Add @HalfFloat annotation for fp16 data types stored in shorts (5d7e2352) · Commits · e / os / android_frameworks_base

core/java/android/annotation/HalfFloat.java

0 → 100644

+48 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2016 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/
		package android.annotation;

		import java.lang.annotation.Retention;
		import java.lang.annotation.Target;

		import static java.lang.annotation.ElementType.FIELD;
		import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
		import static java.lang.annotation.ElementType.METHOD;
		import static java.lang.annotation.ElementType.PARAMETER;
		import static java.lang.annotation.RetentionPolicy.SOURCE;

		/**
		* <p>Denotes that the annotated element represents a half-precision floating point
		* value. Such values are stored in short data types and can be manipulated with
		* the {@link android.util.Half} class. If applied to an array of short, every
		* element in the array represents a half-precision float.</p>
		*
		* <p>Example:</p>
		*
		* <pre>{@code
		* public abstract void setPosition(@HalfFloat short x, @HalfFloat short y, @HalfFloat short z);
		* }</pre>
		*
		* @see android.util.Half
		* @see android.util.Half#valueOf(float)
		* @see android.util.Half#toFloat(short)
		*
		* @hide
		*/
		@Retention(SOURCE)
		@Target({PARAMETER, METHOD, LOCAL_VARIABLE, FIELD})
		public @interface HalfFloat {
		}

core/java/android/util/Half.java

+47 −42

Original line number	Diff line number	Diff line
		@@ -16,12 +16,15 @@

		package android.util;

		import android.annotation.HalfFloat;

		/**
		* <p>Half is a utility class to manipulate half-precision 16-bit
		* <a href="https://en.wikipedia.org/wiki/Half-precision_floating-point_format">IEEE 754</a>
		* floating point data types (also called fp16 or binary16). A half-precision
		* float is stored in a short data type. A half-precision float can be
		* created from or converted to single-precision floats.</p>
		* floating point data types (also called fp16 or binary16). A half-precision float can be
		* created from or converted to single-precision floats, and is stored in a short data type.
		* To distinguish short values holding half-precision floats from regular short values,
		* it is recommended to use the <code>@HalfFloat</code> annotation.</p>
		*
		* <p>The IEEE 754 standard specifies an fp16 as having the following format:</p>
		* <ul>
		@@ -95,51 +98,53 @@ public final class Half {
		* Epsilon is the difference between 1.0 and the next value representable
		* by a half-precision floating-point.
		*/
		public static final short EPSILON = (short) 0x1400;
		/**
		* Smallest negative value a half-precision float may have.
		*/
		public static final short LOWEST_VALUE = (short) 0xfbff;
		public static final @HalfFloat short EPSILON = (short) 0x1400;

		/**
		* Maximum exponent a finite half-precision float may have.
		*/
		public static final int MAX_EXPONENT = 15;
		/**
		* Maximum positive finite value a half-precision float may have.
		*/
		public static final short MAX_VALUE = (short) 0x7bff;
		/**
		* Minimum exponent a normalized half-precision float may have.
		*/
		public static final int MIN_EXPONENT = -14;

