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    Subject[PATCH 11/14] crc32: Bolt on crc32c
    From
    Date
    Reuse the existing crc32 code to stamp out a crc32c implementation.

    Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
    ---
    include/linux/crc32.h | 2 ++
    lib/Kconfig | 8 +++---
    lib/crc32.c | 62 +++++++++++++++++++++++++++++++------------------
    lib/crc32defs.h | 7 ++++++
    lib/gen_crc32table.c | 35 ++++++++++++++++++++++------
    5 files changed, 80 insertions(+), 34 deletions(-)


    diff --git a/include/linux/crc32.h b/include/linux/crc32.h
    index 391a259..68267b6 100644
    --- a/include/linux/crc32.h
    +++ b/include/linux/crc32.h
    @@ -11,6 +11,8 @@
    extern u32 crc32_le(u32 crc, unsigned char const *p, size_t len);
    extern u32 crc32_be(u32 crc, unsigned char const *p, size_t len);

    +extern u32 __crc32c_le(u32 crc, unsigned char const *p, size_t len);
    +
    #define crc32(seed, data, length) crc32_le(seed, (unsigned char const *)(data), length)

    /*
    diff --git a/lib/Kconfig b/lib/Kconfig
    index 2bc5834..cfddafc 100644
    --- a/lib/Kconfig
    +++ b/lib/Kconfig
    @@ -51,14 +51,14 @@ config CRC_ITU_T
    functions require M here.

    config CRC32
    - tristate "CRC32 functions"
    + tristate "CRC32/CRC32c functions"
    default y
    select BITREVERSE
    help
    This option is provided for the case where no in-kernel-tree
    - modules require CRC32 functions, but a module built outside the
    - kernel tree does. Such modules that use library CRC32 functions
    - require M here.
    + modules require CRC32/CRC32c functions, but a module built outside
    + the kernel tree does. Such modules that use library CRC32/CRC32c
    + functions require M here.

    config CRC32_SELFTEST
    bool "CRC32 perform self test on init"
    diff --git a/lib/crc32.c b/lib/crc32.c
    index d56516d..8df9561 100644
    --- a/lib/crc32.c
    +++ b/lib/crc32.c
    @@ -46,7 +46,7 @@
    #include "crc32table.h"

    MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
    -MODULE_DESCRIPTION("Ethernet CRC32 calculations");
    +MODULE_DESCRIPTION("Various CRC32 calculations");
    MODULE_LICENSE("GPL");

    #if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
    @@ -135,46 +135,57 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
    * @p: pointer to buffer over which CRC is run
    * @len: length of buffer @p
    */
    -u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
    +static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
    + size_t len, const u32 (*tab)[256],
    + u32 polynomial)
    {
    #if CRC_LE_BITS == 1
    int i;
    while (len--) {
    crc ^= *p++;
    for (i = 0; i < 8; i++)
    - crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
    + crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
    }
    # elif CRC_LE_BITS == 2
    while (len--) {
    crc ^= *p++;
    - crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
    - crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
    - crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
    - crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
    + crc = (crc >> 2) ^ tab[0][crc & 3];
    + crc = (crc >> 2) ^ tab[0][crc & 3];
    + crc = (crc >> 2) ^ tab[0][crc & 3];
    + crc = (crc >> 2) ^ tab[0][crc & 3];
    }
    # elif CRC_LE_BITS == 4
    while (len--) {
    crc ^= *p++;
    - crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
    - crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
    + crc = (crc >> 4) ^ tab[0][crc & 15];
    + crc = (crc >> 4) ^ tab[0][crc & 15];
    }
    # elif CRC_LE_BITS == 8
    /* aka Sarwate algorithm */
    while (len--) {
    crc ^= *p++;
    - crc = (crc >> 8) ^ crc32table_le[0][crc & 255];
    + crc = (crc >> 8) ^ tab[0][crc & 255];
    }
    # else
    - const u32 (*tab)[] = crc32table_le;
    -
    crc = (__force u32) __cpu_to_le32(crc);
    crc = crc32_body(crc, p, len, tab);
    crc = __le32_to_cpu((__force __le32)crc);
    #endif
    return crc;
    }
    +
    +u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
    +{
    + return crc32_le_generic(crc, p, len, crc32table_le, CRCPOLY_LE);
    +}
    EXPORT_SYMBOL(crc32_le);

