test/half_to_double_from_rfc7049.c

/*

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 */

/*
 This code is from RFC 7049/8949. It is not used in the main implementation
 because:
   a) it adds a dependency on <math.h> and ldexp().
   b) the license may be an issue

 QCBOR does support half-precision, but rather than using
 floating-point math like this, it does it with bit shifting
 and masking.

 This code is here to test that code.

 */

#include "half_to_double_from_rfc7049.h"

#include <math.h>

double decode_half(unsigned char *halfp) {
    int half = (halfp[0] << 8) + halfp[1];
    int exp = (half >> 10) & 0x1f;
    int mant = half & 0x3ff;
    double val;
    if (exp == 0) val = ldexp(mant, -24);
    else if (exp != 31) val = ldexp(mant + 1024, exp - 25);
    else val = mant == 0 ? INFINITY : NAN;
    return half & 0x8000 ? -val : val;
}