/*

 * 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

 * @author Joseph D. Darcy

 * @key randomness

 */

public class ParseHexFloatingPoint {

    private ParseHexFloatingPoint(){}

    public static final double infinityD = Double.POSITIVE_INFINITY;

    public static final double NaND = Double.NaN;

    static int test(String testName, String input,

                    double result, double expected) {

        int failures =0;

        if (Double.compare(result, expected) != 0 ) {

            System.err.println("Failure for " + testName +

                               ": For input " + input +

                               " expected " + expected +

                               " got " + result + ".");

        }

        return failures;

    }

    static int testCase(String input, double expected) {

        int failures =0;

        // Try different combination of letter components

        input = input.toLowerCase(java.util.Locale.US);

        String [] suffices = {"", "f", "F", "d", "D"};

        String [] signs = {"", "-", "+"};

        for(int i = 0; i < 2; i++) {

            String s1 = input;

            if(i == 1)

                s1 = s1.replace('x', 'X');

            for(int j = 0; j < 2; j++) {

                String s2 = s1;

                if(j == 1)

                    s2 = s2.replace('p', 'P');

                for(int k = 0; k < 2; k++) {

                    String s3 = s2;

                    if(k == 1)

                        s3 = upperCaseHex(s3);

                    for(int m = 0; m < suffices.length; m++) {

                        String s4 = s3 + suffices[m];

                        for(int n = 0; n < signs.length; n++) {

                            String s5 = signs[n] + s4;

                            double result = Double.parseDouble(s5);

                            failures += test("Double.parseDouble",

                                             s5, result, (signs[n].equals("-") ?

                                                          -expected:

                                                          expected));

                        }

                    }

                }

            }

        }

        return failures;

    }

    static String upperCaseHex(String s) {

        return s.replace('a', 'A').replace('b', 'B').replace('c', 'C').

                 replace('d', 'D').replace('e','E').replace('f', 'F');

    }

    /*

     * Test easy and tricky double rounding cases.

     */

    static int doubleTests() {

        /*

         * A String, double pair

         */

        class PairSD {

            public String s;

            public double d;

            PairSD(String s, double d) {

                this.s = s;

                this.d = d;

            }

        }

        int failures = 0;

        // Hex strings that convert to three; test basic functionality

        // of significand and exponent shift adjusts along with the

        // no-op of adding leading zeros.  These cases don't exercise

        // the rounding code.

        String leadingZeros = "0x0000000000000000000";

        String [] threeTests = {

            "0x.003p12",

            "0x.006p11",

            "0x.00cp10",

            "0x.018p9",

            "0x.3p4",

            "0x.6p3",

            "0x.cp2",

            "0x1.8p1",

            "0x3p0",

            "0x6.0p-1",

            "0xc.0p-2",

            "0x18.0p-3",

            "0x3000000p-24",

            "0x3.0p0",

            "0x3.000000p0",

        };

        for(int i=0; i < threeTests.length; i++) {

            String input = threeTests[i];

            failures += testCase(input, 3.0);

            input.replaceFirst("^0x", leadingZeros);

            failures += testCase(input, 3.0);

        }

        long bigExponents [] = {

            2*Double.MAX_EXPONENT,

            2*Double.MIN_EXPONENT,

            (long)Integer.MAX_VALUE-1,

            (long)Integer.MAX_VALUE,

            (long)Integer.MAX_VALUE+1,

            (long)Integer.MIN_VALUE-1,

            (long)Integer.MIN_VALUE,

            (long)Integer.MIN_VALUE+1,

            Long.MAX_VALUE-1,

            Long.MAX_VALUE,

            Long.MIN_VALUE+1,

            Long.MIN_VALUE,

        };

        // Test zero significand with large exponents.

        for(int i = 0; i < bigExponents.length; i++) {

            failures += testCase("0x0.0p"+Long.toString(bigExponents[i]) , 0.0);

        }

        // Test nonzero significand with large exponents.

        for(int i = 0; i < bigExponents.length; i++) {

            long exponent = bigExponents[i];

            failures += testCase("0x10000.0p"+Long.toString(exponent) ,

                                 (exponent <0?0.0:infinityD));

        }

        // Test significands with different lengths and bit patterns.

