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    Subject[PATCH 06/13] crc32: Make CRC_*_BITS definition correspond to actual bit counts
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    crc32.c provides a choice of one of several algorithms for
    computing the LSB and LSB versions of the CRC32 checksum
    based on the parameters CRC_LE_BITS and CRC_BE_BITS. In the
    original version the values 1, 2, 4 and 8 respectively selected
    versions of the alrogithm that computed the crc 1, 2, 4 and 32
    bits as a time. This patch series adds a new version that computes
    the CRC 64 bits at a time. To make things easier to understand
    the parameter has been reinterpreted to actually stand for the
    number of bits processed in each step of the algorithm so that
    the old value 8 has been replaced with the value 32. This also
    allows us to add in a widely used crc algorithm that
    computes the crc 8 bits at a time called the Sarwate algorithm.

    From: Bob Pearson <rpearson@systemfabricworks.com>
    Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>
    [djwong@us.ibm.com: Minor changelog tweaks]
    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---
    lib/crc32.c | 17 ++++++++++++++---
    lib/crc32defs.h | 18 ++++++++++--------
    lib/gen_crc32table.c | 11 ++++++++++-
    3 files changed, 34 insertions(+), 12 deletions(-)


    diff --git a/lib/crc32.c b/lib/crc32.c
    index 7394288..5971f2a 100644
    --- a/lib/crc32.c
    +++ b/lib/crc32.c
    @@ -27,13 +27,13 @@
    #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)
    @@ -45,7 +45,7 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
    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])
    @@ -126,6 +126,12 @@ u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
    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);
    @@ -169,6 +175,11 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
    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);
    diff --git a/lib/crc32defs.h b/lib/crc32defs.h
    index f5a5401..daa3a5e 100644
    --- a/lib/crc32defs.h
    +++ b/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
    diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c
    index eced769..99ac744 100644
    --- a/lib/gen_crc32table.c
    +++ b/lib/gen_crc32table.c
    @@ -4,8 +4,17 @@

    #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][256];
    static uint32_t crc32table_be[4][256];
    @@ -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];


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