    +u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
    +{
    + return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
    +}
    +EXPORT_SYMBOL(__crc32c_le);
    +
    /**
    * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
    * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for
    @@ -182,7 +193,9 @@ EXPORT_SYMBOL(crc32_le);
    * @p: pointer to buffer over which CRC is run
    * @len: length of buffer @p
    */
    -u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
    +static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
    + size_t len, const u32 (*tab)[256],
    + u32 polynomial)
    {
    #if CRC_BE_BITS == 1
    int i;
    @@ -190,37 +203,40 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
    crc ^= *p++ << 24;
    for (i = 0; i < 8; i++)
    crc =
    - (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE :
    + (crc << 1) ^ ((crc & 0x80000000) ? polynomial :
    0);
    }
    # elif CRC_BE_BITS == 2
    while (len--) {
    crc ^= *p++ << 24;
    - crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
    - crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
    - crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
    - crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
    + crc = (crc << 2) ^ tab[0][crc >> 30];
    + crc = (crc << 2) ^ tab[0][crc >> 30];
    + crc = (crc << 2) ^ tab[0][crc >> 30];
    + crc = (crc << 2) ^ tab[0][crc >> 30];
    }
    # elif CRC_BE_BITS == 4
    while (len--) {
    crc ^= *p++ << 24;
    - crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
    - crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
    + crc = (crc << 4) ^ tab[0][crc >> 28];
    + crc = (crc << 4) ^ tab[0][crc >> 28];
    }
    # elif CRC_BE_BITS == 8
    while (len--) {
    crc ^= *p++ << 24;
    - crc = (crc << 8) ^ crc32table_be[0][crc >> 24];
    + crc = (crc << 8) ^ tab[0][crc >> 24];
    }
    # else
    - const u32 (*tab)[] = crc32table_be;
    -
    crc = (__force u32) __cpu_to_be32(crc);
    crc = crc32_body(crc, p, len, tab);
    crc = __be32_to_cpu((__force __be32)crc);
    # endif
    return crc;
    }
    +
    +u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
    +{
    + return crc32_be_generic(crc, p, len, crc32table_be, CRCPOLY_BE);
    +}
    EXPORT_SYMBOL(crc32_be);

    #ifdef CONFIG_CRC32_SELFTEST
    diff --git a/lib/crc32defs.h b/lib/crc32defs.h
    index 8181592..6fd1917 100644
    --- a/lib/crc32defs.h
    +++ b/lib/crc32defs.h
    @@ -7,6 +7,13 @@
    #define CRCPOLY_BE 0x04c11db7

    /*
    + * This is the CRC32c polynomial, as outlined by Castagnoli.
    + * x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+
    + * x^8+x^6+x^0
    + */
    +#define CRC32C_POLY_LE 0x82F63B78
    +
    +/*
    * 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 to save table size.
    * For larger systems choose same as CPU architecture as default.
    diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c
    index 0d9edd1..8f8d543 100644
    --- a/lib/gen_crc32table.c
    +++ b/lib/gen_crc32table.c
    @@ -23,6 +23,7 @@

    static uint32_t crc32table_le[LE_TABLE_ROWS][256];
    static uint32_t crc32table_be[BE_TABLE_ROWS][256];
    +static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];

    /**
    * crc32init_le() - allocate and initialize LE table data
    @@ -31,27 +32,38 @@ static uint32_t crc32table_be[BE_TABLE_ROWS][256];
    * fact that crctable[i^j] = crctable[i] ^ crctable[j].
    *
    */
    -static void crc32init_le(void)
    +static void crc32init_le_generic(const uint32_t polynomial,
    + uint32_t (*tab)[256])
    {
    unsigned i, j;
    uint32_t crc = 1;

    - crc32table_le[0][0] = 0;
    + tab[0][0] = 0;

    for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
    - crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
    + crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
    for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
    - crc32table_le[0][i + j] = crc ^ crc32table_le[0][j];
    + tab[0][i + j] = crc ^ tab[0][j];
    }
    for (i = 0; i < LE_TABLE_SIZE; i++) {
    - crc = crc32table_le[0][i];
    + crc = tab[0][i];
    for (j = 1; j < LE_TABLE_ROWS; j++) {
    - crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8);
    - crc32table_le[j][i] = crc;
    + crc = tab[0][crc & 0xff] ^ (crc >> 8);
    + tab[j][i] = crc;
    }
    }
    }

    +static void crc32init_le(void)
    +{
    + crc32init_le_generic(CRCPOLY_LE, crc32table_le);
    +}
    +
    +static void crc32cinit_le(void)
    +{
    + crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
    +}
    +
    /**
    * crc32init_be() - allocate and initialize BE table data
    */
    @@ -114,6 +126,15 @@ int main(int argc, char** argv)
    BE_TABLE_SIZE, "tobe");
    printf("};\n");
    }
    + if (CRC_LE_BITS > 1) {
    + crc32cinit_le();
    + printf("static const u32 __cacheline_aligned "
    + "crc32ctable_le[%d][%d] = {",
    + LE_TABLE_ROWS, LE_TABLE_SIZE);
    + output_table(crc32ctable_le, LE_TABLE_ROWS,
    + LE_TABLE_SIZE, "tole");
    + printf("};\n");
    + }

    return 0;
    }


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      Last update: 2011-11-28 23:41    [W:0.037 / U:0.320 seconds]
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