Simple 4 char bech32 bruteforce

dummy.c

    char hrp[8];
    char bech32_str[128] = "xp1qqqqqq8z4rsgv54z9a92yla4m2yrsqdlwdl7gn6qldvwkuh3zrg66z8ad2snf832tgaxcuv3kmwugzl5x8wtnkj2q3a03ky0kg8p7dvv4czpjqgvv4zgn";
    int range[4] = {10, 15, 20, 36};
    uint8_t dblcheck5[100] = {};
    size_t dblcheck5_len = 0;
    if (!bech32_decode(hrp, dblcheck5, &dblcheck5_len, bech32_str)) {
        printf("bech32_decode fails: '%s'\n", bech32_str);
    }
    uint8_t dblcheck8[128] = {};
    size_t dblcheck8_len = 0;
    convert_bits(dblcheck8, &dblcheck8_len, 8, dblcheck5, dblcheck5_len, 5, 1);

    int rcnt[4] = {0,0,0,0};
    char ochar[4] = {bech32_str[range[0]],bech32_str[range[1]],bech32_str[range[2]],bech32_str[range[3]]};
    int total = 0;
    btc_hdnode *node = btc_hdnode_new();
    char addr[128];
    while(1) {
        dblcheck8_len = 0;
        bech32_str[range[0]] = charset[rcnt[0]];
        bech32_str[range[1]] = charset[rcnt[1]];
        bech32_str[range[2]] = charset[rcnt[2]];
        bech32_str[range[3]] = charset[rcnt[3]];
        if (!bech32_decode(hrp, dblcheck5, &dblcheck5_len, bech32_str)) {

        }
        convert_bits(dblcheck8, &dblcheck8_len, 8, dblcheck5, dblcheck5_len, 5, 1);
        memcpy(node->chain_code, dblcheck8+8, 32);
        memcpy(node->private_key, dblcheck8+8+32, 32);
        btc_hdnode_private_ckd(node, 1);
        btc_hdnode_get_p2pkh_address(node, &btc_chainparams_main, addr, 128);
        rcnt[3]++;
        if (rcnt[3]>31) {
            rcnt[2]++;rcnt[3]=0;
            printf("stupup l2: %d %d %d %d\n", rcnt[0], rcnt[1], rcnt[2], rcnt[3]);
            if (rcnt[2]>31) {
                rcnt[1]++;rcnt[2]=0;
                if (rcnt[1]>31) {
                    rcnt[0]++;rcnt[1]=0;
                    if (rcnt[0]>31) {
                        break;
                    }
                }
            }
        }
        total++;
    }
    printf("total: %d\n", total);
    exit(1);
}

Compiled with -O0 (should probably compile -O2). Code runs non-parallelized.

total: 1048575

real	1m5.231s
user	1m4.056s
sys	0m0.796s