[GB] Save MBC7 EEPROM data to gbRam

Previously, MBC7 EEPROM was saved at address 0xa000 in memory, rather than inside the `gbRam` data buffer. This was inconsistent with other mappers, resulting in issues like the EEPROM data being cleared on `gbReset`. Fixes #1173
visualboyadvance-m · Aug 28, 2023 · 803ab35 · 803ab35
1 parent 24b6ac5
commit 803ab35
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Showing 3 changed files with 15 additions and 9 deletions.
diff --git a/src/gb/GB.cpp b/src/gb/GB.cpp
@@ -422,7 +422,8 @@ bool gbInitializeRom(size_t romSize) {
 
     const size_t ramSize = g_gbCartData.ram_size();
     if (g_gbCartData.HasRam()) {
-        gbRam = (uint8_t*)malloc(ramSize);
+        // Always allocate 4 KiB to prevent access issues down the line.
+        gbRam = (uint8_t*)malloc(std::max(k4KiB, ramSize));
         if (gbRam == nullptr) {
             return false;
         }
@@ -3062,6 +3063,9 @@ void gbReset()
     memset(&gbDataHuC1, 0, sizeof(gbDataHuC1));
     gbDataHuC1.mapperROMBank = 1;
 
+    memset(&gbDataMBC7, 0, sizeof(gbDataMBC7));
+    gbDataMBC7.mapperROMBank = 1;
+
     memset(&gbDataHuC3, 0, sizeof(gbDataHuC3));
     gbDataHuC3.mapperROMBank = 1;
     gbDataHuC3.mapperRAMValue = 1;

diff --git a/src/gb/gbMemory.cpp b/src/gb/gbMemory.cpp
@@ -640,8 +640,9 @@ void mapperMBC7ROM(uint16_t address, uint8_t value)
         if (value < 8) {
             tmpAddress = (value & 3) << 13;
             tmpAddress &= g_gbCartData.ram_mask();
-            gbMemoryMap[0x0a] = &gbMemory[0xa000];
-            gbMemoryMap[0x0b] = &gbMemory[0xb000];
+            gbMemoryMap[0x0a] = &gbRam[0];
+            // Only one RAM bank for MBC7 so wrap around.
+            gbMemoryMap[0x0b] = &gbRam[0];
 
             gbDataMBC7.mapperRAMBank = value;
             gbDataMBC7.mapperRAMAddress = tmpAddress;
@@ -694,8 +695,8 @@ void mapperMBC7RAM(uint16_t address, uint8_t value)
         if (!oldCs && gbDataMBC7.cs) {
             if (gbDataMBC7.state == 5) {
                 if (gbDataMBC7.writeEnable) {
-                    gbMemory[0xa000 + gbDataMBC7.address * 2] = gbDataMBC7.buffer >> 8;
-                    gbMemory[0xa000 + gbDataMBC7.address * 2 + 1] = gbDataMBC7.buffer & 0xff;
+                    gbRam[gbDataMBC7.address * 2] = gbDataMBC7.buffer >> 8;
+                    gbRam[gbDataMBC7.address * 2 + 1] = gbDataMBC7.buffer & 0xff;
                     systemSaveUpdateCounter = SYSTEM_SAVE_UPDATED;
                 }
                 gbDataMBC7.state = 0;
@@ -762,16 +763,16 @@ void mapperMBC7RAM(uint16_t address, uint8_t value)
                             } else if ((gbDataMBC7.address >> 6) == 1) {
                                 if (gbDataMBC7.writeEnable) {
                                     for (int i = 0; i < 256; i++) {
-                                        gbMemory[0xa000 + i * 2] = gbDataMBC7.buffer >> 8;
-                                        gbMemory[0xa000 + i * 2 + 1] = gbDataMBC7.buffer & 0xff;
+                                        gbRam[i * 2] = gbDataMBC7.buffer >> 8;
+                                        gbRam[i * 2 + 1] = gbDataMBC7.buffer & 0xff;
                                         systemSaveUpdateCounter = SYSTEM_SAVE_UPDATED;
                                     }
                                 }
                                 gbDataMBC7.state = 5;
                             } else if ((gbDataMBC7.address >> 6) == 2) {
                                 if (gbDataMBC7.writeEnable) {
                                     for (int i = 0; i < 256; i++)
-                                        WRITE16LE((uint16_t*)&gbMemory[0xa000 + i * 2], 0xffff);
+                                        WRITE16LE((uint16_t*)&gbRam[i * 2], 0xffff);
                                     systemSaveUpdateCounter = SYSTEM_SAVE_UPDATED;
                                 }
                                 gbDataMBC7.state = 5;
@@ -793,7 +794,7 @@ void mapperMBC7RAM(uint16_t address, uint8_t value)
                         if (gbDataMBC7.count == 1) {
                             gbDataMBC7.state = 4;
                             gbDataMBC7.count = 0;
-                            gbDataMBC7.buffer = (gbMemory[0xa000 + gbDataMBC7.address * 2] << 8) | (gbMemory[0xa000 + gbDataMBC7.address * 2 + 1]);
+                            gbDataMBC7.buffer = (gbRam[gbDataMBC7.address * 2] << 8) | (gbRam[gbDataMBC7.address * 2 + 1]);
                         }
                         break;
                     case 3:

diff --git a/src/gb/gbMemory.h b/src/gb/gbMemory.h
@@ -157,6 +157,7 @@ extern mapperMBC1 gbDataMBC1;
 extern mapperMBC2 gbDataMBC2;
 extern mapperMBC3 gbDataMBC3;
 extern mapperMBC5 gbDataMBC5;
+extern mapperMBC7 gbDataMBC7;
 extern mapperHuC1 gbDataHuC1;
 extern mapperHuC3 gbDataHuC3;
 extern mapperHuC3RTC gbRTCHuC3;