[PATCH] ARM optimized SHA1 implementation

This is my ARM assembly SHA1 implementation for GIT. It is approximately
50% faster than the generic C version. On an XScale processor running at
400MHz:

	generic C version:	9.8 MB/s
	my version:		14.5 MB/s

It's not that I expect a lot of big GIT users on ARM, but I stillknow
about one important ARM user that might benefit from it, and writing
that code was fun.

I also reworked the makefile a bit so any optimized SHA1 implementations
is used regardless of whether NO_OPENSSL is defined or not.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 82 insertions, 0 deletions

diff --git a/arm/sha1.c b/arm/sha1.c
new file mode 100644
index 000000000..11b1a048b
--- /dev/null
+++ b/arm/sha1.c
@@ -0,0 +1,82 @@
+/*
+ * SHA-1 implementation optimized for ARM
+ *
+ * Copyright:   (C) 2005 by Nicolas Pitre <nico@cam.org>
+ * Created:     September 17, 2005
+ */
+
+#include <string.h>
+#include "sha1.h"
+
+extern void sha_transform(uint32_t *hash, const unsigned char *data, uint32_t *W);
+
+void SHA1_Init(SHA_CTX *c)
+{
+	c->len = 0;
+	c->hash[0] = 0x67452301;
+	c->hash[1] = 0xefcdab89;
+	c->hash[2] = 0x98badcfe;
+	c->hash[3] = 0x10325476;
+	c->hash[4] = 0xc3d2e1f0;
+}
+
+void SHA1_Update(SHA_CTX *c, const void *p, unsigned long n)
+{
+	uint32_t workspace[80];
+	unsigned int partial;
+	unsigned long done;
+
+	partial = c->len & 0x3f;
+	c->len += n;
+	if ((partial + n) >= 64) {
+		if (partial) {
+			done = 64 - partial;
+			memcpy(c->buffer + partial, p, done);
+			sha_transform(c->hash, c->buffer, workspace);
+			partial = 0;
+		} else
+			done = 0;
+		while (n >= done + 64) {
+			sha_transform(c->hash, p + done, workspace);
+			done += 64;
+		}
+	} else
+		done = 0;
+	if (n - done)
+		memcpy(c->buffer + partial, p + done, n - done);
+}
+
+void SHA1_Final(unsigned char *hash, SHA_CTX *c)
+{
+	uint64_t bitlen;
+	uint32_t bitlen_hi, bitlen_lo; 
+	unsigned int i, offset, padlen;
+	unsigned char bits[8];
+	static const unsigned char padding[64] = { 0x80, };
+
+	bitlen = c->len << 3;
+	offset = c->len & 0x3f;
+	padlen = ((offset < 56) ? 56 : (64 + 56)) - offset;
+	SHA1_Update(c, padding, padlen);
+
+	bitlen_hi = bitlen >> 32;
+	bitlen_lo = bitlen & 0xffffffff;
+	bits[0] = bitlen_hi >> 24;
+	bits[1] = bitlen_hi >> 16;
+	bits[2] = bitlen_hi >> 8;
+	bits[3] = bitlen_hi;
+	bits[4] = bitlen_lo >> 24;
+	bits[5] = bitlen_lo >> 16;
+	bits[6] = bitlen_lo >> 8;
+	bits[7] = bitlen_lo;
+	SHA1_Update(c, bits, 8); 
+
+	for (i = 0; i < 5; i++) {
+		uint32_t v = c->hash[i];
+		hash[0] = v >> 24;
+		hash[1] = v >> 16;
+		hash[2] = v >> 8;
+		hash[3] = v;
+		hash += 4;
+	}
+}