From 9f0715c82550aaae187342711b42bc7f080850f4 Mon Sep 17 00:00:00 2001
From: Samuel Walker <swalker@piwalker.net>
Date: Fri, 30 May 2025 12:30:54 -0600
Subject: [PATCH] mbc2 passing

---
 .vscode/launch.json |   2 +-
 lib/cart.c          | 226 ++++++++++++++++++++++++++------------------
 2 files changed, 135 insertions(+), 93 deletions(-)

diff --git a/.vscode/launch.json b/.vscode/launch.json
index 2cb39d5..fa27ddc 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -9,7 +9,7 @@
             "request": "launch",
             "name": "Debug",
             "program": "${workspaceFolder}/build/gbemu/Debug/gbemu.exe",
-            "args": [ "C:\\Users\\piwalker\\Downloads\\mts-20240926-1737-443f6e1\\mts-20240926-1737-443f6e1\\emulator-only\\mbc1\\rom_512kb.gb" ],
+            "args": [ "C:\\Users\\piwalker\\Downloads\\mts-20240926-1737-443f6e1\\mts-20240926-1737-443f6e1\\emulator-only\\mbc2\\ram.gb" ],
             "cwd": "${workspaceFolder}"
         }
     ]
diff --git a/lib/cart.c b/lib/cart.c
index 41e973f..a1ffcde 100644
--- a/lib/cart.c
+++ b/lib/cart.c
@@ -13,16 +13,24 @@ bool cart_mbc1() {
     return BETWEEN(ctx.header->type, 1, 3);
 }
 
+bool cart_mbc2() {
+    return BETWEEN(ctx.header->type, 5, 6);
+}
+
 bool cart_mbc3() {
     return BETWEEN(ctx.header->type, 15, 19);
 }
 
+bool cart_mbc5() {
+    return BETWEEN(ctx.header->type, 25, 30)
+}
+
 bool cart_mbc() {
-    return cart_mbc1() || cart_mbc3();
+    return cart_mbc1() || cart_mbc2() || cart_mbc3() || cart_mbc5();
 }
 
 bool cart_battery() {
-    return ctx.header->type == 3 || BETWEEN(ctx.header->type, 15, 16) || ctx.header->type == 19;
+    return ctx.header->type == 3 || BETWEEN(ctx.header->type, 15, 16) || ctx.header->type == 19 || ctx.header->type == 6;
 }
 
 static const char *ROM_TYPES[] = {
@@ -160,6 +168,11 @@ void cart_setup_bamking() {
         }
     }
 
+    if(cart_mbc2()) {
+        ctx.ram_banks[0] = malloc(0x2000);
+        memset(ctx.ram_banks[0], 0, 0x2000);
+    }
+
     ctx.ram_bank = ctx.ram_banks[0];
     ctx.rom_bank_x = ctx.rom_data + 0x4000;
     ctx.rom_bank_x2 = ctx.rom_data;
@@ -286,6 +299,8 @@ u8 cart_read(u16 address){
     }
 
     if((address & 0xE000) == 0xA000) {
+        if(cart_mbc2())
+            address &= 0xE1FF;
         if (!ctx.ram_enabled) {
             return 0xFF;
         }
@@ -294,7 +309,7 @@ u8 cart_read(u16 address){
             return 0xFF;
         }
 
-        return ctx.ram_bank[address - 0xA000];
+        return cart_mbc2() ? ctx.ram_bank[address - 0xA000] | 0xF0 : ctx.ram_bank[address - 0xA000];
     }
 
     return ctx.rom_bank_x[address - 0x4000];
@@ -307,95 +322,82 @@ void cart_write(u16 address, u8 value){
         return;
     }
 
