From 3f96861df909c69f7e17447983b127379bc71f50 Mon Sep 17 00:00:00 2001
From: n-a-c-h <>
Date: Sun, 4 Jan 2004 20:24:46 +0000
Subject: [PATCH] Fixed checksum and CRC32 on add on ROMs.

---
 zsnes/src/init.asm | 18 +++++++++++++++++-
 zsnes/src/initc.c  | 17 ++++++++++++-----
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/zsnes/src/init.asm b/zsnes/src/init.asm
index ac7511c8..f9735493 100644
--- a/zsnes/src/init.asm
+++ b/zsnes/src/init.asm
@@ -122,6 +122,10 @@ EXTSYM loadROM
 EXTSYM CalcChecksum
 EXTSYM BankCheck
 EXTSYM MirrorROM
+EXTSYM SplittedROM
+EXTSYM addOnStart
+EXTSYM addOnSize
+
 
 EXTSYM SetaCmdEnable,setaramdata
 EXTSYM setaaccessbankr8,setaaccessbankw8,setaaccessbankr8a,setaaccessbankw8a
@@ -3755,12 +3759,19 @@ NEWSYM showinfogui
     je .nointlv
     mov dword[CSStatus2+12],'Yes '
 .nointlv
-
+ 
     ; calculate CRC32
     xor edx,edx         
     mov eax,0FFFFFFFFh
     mov ecx,dword[NumofBytes]
     mov esi,[romdata]   
+
+    ;Only calculate Add on ROM?
+    cmp byte[SplittedROM],1
+    jne .calcloop
+    mov ecx,dword[addOnSize]
+    add esi,dword[addOnStart]
+
  .calcloop
     mov dl,byte[esi] 
     mov ebx,eax                     ;ebx = CRC32
@@ -3805,6 +3816,11 @@ NEWSYM showinfogui
     add esi,[infoloc]
     add esi,1Eh
     mov ax,[Checksumvalue]
+    ;On add on ROMs we check the add on
+    cmp byte[SplittedROM],1
+    jne .check
+    add esi,dword[addOnStart]
+.check
     cmp ax,[esi]
     jne .failed
 .passed2
diff --git a/zsnes/src/initc.c b/zsnes/src/initc.c
index 882c1401..4ad5bd4a 100755
--- a/zsnes/src/initc.c
+++ b/zsnes/src/initc.c
@@ -61,6 +61,11 @@ unsigned int maxromspace;
 unsigned int curromspace;
 unsigned int infoloc;
 
+bool SplittedROM;
+unsigned int addOnStart;
+unsigned int addOnSize;
+
+
 //Deinterleave functions
 bool validChecksum(unsigned char *ROM, int BankLoc)
 {
@@ -314,7 +319,13 @@ extern unsigned short Checksumvalue;
 void CalcChecksum()
 {
   unsigned char *ROM = (unsigned char *)romdata;
-  if (SPC7110Enable)
+
+  if (SplittedROM)
+  {
+    Checksumvalue = sum(ROM+addOnStart, addOnSize);
+    Checksumvalue -= sum(&ROM[infoloc+addOnStart - 16], 48);
+  }
+  else if (SPC7110Enable)
   {
     Checksumvalue = sum(ROM, NumofBytes);
     if (NumofBanks == 96)
@@ -598,10 +609,6 @@ void loadZipFile()
   }
 }
 
-bool SplittedROM;
-int addOnStart;
-int addOnSize;
-
 void SplitSetup(const char *basefile, unsigned int MirrorSystem)
 {
   unsigned char *ROM = (unsigned char *)romdata;