From 210d19111bbb26892bb9f750f1e62fcfb4780d97 Mon Sep 17 00:00:00 2001
From: EkeEke <ekeeke31@gmail.com>
Date: Tue, 26 Feb 2013 20:30:52 +0100
Subject: [PATCH] [Core/MD] added support for earlier revision of SF-001 mapper

---
 source/cart_hw/md_cart.c | 13 +++++++------
 source/cart_hw/md_cart.h |  2 +-
 source/cart_hw/sram.c    | 22 ++++++++++++++++------
 source/cart_hw/sram.h    |  2 +-
 4 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/source/cart_hw/md_cart.c b/source/cart_hw/md_cart.c
index 5eb3a6f..35a9ec8 100644
--- a/source/cart_hw/md_cart.c
+++ b/source/cart_hw/md_cart.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Mega Drive cartridge hardware support
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2013  Eke-Eke (Genesis Plus GX)
  *
  *  Most cartridge protections were initially documented by Haze
  *  (http://haze.mameworld.info/)
@@ -904,8 +904,8 @@ static void mapper_sf001_w(uint32 address, uint32 data)
           zbank_memory_map[i].read    = NULL;
         }
 
-        /* 256K ROM banks #2 to #15 mapped to $040000-$3BFFFF  */
-        for (i=0x04; i<0x3c; i++)
+        /* 256K ROM banks #2 to #15 mapped to $040000-$3BFFFF (last revision) or $040000-$3FFFFF (older revisions) */
+        for (i=0x04; i<(sram.start >> 16); i++)
         {
           m68k.memory_map[i].base     = cart.rom + (i << 16);
           m68k.memory_map[i].read8    = NULL;
@@ -913,8 +913,8 @@ static void mapper_sf001_w(uint32 address, uint32 data)
           zbank_memory_map[i].read    = NULL;
         }
 
-        /* 32K static RAM mirrored into $3C0000-$3FFFFF (odd bytes only) */
-        for (i=0x3c; i<0x40; i++)
+        /* 32K static RAM mirrored into $3C0000-$3FFFFF (odd bytes only) (last revision only) */
+        while (i<0x40)
         {
           m68k.memory_map[i].base     = sram.sram;
           m68k.memory_map[i].read8    = NULL;
@@ -923,11 +923,12 @@ static void mapper_sf001_w(uint32 address, uint32 data)
           m68k.memory_map[i].write16  = NULL;
           zbank_memory_map[i].read    = NULL;
           zbank_memory_map[i].write   = NULL;
+          i++;
         }
       }
       else
       {
-        /* 256K ROM banks #1 to #16 mapped to $000000-$3FFFFF  */
+        /* 256K ROM banks #1 to #16 mapped to $000000-$3FFFFF (default) */
         for (i=0x00; i<0x40; i++)
         {
           m68k.memory_map[i].base     = cart.rom + (i << 16);
diff --git a/source/cart_hw/md_cart.h b/source/cart_hw/md_cart.h
index 34858aa..24c0bee 100644
--- a/source/cart_hw/md_cart.h
+++ b/source/cart_hw/md_cart.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Mega Drive cartridge hardware support
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2013  Eke-Eke (Genesis Plus GX)
  *
  *  Most cartridge protections were initially documented by Haze
  *  (http://haze.mameworld.info/)
diff --git a/source/cart_hw/sram.c b/source/cart_hw/sram.c
index ae83e01..665a864 100644
--- a/source/cart_hw/sram.c
+++ b/source/cart_hw/sram.c
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Backup RAM support
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2013  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -122,15 +122,25 @@ void sram_init()
     {
       /* Xin Qigai Wangzi (use uncommon area) */
       sram.on = 1;
-      sram.start = 0x400000;
+      sram.start = 0x400001;
       sram.end = 0x40ffff;
     }
     else if ((strstr(rominfo.ROMType,"SF") != NULL) && (strstr(rominfo.product,"001") != NULL))
     {
-      /* SF-001 (use bankswitching) */
+      /* SF-001 */
       sram.on = 1;
-      sram.start = 0x3c0001;
-      sram.end = 0x3cffff;
+      if (rominfo.checksum == 0x3e08)
+      {
+        /* last revision (use bankswitching) */
+        sram.start = 0x3c0001;
+        sram.end = 0x3cffff;
+      }
+      else
+      {
+        /* older revisions (use uncommon area) */
+        sram.start = 0x400001;
+        sram.end = 0x40ffff;
+      }
     }
     else if ((strstr(rominfo.ROMType,"SF") != NULL) && (strstr(rominfo.product,"004") != NULL))
     {
@@ -147,7 +157,7 @@ void sram_init()
         /* Sonic 3 & Knuckles combined ROM */
         /* it shows S&K header but should obviously use FRAM from Sonic 3 */
         sram.on = 1;
-        sram.start = 0x200000;
+        sram.start = 0x200001;
         sram.end = 0x203fff;
       }
     }
diff --git a/source/cart_hw/sram.h b/source/cart_hw/sram.h
index f7fd926..d838e69 100644
--- a/source/cart_hw/sram.h
+++ b/source/cart_hw/sram.h
@@ -2,7 +2,7 @@
  *  Genesis Plus
  *  Backup RAM support
  *
- *  Copyright (C) 2007-2011  Eke-Eke (Genesis Plus GX)
+ *  Copyright (C) 2007-2013  Eke-Eke (Genesis Plus GX)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met: