[Gamecube/Wii][libretro] added Mega-CD PRG-RAM & Word-RAM cheat codes support

gx/gui/cheats.c

@@ -3,7 +3,7 @@
  * 
  *  Genesis Plus GX Cheats menu
  *
- *  Copyright Eke-Eke (2010-2019)
+ *  Copyright Eke-Eke (2010-2022)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -456,7 +456,33 @@ static void apply_cheats(void)
   {
     if (cheatlist[i].enable)
     {
-      if (cheatlist[i].address < cart.romsize)
+      /* detect Work RAM patch */
+      if (cheatlist[i].address >= 0xFF0000)
+      {
+        /* add RAM patch */
+        cheatIndexes[maxRAMcheats++] = i;
+      }
+
+      /* check if Mega-CD game is running */
+      else if ((system_hw == SYSTEM_MCD) && !scd.cartridge.boot)
+      {
+        /* detect PRG-RAM patch (Sub-CPU side) */
+        if (cheatlist[i].address < 0x80000)
+        {
+          /* add RAM patch */
+          cheatIndexes[maxRAMcheats++] = i;
+        }
+
+        /* detect Word-RAM patch (Main-CPU side)*/
+        else if ((cheatlist[i].address >= 0x200000) && (cheatlist[i].address < 0x240000))
+        {
+          /* add RAM patch */
+          cheatIndexes[maxRAMcheats++] = i;
+        }
+      }
+
+      /* detect cartridge ROM patch */
+      else if (cheatlist[i].address < cart.romsize)
       {
         if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
         {
@@ -489,20 +515,20 @@ static void apply_cheats(void)
           }
         }
       }
-      else if (cheatlist[i].address >= 0xFF0000)
-      {
-        /* add RAM patch */
-        cheatIndexes[maxRAMcheats++] = i;
-      }
     }
   }
 }
 
 static void clear_cheats(void)
 {
-  int i = maxcheats;
+  int i;
 
-  /* disable cheats in reversed order in case the same address is used by multiple patches */
+  /* no ROM patches with Mega-CD games */
+  if ((system_hw == SYSTEM_MCD) && !scd.cartridge.boot)
+    return;
+
+  /* disable cheats in reversed order in case the same address is used by multiple ROM patches */
+  i = maxcheats;
   while (i > 0)
   {
     if (cheatlist[i-1].enable)
@@ -1501,6 +1527,8 @@ void CheatLoad(void)
  ****************************************************************************/ 
 void RAMCheatUpdate(void)
 {
+  uint8 *base;
+  uint32 mask;
   int index, cnt = maxRAMcheats;
   
   while (cnt)
@@ -1508,16 +1536,36 @@ void RAMCheatUpdate(void)
     /* get cheat index */
     index = cheatIndexes[--cnt];
 
+    /* detect destination RAM */
+    switch ((cheatlist[index].address >> 20) & 0xf)
+    {
+      case 0x0: /* Mega-CD PRG-RAM (512 KB) */
+        base = scd.prg_ram;
+        mask = 0x7fffe;
+        break;
+
+      case 0x2: /* Mega-CD 2M Word-RAM (256 KB) */
+        base = scd.word_ram_2M;
+        mask = 0x3fffe;
+        break;
+
+      default: /* Work-RAM (64 KB) */
+        base = work_ram;
+        mask = 0xfffe;
+        break;
+    }
+
     /* apply RAM patch */
     if (cheatlist[index].data & 0xFF00)
     {
       /* word patch */
-      *(u16 *)(work_ram + (cheatlist[index].address & 0xFFFE)) = cheatlist[index].data;
+      *(u16 *)(base + (cheatlist[index].address & mask)) = cheatlist[index].data;
     }
     else
     {
       /* byte patch */
-      work_ram[cheatlist[index].address & 0xFFFF] = cheatlist[index].data;
+      mask |= 1;
+      base[cheatlist[index].address & mask] = cheatlist[index].data;
     }
   }
 }

