Hex digit to integer (full)

#include <stdio.h>
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <time.h>

char lut[256];
int hextoint_lut(char x) {
    return lut[uint8_t(x)];
}

int hextoint_cond(char x) {
    uint32_t dig = x - '0';
    uint32_t alp = dig + ('0' - 'a' + 10);
    return dig <= 9U ? dig : alp;
}

int hextoint_cond2(char x) {
    uint32_t offset = (uint8_t(x) <= uint8_t('9') ? '0' : 'a' - 10);
    return uint8_t(x) - offset;
}

int hextoint_bit(char x) {
    int b = uint8_t(x);
    int mask = (('9' - b) >> 31);
    int offset = '0' + (mask & int('a' - '0' - 10));
    return b - offset;
}



int hextoint_bit_ci(char x) {
    int b = uint8_t(x);
    int maskLetter = (('9' - b) >> 31);
    int maskSmall = (('Z' - b) >> 31);
    int offset = '0' + (maskLetter & int('A' - '0' - 10)) + (maskSmall & int('a' - 'A'));
    return b - offset;
}


int main() {
    const char all[] = {
        '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
        'a', 'b', 'c', 'd', 'e', 'f',
        'A', 'B', 'C', 'D', 'E', 'F'
    };
    const char idx[] = {
        0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
        10, 11, 12, 13, 14, 15,
        10, 11, 12, 13, 14, 15
    };
    for (int i = 0; i < 22; i++)
        lut[uint8_t(all[i])] = idx[i];

    for (int i = 0; i < 16; i++)
        assert(idx[i] == hextoint_lut(all[i]));
    for (int i = 0; i < 16; i++)
        assert(idx[i] == hextoint_cond(all[i]));
    for (int i = 0; i < 16; i++)
        assert(idx[i] == hextoint_cond2(all[i]));
    for (int i = 0; i < 16; i++)
        assert(idx[i] == hextoint_bit(all[i]));

    for (int i = 0; i < 22; i++)
        assert(idx[i] == hextoint_bit_ci(all[i]));


    static const int VALUES = 64<<10;
    static const int TRIES = 16<<10;
    static const double FREQ = 3.4e+9;  //Note write your CPU's frequency here

    #define BENCHMARK(func, data) {                                     \
        int sum = 0;                                                    \
        int start = clock();                                            \
        for (int i = 0; i < TRIES; i++)                                 \
            for (int j = 0; j < VALUES; j+=8) {                         \
                sum += func(data[j + 0]);                               \
                sum += func(data[j + 1]);                               \
                sum += func(data[j + 2]);                               \
                sum += func(data[j + 3]);                               \
                sum += func(data[j + 4]);                               \
                sum += func(data[j + 5]);                               \
                sum += func(data[j + 6]);                               \
                sum += func(data[j + 7]);                               \
            }                                                           \
        double elapsed = double(clock() - start) / CLOCKS_PER_SEC;      \
        double cycles = elapsed / TRIES / VALUES * FREQ;                \
        printf("%s: %0.3lf sec, %0.1lf cycles  (check: %d)\n",          \
            #func, elapsed, cycles, sum); \
    }

    char input[VALUES];
    for (int i = 0; i < VALUES; i++)
        input[i] = all[rand() % 16];

    BENCHMARK(hextoint_lut, input);
    BENCHMARK(hextoint_cond, input);
    BENCHMARK(hextoint_cond2, input);
    BENCHMARK(hextoint_bit, input);

    return 0;
}