        {

            long signif = 0;

                for(int i = 1; i <= 0xe; i++) {

                    signif = (signif <<4) | (long)i;

                    failures += testCase("0x"+Long.toHexString(signif)+"p0", signif);

                }

        }

        PairSD [] testCases = {

            new PairSD("0x0.0p0",               0.0/16.0),

            new PairSD("0x0.1p0",               1.0/16.0),

            new PairSD("0x0.2p0",               2.0/16.0),

            new PairSD("0x0.3p0",               3.0/16.0),

            new PairSD("0x0.4p0",               4.0/16.0),

            new PairSD("0x0.5p0",               5.0/16.0),

            new PairSD("0x0.6p0",               6.0/16.0),

            new PairSD("0x0.7p0",               7.0/16.0),

            new PairSD("0x0.8p0",               8.0/16.0),

            new PairSD("0x0.9p0",               9.0/16.0),

            new PairSD("0x0.ap0",               10.0/16.0),

            new PairSD("0x0.bp0",               11.0/16.0),

            new PairSD("0x0.cp0",               12.0/16.0),

            new PairSD("0x0.dp0",               13.0/16.0),

            new PairSD("0x0.ep0",               14.0/16.0),

            new PairSD("0x0.fp0",               15.0/16.0),

            // Half-way case between zero and MIN_VALUE rounds down to

            // zero

            new PairSD("0x1.0p-1075",           0.0),

            // Slighly more than half-way case between zero and

            // MIN_VALUES rounds up to zero.

            new PairSD("0x1.1p-1075",                   Double.MIN_VALUE),

            new PairSD("0x1.000000000001p-1075",        Double.MIN_VALUE),

            new PairSD("0x1.000000000000001p-1075",     Double.MIN_VALUE),

            // More subnormal rounding tests

            new PairSD("0x0.fffffffffffff7fffffp-1022", Math.nextDown(Double.MIN_NORMAL)),

            new PairSD("0x0.fffffffffffff8p-1022",      Double.MIN_NORMAL),

            new PairSD("0x0.fffffffffffff800000001p-1022",Double.MIN_NORMAL),

            new PairSD("0x0.fffffffffffff80000000000000001p-1022",Double.MIN_NORMAL),

            new PairSD("0x1.0p-1022",                   Double.MIN_NORMAL),

            // Large value and overflow rounding tests

            new PairSD("0x1.fffffffffffffp1023",        Double.MAX_VALUE),

            new PairSD("0x1.fffffffffffff0000000p1023", Double.MAX_VALUE),

            new PairSD("0x1.fffffffffffff4p1023",       Double.MAX_VALUE),

            new PairSD("0x1.fffffffffffff7fffffp1023",  Double.MAX_VALUE),

            new PairSD("0x1.fffffffffffff8p1023",       infinityD),

            new PairSD("0x1.fffffffffffff8000001p1023", infinityD),

            new PairSD("0x1.ffffffffffffep1023",        Math.nextDown(Double.MAX_VALUE)),

            new PairSD("0x1.ffffffffffffe0000p1023",    Math.nextDown(Double.MAX_VALUE)),

            new PairSD("0x1.ffffffffffffe8p1023",       Math.nextDown(Double.MAX_VALUE)),

            new PairSD("0x1.ffffffffffffe7p1023",       Math.nextDown(Double.MAX_VALUE)),

            new PairSD("0x1.ffffffffffffeffffffp1023",  Double.MAX_VALUE),

            new PairSD("0x1.ffffffffffffe8000001p1023", Double.MAX_VALUE),

        };

        for (int i = 0; i < testCases.length; i++) {

            failures += testCase(testCases[i].s,testCases[i].d);

        }

        failures += significandAlignmentTests();

        {

            // Consistency check; double => hexadecimal => double

            // preserves the original value.

            for(int i = 0; i < 1000; i++) {

                double d = rand.nextDouble();

                failures += testCase(Double.toHexString(d), d);

            }

        }

        return failures;

    }

    /*

     * Verify rounding works the same regardless of how the

     * significand is aligned on input.  A useful extension could be

     * to have this sort of test for strings near the overflow

     * threshold.

     */

    static int significandAlignmentTests() {

        int failures = 0;

                // baseSignif * 2^baseExp = nextDown(2.0)

        long [] baseSignifs = {

            0x1ffffffffffffe00L,

            0x1fffffffffffff00L

        };

        double [] answers = {

            Math.nextDown(Math.nextDown(2.0)),

            Math.nextDown(2.0),

            2.0

        };

        int baseExp = -60;

        int count = 0;

        for(int i = 0; i < 2; i++) {

            for(long j = 0; j <= 0xfL; j++) {

                for(long k = 0; k <= 8; k+= 4) { // k = {0, 4, 8}

                    long base = baseSignifs[i];

                    long testValue = base | (j<<4) | k;

                    int offset = 0;

                    // Calculate when significand should be incremented

                    // see table 4.7 in Koren book

                    if ((base & 0x100L) == 0L ) { // lsb is 0

                        if ( (j >= 8L) &&         // round is 1

                             ((j & 0x7L) != 0 || k != 0 ) ) // sticky is 1

                            offset = 1;

                    }

                    else {                        // lsb is 1

                        if (j >= 8L)              // round is 1

                            offset = 1;

                    }

                    double expected = answers[i+offset];

                    for(int m = -2; m <= 3; m++) {

                        count ++;

                        // Form equal value string and evaluate it

                        String s = "0x" +

                            Long.toHexString((m >=0) ?(testValue<<m):(testValue>>(-m))) +

                            "p" + (baseExp - m);

                        failures += testCase(s, expected);

                    }

                }

            }

        }

        return failures;

    }

    /*

     * Test tricky float rounding cases.  The code which

     * reads in a hex string converts the string to a double value.