		/**
		* Smallest negative value a half-precision float may have.
		*/
		public static final @HalfFloat short LOWEST_VALUE = (short) 0xfbff;
		/**
		* Maximum positive finite value a half-precision float may have.
		*/
		public static final @HalfFloat short MAX_VALUE = (short) 0x7bff;
		/**
		* Smallest positive normal value a half-precision float may have.
		*/
		public static final short MIN_NORMAL = (short) 0x0400;
		public static final @HalfFloat short MIN_NORMAL = (short) 0x0400;
		/**
		* Smallest positive non-zero value a half-precision float may have.
		*/
		public static final short MIN_VALUE = (short) 0x0001;
		public static final @HalfFloat short MIN_VALUE = (short) 0x0001;
		/**
		* A Not-a-Number representation of a half-precision float.
		*/
		public static final short NaN = (short) 0x7e00;
		public static final @HalfFloat short NaN = (short) 0x7e00;
		/**
		* Negative infinity of type half-precision float.
		*/
		public static final short NEGATIVE_INFINITY = (short) 0xfc00;
		public static final @HalfFloat short NEGATIVE_INFINITY = (short) 0xfc00;
		/**
		* Negative 0 of type half-precision float.
		*/
		public static final short NEGATIVE_ZERO = (short) 0x8000;
		public static final @HalfFloat short NEGATIVE_ZERO = (short) 0x8000;
		/**
		* Positive infinity of type half-precision float.
		*/
		public static final short POSITIVE_INFINITY = (short) 0x7c00;
		public static final @HalfFloat short POSITIVE_INFINITY = (short) 0x7c00;
		/**
		* Positive 0 of type half-precision float.
		*/
		public static final short POSITIVE_ZERO = (short) 0x0000;
		public static final @HalfFloat short POSITIVE_ZERO = (short) 0x0000;

		private static final int FP16_SIGN_SHIFT = 15;
		private static final int FP16_SIGN_MASK = 0x8000;
		@@ -171,7 +176,7 @@ public final class Half {
		* @return A value with the magnitude of the first parameter and the sign
		* of the second parameter
		*/
		public static short copySign(short magnitude, short sign) {
		public static @HalfFloat short copySign(@HalfFloat short magnitude, @HalfFloat short sign) {
		return (short) ((sign & FP16_SIGN_MASK) \| (magnitude & FP16_COMBINED));
		}

		@@ -189,7 +194,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return The absolute value of the specified half-precision float
		*/
		public static short abs(short h) {
		public static @HalfFloat short abs(@HalfFloat short h) {
		return (short) (h & FP16_COMBINED);
		}

		@@ -209,7 +214,7 @@ public final class Half {
		* @return The value of the specified half-precision float rounded to the nearest
		* half-precision float value
		*/
		public static short round(short h) {
		public static @HalfFloat short round(@HalfFloat short h) {
		int bits = h & 0xffff;
		int e = bits & 0x7fff;
		int result = bits;
		@@ -243,7 +248,7 @@ public final class Half {
		* @return The smallest half-precision float value toward negative infinity
		* greater than or equal to the specified half-precision float value
		*/
		public static short ceil(short h) {
		public static @HalfFloat short ceil(@HalfFloat short h) {
		int bits = h & 0xffff;
		int e = bits & 0x7fff;
		int result = bits;
		@@ -277,7 +282,7 @@ public final class Half {
		* @return The largest half-precision float value toward positive infinity
		* less than or equal to the specified half-precision float value
		*/
		public static short floor(short h) {
		public static @HalfFloat short floor(@HalfFloat short h) {
		int bits = h & 0xffff;
		int e = bits & 0x7fff;
		int result = bits;
		@@ -310,7 +315,7 @@ public final class Half {
		* @return The truncated half-precision float value of the specified
		* half-precision float value
		*/
		public static short trunc(short h) {
		public static @HalfFloat short trunc(@HalfFloat short h) {
		int bits = h & 0xffff;
		int e = bits & 0x7fff;
		int result = bits;
		@@ -338,7 +343,7 @@ public final class Half {
		* @param y The second half-precision value
		* @return The smaller of the two specified half-precision values
		*/
		public static short min(short x, short y) {
		public static @HalfFloat short min(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return NaN;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return NaN;

		@@ -363,7 +368,7 @@ public final class Half {
		*
		* @return The larger of the two specified half-precision values
		*/
		public static short max(short x, short y) {
		public static @HalfFloat short max(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return NaN;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return NaN;

		@@ -385,7 +390,7 @@ public final class Half {
		*
		* @return True if x is less than y, false otherwise
		*/
		public static boolean less(short x, short y) {
		public static boolean less(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;

		@@ -403,7 +408,7 @@ public final class Half {
		*
		* @return True if x is less than or equal to y, false otherwise
		*/
		public static boolean lessEquals(short x, short y) {
		public static boolean lessEquals(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;

