Move Half implementations to libcore to allow ART optimizations
Move Half FP16 implementations to libcore, to allow ART compiler to
optimize them with intrinsic implementations.
For example, on ARM64 with ARMv8.2 FP16 half registers and instructions:
- Half toFloat/toHalf can be implemented with FCVT;
- Half floor/ceil/round can be implmented with FRINT(pna);
- Half max/min can be implmented with FMIN/FMAX.
Such fast Half FP16 intrinsics can help accelerate ColorLong ARGB
encoding/decoding in Android framework.
Change-Id: I10b835fa6a3a33c9ec19df5de4949681c97b4667
diff --git a/luni/src/main/java/libcore/util/FP16.java b/luni/src/main/java/libcore/util/FP16.java
new file mode 100644
index 0000000..88fe43a
--- /dev/null
+++ b/luni/src/main/java/libcore/util/FP16.java
@@ -0,0 +1,719 @@
+/*
+ * Copyright (C) 2019 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 libcore.util;
+
+/**
+ * <p>The {@code FP16} class is a wrapper and 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 can be
+ * created from or converted to single-precision floats, and is stored in a short data type.
+ *
+ * <p>The IEEE 754 standard specifies an fp16 as having the following format:</p>
+ * <ul>
+ * <li>Sign bit: 1 bit</li>
+ * <li>Exponent width: 5 bits</li>
+ * <li>Significand: 10 bits</li>
+ * </ul>
+ *
+ * <p>The format is laid out as follows:</p>
+ * <pre>
+ * 1 11111 1111111111
+ * ^ --^-- -----^----
+ * sign | |_______ significand
+ * |
+ * -- exponent
+ * </pre>
+ *
+ * <p>Half-precision floating points can be useful to save memory and/or
+ * bandwidth at the expense of range and precision when compared to single-precision
+ * floating points (fp32).</p>
+ * <p>To help you decide whether fp16 is the right storage type for you need, please
+ * refer to the table below that shows the available precision throughout the range of
+ * possible values. The <em>precision</em> column indicates the step size between two
+ * consecutive numbers in a specific part of the range.</p>
+ *
+ * <table summary="Precision of fp16 across the range">
+ * <tr><th>Range start</th><th>Precision</th></tr>
+ * <tr><td>0</td><td>1 ⁄ 16,777,216</td></tr>
+ * <tr><td>1 ⁄ 16,384</td><td>1 ⁄ 16,777,216</td></tr>
+ * <tr><td>1 ⁄ 8,192</td><td>1 ⁄ 8,388,608</td></tr>
+ * <tr><td>1 ⁄ 4,096</td><td>1 ⁄ 4,194,304</td></tr>
+ * <tr><td>1 ⁄ 2,048</td><td>1 ⁄ 2,097,152</td></tr>
+ * <tr><td>1 ⁄ 1,024</td><td>1 ⁄ 1,048,576</td></tr>
+ * <tr><td>1 ⁄ 512</td><td>1 ⁄ 524,288</td></tr>
+ * <tr><td>1 ⁄ 256</td><td>1 ⁄ 262,144</td></tr>
+ * <tr><td>1 ⁄ 128</td><td>1 ⁄ 131,072</td></tr>
+ * <tr><td>1 ⁄ 64</td><td>1 ⁄ 65,536</td></tr>
+ * <tr><td>1 ⁄ 32</td><td>1 ⁄ 32,768</td></tr>
+ * <tr><td>1 ⁄ 16</td><td>1 ⁄ 16,384</td></tr>
+ * <tr><td>1 ⁄ 8</td><td>1 ⁄ 8,192</td></tr>
+ * <tr><td>1 ⁄ 4</td><td>1 ⁄ 4,096</td></tr>
+ * <tr><td>1 ⁄ 2</td><td>1 ⁄ 2,048</td></tr>
+ * <tr><td>1</td><td>1 ⁄ 1,024</td></tr>
+ * <tr><td>2</td><td>1 ⁄ 512</td></tr>
+ * <tr><td>4</td><td>1 ⁄ 256</td></tr>
+ * <tr><td>8</td><td>1 ⁄ 128</td></tr>
+ * <tr><td>16</td><td>1 ⁄ 64</td></tr>
+ * <tr><td>32</td><td>1 ⁄ 32</td></tr>
+ * <tr><td>64</td><td>1 ⁄ 16</td></tr>
+ * <tr><td>128</td><td>1 ⁄ 8</td></tr>
+ * <tr><td>256</td><td>1 ⁄ 4</td></tr>
+ * <tr><td>512</td><td>1 ⁄ 2</td></tr>
+ * <tr><td>1,024</td><td>1</td></tr>
+ * <tr><td>2,048</td><td>2</td></tr>
+ * <tr><td>4,096</td><td>4</td></tr>
+ * <tr><td>8,192</td><td>8</td></tr>
+ * <tr><td>16,384</td><td>16</td></tr>
+ * <tr><td>32,768</td><td>32</td></tr>
+ * </table>
+ *
+ * <p>This table shows that numbers higher than 1024 lose all fractional precision.</p>
+ *
+ * @hide
+ */
+
+@libcore.api.CorePlatformApi
+public class FP16 {
+ /**
+ * The number of bits used to represent a half-precision float value.