-    if(address < 0x2000) {
-        ctx.ram_enabled = ((value & 0xF) == 0xA);
-    }
-
-    if((address & 0xE000) == 0x2000) {
-        //rom bank
-        if(cart_mbc3()) {
-            value &= 0b1111111;
-            if(value == 0) {
-                value = 1;
-            }
-            ctx.rom_bank_value = value;
-            ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
-        }else {
-            //printf("Bank Value: %d\n", value);
-            value &= 0b11111;
-            if(value == 0) {
-                value = 1;
-            }
-            if(ctx.is_multicart)
+    if(cart_mbc2()) {
+        if(address < 0x4000){
+            if(address & 0x100) {
                 value &= 0b1111;
-            //printf("Bank Value after filter: %d\n", value);
-            switch(ctx.header->rom_size) {
-                case 0: value &= 0b1; break;
-                case 1: value &= 0b11; break;
-                case 2: value &= 0b111; break;
-                case 3: value &= 0b1111; break;
-                default: break;
-            }
-            ctx.rom_bank_value = value;
-            if(ctx.header->rom_size >= 5) {
-                ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
-                //printf("(REG1 >5) Banked %d\n", ctx.rom_bank_value+ctx.rom_bank_value_2);
-                return;
-            }
-            ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
-            //printf("(REG1 <5) Banked %d\n", ctx.rom_bank_value);
-        }
-    }
-
-    if((address & 0xE000) == 0x4000) {
-        //ram bank number
-        if(cart_mbc1() && ctx.header->rom_size >= 5) {
-            if(ctx.header->rom_size == 5)
-                value &= 0b1;
-            ctx.rom_bank_value_2 = (value & 0b11) << 5;
-            if(ctx.is_multicart)
-                ctx.rom_bank_value_2 = (value & 0b11) << 4;
-            ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
-            //printf("(REG2 >5) Banked %d\n", ctx.rom_bank_value+ctx.rom_bank_value_2);
-            if(ctx.banking_mode)
-                ctx.rom_bank_x2 = ctx.rom_data + (0x4000 * (ctx.rom_bank_value_2));
-            return;
-        }
-        ctx.ram_bank_value = value & 0b11;
-        if(ctx.ram_banking) {
-            if(cart_need_save()) {
-                cart_battery_save();
-            }
-            if((ctx.header->ram_size == 2 && ctx.ram_bank_value == 0) || 
-                (ctx.header->ram_size == 3 && ctx.ram_bank_value < 4) ||
-                (ctx.header->ram_size == 5 && ctx.ram_bank_value < 8) ||
-                (ctx.header->ram_size == 4)) {
-                ctx.ram_bank = ctx.ram_banks[ctx.ram_bank_value];
-            }
-            
-        }
-    }
-
-    if((address & 0xE000) == 0x6000) {
-        //banking mode select
-        if(cart_mbc1()){
-            ctx.banking_mode = value & 1;
-
-            ctx.ram_banking = ctx.banking_mode;
-
-            if(cart_mbc1() && ctx.header->rom_size >= 5) {
-                if(ctx.banking_mode) {
-                    ctx.rom_bank_value_2 = (value & 0b11) << 5;
-                    ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
-                    ctx.rom_bank_x2 = ctx.rom_data + (0x4000 * (ctx.rom_bank_value_2));
-                } else {
-                    ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value));
-                    ctx.rom_bank_x2 = ctx.rom_data;
+                if(value == 0) {
+                    value = 1;
                 }
+                switch(ctx.header->rom_size) {
+                    case 0: value &= 0b1; break;
+                    case 1: value &= 0b11; break;
+                    case 2: value &= 0b111; break;
+                    default: break;
+                }
+                ctx.rom_bank_value = value;
+                ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
+            } else {
+                ctx.ram_enabled = ((value & 0xF) == 0xA);
+            }
+        }
+    } else {
+        if(address < 0x2000) {
+            ctx.ram_enabled = ((value & 0xF) == 0xA);
+        }
+
+        if((address & 0xE000) == 0x2000) {
+            //rom bank
+            if(cart_mbc3()) {
+                value &= 0b1111111;
+                if(value == 0) {
+                    value = 1;
+                }
+                ctx.rom_bank_value = value;
+                ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
