gen_crc32table.c

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#include <stdio.h>
#include "../include/generated/autoconf.h"
#include "crc32defs.h"
#include <inttypes.h>

#define ENTRIES_PER_LINE 4

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

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

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];

static void crc32init_le_generic(const uint32_t polynomial,
                 uint32_t (*tab)[256])
{
    unsigned i, j;
    uint32_t crc = 1;

    tab[0][0] = 0;

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

static void crc32init_be(void)
{
    unsigned i, j;
    uint32_t crc = 0x80000000;

    crc32table_be[0][0] = 0;

    for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
        crc = (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0);
        for (j = 0; j < i; j++)
            crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
    }
    for (i = 0; i < BE_TABLE_SIZE; i++) {
        crc = crc32table_be[0][i];
        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)[256], int rows, int len, char *trans)
{
    int i, j;

    for (j = 0 ; j < rows; j++) {
        printf("{");
        for (i = 0; i < len - 1; i++) {
            if (i % ENTRIES_PER_LINE == 0)
                printf("\n");
            printf("%s(0x%8.8xL), ", trans, table[j][i]);
        }
        printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
    }
}

int main(int argc, char** argv)
{
    printf("/* this file is generated - do not edit */\n\n");

    if (CRC_LE_BITS > 1) {
        crc32init_le();
        printf("static 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 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");
    }
    if (CRC_LE_BITS > 1) {
        crc32cinit_le();
        printf("static 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;
}