Double codec

doublecodec

typedef union {
    double dv;
    long long unsigned int lv;
} doubleLong;

void memrev64(void *p) {
    unsigned char *x = p, t;

    t = x[0];
    x[0] = x[7];
    x[7] = t;
    t = x[1];
    x[1] = x[6];
    x[6] = t;
    t = x[2];
    x[2] = x[5];
    x[5] = t;
    t = x[3];
    x[3] = x[4];
    x[4] = t;
}

void encodeDouble(char *encoded, double val) {
    doubleLong x;
    x.dv = val;
    if (val >= 0) {
        x.lv |= 1L<<63;
    } else {
        x.lv = ~x.lv;
    }
    memrev64(&x);
    memcpy(encoded, &x, 8);
}

double decodeDouble(char *encoded) {
    doubleLong x;
    memcpy(&x, encoded, 8);
    memrev64(&x);
    if (x.lv & 1L<<63) {
        x.lv &= ~(1L<<63);
    } else {
        x.lv = ~x.lv;
    }
    return x.dv;
}