+            }else {
+                //printf("Bank Value: %d\n", value);
+                value &= 0b11111;
+                if(value == 0) {
+                    value = 1;
+                }
+                if(ctx.is_multicart)
+                    value &= 0b1111;
+                //printf("Bank Value after filter: %d\n", value);
+                switch(ctx.header->rom_size) {
+                    case 0: value &= 0b1; break;
+                    case 1: value &= 0b11; break;
+                    case 2: value &= 0b111; break;
+                    case 3: value &= 0b1111; break;
+                    default: break;
+                }
+                ctx.rom_bank_value = value;
+                if(ctx.header->rom_size >= 5) {
+                    ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
+                    //printf("(REG1 >5) Banked %d\n", ctx.rom_bank_value+ctx.rom_bank_value_2);
+                    return;
+                }
+                ctx.rom_bank_x = ctx.rom_data + (0x4000 * ctx.rom_bank_value);
+                //printf("(REG1 <5) Banked %d\n", ctx.rom_bank_value);
+            }
+        }
+
+        if((address & 0xE000) == 0x4000) {
+            //ram bank number
+            if(cart_mbc1() && ctx.header->rom_size >= 5) {
+                if(ctx.header->rom_size == 5)
+                    value &= 0b1;
+                ctx.rom_bank_value_2 = (value & 0b11) << 5;
+                if(ctx.is_multicart)
+                    ctx.rom_bank_value_2 = (value & 0b11) << 4;
+                ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
+                //printf("(REG2 >5) Banked %d\n", ctx.rom_bank_value+ctx.rom_bank_value_2);
+                if(ctx.banking_mode)
+                    ctx.rom_bank_x2 = ctx.rom_data + (0x4000 * (ctx.rom_bank_value_2));
                 return;
             }
-
-            if (ctx.ram_banking) {
+            ctx.ram_bank_value = value & 0b11;
+            if(ctx.ram_banking) {
                 if(cart_need_save()) {
                     cart_battery_save();
                 }
@@ -405,20 +407,60 @@ void cart_write(u16 address, u8 value){
                     (ctx.header->ram_size == 4)) {
                     ctx.ram_bank = ctx.ram_banks[ctx.ram_bank_value];
                 }
-            } else {
-                ctx.ram_bank = ctx.ram_banks[0];
+                
+            }
+        }
+
+        if((address & 0xE000) == 0x6000) {
+            //banking mode select
+            if(cart_mbc1()){
+                ctx.banking_mode = value & 1;
+
+                ctx.ram_banking = ctx.banking_mode;
+
+                if(cart_mbc1() && ctx.header->rom_size >= 5) {
+                    if(ctx.banking_mode) {
+                        ctx.rom_bank_value_2 = (value & 0b11) << 5;
+                        ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value+ctx.rom_bank_value_2));
+                        ctx.rom_bank_x2 = ctx.rom_data + (0x4000 * (ctx.rom_bank_value_2));
+                    } else {
+                        ctx.rom_bank_x = ctx.rom_data + (0x4000 * (ctx.rom_bank_value));
+                        ctx.rom_bank_x2 = ctx.rom_data;
+                    }
+                    return;
+                }
+
+                if (ctx.ram_banking) {
+                    if(cart_need_save()) {
+                        cart_battery_save();
+                    }
+                    if((ctx.header->ram_size == 2 && ctx.ram_bank_value == 0) || 
+                        (ctx.header->ram_size == 3 && ctx.ram_bank_value < 4) ||
+                        (ctx.header->ram_size == 5 && ctx.ram_bank_value < 8) ||
+                        (ctx.header->ram_size == 4)) {
+                        ctx.ram_bank = ctx.ram_banks[ctx.ram_bank_value];
+                    }
+                } else {
+                    ctx.ram_bank = ctx.ram_banks[0];
+                }
             }
         }
     }
 
+    
+
     if((address & 0xE000) == 0xA000) {
-        if(!ctx.ram_enabled)
+        if(cart_mbc2())
+            address &= 0xE1FF;
+
+        if(!ctx.ram_enabled){
             return;
+        }
 
         if(!ctx.ram_bank)
             return;
 
-        ctx.ram_bank[address - 0xA000] = value;
+        ctx.ram_bank[address - 0xA000] = cart_mbc2() ? value & 0xF : value;
 
         if(ctx.battery) {
             ctx.need_save = true;