ieee754_bits_from_scaled_u64()

u32 fl::detail::ieee754_bits_from_scaled_u64 ( u32 sign, u64 magnitude, int binary_exp )

inline

Definition at line 159 of file json.h.

                                                          {
    if (magnitude == 0) {
        return sign;
    }
 
    const int top_bit = json_floor_log2_u64(magnitude);
    int exponent = top_bit + binary_exp;
    if (exponent > 127) {
        return sign | 0x7F800000u;
    }
 
    if (exponent >= -126) {
        const int shift = top_bit - 23;
        u32 significand = 0;
        if (shift > 0) {
            significand = round_shift_right_u64(magnitude, shift);
        } else {
            significand = static_cast<u32>(magnitude << -shift);
        }
        if (significand >= 0x01000000u) {
            significand >>= 1;
            ++exponent;
            if (exponent > 127) {
                return sign | 0x7F800000u;
            }
        }
        return sign | (static_cast<u32>(exponent + 127) << 23) |
               (significand & 0x007FFFFFu);
    }
 
    const int subnormal_shift = -(binary_exp + 149);
    u32 mantissa = 0;
    if (subnormal_shift > 0) {
        mantissa = round_shift_right_u64(magnitude, subnormal_shift);
    } else {
        const int left_shift = -subnormal_shift;
        if (left_shift >= 64 || magnitude > (u64(-1) >> left_shift)) {
            return sign | 0x7F800000u;
        }
        const u64 shifted = magnitude << left_shift;
        mantissa = shifted > 0x007FFFFFu ? 0x00800000u : static_cast<u32>(shifted);
    }
    if (mantissa >= 0x00800000u) {
        return sign | 0x00800000u;
    }