+ */
+ @libcore.api.CorePlatformApi
+ public static final int SIZE = 16;
+
+ /**
+ * Epsilon is the difference between 1.0 and the next value representable
+ * by a half-precision floating-point.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short EPSILON = (short) 0x1400;
+
+ /**
+ * Maximum exponent a finite half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final int MAX_EXPONENT = 15;
+ /**
+ * Minimum exponent a normalized half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final int MIN_EXPONENT = -14;
+
+ /**
+ * Smallest negative value a half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short LOWEST_VALUE = (short) 0xfbff;
+ /**
+ * Maximum positive finite value a half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short MAX_VALUE = (short) 0x7bff;
+ /**
+ * Smallest positive normal value a half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short MIN_NORMAL = (short) 0x0400;
+ /**
+ * Smallest positive non-zero value a half-precision float may have.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short MIN_VALUE = (short) 0x0001;
+ /**
+ * A Not-a-Number representation of a half-precision float.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short NaN = (short) 0x7e00;
+ /**
+ * Negative infinity of type half-precision float.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short NEGATIVE_INFINITY = (short) 0xfc00;
+ /**
+ * Negative 0 of type half-precision float.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short NEGATIVE_ZERO = (short) 0x8000;
+ /**
+ * Positive infinity of type half-precision float.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short POSITIVE_INFINITY = (short) 0x7c00;
+ /**
+ * Positive 0 of type half-precision float.
+ */
+ @libcore.api.CorePlatformApi
+ public static final short POSITIVE_ZERO = (short) 0x0000;
+
+ @libcore.api.CorePlatformApi
+ public static final int SIGN_SHIFT = 15;
+ @libcore.api.CorePlatformApi
+ public static final int EXPONENT_SHIFT = 10;
+ @libcore.api.CorePlatformApi
+ public static final int SIGN_MASK = 0x8000;
+ @libcore.api.CorePlatformApi
+ public static final int SHIFTED_EXPONENT_MASK = 0x1f;
+ @libcore.api.CorePlatformApi
+ public static final int SIGNIFICAND_MASK = 0x3ff;
+ @libcore.api.CorePlatformApi
+ public static final int EXPONENT_SIGNIFICAND_MASK = 0x7fff;
+ @libcore.api.CorePlatformApi
+ public static final int EXPONENT_BIAS = 15;
+
+ private static final int FP32_SIGN_SHIFT = 31;
+ private static final int FP32_EXPONENT_SHIFT = 23;
+ private static final int FP32_SHIFTED_EXPONENT_MASK = 0xff;
+ private static final int FP32_SIGNIFICAND_MASK = 0x7fffff;
+ private static final int FP32_EXPONENT_BIAS = 127;
+ private static final int FP32_QNAN_MASK = 0x400000;
+ private static final int FP32_DENORMAL_MAGIC = 126 << 23;
+ private static final float FP32_DENORMAL_FLOAT = Float.intBitsToFloat(FP32_DENORMAL_MAGIC);
+
+ /** Hidden constructor to prevent instantiation. */
+ private FP16() {}
+
+ /**
+ * <p>Compares the two specified half-precision float values. The following
+ * conditions apply during the comparison:</p>
+ *
+ * <ul>
+ * <li>{@link #NaN} is considered by this method to be equal to itself and greater
+ * than all other half-precision float values (including {@code #POSITIVE_INFINITY})</li>
+ * <li>{@link #POSITIVE_ZERO} is considered by this method to be greater than
+ * {@link #NEGATIVE_ZERO}.</li>
+ * </ul>
+ *
+ * @param x The first half-precision float value to compare.
