public release of panzgb

2025-11-24 13:37:49 +01:00
commit d08fbfe1aa
18 changed files with 3827 additions and 0 deletions
--- a/lib/mbc1.c
+++ b/lib/mbc1.c
@@ -0,0 +1,45 @@
+#include "gb-impl.h"
+
+void mbc1_changeBank(gb *cpu, WORD addr, BYTE data) {
+    // RAM enabling
+    if (addr < 0x2000) {
+        BYTE testData = data & 0xF;
+        if (testData == 0x0) {
+            cpu->isRAMEnable = 0;
+        } else {
+            cpu->isRAMEnable = 1;
+        }
+    }
+
+    /*Change ROM bank*/
+    else if ((addr >= 0x2000) && (addr < 0x4000)) {
+        BYTE lower5 = data & 31;
+        cpu->currentROMBank &= 224; // turn off the lower 5
+        cpu->currentROMBank |= lower5;
+        if (cpu->currentROMBank == 0 || cpu->currentROMBank == 0x20 ||
+            cpu->currentROMBank == 0x40 || cpu->currentROMBank == 0x60)
+            cpu->currentROMBank++;
+    }
+
+    /*Depending from the MBC1 type, I have to change something*/
+    else if ((addr >= 0x4000) && (addr < 0x6000)) {
+        if (cpu->ROMBankType == 1) {
+            cpu->currentROMBank &= 31;
+            data &= 0x3;
+            data <<= 5;
+            cpu->currentROMBank |= data;
+            if (cpu->currentROMBank == 0 || cpu->currentROMBank == 0x20 ||
+                cpu->currentROMBank == 0x40 || cpu->currentROMBank == 0x60)
+                cpu->currentROMBank++;
+        } else
+            cpu->currentRAMBank = data & 0x3;
+    }
+
+    /*Determine which type of MBC1 is*/
+    else if ((addr >= 0x6000) && (addr < 0x8000)) {
+        BYTE newData = data & 0x1;
+        cpu->ROMBankType = (newData == 0) ? 1 : 0;
+        if (cpu->ROMBankType == 1)
+            cpu->currentRAMBank = 0;
+    }
+}