Merge branch 'lt/block-sha1'

* lt/block-sha1:
  block-sha1/sha1.c: silence compiler complaints by casting void * to char *
  block-sha1: more good unaligned memory access candidates
  block-sha1: support for architectures with memory alignment restrictions
  block-sha1: split the different "hacks" to be individually selected
  block-sha1: move code around
  block-sha1: improve code on large-register-set machines
  block-sha1: improved SHA1 hashing
  block-sha1: perform register rotation using cpp
  block-sha1: get rid of redundant 'lenW' context
  block-sha1: Use '(B&C)+(D&(B^C))' instead of '(B&C)|(D&(B|C))' in round 3
  block-sha1: macroize the rounds a bit further
  block-sha1: re-use the temporary array as we calculate the SHA1
  block-sha1: make the 'ntohl()' part of the first SHA1 loop
  block-sha1: minor fixups
  block-sha1: try to use rol/ror appropriately
  block-sha1: undo ctx->size change
  Add new optimized C 'block-sha1' routines

Author: gitster

Makefile

@@ -84,6 +84,10 @@ all::
 # specify your own (or DarwinPort's) include directories and
 # library directories by defining CFLAGS and LDFLAGS appropriately.
 #
+# Define BLK_SHA1 environment variable if you want the C version
+# of the SHA1 that assumes you can do unaligned 32-bit loads and
+# have a fast htonl() function.
+#
 # Define PPC_SHA1 environment variable when running make to make use of
 # a bundled SHA1 routine optimized for PowerPC.
 #
@@ -1167,6 +1171,10 @@ ifdef NO_DEFLATE_BOUND
 	BASIC_CFLAGS += -DNO_DEFLATE_BOUND
 endif
 
+ifdef BLK_SHA1
+	SHA1_HEADER = "block-sha1/sha1.h"
+	LIB_OBJS += block-sha1/sha1.o
+else
 ifdef PPC_SHA1
 	SHA1_HEADER = "ppc/sha1.h"
 	LIB_OBJS += ppc/sha1.o ppc/sha1ppc.o
@@ -1184,6 +1192,7 @@ else
 endif
 endif
 endif
+endif
 ifdef NO_PERL_MAKEMAKER
 	export NO_PERL_MAKEMAKER
 endif