+ * @param y The second half-precision float value to compare
+ *
+ * @return The value {@code 0} if {@code x} is numerically equal to {@code y}, a
+ * value less than {@code 0} if {@code x} is numerically less than {@code y},
+ * and a value greater than {@code 0} if {@code x} is numerically greater
+ * than {@code y}
+ */
+ @libcore.api.CorePlatformApi
+ public static int compare(short x, short y) {
+ if (less(x, y)) return -1;
+ if (greater(x, y)) return 1;
+
+ // Collapse NaNs, akin to halfToIntBits(), but we want to keep
+ // (signed) short value types to preserve the ordering of -0.0
+ // and +0.0
+ short xBits = (x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY ? NaN : x;
+ short yBits = (y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY ? NaN : y;
+
+ return (xBits == yBits ? 0 : (xBits < yBits ? -1 : 1));
+ }
+
+ /**
+ * Returns the closest integral half-precision float value to the specified
+ * half-precision float value. Special values are handled in the
+ * following ways:
+ * <ul>
+ * <li>If the specified half-precision float is NaN, the result is NaN</li>
+ * <li>If the specified half-precision float is infinity (negative or positive),
+ * the result is infinity (with the same sign)</li>
+ * <li>If the specified half-precision float is zero (negative or positive),
+ * the result is zero (with the same sign)</li>
+ * </ul>
+ *
+ * @param h A half-precision float value
+ * @return The value of the specified half-precision float rounded to the nearest
+ * half-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static short rint(short h) {
+ int bits = h & 0xffff;
+ int e = bits & EXPONENT_SIGNIFICAND_MASK;
+ int result = bits;
+
+ if (e < 0x3c00) {
+ result &= SIGN_MASK;
+ result |= (0x3c00 & (e >= 0x3800 ? 0xffff : 0x0));
+ } else if (e < 0x6400) {
+ e = 25 - (e >> 10);
+ int mask = (1 << e) - 1;
+ result += (1 << (e - 1));
+ result &= ~mask;
+ }
+
+ return (short) result;
+ }
+
+ /**
+ * Returns the smallest half-precision float value toward negative infinity
+ * greater than or equal to the specified half-precision float value.
+ * Special values are handled in the following ways:
+ * <ul>
+ * <li>If the specified half-precision float is NaN, the result is NaN</li>
+ * <li>If the specified half-precision float is infinity (negative or positive),
+ * the result is infinity (with the same sign)</li>
+ * <li>If the specified half-precision float is zero (negative or positive),
+ * the result is zero (with the same sign)</li>
+ * </ul>
+ *
+ * @param h A half-precision float value
+ * @return The smallest half-precision float value toward negative infinity
+ * greater than or equal to the specified half-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static short ceil(short h) {
+ int bits = h & 0xffff;
+ int e = bits & EXPONENT_SIGNIFICAND_MASK;
+ int result = bits;
+
+ if (e < 0x3c00) {
+ result &= SIGN_MASK;
+ result |= 0x3c00 & -(~(bits >> 15) & (e != 0 ? 1 : 0));
+ } else if (e < 0x6400) {
+ e = 25 - (e >> 10);
+ int mask = (1 << e) - 1;
+ result += mask & ((bits >> 15) - 1);
+ result &= ~mask;
+ }
+
+ return (short) result;
+ }
+
+ /**
+ * Returns the largest half-precision float value toward positive infinity
+ * less than or equal to the specified half-precision float value.
