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Add @HalfFloat annotation for fp16 data types stored in shorts

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This CL has a companion CL to add the @HalfFloat annotation to the
support library.

Test: cts-tradefed run singleCommand cts-dev --module CtsUtilTestCases --test android.util.cts.HalfTest
Bug: 29940137
Change-Id: I4e1dc456687c1c026437150e9cc94a54f3264d4e
This commit is contained in:
Romain Guy
2016-11-14 09:20:39 -08:00
parent 12ae9a0736
commit 5d7e2352e7
2 changed files with 97 additions and 44 deletions
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48
core/java/android/annotation/HalfFloat.java Normal file
View File

@@ -0,0 +1,48 @@
/*
* 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 {
}

93
core/java/android/util/Half.java
View File

@@ -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;
public static final int MAX_EXPONENT = 15;
/**
* Minimum exponent a normalized half-precision float may have.
*/
public static final int MIN_EXPONENT = -14;
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;