gx/gui/cheats.h

@@ -3,7 +3,7 @@
  * 
  *  Genesis Plus GX Cheats menu
  *
- *  Copyright Eke-Eke (2010-2019)
+ *  Copyright Eke-Eke (2010-2022)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:

libretro/libretro.c

@@ -2245,12 +2245,32 @@ static void apply_cheats(void)
       {
          if (cheatlist[i].address < cart.romsize)
          {
-            if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
+            /* detect Work RAM patch */
+            if (cheatlist[i].address >= 0xFF0000)
             {
-               /* patch ROM data */
+              /* add RAM patch */
-               cheatlist[i].old = *(uint16_t *)(cart.rom + (cheatlist[i].address & 0xFFFFFE));
+              cheatIndexes[maxRAMcheats++] = i;
-               *(uint16_t *)(cart.rom + (cheatlist[i].address & 0xFFFFFE)) = cheatlist[i].data;
             }
+
+            /* check if Mega-CD game is running */
+            else if ((system_hw == SYSTEM_MCD) && !scd.cartridge.boot)
+            {
+               /* detect PRG-RAM patch (Sub-CPU side) */
+               if (cheatlist[i].address < 0x80000)
+               {
+                  /* add RAM patch */
+                  cheatIndexes[maxRAMcheats++] = i;
+               }
+
+               /* detect Word-RAM patch (Main-CPU side)*/
+               else if ((cheatlist[i].address >= 0x200000) && (cheatlist[i].address < 0x240000))
+               {
+                  /* add RAM patch */
+                  cheatIndexes[maxRAMcheats++] = i;
+               }
+            }
+
+            /* detect cartridge ROM patch */
             else
             {
                /* add ROM patch */
@@ -2273,19 +2293,20 @@ static void apply_cheats(void)
                }
             }
          }
-         else if (cheatlist[i].address >= 0xFF0000)
-         {
-            /* add RAM patch */
-            cheatIndexes[maxRAMcheats++] = i;
-         }
       }
    }
 }
 
 static void clear_cheats(void)
 {
-   int i = maxcheats;
+   int i;
-   /* disable cheats in reversed order in case the same address is used by multiple patches */
+
+  /* no ROM patches with Mega-CD games */
+   if ((system_hw == SYSTEM_MCD) && !scd.cartridge.boot)
+      return;
+
+   /* disable cheats in reversed order in case the same address is used by multiple ROM patches */
+   i = maxcheats;
    while (i > 0)
    {
       if (cheatlist[i-1].enable)
@@ -2322,21 +2343,45 @@ static void clear_cheats(void)
 ****************************************************************************/
 static void RAMCheatUpdate(void)
 {
+   uint8_t *base;
+   uint32_t mask;
    int index, cnt = maxRAMcheats;
+
    while (cnt)
    {
       /* get cheat index */
       index = cheatIndexes[--cnt];
+
+      /* detect destination RAM */
+      switch ((cheatlist[index].address >> 20) & 0xf)
+      {
+         case 0x0: /* Mega-CD PRG-RAM (512 KB) */
+            base = scd.prg_ram;
+            mask = 0x7fffe;
+            break;
+
+         case 0x2: /* Mega-CD 2M Word-RAM (256 KB) */
+            base = scd.word_ram_2M;
+            mask = 0x3fffe;
+            break;
+
+         default: /* Work-RAM (64 KB) */
+            base = work_ram;
+            mask = 0xfffe;
+            break;
+      }
+
       /* apply RAM patch */
       if (cheatlist[index].data & 0xFF00)
       {
-         /* 16-bit patch */
+         /* word patch */
-         *(uint16_t *)(work_ram + (cheatlist[index].address & 0xFFFE)) = cheatlist[index].data;
+         *(uint16_t *)(base + (cheatlist[index].address & mask)) = cheatlist[index].data;
       }
       else
       {
-         /* 8-bit patch */
+          /* byte patch */
-         work_ram[cheatlist[index].address & 0xFFFF] = cheatlist[index].data;
+          mask |= 1;
+          base[cheatlist[index].address & mask] = cheatlist[index].data;
       }
    }
 }