+ * Special values are handled in the following ways:
+ * <ul>
+ * <li>If the specified half-precision float is NaN, the result is NaN</li>
+ * <li>If the specified half-precision float is infinity (negative or positive),
+ * the result is infinity (with the same sign)</li>
+ * <li>If the specified half-precision float is zero (negative or positive),
+ * the result is zero (with the same sign)</li>
+ * </ul>
+ *
+ * @param h A half-precision float value
+ * @return The largest half-precision float value toward positive infinity
+ * less than or equal to the specified half-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static short floor(short h) {
+ int bits = h & 0xffff;
+ int e = bits & EXPONENT_SIGNIFICAND_MASK;
+ int result = bits;
+
+ if (e < 0x3c00) {
+ result &= SIGN_MASK;
+ result |= 0x3c00 & (bits > 0x8000 ? 0xffff : 0x0);
+ } else if (e < 0x6400) {
+ e = 25 - (e >> 10);
+ int mask = (1 << e) - 1;
+ result += mask & -(bits >> 15);
+ result &= ~mask;
+ }
+
+ return (short) result;
+ }
+
+ /**
+ * Returns the truncated half-precision float value of the specified
+ * half-precision float value. Special values are handled in the following ways:
+ * <ul>
+ * <li>If the specified half-precision float is NaN, the result is NaN</li>
+ * <li>If the specified half-precision float is infinity (negative or positive),
+ * the result is infinity (with the same sign)</li>
+ * <li>If the specified half-precision float is zero (negative or positive),
+ * the result is zero (with the same sign)</li>
+ * </ul>
+ *
+ * @param h A half-precision float value
+ * @return The truncated half-precision float value of the specified
+ * half-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static short trunc(short h) {
+ int bits = h & 0xffff;
+ int e = bits & EXPONENT_SIGNIFICAND_MASK;
+ int result = bits;
+
+ if (e < 0x3c00) {
+ result &= SIGN_MASK;
+ } else if (e < 0x6400) {
+ e = 25 - (e >> 10);
+ int mask = (1 << e) - 1;
+ result &= ~mask;
+ }
+
+ return (short) result;
+ }
+
+ /**
+ * Returns the smaller of two half-precision float values (the value closest
+ * to negative infinity). Special values are handled in the following ways:
+ * <ul>
+ * <li>If either value is NaN, the result is NaN</li>
+ * <li>{@link #NEGATIVE_ZERO} is smaller than {@link #POSITIVE_ZERO}</li>
+ * </ul>
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ * @return The smaller of the two specified half-precision values
+ */
+ @libcore.api.CorePlatformApi
+ public static short min(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return NaN;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return NaN;
+
+ if ((x & EXPONENT_SIGNIFICAND_MASK) == 0 && (y & EXPONENT_SIGNIFICAND_MASK) == 0) {
+ return (x & SIGN_MASK) != 0 ? x : y;
+ }
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) <
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff) ? x : y;
+ }
+
+ /**
+ * Returns the larger of two half-precision float values (the value closest
+ * to positive infinity). Special values are handled in the following ways:
+ * <ul>
+ * <li>If either value is NaN, the result is NaN</li>
+ * <li>{@link #POSITIVE_ZERO} is greater than {@link #NEGATIVE_ZERO}</li>
+ * </ul>
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return The larger of the two specified half-precision values
+ */
+ @libcore.api.CorePlatformApi
+ public static short max(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return NaN;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return NaN;
+
+ if ((x & EXPONENT_SIGNIFICAND_MASK) == 0 && (y & EXPONENT_SIGNIFICAND_MASK) == 0) {
+ return (x & SIGN_MASK) != 0 ? y : x;
+ }
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) >
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff) ? x : y;
+ }
+
+ /**
+ * Returns true if the first half-precision float value is less (smaller
+ * toward negative infinity) than the second half-precision float value.
+ * If either of the values is NaN, the result is false.
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return True if x is less than y, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean less(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) <
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff);
+ }
+
+ /**
+ * Returns true if the first half-precision float value is less (smaller
+ * toward negative infinity) than or equal to the second half-precision
+ * float value. If either of the values is NaN, the result is false.
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return True if x is less than or equal to y, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean lessEquals(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) <=
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff);
+ }
+
+ /**
+ * Returns true if the first half-precision float value is greater (larger
+ * toward positive infinity) than the second half-precision float value.
+ * If either of the values is NaN, the result is false.
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return True if x is greater than y, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean greater(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) >
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff);
+ }
+
+ /**
+ * Returns true if the first half-precision float value is greater (larger
+ * toward positive infinity) than or equal to the second half-precision float
+ * value. If either of the values is NaN, the result is false.
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return True if x is greater than y, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean greaterEquals(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+
+ return ((x & SIGN_MASK) != 0 ? 0x8000 - (x & 0xffff) : x & 0xffff) >=
+ ((y & SIGN_MASK) != 0 ? 0x8000 - (y & 0xffff) : y & 0xffff);
+ }
+
+ /**
+ * Returns true if the two half-precision float values are equal.
+ * If either of the values is NaN, the result is false. {@link #POSITIVE_ZERO}
+ * and {@link #NEGATIVE_ZERO} are considered equal.
