Java example source code file (ToHexString.java)
The ToHexString.java Java example source code/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 4826774 4926547
* @summary Tests for {Float, Double}.toHexString methods
* @author Joseph D. Darcy
*/
import java.util.regex.*;
import sun.misc.DoubleConsts;
public class ToHexString {
private ToHexString() {}
/*
* Given a double value, create a hexadecimal floating-point
* string via an intermediate long hex string.
*/
static String doubleToHexString(double d) {
return hexLongStringtoHexDoubleString(Long.toHexString(Double.doubleToLongBits(d)));
}
/*
* Transform the hexadecimal long output into the equivalent
* hexadecimal double value.
*/
static String hexLongStringtoHexDoubleString(String transString) {
transString = transString.toLowerCase();
String zeros = "";
StringBuffer result = new StringBuffer(24);
for(int i = 0; i < (16 - transString.length()); i++, zeros += "0");
transString = zeros + transString;
// assert transString.length == 16;
char topChar;
// Extract sign
if((topChar=transString.charAt(0)) >= '8' ) {// 8, 9, a, A, b, B, ...
result.append("-");
// clear sign bit
transString =
Character.toString(Character.forDigit(Character.digit(topChar, 16) - 8, 16)) +
transString.substring(1,16);
}
// check for NaN and infinity
String signifString = transString.substring(3,16);
if( transString.substring(0,3).equals("7ff") ) {
if(signifString.equals("0000000000000")) {
result.append("Infinity");
}
else
result.append("NaN");
}
else { // finite value
// Extract exponent
int exponent = Integer.parseInt(transString.substring(0,3), 16) -
DoubleConsts.EXP_BIAS;
result.append("0x");
if (exponent == DoubleConsts.MIN_EXPONENT - 1) { // zero or subnormal
if(signifString.equals("0000000000000")) {
result.append("0.0p0");
}
else {
result.append("0." + signifString.replaceFirst("0+$", "").replaceFirst("^$", "0") +
"p-1022");
}
}
else { // normal value
result.append("1." + signifString.replaceFirst("0+$", "").replaceFirst("^$", "0") +
"p" + exponent);
}
}
return result.toString();
}
public static int toHexStringTests() {
int failures = 0;
String [][] testCases1 = {
{"Infinity", "Infinity"},
{"-Infinity", "-Infinity"},
{"NaN", "NaN"},
{"-NaN", "NaN"},
{"0.0", "0x0.0p0"},
{"-0.0", "-0x0.0p0"},
{"1.0", "0x1.0p0"},
{"-1.0", "-0x1.0p0"},
{"2.0", "0x1.0p1"},
{"3.0", "0x1.8p1"},
{"0.5", "0x1.0p-1"},
{"0.25", "0x1.0p-2"},
{"1.7976931348623157e+308", "0x1.fffffffffffffp1023"}, // MAX_VALUE
{"2.2250738585072014E-308", "0x1.0p-1022"}, // MIN_NORMAL
{"2.225073858507201E-308", "0x0.fffffffffffffp-1022"}, // MAX_SUBNORMAL
{"4.9e-324", "0x0.0000000000001p-1022"} // MIN_VALUE
};
// Compare decimal string -> double -> hex string to hex string
for (int i = 0; i < testCases1.length; i++) {
String result;
if(! (result=Double.toHexString(Double.parseDouble(testCases1[i][0]))).
equals(testCases1[i][1])) {
failures ++;
System.err.println("For floating-point string " + testCases1[i][0] +
", expected hex output " + testCases1[i][1] + ", got " + result +".");
}
}
// Except for float subnormals, the output for numerically
// equal float and double values should be the same.
// Therefore, we will explicitly test float subnormal values.
