Function Dragon4_PrintFloat_IEEE_binary16

numpy/core/src/multiarray/dragon4.c:2211–2289

* IEEE binary16 floating-point format * * sign: 1 bit * exponent: 5 bits * mantissa: 10 bits */

 * mantissa: 10 bits
 */
static npy_uint32
Dragon4_PrintFloat_IEEE_binary16(
        Dragon4_Scratch *scratch, npy_half *value, Dragon4_Options *opt)
{
    char *buffer = scratch->repr;
    const npy_uint32 bufferSize = sizeof(scratch->repr);
    BigInt *bigints = scratch->bigints;

    npy_uint16 val = *value;
    npy_uint32 floatExponent, floatMantissa, floatSign;

    npy_uint32 mantissa;
    npy_int32 exponent;
    npy_uint32 mantissaBit;
    npy_bool hasUnequalMargins;
    char signbit = '\0';

    /* deconstruct the floating point value */
    floatMantissa = val & bitmask_u32(10);
    floatExponent = (val >> 10) & bitmask_u32(5);
    floatSign = val >> 15;

    /* output the sign */
    if (floatSign != 0) {
        signbit = '-';
    }
    else if (opt->sign) {
        signbit = '+';
    }

    /* if this is a special value */
    if (floatExponent == bitmask_u32(5)) {
        return PrintInfNan(buffer, bufferSize, floatMantissa, 3, signbit);
    }
    /* else this is a number */

    /* factor the value into its parts */
    if (floatExponent != 0) {
        /*
         * normalized
         * The floating point equation is:
         *  value = (1 + mantissa/2^10) * 2 ^ (exponent-15)
         * We convert the integer equation by factoring a 2^10 out of the
         * exponent
         *  value = (1 + mantissa/2^10) * 2^10 * 2 ^ (exponent-15-10)
         *  value = (2^10 + mantissa) * 2 ^ (exponent-15-10)
         * Because of the implied 1 in front of the mantissa we have 10 bits of
         * precision.
         *   m = (2^10 + mantissa)
         *   e = (exponent-15-10)
         */
        mantissa            = (1UL << 10) | floatMantissa;
        exponent            = floatExponent - 15 - 10;
        mantissaBit         = 10;
        hasUnequalMargins   = (floatExponent != 1) && (floatMantissa == 0);
    }
    else {
        /*