		@@ -421,7 +426,7 @@ public final class Half {
		*
		* @return True if x is greater than y, false otherwise
		*/
		public static boolean greater(short x, short y) {
		public static boolean greater(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;

		@@ -439,7 +444,7 @@ public final class Half {
		*
		* @return True if x is greater than y, false otherwise
		*/
		public static boolean greaterEquals(short x, short y) {
		public static boolean greaterEquals(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;

		@@ -457,7 +462,7 @@ public final class Half {
		*
		* @return True if x is equal to y, false otherwise
		*/
		public static boolean equals(short x, short y) {
		public static boolean equals(@HalfFloat short x, @HalfFloat short y) {
		if ((x & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;
		if ((y & FP16_COMBINED) > FP16_EXPONENT_MAX) return false;

		@@ -470,7 +475,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return 1 if the value is positive, -1 if the value is negative
		*/
		public static int getSign(short h) {
		public static int getSign(@HalfFloat short h) {
		return (h & FP16_SIGN_MASK) == 0 ? 1 : -1;
		}

		@@ -484,7 +489,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return The unbiased exponent of the specified value
		*/
		public static int getExponent(short h) {
		public static int getExponent(@HalfFloat short h) {
		return ((h >>> FP16_EXPONENT_SHIFT) & FP16_EXPONENT_MASK) - FP16_EXPONENT_BIAS;
		}

		@@ -495,7 +500,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return The significand, or significand, of the specified vlaue
		*/
		public static int getSignificand(short h) {
		public static int getSignificand(@HalfFloat short h) {
		return h & FP16_SIGNIFICAND_MASK;
		}

		@@ -507,7 +512,7 @@ public final class Half {
		* @return true if the value is positive infinity or negative infinity,
		* false otherwise
		*/
		public static boolean isInfinite(short h) {
		public static boolean isInfinite(@HalfFloat short h) {
		return (h & FP16_COMBINED) == FP16_EXPONENT_MAX;
		}

		@@ -518,7 +523,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return true if the value is a NaN, false otherwise
		*/
		public static boolean isNaN(short h) {
		public static boolean isNaN(@HalfFloat short h) {
		return (h & FP16_COMBINED) > FP16_EXPONENT_MAX;
		}

		@@ -532,7 +537,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return true if the value is normalized, false otherwise
		*/
		public static boolean isNormalized(short h) {
		public static boolean isNormalized(@HalfFloat short h) {
		return (h & FP16_EXPONENT_MAX) != 0 && (h & FP16_EXPONENT_MAX) != FP16_EXPONENT_MAX;
		}

		@@ -551,7 +556,7 @@ public final class Half {
		* @param h The half-precision float value to convert to single-precision
		* @return A normalized single-precision float value
		*/
		public static float toFloat(short h) {
		public static float toFloat(@HalfFloat short h) {
		int bits = h & 0xffff;
		int s = bits & FP16_SIGN_MASK;
		int e = (bits >>> FP16_EXPONENT_SHIFT) & FP16_EXPONENT_MASK;
		@@ -603,7 +608,7 @@ public final class Half {
		* @return A half-precision float value
		*/
		@SuppressWarnings("StatementWithEmptyBody")
		public static short valueOf(float f) {
		public static @HalfFloat short valueOf(float f) {
		int bits = Float.floatToRawIntBits(f);
		int s = (bits >>> FP32_SIGN_SHIFT );
		int e = (bits >>> FP32_EXPONENT_SHIFT) & FP32_EXPONENT_MASK;
		@@ -653,7 +658,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return A string representation of the specified value
		*/
		public static String toString(short h) {
		public static String toString(@HalfFloat short h) {
		return Float.toString(toFloat(h));
		}

		@@ -683,7 +688,7 @@ public final class Half {
		* @param h A half-precision float value
		* @return A hexadecimal string representation of the specified value
		*/
		public static String toHexString(short h) {
		public static String toHexString(@HalfFloat short h) {
		StringBuilder o = new StringBuilder();

		int bits = h & 0xffff;