[patches v5 resending 6/8] crc32: add-real-8-bit.diff

[Bob Pearson <rpearson@systemfabricworks.com>]

crc32.c encodes an algorithm that processes 32 bits at a time
with the value BITS = 8 and leaves out the most common 8 bit algorithm
for computing the crc. This patch reencodes the 32 bit algorithm
with the value 32 and adds back the 'standard' 8 bit algorithm.

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

---
 lib/crc32.c          |   17 ++++++++++++++---
 lib/crc32defs.h      |   18 ++++++++++--------
 lib/gen_crc32table.c |   15 ++++++++++++---
 3 files changed, 36 insertions(+), 14 deletions(-)

Index: infiniband/lib/crc32.c
===================================================================
--- infiniband.orig/lib/crc32.c
+++ infiniband/lib/crc32.c
@@ -25,13 +25,13 @@
 #include <linux/types.h>
 #include "crc32defs.h"

-#if CRC_LE_BITS == 8
+#if CRC_LE_BITS > 8
 # define tole(x) (__force u32) __constant_cpu_to_le32(x)
 #else
 # define tole(x) (x)
 #endif

-#if CRC_BE_BITS == 8
+#if CRC_BE_BITS > 8
 # define tobe(x) (__force u32) __constant_cpu_to_be32(x)
 #else
 # define tobe(x) (x)
@@ -43,7 +43,7 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@
 MODULE_DESCRIPTION("Ethernet CRC32 calculations");
 MODULE_LICENSE("GPL");

-#if CRC_LE_BITS == 8 || CRC_BE_BITS == 8
+#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8

 static inline u32
 crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
@@ -124,6 +124,12 @@ u32 __pure crc32_le(u32 crc, unsigned ch
 		crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
 	}
 # elif CRC_LE_BITS == 8
+	/* aka Sarwate algorithm */
+	while (len--) {
+		crc ^= *p++;
+		crc = (crc >> 8) ^ crc32table_le[0][crc & 255];
+	}
+# else
 	const u32      (*tab)[] = crc32table_le;

 	crc = (__force u32) __cpu_to_le32(crc);
@@ -167,6 +173,11 @@ u32 __pure crc32_be(u32 crc, unsigned ch
 		crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
 	}
 # elif CRC_BE_BITS == 8
+	while (len--) {
+		crc ^= *p++ << 24;
+		crc = (crc << 8) ^ crc32table_be[0][crc >> 24];
+	}
+# else
 	const u32      (*tab)[] = crc32table_be;

 	crc = (__force u32) __cpu_to_be32(crc);
Index: infiniband/lib/crc32defs.h
===================================================================
--- infiniband.orig/lib/crc32defs.h
+++ infiniband/lib/crc32defs.h
@@ -6,27 +6,29 @@
 #define CRCPOLY_LE 0xedb88320
 #define CRCPOLY_BE 0x04c11db7

-/* How many bits at a time to use.  Requires a table of 4<<CRC_xx_BITS bytes. */
-/* For less performance-sensitive, use 4 */
+/* How many bits at a time to use.  Valid values are 1, 2, 4, 8, and 32. */
+/* For less performance-sensitive, use 4 or 8 */
 #ifndef CRC_LE_BITS
-# define CRC_LE_BITS 8
+# define CRC_LE_BITS 32
 #endif
 #ifndef CRC_BE_BITS
-# define CRC_BE_BITS 8
+# define CRC_BE_BITS 32
 #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 > 8 || CRC_LE_BITS < 1 || CRC_LE_BITS & CRC_LE_BITS-1
-# error CRC_LE_BITS must be a power of 2 between 1 and 8
+#if CRC_LE_BITS > 32 || 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}"
 #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 > 8 || CRC_BE_BITS < 1 || CRC_BE_BITS & CRC_BE_BITS-1
-# error CRC_BE_BITS must be a power of 2 between 1 and 8
+#if CRC_BE_BITS > 32 || 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}"
 #endif
Index: infiniband/lib/gen_crc32table.c
===================================================================
--- infiniband.orig/lib/gen_crc32table.c
+++ infiniband/lib/gen_crc32table.c
@@ -4,11 +4,20 @@

 #define ENTRIES_PER_LINE 4

+#if CRC_LE_BITS <= 8
 #define LE_TABLE_SIZE (1 << CRC_LE_BITS)
+#else
+#define LE_TABLE_SIZE 256
+#endif
+
+#if CRC_BE_BITS <= 8
 #define BE_TABLE_SIZE (1 << CRC_BE_BITS)
+#else
+#define BE_TABLE_SIZE 256
+#endif

-static uint32_t crc32table_le[4][LE_TABLE_SIZE];
-static uint32_t crc32table_be[4][BE_TABLE_SIZE];
+static uint32_t crc32table_le[4][256];
+static uint32_t crc32table_be[4][256];

 /**
  * crc32init_le() - allocate and initialize LE table data
@@ -24,7 +33,7 @@ static void crc32init_le(void)

 	crc32table_le[0][0] = 0;

-	for (i = 1 << (CRC_LE_BITS - 1); i; i >>= 1) {
+	for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
 		crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
 		for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
 			crc32table_le[0][i + j] = crc ^ crc32table_le[0][j];