C Implementatation of TI BASIC's RND function

gistfile1.c

/* Equivalent to PRINT RND in TI Basic */   
char *rnd() {
    uint8_t rnds[7]; int i; char *n; 
    
    /* Try up to 64 times to come up with a non-zero pseudo-random integer */
    for (i=0;i<63;i++) if ((rnds[0] = gpl_rand(100)) != 0) break;
    if (rnds[0] == 0) return strdup("0");
    
    /* Generate the rest of the set */   
    for (i=1;i<7;i++) rnds[i] = gpl_rand(100);

    /* PRINT rounds up if the 6th number generated is >= 0x32 (50) */
    if (rnds[5] >= 0x32) rnds[4]++;

    /* PRINT prepends a leading zero if the first byte is < 0x10 */
    if (rnds[0] < 0x10) {
        memmove(&rnds[1],&rnds[0],6);
        rnds[0] = 0;
    }

    /* Convert to string */
    n = malloc(22);
    snprintf(n,22,".%02d%02d%02d%02d%02d",rnds[0],rnds[1],rnds[2],rnds[3],rnds[4]);
    return n;
}