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 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.

 * 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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

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 */

package sun.java2d.marlin;

import jdk.internal.math.FloatConsts;

/**

 * Faster Math ceil / floor routines derived from StrictMath

 */

public final class FloatMath implements MarlinConst {

    // overflow / NaN handling enabled:

    static final boolean CHECK_OVERFLOW = true;

    static final boolean CHECK_NAN = true;

    private FloatMath() {

        // utility class

    }

    // faster inlined min/max functions in the branch prediction is high

    static float max(final float a, final float b) {

        // no NaN handling

        return (a >= b) ? a : b;

    }

    static int max(final int a, final int b) {

        return (a >= b) ? a : b;

    }

    static int min(final int a, final int b) {

        return (a <= b) ? a : b;

    }

    /**

     * Returns the smallest (closest to negative infinity) {@code float} value

     * that is greater than or equal to the argument and is equal to a

     * mathematical integer. Special cases:

     * <ul><li>If the argument value is already equal to a mathematical integer,

     * then the result is the same as the argument.  <li>If the argument is NaN

     * or an infinity or positive zero or negative zero, then the result is the

     * same as the argument.  <li>If the argument value is less than zero but

     * greater than -1.0, then the result is negative zero.</ul> Note that the

     * value of {@code StrictMath.ceil(x)} is exactly the value of

     * {@code -StrictMath.floor(-x)}.

     *

     * @param a a value.

     * @return the smallest (closest to negative infinity) floating-point value

     * that is greater than or equal to the argument and is equal to a

     * mathematical integer.

     */

    public static float ceil_f(final float a) {

        // Derived from StrictMath.ceil(double):

        // Inline call to Math.getExponent(a) to

        // compute only once Float.floatToRawIntBits(a)

        final int doppel = Float.floatToRawIntBits(a);

        final int exponent = ((doppel & FloatConsts.EXP_BIT_MASK)

                >> (FloatConsts.SIGNIFICAND_WIDTH - 1))

                - FloatConsts.EXP_BIAS;

        if (exponent < 0) {

            /*

             * Absolute value of argument is less than 1.

             * floorOrceil(-0.0) => -0.0

             * floorOrceil(+0.0) => +0.0

             */

            return ((a == 0) ? a :

                    ( (a < 0f) ? -0f : 1f) );

        }

        if (CHECK_OVERFLOW && (exponent >= 23)) { // 52 for double

            /*

             * Infinity, NaN, or a value so large it must be integral.

             */

            return a;

        }

        // Else the argument is either an integral value already XOR it

        // has to be rounded to one.

        assert exponent >= 0 && exponent <= 22; // 51 for double

        final int intpart = doppel

                & (~(FloatConsts.SIGNIF_BIT_MASK >> exponent));

        if (intpart == doppel) {

            return a; // integral value (including 0)

        }

        // 0 handled above as an integer

        // sign: 1 for negative, 0 for positive numbers

        // add : 0 for negative and 1 for positive numbers

        return Float.intBitsToFloat(intpart) + ((~intpart) >>> 31);

    }

    /**

     * Returns the largest (closest to positive infinity) {@code float} value

     * that is less than or equal to the argument and is equal to a mathematical

     * integer. Special cases:

     * <ul><li>If the argument value is already equal to a mathematical integer,

     * then the result is the same as the argument.  <li>If the argument is NaN

     * or an infinity or positive zero or negative zero, then the result is the

     * same as the argument.</ul>

     *

     * @param a a value.

     * @return the largest (closest to positive infinity) floating-point value

     * that less than or equal to the argument and is equal to a mathematical

     * integer.

     */

    public static float floor_f(final float a) {

        // Derived from StrictMath.floor(double):

        // Inline call to Math.getExponent(a) to

        // compute only once Float.floatToRawIntBits(a)

        final int doppel = Float.floatToRawIntBits(a);

        final int exponent = ((doppel & FloatConsts.EXP_BIT_MASK)

                >> (FloatConsts.SIGNIFICAND_WIDTH - 1))

                - FloatConsts.EXP_BIAS;

        if (exponent < 0) {

            /*

             * Absolute value of argument is less than 1.

             * floorOrceil(-0.0) => -0.0

             * floorOrceil(+0.0) => +0.0

             */

            return ((a == 0) ? a :

                    ( (a < 0f) ? -1f : 0f) );

        }

        if (CHECK_OVERFLOW && (exponent >= 23)) { // 52 for double

            /*

             * Infinity, NaN, or a value so large it must be integral.

             */

            return a;

        }

        // Else the argument is either an integral value already XOR it

        // has to be rounded to one.

        assert exponent >= 0 && exponent <= 22; // 51 for double

        final int intpart = doppel

                & (~(FloatConsts.SIGNIF_BIT_MASK >> exponent));

        if (intpart == doppel) {

            return a; // integral value (including 0)

        }

        // 0 handled above as an integer

        // sign: 1 for negative, 0 for positive numbers

        // add : -1 for negative and 0 for positive numbers

        return Float.intBitsToFloat(intpart) + (intpart >> 31);

    }

    /**

     * Faster alternative to ceil(float) optimized for the integer domain

     * and supporting NaN and +/-Infinity.

     *

     * @param a a value.

     * @return the largest (closest to positive infinity) integer value

     * that less than or equal to the argument and is equal to a mathematical

     * integer.

     */

    public static int ceil_int(final float a) {

        final int intpart = (int) a;

        if (a <= intpart

                || (CHECK_OVERFLOW && intpart == Integer.MAX_VALUE)

                || CHECK_NAN && Float.isNaN(a)) {

            return intpart;

        }

        return intpart + 1;

    }

    /**

     * Faster alternative to floor(float) optimized for the integer domain

     * and supporting NaN and +/-Infinity.

     *

     * @param a a value.

     * @return the largest (closest to positive infinity) floating-point value

     * that less than or equal to the argument and is equal to a mathematical

     * integer.

     */

    public static int floor_int(final float a) {

        final int intpart = (int) a;

        if (a >= intpart

                || (CHECK_OVERFLOW && intpart == Integer.MIN_VALUE)

                || CHECK_NAN && Float.isNaN(a)) {

            return intpart;

        }

        return intpart - 1;

    }

}