crc32

crc32/crc32_nolookup.h

@@ -0,0 +1,33 @@
+#ifndef CRC32_H
+#define CRC32_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*
+ * CRC-32 (IEEE 802.3) implementation
+ * Polynomial: 0xEDB88320 (reflected)
+ * Initial value: 0xFFFFFFFF
+ * Final XOR: 0xFFFFFFFF
+ * Input reflected: Yes
+ * Output reflected: Yes
+ */
+
+static inline uint32_t crc32_ieee(const void *data, size_t len) {
+    const uint8_t *p = (const uint8_t *)data;
+    uint32_t       crc = 0xFFFFFFFF;
+
+    while (len--) {
+        crc ^= *p++;
+        for (int i = 0; i < 8; i++) {
+            if (crc & 1)
+                crc = (crc >> 1) ^ 0xEDB88320;
+            else
+                crc >>= 1;
+        }
+    }
+
+    return crc ^ 0xFFFFFFFF;
+}
+
+#endif // CRC32_H