     * If a float value is needed, the double value is cast to float.

     * However, the cast be itself not always guaranteed to return the

     * right result since:

     *

     * 1. hex string => double can discard a sticky bit which would

     * influence a direct hex string => float conversion.

     *

     * 2. hex string => double => float can have a rounding to double

     * precision which results in a larger float value while a direct

     * hex string => float conversion would not round up.

     *

     * This method includes tests of the latter two possibilities.

     */

    static int floatTests(){

        int failures = 0;

        /*

         * A String, float pair

         */

        class PairSD {

            public String s;

            public float f;

            PairSD(String s, float f) {

                this.s = s;

                this.f = f;

            }

        }

        String [][] roundingTestCases = {

            // Target float value       hard rouding version

            {"0x1.000000p0",    "0x1.0000000000001p0"},

            // Try some values that should round up to nextUp(1.0f)

            {"0x1.000002p0",    "0x1.0000010000001p0"},

            {"0x1.000002p0",    "0x1.00000100000008p0"},

            {"0x1.000002p0",    "0x1.0000010000000fp0"},

            {"0x1.000002p0",    "0x1.00000100000001p0"},

            {"0x1.000002p0",    "0x1.00000100000000000000000000000000000000001p0"},

            {"0x1.000002p0",    "0x1.0000010000000fp0"},

            // Potential double rounding cases

            {"0x1.000002p0",    "0x1.000002fffffffp0"},

            {"0x1.000002p0",    "0x1.000002fffffff8p0"},

            {"0x1.000002p0",    "0x1.000002ffffffffp0"},

            {"0x1.000002p0",    "0x1.000002ffff0ffp0"},

            {"0x1.000002p0",    "0x1.000002ffff0ff8p0"},

            {"0x1.000002p0",    "0x1.000002ffff0fffp0"},

            {"0x1.000000p0",    "0x1.000000fffffffp0"},

            {"0x1.000000p0",    "0x1.000000fffffff8p0"},

            {"0x1.000000p0",    "0x1.000000ffffffffp0"},

            {"0x1.000000p0",    "0x1.000000ffffffep0"},

            {"0x1.000000p0",    "0x1.000000ffffffe8p0"},

            {"0x1.000000p0",    "0x1.000000ffffffefp0"},

            // Float subnormal cases

            {"0x0.000002p-126", "0x0.0000010000001p-126"},

            {"0x0.000002p-126", "0x0.00000100000000000001p-126"},

            {"0x0.000006p-126", "0x0.0000050000001p-126"},

            {"0x0.000006p-126", "0x0.00000500000000000001p-126"},

            {"0x0.0p-149",      "0x0.7ffffffffffffffp-149"},

            {"0x1.0p-148",      "0x1.3ffffffffffffffp-148"},

            {"0x1.cp-147",      "0x1.bffffffffffffffp-147"},

            {"0x1.fffffcp-127", "0x1.fffffdffffffffp-127"},

        };

        String [] signs = {"", "-"};

        for(int i = 0; i < roundingTestCases.length; i++) {

            for(int j = 0; j < signs.length; j++) {

                String expectedIn = signs[j]+roundingTestCases[i][0];

                String resultIn   = signs[j]+roundingTestCases[i][1];

                float expected =  Float.parseFloat(expectedIn);

                float result   =  Float.parseFloat(resultIn);

                if( Float.compare(expected, result) != 0) {

                    failures += 1;

                    System.err.println("" + (i+1));

                    System.err.println("Expected = " + Float.toHexString(expected));

                    System.err.println("Rounded  = " + Float.toHexString(result));

                    System.err.println("Double   = " + Double.toHexString(Double.parseDouble(resultIn)));

                    System.err.println("Input    = " + resultIn);

                    System.err.println("");

                }

            }

        }

        return failures;

    }

    public static void main(String argv[]) {

        int failures = 0;

        failures += doubleTests();

        failures += floatTests();

        if (failures != 0) {

            throw new RuntimeException("" + failures + " failures while " +

                                       "testing hexadecimal floating-point " +

                                       "parsing.");

        }

    }

}