[patches v5 resending 7/8] crc32: add-slicing-by-8.diff

[Bob Pearson <rpearson@systemfabricworks.com>]

extend add slicing-by-8 algorithm to the existing
slicing-by-4 algorithm. This consists of:

	- extend largest BITS size from 32 to 64
	- extend table from tab[4][256] to tab[8][256]
	- change algorithm to align on 8 byte boundary
	  (it was noted that all that is really required
	  is that the inner loop must comsume 8 bytes.
	  As written it can start on even or odd 4 byte
	  boundary.)
	- Add code for inner loop.

Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>

---
 lib/crc32.c          |   60 ++++++++++++++++++++++++++++++++++++++++++---------
 lib/crc32defs.h      |   14 +++++------
 lib/gen_crc32table.c |   42 ++++++++++++++++++++++-------------
 3 files changed, 83 insertions(+), 33 deletions(-)

Index: infiniband/lib/crc32.c
===================================================================
--- infiniband.orig/lib/crc32.c
+++ infiniband/lib/crc32.c
@@ -45,6 +45,7 @@ MODULE_LICENSE("GPL");

 #if CRC_LE_BITS > 8 || CRC_BE_BITS > 8

+/* implements slicing-by-4 or slicing-by-8 algorithm */
 static inline u32
 crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
 {
@@ -54,42 +55,81 @@ crc32_body(u32 crc, unsigned char const
 			t2[(crc >> 8) & 255] ^ \
 			t1[(crc >> 16) & 255] ^ \
 			t0[(crc >> 24) & 255]
+#  define DO_CRC8a (t7[(q) & 255] ^ \
+			t6[(q >> 8) & 255] ^ \
+			t5[(q >> 16) & 255] ^ \
+			t4[(q >> 24) & 255])
+#  define DO_CRC8b (t3[(q) & 255] ^ \
+			t2[(q >> 8) & 255] ^ \
+			t1[(q >> 16) & 255] ^ \
+			t0[(q >> 24) & 255])
 # else
 #  define DO_CRC(x) (crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8))
 #  define DO_CRC4 crc = t0[(crc) & 255] ^ \
 			t1[(crc >> 8) & 255] ^ \
 			t2[(crc >> 16) & 255] ^ \
 			t3[(crc >> 24) & 255]
+#  define DO_CRC8a (t4[(q) & 255] ^ \
+			t5[(q >> 8) & 255] ^ \
+			t6[(q >> 16) & 255] ^ \
+			t7[(q >> 24) & 255])
+#  define DO_CRC8b (t0[(q) & 255] ^ \
+			t1[(q >> 8) & 255] ^ \
+			t2[(q >> 16) & 255] ^ \
+			t3[(q >> 24) & 255])
 # endif
 	const u32 *b;
-	size_t    rem_len;
 	const u32 *t0 = tab[0], *t1 = tab[1], *t2 = tab[2], *t3 = tab[3];
+	const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
+	size_t init_len;
+	size_t middle_len;
+	size_t rem_len;
+
+	/* break buf into init_len bytes before and
+	 * rem_len bytes after a middle section with
+	 * middle_len properly aligned words
+	 * note 8 byte loop need only be aligned on
+	 * a 4 byte boundary */
+	init_len = min((-((uintptr_t)buf)) & 3, len);
+# if CRC_LE_BITS == 32
+	middle_len = (len - init_len) >> 2;
+	rem_len = (len - init_len) & 3;
+# else
+	middle_len = (len - init_len) >> 3;
+	rem_len = (len - init_len) & 7;
+# endif

 	/* Align it */
-	if (unlikely((long)buf & 3 && len)) {
+	if (unlikely(init_len)) {
 		do {
 			DO_CRC(*buf++);
-		} while ((--len) && ((long)buf)&3);
+		} while (--init_len);
 	}
-	rem_len = len & 3;
-	/* load data 32 bits wide, xor data 32 bits wide. */
-	len = len >> 2;
 	b = (const u32 *)buf;
-	for (--b; len; --len) {
+	for (--b; middle_len; --middle_len) {
+# if CRC_LE_BITS == 32
 		crc ^= *++b; /* use pre increment for speed */
 		DO_CRC4;
+# else
+		u32 q;
+		q = crc ^ *++b;
+		crc = DO_CRC8a;
+		q = *++b;
+		crc ^= DO_CRC8b;
+# endif
 	}
-	len = rem_len;
 	/* And the last few bytes */
-	if (len) {
+	if (rem_len) {
 		u8 *p = (u8 *)(b + 1) - 1;
 		do {
 			DO_CRC(*++p); /* use pre increment for speed */
-		} while (--len);
+		} while (--rem_len);
 	}
 	return crc;
 #undef DO_CRC
 #undef DO_CRC4
+#undef DO_CRC8a
+#undef DO_CRC8b
 }
 #endif

Index: infiniband/lib/crc32defs.h
===================================================================
--- infiniband.orig/lib/crc32defs.h
+++ infiniband/lib/crc32defs.h
@@ -6,29 +6,29 @@
 #define CRCPOLY_LE 0xedb88320
 #define CRCPOLY_BE 0x04c11db7

