o crc checking rom

snes/crc/crc.c

@@ -0,0 +1,39 @@
+#include "data.h"
+
+
+word crc_update (byte *data, word size)
+{
+	word i;
+    word j;
+	word crc=0;
+	for (j=0; j<size; j++){
+		crc = crc ^ ((word)data[j]<< 8);
+		for (i=0; i<8; i++){
+        	if (crc & 0x8000)
+            	crc = (crc << 1) ^ 0x1021;
+        	else
+            	crc <<= 1;
+    	}
+	}
+	return crc;
+}
+
+
+word crc_update_mem (word addr, word size)
+{
+	word i;
+    word j;
+	word crc=0;
+    word v;
+	for (j=0; j<size; j++){
+        v = addr;
+		crc = crc ^ ((word)v<< 8);
+		for (i=0; i<8; i++){
+        	if (crc & 0x8000)
+            	crc = (crc << 1) ^ 0x1021;
+        	else
+            	crc <<= 1;
+    	}
+	}
+	return crc;
+}