Initial Commit.

crc.c

@@ -0,0 +1,69 @@
+#include <stdio.h>
+
+unsigned long CRCTable[256];
+int CRCTable_initialized=0;
+
+#define CRC32_POLYNOMIAL     0xEDB88320L
+
+void CRCTable_Init(){
+    int i;
+    int j;
+    unsigned long crc;
+
+	if(CRCTable_initialized){
+		return;
+	}
+	CRCTable_initialized=1;
+
+    for (i=0;i<256;i++){
+        crc=i;
+        for (j=8;j>0;j--){
+            if (crc&1)
+                crc=(crc>>1)^CRC32_POLYNOMIAL;
+            else
+                crc>>=1;
+        }
+        CRCTable[i]=crc;
+    }
+}
+
+
+unsigned long CRC_Buffer(unsigned char *buffer,int len,unsigned long crc){
+    unsigned char *p;
+    unsigned long temp1;
+    unsigned long temp2;
+
+	// Calcular CRC del buffer
+	p=(unsigned char*)buffer;
+	while(len--!=0) {
+		temp1=(crc>>8)&0x00FFFFFFL;
+		temp2=CRCTable[((int)crc^*p++)&0xff];
+		crc=temp1^temp2;
+	}
+
+	return(crc);
+}
+
+
+unsigned long CRC_File(FILE *file){
+    unsigned long crc;
+    int count;
+    unsigned char buffer[512];
+    unsigned char *p;
+    unsigned long temp1;
+    unsigned long temp2;
+
+	CRCTable_Init();
+
+    crc=0xFFFFFFFFL;
+    for(;;){
+		// Llenar el buffer
+        count=fread(buffer,1,512,file);
+        if(count==0)
+            break;
+
+		// Calcular CRC del buffer
+		crc=CRC_Buffer(buffer,count,crc);
+    }
+    return(crc^=0xFFFFFFFFL);
+}