E';
+    case '4':
+      return '2';
+    case '5':
+      return '7';
+    case '6':
+      return '8';
+    case '7':
+      return '3';
+    case '8':
+      return 'B';
+    case '9':
+      return '5';
+    case 'A':
+    case 'a':
+      return 'C';
+    case 'B':
+    case 'b':
+      return '9';
+    case 'C':
+    case 'c':
+      return 'A';
+    case 'D':
+    case 'd':
+      return '0';
+    case 'E':
+    case 'e':
+      return 'F';
+    case 'F':
+    case 'f':
+      return '1';
+  }
+}
+
 bool Cheat::decode(const char *part, unsigned &addr, unsigned &data) {
-  std::cerr << "[bsnes]: Decoding cheats not implemented." << std::endl;
-  return false;
+  char addr_str[7], data_str[3];
+  addr_str[6]=0;
+  data_str[2]=0;
+  addr=data=0;
+
+  //RAW
+  if (strlen(part)>=9 && part[6]==':') {
+    strncpy(addr_str,part,6);
+    strncpy(data_str,part+7,2);
+    addr=strtoul(addr_str,'\0',16);
+    data=strtoul(data_str,'\0',16);
+  }
+
+  //Game Genie
+  else if (strlen(part)>=9 && part[4]=='-') {
+    strncpy(data_str,part,2);
+    strncpy(addr_str,part+2,2);
+    strncpy(addr_str+2,part+5,4);
+    for (int i=0;i<2;i++)
+      data_str[i]=genie_replace(data_str[i]);
+    for (int i=0;i<6;i++)
+      addr_str[i]=genie_replace(addr_str[i]);
+    data=strtoul(data_str,'\0',16);
+    int addr_scrambled=strtoul(addr_str,'\0',16);
+    addr=(addr_scrambled&0x003C00)<<10;
+    addr|=(addr_scrambled&0x00003C)<<14;
+    addr|=(addr_scrambled&0xF00000)>>8;
+    addr|=(addr_scrambled&0x000003)<<10;
+    addr|=(addr_scrambled&0x00C000)>>6;
+    addr|=(addr_scrambled&0x0F0000)>>12;
+    addr|=(addr_scrambled&0x0003C0)>>6;
+    return true;
+  }
+
+  //PAR & X-Terminator
+  else if (strlen(part)==8) {
+    strncpy(addr_str,part,6);
+    strncpy(data_str,part+6,2);
+    addr=strtoul(addr_str,'\0',16);
+    data=strtoul(data_str,'\0',16);
+  }
+
+  //Gold Finger
+  else if (strlen(part)==14) {
+    if (part[13]=='1'){
+      std::cout << "[bsnes]: CHEAT: Goldfinger SRAM cheats not supported: " << part << std::endl;
+      return false;
+    }
+    addr_str[0]='0';
+    strncpy(addr_str+1,part,5);
+    strncpy(data_str,part+5,2);
+    if (part[7]!='X' && part[7]!='x')
+      std::cout << "[bsnes]: CHEAT: Goldfinger multibyte cheats not supported: " << part << std::endl;
+
+    char pair_str[3];
+    pair_str[2]=0;
+    int csum_calc=0,csum_code;
+    for (int i=0;i<6;i++){
+      if (i<3){
+        strncpy(pair_str,addr_str+2*i,2);
+      } else {
+        strncpy(pair_str,part+2*i-1,2);
+      }
+      csum_calc+=strtoul(pair_str,'\0',16);
+    }
+    csum_calc-=0x160;
+    csum_calc&=0xFF;
+    strncpy(pair_str,part+11,2);
+    csum_code=strtoul(pair_str,'\0',16);
+    if (csum_calc!=csum_code){
+      std::cout << "[bsnes]: CHEAT: Goldfinger calculated checksum '" << std::hex << csum_calc <<  "' doesn't match code: " << part << std::endl;
+      return false;
+    }
+
+    int addr_scrambled=strtoul(addr_str,'\0',16);
+    addr=(addr_scrambled&0x7FFF)|((addr_scrambled&0x7F8000)<<1)|0x8000;
+    data=strtoul(data_str,'\0',16);
+    std::cout << "CHEAT: " << part << " decoded as " << std::hex <<  addr << ":" << data << std::endl;
+  }
+
+  //Unknown
+  else {
+    std::cout << "[bsnes]: CHEAT: Unrecognized code type: " << part << std::endl;
+    return false;
+  }
+
+  if (addr == 0 || data == 0){
+    std::cout << "[bsnes]: CHEAT: Decoding failed: " << part << std::endl;
+    return false;
+  }
+
+  return true;
 }
 
 void Cheat::synchronize() {
-  std::cerr << "[bsnes]: Synchronizing cheats not implemented." << std::endl;
   return;
 }