std::string Double::toHexString()

in activemq-cpp/src/main/decaf/lang/Double.cpp [167:249]
54 lines of code
19 McCabe index (conditional complexity)

std::string Double::toHexString(double value) {
    /*
     * Reference: http://en.wikipedia.org/wiki/IEEE_754
     */
    if (value != value) {
        return "NaN";
    }
    if (value == POSITIVE_INFINITY) {
        return "Infinity";
    }
    if (value == NEGATIVE_INFINITY) {
        return "-Infinity";
    }

    unsigned long long bitValue = Double::doubleToLongBits(value);

    bool negative = (bitValue & 0x8000000000000000LL) != 0;
    // mask exponent bits and shift down
    unsigned long long exponent = (bitValue & 0x7FF0000000000000LL) >> 52;
    // mask significand bits and shift up
    unsigned long long significand = bitValue & 0x000FFFFFFFFFFFFFLL;

    if (exponent == 0 && significand == 0) {
        return (negative ? "-0x0.0p0" : "0x0.0p0");
    }

    // Start with sign and hex indicator
    std::string hexString(negative ? "-0x" : "0x");

    if (exponent == 0) {
        // denormal (subnormal) value
        hexString.append("0.");
        // significand is 52-bits, so there can be 13 hex digits
        unsigned int fractionDigits = 13;
        // remove trailing hex zeros, so Integer.toHexString() won't print
        // them
        while ((significand != 0) && ((significand & 0xF) == 0)) {
            significand >>= 4;
            fractionDigits--;
        }
        // this assumes Integer.toHexString() returns lowercase characters
        std::string hexSignificand = Long::toHexString(significand);

        // if there are digits left, then insert some '0' chars first
        if (significand != 0 && fractionDigits > hexSignificand.length()) {
            int digitDiff = fractionDigits - (int) hexSignificand.length();
            while (digitDiff-- != 0) {
                hexString.append("0");
            }
        }

        hexString.append(hexSignificand);
        hexString.append("p-1022");
    } else {
        // normal value
        hexString.append("1.");
        // significand is 52-bits, so there can be 13 hex digits
        unsigned int fractionDigits = 13;
        // remove trailing hex zeros, so Integer.toHexString() won't print
        // them
        while ((significand != 0) && ((significand & 0xF) == 0)) {
            significand >>= 4;
            fractionDigits--;
        }
        // this assumes Integer.toHexString() returns lowercase characters
        std::string hexSignificand = Long::toHexString(significand);

        // if there are digits left, then insert some '0' chars first
        if (significand != 0 && fractionDigits > hexSignificand.length()) {
            int digitDiff = fractionDigits - (int) hexSignificand.length();
            while (digitDiff-- != 0) {
                hexString.append("0");
            }
        }

        hexString.append(hexSignificand);
        hexString.append("p");
        // remove exponent's 'bias' and convert to a string
        hexString.append(Long::toString(exponent - 1023));
    }

    return hexString;
}