String [][] floatTestCases = {
{"Infinity", "Infinity"},
{"-Infinity", "-Infinity"},
{"NaN", "NaN"},
{"-NaN", "NaN"},
{"0.0", "0x0.0p0"},
{"-0.0", "-0x0.0p0"},
{"1.0", "0x1.0p0"},
{"-1.0", "-0x1.0p0"},
{"2.0", "0x1.0p1"},
{"3.0", "0x1.8p1"},
{"0.5", "0x1.0p-1"},
{"0.25", "0x1.0p-2"},
{"3.4028235e+38f", "0x1.fffffep127"}, // MAX_VALUE
{"1.17549435E-38f", "0x1.0p-126"}, // MIN_NORMAL
{"1.1754942E-38", "0x0.fffffep-126"}, // MAX_SUBNORMAL
{"1.4e-45f", "0x0.000002p-126"} // MIN_VALUE
};
// Compare decimal string -> double -> hex string to hex string
for (int i = 0; i < floatTestCases.length; i++) {
String result;
if(! (result=Float.toHexString(Float.parseFloat(floatTestCases[i][0]))).
equals(floatTestCases[i][1])) {
failures++;
System.err.println("For floating-point string " + floatTestCases[i][0] +
", expected hex output\n" + floatTestCases[i][1] + ", got\n" + result +".");
}
}
// Particular floating-point values and hex equivalents, mostly
// taken from fdlibm source.
String [][] testCases2 = {
{"+0.0", "0000000000000000"},
{"-0.0", "8000000000000000"},
{"+4.9e-324", "0000000000000001"},
{"-4.9e-324", "8000000000000001"},
// fdlibm k_sin.c
{"+5.00000000000000000000e-01", "3FE0000000000000"},
{"-1.66666666666666324348e-01", "BFC5555555555549"},
{"+8.33333333332248946124e-03", "3F8111111110F8A6"},
{"-1.98412698298579493134e-04", "BF2A01A019C161D5"},
{"+2.75573137070700676789e-06", "3EC71DE357B1FE7D"},
{"-2.50507602534068634195e-08", "BE5AE5E68A2B9CEB"},
{"+1.58969099521155010221e-10", "3DE5D93A5ACFD57C"},
// fdlibm k_cos.c
{"+4.16666666666666019037e-02", "3FA555555555554C"},
{"-1.38888888888741095749e-03", "BF56C16C16C15177"},
{"+2.48015872894767294178e-05", "3EFA01A019CB1590"},
{"-2.75573143513906633035e-07", "BE927E4F809C52AD"},
{"+2.08757232129817482790e-09", "3E21EE9EBDB4B1C4"},
{"-1.13596475577881948265e-11", "BDA8FAE9BE8838D4"},
// fdlibm e_rempio.c
{"1.67772160000000000000e+07", "4170000000000000"},
{"6.36619772367581382433e-01", "3FE45F306DC9C883"},
{"1.57079632673412561417e+00", "3FF921FB54400000"},
{"6.07710050650619224932e-11", "3DD0B4611A626331"},
{"6.07710050630396597660e-11", "3DD0B4611A600000"},
{"2.02226624879595063154e-21", "3BA3198A2E037073"},
{"2.02226624871116645580e-21", "3BA3198A2E000000"},
{"8.47842766036889956997e-32", "397B839A252049C1"},
// fdlibm s_cbrt.c
{"+5.42857142857142815906e-01", "3FE15F15F15F15F1"},
{"-7.05306122448979611050e-01", "BFE691DE2532C834"},
{"+1.41428571428571436819e+00", "3FF6A0EA0EA0EA0F"},
{"+1.60714285714285720630e+00", "3FF9B6DB6DB6DB6E"},
{"+3.57142857142857150787e-01", "3FD6DB6DB6DB6DB7"},
};
// Compare decimal string -> double -> hex string to
// long hex string -> double hex string
for (int i = 0; i < testCases2.length; i++) {
String result;
String expected;
if(! (result=Double.toHexString(Double.parseDouble(testCases2[i][0]))).
equals( expected=hexLongStringtoHexDoubleString(testCases2[i][1]) )) {
failures ++;
System.err.println("For floating-point string " + testCases2[i][0] +
", expected hex output " + expected + ", got " + result +".");
}
}
// Test random double values;
// compare double -> Double.toHexString with local doubleToHexString
java.util.Random rand = new java.util.Random(0);
for (int i = 0; i < 1000; i++) {
String result;
String expected;
double d = rand.nextDouble();
if(! (expected=doubleToHexString(d)).equals(result=Double.toHexString(d)) ) {
failures ++;
System.err.println("For floating-point value " + d +
", expected hex output " + expected + ", got " + result +".");
}
}
return failures;
}
public static void main(String argv[]) {
int failures = 0;
failures = toHexStringTests();
if (failures != 0) {
throw new RuntimeException("" + failures + " failures while testing Double.toHexString");
}
}
}
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