block-sha1/sha1.c

@@ -0,0 +1,280 @@
+/*
+ * Based on the Mozilla SHA1 (see mozilla-sha1/sha1.c),
+ * optimized to do word accesses rather than byte accesses,
+ * and to avoid unnecessary copies into the context array.
+ */
+
+#include <string.h>
+#include <arpa/inet.h>
+
+#include "sha1.h"
+
+#if defined(__i386__) || defined(__x86_64__)
+
+/*
+ * Force usage of rol or ror by selecting the one with the smaller constant.
+ * It _can_ generate slightly smaller code (a constant of 1 is special), but
+ * perhaps more importantly it's possibly faster on any uarch that does a
+ * rotate with a loop.
+ */
+
+#define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })
+#define SHA_ROL(x,n)	SHA_ASM("rol", x, n)
+#define SHA_ROR(x,n)	SHA_ASM("ror", x, n)
+
+#else
+
+#define SHA_ROT(X,l,r)	(((X) << (l)) | ((X) >> (r)))
+#define SHA_ROL(X,n)	SHA_ROT(X,n,32-(n))
+#define SHA_ROR(X,n)	SHA_ROT(X,32-(n),n)
+
+#endif
+
+/*
+ * If you have 32 registers or more, the compiler can (and should)
+ * try to change the array[] accesses into registers. However, on
+ * machines with less than ~25 registers, that won't really work,
+ * and at least gcc will make an unholy mess of it.
+ *
+ * So to avoid that mess which just slows things down, we force
+ * the stores to memory to actually happen (we might be better off
+ * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
+ * suggested by Artur Skawina - that will also make gcc unable to
+ * try to do the silly "optimize away loads" part because it won't
+ * see what the value will be).
+ *
+ * Ben Herrenschmidt reports that on PPC, the C version comes close
+ * to the optimized asm with this (ie on PPC you don't want that
+ * 'volatile', since there are lots of registers).
+ *
+ * On ARM we get the best code generation by forcing a full memory barrier
+ * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
+ * the stack frame size simply explode and performance goes down the drain.
+ */
+
+#if defined(__i386__) || defined(__x86_64__)
+  #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
+#elif defined(__arm__)
+  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
+#else
+  #define setW(x, val) (W(x) = (val))
+#endif
+
+/*
+ * Performance might be improved if the CPU architecture is OK with
+ * unaligned 32-bit loads and a fast ntohl() is available.
+ * Otherwise fall back to byte loads and shifts which is portable,
+ * and is faster on architectures with memory alignment issues.
+ */
+
+#if defined(__i386__) || defined(__x86_64__) || \
+    defined(__ppc__) || defined(__ppc64__) || \
+    defined(__powerpc__) || defined(__powerpc64__) || \
+    defined(__s390__) || defined(__s390x__)
+
+#define get_be32(p)	ntohl(*(unsigned int *)(p))
+#define put_be32(p, v)	do { *(unsigned int *)(p) = htonl(v); } while (0)
+
+#else
+
+#define get_be32(p)	( \
+	(*((unsigned char *)(p) + 0) << 24) | \
+	(*((unsigned char *)(p) + 1) << 16) | \
+	(*((unsigned char *)(p) + 2) <<  8) | \
+	(*((unsigned char *)(p) + 3) <<  0) )
+#define put_be32(p, v)	do { \
+	unsigned int __v = (v); \
+	*((unsigned char *)(p) + 0) = __v >> 24; \
+	*((unsigned char *)(p) + 1) = __v >> 16; \
+	*((unsigned char *)(p) + 2) = __v >>  8; \
+	*((unsigned char *)(p) + 3) = __v >>  0; } while (0)
+
+#endif
+
+/* This "rolls" over the 512-bit array */
+#define W(x) (array[(x)&15])
+
+/*
+ * Where do we get the source from? The first 16 iterations get it from
+ * the input data, the next mix it from the 512-bit array.
+ */
+#define SHA_SRC(t) get_be32(data + t)
+#define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
+
+#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
+	unsigned int TEMP = input(t); setW(t, TEMP); \
+	E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
+	B = SHA_ROR(B, 2); } while (0)
+
+#define T_0_15(t, A, B, C, D, E)  SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
+#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
+#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
+#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
+#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
+
+static void blk_SHA1_Block(blk_SHA_CTX *ctx, const unsigned int *data)
+{
+	unsigned int A,B,C,D,E;
+	unsigned int array[16];
+
+	A = ctx->H[0];
+	B = ctx->H[1];
+	C = ctx->H[2];
+	D = ctx->H[3];
+	E = ctx->H[4];
+
+	/* Round 1 - iterations 0-16 take their input from 'data' */
+	T_0_15( 0, A, B, C, D, E);
+	T_0_15( 1, E, A, B, C, D);
+	T_0_15( 2, D, E, A, B, C);
+	T_0_15( 3, C, D, E, A, B);
+	T_0_15( 4, B, C, D, E, A);