+ *
+ * @param x The first half-precision value
+ * @param y The second half-precision value
+ *
+ * @return True if x is equal to y, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean equals(short x, short y) {
+ if ((x & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+ if ((y & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY) return false;
+
+ return x == y || ((x | y) & EXPONENT_SIGNIFICAND_MASK) == 0;
+ }
+
+ /**
+ * Returns true if the specified half-precision float value represents
+ * infinity, false otherwise.
+ *
+ * @param h A half-precision float value
+ * @return True if the value is positive infinity or negative infinity,
+ * false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean isInfinite(short h) {
+ return (h & EXPONENT_SIGNIFICAND_MASK) == POSITIVE_INFINITY;
+ }
+
+ /**
+ * Returns true if the specified half-precision float value represents
+ * a Not-a-Number, false otherwise.
+ *
+ * @param h A half-precision float value
+ * @return True if the value is a NaN, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean isNaN(short h) {
+ return (h & EXPONENT_SIGNIFICAND_MASK) > POSITIVE_INFINITY;
+ }
+
+ /**
+ * Returns true if the specified half-precision float value is normalized
+ * (does not have a subnormal representation). If the specified value is
+ * {@link #POSITIVE_INFINITY}, {@link #NEGATIVE_INFINITY},
+ * {@link #POSITIVE_ZERO}, {@link #NEGATIVE_ZERO}, NaN or any subnormal
+ * number, this method returns false.
+ *
+ * @param h A half-precision float value
+ * @return True if the value is normalized, false otherwise
+ */
+ @libcore.api.CorePlatformApi
+ public static boolean isNormalized(short h) {
+ return (h & POSITIVE_INFINITY) != 0 && (h & POSITIVE_INFINITY) != POSITIVE_INFINITY;
+ }
+
+ /**
+ * <p>Converts the specified half-precision float value into a
+ * single-precision float value. The following special cases are handled:</p>
+ * <ul>
+ * <li>If the input is {@link #NaN}, the returned value is {@link Float#NaN}</li>
+ * <li>If the input is {@link #POSITIVE_INFINITY} or
+ * {@link #NEGATIVE_INFINITY}, the returned value is respectively
+ * {@link Float#POSITIVE_INFINITY} or {@link Float#NEGATIVE_INFINITY}</li>
+ * <li>If the input is 0 (positive or negative), the returned value is +/-0.0f</li>
+ * <li>Otherwise, the returned value is a normalized single-precision float value</li>
+ * </ul>
+ *
+ * @param h The half-precision float value to convert to single-precision
+ * @return A normalized single-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static float toFloat(short h) {
+ int bits = h & 0xffff;
+ int s = bits & SIGN_MASK;
+ int e = (bits >>> EXPONENT_SHIFT) & SHIFTED_EXPONENT_MASK;
+ int m = (bits ) & SIGNIFICAND_MASK;
+
+ int outE = 0;
+ int outM = 0;
+
+ if (e == 0) { // Denormal or 0
+ if (m != 0) {
+ // Convert denorm fp16 into normalized fp32
+ float o = Float.intBitsToFloat(FP32_DENORMAL_MAGIC + m);
+ o -= FP32_DENORMAL_FLOAT;
+ return s == 0 ? o : -o;
+ }
+ } else {
+ outM = m << 13;
+ if (e == 0x1f) { // Infinite or NaN
+ outE = 0xff;
+ if (outM != 0) { // SNaNs are quieted
+ outM |= FP32_QNAN_MASK;
+ }
+ } else {
+ outE = e - EXPONENT_BIAS + FP32_EXPONENT_BIAS;
+ }
+ }
+
+ int out = (s << 16) | (outE << FP32_EXPONENT_SHIFT) | outM;
+ return Float.intBitsToFloat(out);
+ }
+
+ /**
+ * <p>Converts the specified single-precision float value into a
+ * half-precision float value. The following special cases are handled:</p>
+ * <ul>
+ * <li>If the input is NaN (see {@link Float#isNaN(float)}), the returned
+ * value is {@link #NaN}</li>
+ * <li>If the input is {@link Float#POSITIVE_INFINITY} or
+ * {@link Float#NEGATIVE_INFINITY}, the returned value is respectively
+ * {@link #POSITIVE_INFINITY} or {@link #NEGATIVE_INFINITY}</li>