-/* How many bits at a time to use.  Valid values are 1, 2, 4, 8, and 32. */
+/* How many bits at a time to use.  Valid values are 1, 2, 4, 8, 32 and 64. */
 /* For less performance-sensitive, use 4 or 8 */
 #ifndef CRC_LE_BITS
-# define CRC_LE_BITS 32
+# define CRC_LE_BITS 64
 #endif
 #ifndef CRC_BE_BITS
-# define CRC_BE_BITS 32
+# define CRC_BE_BITS 64
 #endif

 /*
  * Little-endian CRC computation.  Used with serial bit streams sent
  * lsbit-first.  Be sure to use cpu_to_le32() to append the computed CRC.
  */
-#if CRC_LE_BITS > 32 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
+#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
 	CRC_LE_BITS & CRC_LE_BITS-1
-# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32}"
+# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 64}"
 #endif

 /*
  * Big-endian CRC computation.  Used with serial bit streams sent
  * msbit-first.  Be sure to use cpu_to_be32() to append the computed CRC.
  */
-#if CRC_BE_BITS > 32 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
+#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
 	CRC_BE_BITS & CRC_BE_BITS-1
-# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32}"
+# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 64}"
 #endif
Index: infiniband/lib/gen_crc32table.c
===================================================================
--- infiniband.orig/lib/gen_crc32table.c
+++ infiniband/lib/gen_crc32table.c
@@ -4,20 +4,24 @@

 #define ENTRIES_PER_LINE 4

-#if CRC_LE_BITS <= 8
-#define LE_TABLE_SIZE (1 << CRC_LE_BITS)
+#if CRC_LE_BITS > 8
+# define LE_TABLE_ROWS (CRC_LE_BITS/8)
+# define LE_TABLE_SIZE 256
 #else
-#define LE_TABLE_SIZE 256
+# define LE_TABLE_ROWS 1
+# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
 #endif

-#if CRC_BE_BITS <= 8
-#define BE_TABLE_SIZE (1 << CRC_BE_BITS)
+#if CRC_BE_BITS > 8
+# define BE_TABLE_ROWS (CRC_BE_BITS/8)
+# define BE_TABLE_SIZE 256
 #else
-#define BE_TABLE_SIZE 256
+# define BE_TABLE_ROWS 1
+# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
 #endif

-static uint32_t crc32table_le[4][256];
-static uint32_t crc32table_be[4][256];
+static uint32_t crc32table_le[LE_TABLE_ROWS][256];
+static uint32_t crc32table_be[BE_TABLE_ROWS][256];

 /**
  * crc32init_le() - allocate and initialize LE table data
@@ -40,7 +44,7 @@ static void crc32init_le(void)
 	}
 	for (i = 0; i < LE_TABLE_SIZE; i++) {
 		crc = crc32table_le[0][i];
-		for (j = 1; j < 4; j++) {
+		for (j = 1; j < LE_TABLE_ROWS; j++) {
 			crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8);
 			crc32table_le[j][i] = crc;
 		}
@@ -64,18 +68,18 @@ static void crc32init_be(void)
 	}
 	for (i = 0; i < BE_TABLE_SIZE; i++) {
 		crc = crc32table_be[0][i];
-		for (j = 1; j < 4; j++) {
+		for (j = 1; j < BE_TABLE_ROWS; j++) {
 			crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
 			crc32table_be[j][i] = crc;
 		}
 	}
 }

-static void output_table(uint32_t table[4][256], int len, char *trans)
+static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
 {
 	int i, j;

-	for (j = 0 ; j < 4; j++) {
+	for (j = 0 ; j < rows; j++) {
 		printf("{");
 		for (i = 0; i < len - 1; i++) {
 			if (i % ENTRIES_PER_LINE == 0)
@@ -92,15 +96,21 @@ int main(int argc, char** argv)

 	if (CRC_LE_BITS > 1) {
 		crc32init_le();
-		printf("static const u32 crc32table_le[4][256] = {");
-		output_table(crc32table_le, LE_TABLE_SIZE, "tole");
+		printf("static const u32 __cacheline_aligned "
+		       "crc32table_le[%d][%d] = {",
+		       LE_TABLE_ROWS, LE_TABLE_SIZE);
+		output_table(crc32table_le, LE_TABLE_ROWS,
+			     LE_TABLE_SIZE, "tole");
 		printf("};\n");
 	}

 	if (CRC_BE_BITS > 1) {
 		crc32init_be();
-		printf("static const u32 crc32table_be[4][256] = {");
-		output_table(crc32table_be, BE_TABLE_SIZE, "tobe");
+		printf("static const u32 __cacheline_aligned "
+		       "crc32table_be[%d][%d] = {",
+		       BE_TABLE_ROWS, BE_TABLE_SIZE);
+		output_table(crc32table_be, LE_TABLE_ROWS,
+			     BE_TABLE_SIZE, "tobe");
 		printf("};\n");
 	}