#include <stdlib.h>
#include <string.h>
#include <stdint.h>

static const char digits[] =
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

long a64l(const char *s)
{
        int e;
        uint32_t x = 0;
        for (e=0; e<36 && *s; e+=6, s++) {
                const char *d = strchr(digits, *s);
                if (!d) break;
                x |= (uint32_t)(d-digits)<<e;
        }
        return (int32_t)x;
}

char *l64a(long x0)
{
        static char s[7];
        char *p;
        uint32_t x = x0;
        for (p=s; x; p++, x>>=6)
                *p = digits[x&63];
        *p = 0;
        return s;
}