From 1da68742047952880ce8b78b6190cef24f4e411a Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Wed, 20 Jun 2018 13:51:53 -0400
Subject: add mbc2 functions

---
 ops.yaml | 168 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 150 insertions(+), 18 deletions(-)

diff --git a/ops.yaml b/ops.yaml
index aa71087..84696e7 100644
--- a/ops.yaml
+++ b/ops.yaml
@@ -7754,6 +7754,25 @@ templates:
     /* mbc1 functions */
     /******************/
 
+    static uint32_t
+    mbc1_rom_get_addr(
+      gb_t * const ctx,
+      const uint16_t addr
+    ) {
+      // mbc1 rom1 banking (TCAGBD.pdf, 11.2.2)
+      // A ABBB BBCC CCCC CCCC CCCC
+      return (
+        // A: ram_bank (2 bits, if rom_ram_mode == 0)
+        (((ctx->mmu.mbc1.rom_ram_mode ? 0 : ctx->mmu.mbc1.ram_bank) & 0x3) << 19) |
+
+        // B: rom_bank (5 bits, low bit set)
+        (((ctx->mmu.mbc1.rom_bank & 0x1F) | 0x1) << 15) |
+
+        // C: address (14 bits)
+        ((addr - 0x4000) & 0x3FFF)
+      );
+    }
+
     static uint8_t
     mbc1_rom_rb(
       gb_t * const ctx,
@@ -7782,24 +7801,9 @@ templates:
       case 0x6000:
       case 0x7000:
         // ROM1 (16k, banked)
-        {
-          // mbc1 rom1 banking (TCAGBD.pdf, 11.2.2)
-          // FIXME: clamp to rom size?
-
-          // A ABBB BBCC CCCC CCCC CCCC
-          const uint32_t full_addr = (
-            // A: ram_bank (2 bits, if rom_ram_mode == 0)
-            (((ctx->mmu.mbc1.rom_ram_mode ? 0 : ctx->mmu.mbc1.ram_bank) & 0x3) << 19) |
-
-            // B: rom_bank (5 bits, low bit set)
-            (((ctx->mmu.mbc1.rom_bank & 0x1F) | 0x1) << 15) |
-
-            // C: address (14 bits)
-            ((addr - 0x4000) & 0x3FFF)
-          );
-
-          return ctx->mmu.rom[full_addr];
-        }
+        // FIXME: clamp to rom size?
+        // mbc1 rom1 banking (TCAGBD.pdf, 11.2.2)
+        return ctx->mmu.rom[mbc1_rom_get_addr(ctx, addr)];
       default:
         // never reached
         return 0;
@@ -7879,6 +7883,124 @@ templates:
       }
     }
 
+    /******************/
+    /* mbc2 functions */
+    /******************/
+
+    static uint32_t
+    mbc2_rom_get_addr(
+      gb_t * const ctx,
+      const uint16_t addr
+    ) {
+      // mbc2 rom1 banking (TCAGBD.pdf, 11.2.3)
+
+      // AA AABB BBBB BBBB BBBB
+      return (
+        // B: rom_bank (4 bits, low bit set)
+        (((ctx->mmu.mbc2.rom_bank & 0xF) << 13) |
+
+        // C: address (14 bits)
+        ((addr - 0x4000) & 0x3FFF)
+      );
+    }
+
+    static uint8_t
+    mbc2_rom_rb(
+      gb_t * const ctx,
+      const uint16_t addr
+    ) {
+      switch (addr & 0xF000) {
+      case 0x0000:
+        // bios memory (maybe)
+        if (ctx->mmu.in_bios) {
+          if (addr < 0x100) {
+            return ctx->mmu.bios[addr];
+          } else {
+            ctx->mmu.in_bios = false;
+          }
+        }
+
+        // return ROM0 (16k, always mapped)
+        return ctx->mmu.rom[addr];
+      case 0x1000:
+      case 0x2000:
+      case 0x3000:
+        // ROM0 (16k, always mapped)
+        return ctx->mmu.rom[addr];
+      case 0x4000:
+      case 0x5000:
+      case 0x6000:
+      case 0x7000:
+        // ROM1 (16k, banked)
+        // FIXME: clamp to rom size?
+        return ctx->mmu.rom[mbc2_rom_get_addr(ctx, addr)];
+      default:
+        // never reached
+        return 0;
+      }
+    }
+
+    static void
+    mbc2_rom_wb(
+      gb_t * const ctx,
+      const uint16_t addr,
+      const uint8_t val
+    ) {
+      switch (addr & 0xF000) {
+      case 0x0000:
+      case 0x1000:
+        if (!(addr & 0x10)) {
+          // toggle ram_enable
+          ctx->mmu.mbc2.ram_enable = ((val & 0x0F) == 0x0A);
+        }
+        break;
+      case 0x2000:
+      case 0x3000:
+        if (addr & 0x10) {
+          // set rom bank
+          ctx->mmu.mbc2.rom_bank = val & 0x0F;
+        }
+        break;
+      default:
+        // do nothing
+        break;
+      }
+    }
+
+    static uint16_t
+    mbc2_eram_get_addr(
+      const gb_t * const ctx,
+      const uint16_t addr
+    ) {
+      return (addr & 0x1FF);
+    }
+
+    static uint8_t
+    mbc2_eram_rb(
+      const gb_t * const ctx,
+      const uint16_t addr
+    ) {
+      if (ctx->mmu.eram && ctx->mmu.mbc2.ram_enable) {
+        return ctx->mmu.eram[mbc2_eram_get_addr(ctx, addr)] & 0x0F;
+      } else {
+        return 0;
+      }
+    }
+
+    static void
+    mbc2_eram_wb(
+      gb_t * const ctx,
+      const uint16_t addr,
+      const uint8_t val
+    ) {
+      if (ctx->mmu.eram && ctx->mmu.mbc2.ram_enable) {
+        ctx->mmu.eram[mbc2_eram_get_addr(ctx, addr)] = val & 0x0F;
+      }
+    }
+
+    /************************/
+    /* timer shift function */
+    /************************/
 
     static uint8_t
     timer_get_shift(
@@ -8168,6 +8290,8 @@ templates:
         return ctx->mmu.rom[addr];
       case MBC_TYPE_MBC1:
         return mbc1_rom_rb(ctx, addr);
+      case MBC_TYPE_MBC2:
+        return mbc2_rom_rb(ctx, addr);
       default:
         // TODO: implement remaining MBC types
         return 0;
@@ -8190,6 +8314,8 @@ templates:
         switch (rom_get_mbc_type(ctx)) {
         case MBC_TYPE_MBC1:
           return mbc1_eram_rb(ctx, addr);
+        case MBC_TYPE_MBC2:
+          return mbc2_eram_rb(ctx, addr);
         case MBC_TYPE_NONE:
         default:
           return 0;
@@ -8266,6 +8392,9 @@ templates:
       case MBC_TYPE_MBC1:
         mbc1_rom_wb(ctx, addr, val);
         break;
+      case MBC_TYPE_MBC2:
+        mbc2_rom_wb(ctx, addr, val);
+        break;
       default:
         // do nothing
         break;
@@ -8291,6 +8420,9 @@ templates:
         case MBC_TYPE_MBC1:
           mbc1_eram_wb(ctx, addr, val);
           break;
+        case MBC_TYPE_MBC2:
+          mbc2_eram_wb(ctx, addr, val);
+          break;
         case MBC_TYPE_NONE:
           // TODO: implement remaining mbcs
           if (ctx->mmu.eram) {
-- 
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