1 files changed, 56 insertions, 0 deletions
diff --git a/zix/digest.c b/zix/digest.c
new file mode 100644
index 0000000..4e8e974
--- /dev/null
+++ b/zix/digest.c
@@ -0,0 +1,56 @@
+/*
+  Copyright 2012 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "zix/digest.h"
+
+#ifdef __SSE4_2__
+#    include <smmintrin.h>
+#endif
+
+ZIX_API uint32_t
+zix_digest_start(void)
+{
+#ifdef __SSE4_2__
+	return 1;  // CRC32 initial value
+#else
+	return 5381;  // DJB hash initial value
+#endif
+}
+
+ZIX_API uint32_t
+zix_digest_add(uint32_t hash, const void* buf, const size_t len)
+{
+#ifdef __SSE4_2__
+	// SSE 4.2 CRC32
+	for (size_t i = 0; i < (len / sizeof(uint32_t)); ++i) {
+		hash = _mm_crc32_u32(hash, *(uint32_t*)buf);
+		buf += sizeof(uint32_t);
+	}
+	if (len & sizeof(uint16_t)) {
+		hash = _mm_crc32_u16(hash, *(uint16_t*)buf);
+		buf += sizeof(uint16_t);
+	}
+	if (len & sizeof(uint8_t)) {
+		hash = _mm_crc32_u8(hash, *(uint8_t*)buf);
+	}
+#else
+	// Classic DJB hash
+	for (size_t i = 0; i < len; ++i) {
+		hash = (hash << 5) + hash + ((const uint8_t*)buf)[i];
+	}
+#endif
+	return hash;
+}