util/crc.c: Add simple CRC-32 implementation

util/crc.c

@@ -0,0 +1,28 @@
+#include <stddef.h>
+#include <stdint.h>
+
+#include "util/crc.h"
+
+uint32_t crc32(const void *src, size_t nbytes, uint32_t in)
+{
+    const uint8_t *bytes;
+    uint32_t crc;
+    size_t i;
+
+    bytes = src;
+    crc = ~in;
+
+    for (i = 0 ; i < nbytes * 8 ; i++) {
+        if (i % 8 == 0) {
+            crc ^= *bytes++;
+        }
+
+        if (crc & 1) {
+            crc = (crc >> 1) ^ 0xEDB88320;
+        } else {
+            crc = (crc >> 1);
+        }
+    }
+
+    return ~crc;
+}