+	T_0_15( 5, A, B, C, D, E);
+	T_0_15( 6, E, A, B, C, D);
+	T_0_15( 7, D, E, A, B, C);
+	T_0_15( 8, C, D, E, A, B);
+	T_0_15( 9, B, C, D, E, A);
+	T_0_15(10, A, B, C, D, E);
+	T_0_15(11, E, A, B, C, D);
+	T_0_15(12, D, E, A, B, C);
+	T_0_15(13, C, D, E, A, B);
+	T_0_15(14, B, C, D, E, A);
+	T_0_15(15, A, B, C, D, E);
+
+	/* Round 1 - tail. Input from 512-bit mixing array */
+	T_16_19(16, E, A, B, C, D);
+	T_16_19(17, D, E, A, B, C);
+	T_16_19(18, C, D, E, A, B);
+	T_16_19(19, B, C, D, E, A);
+
+	/* Round 2 */
+	T_20_39(20, A, B, C, D, E);
+	T_20_39(21, E, A, B, C, D);
+	T_20_39(22, D, E, A, B, C);
+	T_20_39(23, C, D, E, A, B);
+	T_20_39(24, B, C, D, E, A);
+	T_20_39(25, A, B, C, D, E);
+	T_20_39(26, E, A, B, C, D);
+	T_20_39(27, D, E, A, B, C);
+	T_20_39(28, C, D, E, A, B);
+	T_20_39(29, B, C, D, E, A);
+	T_20_39(30, A, B, C, D, E);
+	T_20_39(31, E, A, B, C, D);
+	T_20_39(32, D, E, A, B, C);
+	T_20_39(33, C, D, E, A, B);
+	T_20_39(34, B, C, D, E, A);
+	T_20_39(35, A, B, C, D, E);
+	T_20_39(36, E, A, B, C, D);
+	T_20_39(37, D, E, A, B, C);
+	T_20_39(38, C, D, E, A, B);
+	T_20_39(39, B, C, D, E, A);
+
+	/* Round 3 */
+	T_40_59(40, A, B, C, D, E);
+	T_40_59(41, E, A, B, C, D);
+	T_40_59(42, D, E, A, B, C);
+	T_40_59(43, C, D, E, A, B);
+	T_40_59(44, B, C, D, E, A);
+	T_40_59(45, A, B, C, D, E);
+	T_40_59(46, E, A, B, C, D);
+	T_40_59(47, D, E, A, B, C);
+	T_40_59(48, C, D, E, A, B);
+	T_40_59(49, B, C, D, E, A);
+	T_40_59(50, A, B, C, D, E);
+	T_40_59(51, E, A, B, C, D);
+	T_40_59(52, D, E, A, B, C);
+	T_40_59(53, C, D, E, A, B);
+	T_40_59(54, B, C, D, E, A);
+	T_40_59(55, A, B, C, D, E);
+	T_40_59(56, E, A, B, C, D);
+	T_40_59(57, D, E, A, B, C);
+	T_40_59(58, C, D, E, A, B);
+	T_40_59(59, B, C, D, E, A);
+
+	/* Round 4 */
+	T_60_79(60, A, B, C, D, E);
+	T_60_79(61, E, A, B, C, D);
+	T_60_79(62, D, E, A, B, C);
+	T_60_79(63, C, D, E, A, B);
+	T_60_79(64, B, C, D, E, A);
+	T_60_79(65, A, B, C, D, E);
+	T_60_79(66, E, A, B, C, D);
+	T_60_79(67, D, E, A, B, C);
+	T_60_79(68, C, D, E, A, B);
+	T_60_79(69, B, C, D, E, A);
+	T_60_79(70, A, B, C, D, E);
+	T_60_79(71, E, A, B, C, D);
+	T_60_79(72, D, E, A, B, C);
+	T_60_79(73, C, D, E, A, B);
+	T_60_79(74, B, C, D, E, A);
+	T_60_79(75, A, B, C, D, E);
+	T_60_79(76, E, A, B, C, D);
+	T_60_79(77, D, E, A, B, C);
+	T_60_79(78, C, D, E, A, B);
+	T_60_79(79, B, C, D, E, A);
+
+	ctx->H[0] += A;
+	ctx->H[1] += B;
+	ctx->H[2] += C;
+	ctx->H[3] += D;
+	ctx->H[4] += E;
+}
+
+void blk_SHA1_Init(blk_SHA_CTX *ctx)
+{
+	ctx->size = 0;
+
+	/* Initialize H with the magic constants (see FIPS180 for constants) */
+	ctx->H[0] = 0x67452301;
+	ctx->H[1] = 0xefcdab89;
+	ctx->H[2] = 0x98badcfe;
+	ctx->H[3] = 0x10325476;
+	ctx->H[4] = 0xc3d2e1f0;
+}
+
+void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
+{
+	int lenW = ctx->size & 63;
+
+	ctx->size += len;
+
+	/* Read the data into W and process blocks as they get full */
+	if (lenW) {
+		int left = 64 - lenW;
+		if (len < left)
+			left = len;
+		memcpy(lenW + (char *)ctx->W, data, left);
+		lenW = (lenW + left) & 63;
+		len -= left;
+		data = ((const char *)data + left);
+		if (lenW)
+			return;
+		blk_SHA1_Block(ctx, ctx->W);
+	}
+	while (len >= 64) {
+		blk_SHA1_Block(ctx, data);
+		data = ((const char *)data + 64);
+		len -= 64;
+	}
+	if (len)
+		memcpy(ctx->W, data, len);
+}
+
+void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
+{
+	static const unsigned char pad[64] = { 0x80 };
+	unsigned int padlen[2];
+	int i;
+
+	/* Pad with a binary 1 (ie 0x80), then zeroes, then length */
+	padlen[0] = htonl(ctx->size >> 29);
+	padlen[1] = htonl(ctx->size << 3);
+
+	i = ctx->size & 63;
+	blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - i)));
+	blk_SHA1_Update(ctx, padlen, 8);
+
+	/* Output hash */
+	for (i = 0; i < 5; i++)
+		put_be32(hashout + i*4, ctx->H[i]);
+}

block-sha1/sha1.h

@@ -0,0 +1,20 @@
+/*
+ * Based on the Mozilla SHA1 (see mozilla-sha1/sha1.h),
+ * optimized to do word accesses rather than byte accesses,
+ * and to avoid unnecessary copies into the context array.
+ */
+
+typedef struct {
+	unsigned int H[5];
+	unsigned int W[16];
+	unsigned long long size;
+} blk_SHA_CTX;
+
+void blk_SHA1_Init(blk_SHA_CTX *ctx);
+void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *dataIn, unsigned long len);
+void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx);
+
+#define git_SHA_CTX	blk_SHA_CTX
+#define git_SHA1_Init	blk_SHA1_Init
+#define git_SHA1_Update	blk_SHA1_Update
+#define git_SHA1_Final	blk_SHA1_Final