Hash to pallet lookup

colourize.c

#include <stdio.h>
#include <stdint.h>

static unsigned colour_table[] = {
    0x24,  0x25,  0x26,  0x27,  0x29,  0x30,  0x31,  0x32,
    0x33,  0x34,  0x35,  0x36,  0x37,  0x38,  0x39,  0x40,
    0x41,  0x42,  0x43,  0x44,  0x45,  0x46,  0x47,  0x48,
    0x49,  0x50,  0x51,  0x59,  0x60,  0x61,  0x62,  0x63,
    0x64,  0x65,  0x66,  0x67,  0x68,  0x69,  0x70,  0x71,
    0x72,  0x73,  0x74,  0x75,  0x76,  0x77,  0x78,  0x79,
    0x80,  0x81,  0x82,  0x83,  0x84,  0x85,  0x86,  0x87,
    0x96,  0x97,  0x98,  0x99,  0x100, 0x101, 0x102, 0x103,
    0x104, 0x105, 0x107, 0x108, 0x109, 0x110, 0x111, 0x112,
    0x113, 0x114, 0x115, 0x116, 0x117, 0x118, 0x119, 0x120,
    0x121, 0x130, 0x131, 0x132, 0x133, 0x134, 0x135, 0x137,
    0x138, 0x139, 0x140, 0x141, 0x143, 0x144, 0x145, 0x146,
    0x147, 0x148, 0x149, 0x150, 0x151, 0x154, 0x155, 0x156,
    0x157, 0x166, 0x167, 0x168, 0x169, 0x170, 0x171, 0x172,
    0x173, 0x174, 0x175, 0x176, 0x177, 0x178, 0x179, 0x180,
    0x181, 0x182, 0x183, 0x184, 0x185, 0x186, 0x190, 0x191,
    0x192, 0x193, 0x197, 0x198, 0x199, 0x200, 0x215, 0x228
};

static uint64_t hash_sdbm(const char *str)
{
    uint64_t hash = 0;
    const char *c;

    for (c = str; c && *c; ++c) {
        hash *= 65599;
        hash += *c;
    }

    return hash;
}

int main(int argc, char *argv[])
{
    int i;
    static const size_t table_length = sizeof(colour_table) / sizeof(colour_table[0]);

    for (i = 1; i < argc; ++i) {
        uint64_t index = hash_sdbm(argv[i]) % table_length;
        unsigned colour = colour_table[index];

        printf("\033[38;5;%um%s\033[0m\n", colour, argv[i]);
    }
}