+ * <li>If the input is 0 (positive or negative), the returned value is
+ * {@link #POSITIVE_ZERO} or {@link #NEGATIVE_ZERO}</li>
+ * <li>If the input is a less than {@link #MIN_VALUE}, the returned value
+ * is flushed to {@link #POSITIVE_ZERO} or {@link #NEGATIVE_ZERO}</li>
+ * <li>If the input is a less than {@link #MIN_NORMAL}, the returned value
+ * is a denorm half-precision float</li>
+ * <li>Otherwise, the returned value is rounded to the nearest
+ * representable half-precision float value</li>
+ * </ul>
+ *
+ * @param f The single-precision float value to convert to half-precision
+ * @return A half-precision float value
+ */
+ @libcore.api.CorePlatformApi
+ public static short toHalf(float f) {
+ int bits = Float.floatToRawIntBits(f);
+ int s = (bits >>> FP32_SIGN_SHIFT );
+ int e = (bits >>> FP32_EXPONENT_SHIFT) & FP32_SHIFTED_EXPONENT_MASK;
+ int m = (bits ) & FP32_SIGNIFICAND_MASK;
+
+ int outE = 0;
+ int outM = 0;
+
+ if (e == 0xff) { // Infinite or NaN
+ outE = 0x1f;
+ outM = m != 0 ? 0x200 : 0;
+ } else {
+ e = e - FP32_EXPONENT_BIAS + EXPONENT_BIAS;
+ if (e >= 0x1f) { // Overflow
+ outE = 0x31;
+ } else if (e <= 0) { // Underflow
+ if (e < -10) {
+ // The absolute fp32 value is less than MIN_VALUE, flush to +/-0
+ } else {
+ // The fp32 value is a normalized float less than MIN_NORMAL,
+ // we convert to a denorm fp16
+ m = (m | 0x800000) >> (1 - e);
+ if ((m & 0x1000) != 0) m += 0x2000;
+ outM = m >> 13;
+ }
+ } else {
+ outE = e;
+ outM = m >> 13;
+ if ((m & 0x1000) != 0) {
+ // Round to nearest "0.5" up
+ int out = (outE << EXPONENT_SHIFT) | outM;
+ out++;
+ return (short) (out | (s << SIGN_SHIFT));
+ }
+ }
+ }
+
+ return (short) ((s << SIGN_SHIFT) | (outE << EXPONENT_SHIFT) | outM);
+ }
+
+ /**
+ * <p>Returns a hexadecimal string representation of the specified half-precision
+ * float value. If the value is a NaN, the result is <code>"NaN"</code>,
+ * otherwise the result follows this format:</p>
+ * <ul>
+ * <li>If the sign is positive, no sign character appears in the result</li>
+ * <li>If the sign is negative, the first character is <code>'-'</code></li>
+ * <li>If the value is inifinity, the string is <code>"Infinity"</code></li>
+ * <li>If the value is 0, the string is <code>"0x0.0p0"</code></li>
+ * <li>If the value has a normalized representation, the exponent and
+ * significand are represented in the string in two fields. The significand
+ * starts with <code>"0x1."</code> followed by its lowercase hexadecimal
+ * representation. Trailing zeroes are removed unless all digits are 0, then
+ * a single zero is used. The significand representation is followed by the
+ * exponent, represented by <code>"p"</code>, itself followed by a decimal
+ * string of the unbiased exponent</li>
+ * <li>If the value has a subnormal representation, the significand starts
+ * with <code>"0x0."</code> followed by its lowercase hexadecimal
+ * representation. Trailing zeroes are removed unless all digits are 0, then
+ * a single zero is used. The significand representation is followed by the
+ * exponent, represented by <code>"p-14"</code></li>
+ * </ul>
+ *
+ * @param h A half-precision float value
+ * @return A hexadecimal string representation of the specified value
+ */
+ @libcore.api.CorePlatformApi
+ public static String toHexString(short h) {
+ StringBuilder o = new StringBuilder();
+
+ int bits = h & 0xffff;
+ int s = (bits >>> SIGN_SHIFT );
+ int e = (bits >>> EXPONENT_SHIFT) & SHIFTED_EXPONENT_MASK;
+ int m = (bits ) & SIGNIFICAND_MASK;
+
+ if (e == 0x1f) { // Infinite or NaN
+ if (m == 0) {
+ if (s != 0) o.append('-');
+ o.append("Infinity");
+ } else {
+ o.append("NaN");
+ }
+ } else {
+ if (s == 1) o.append('-');
+ if (e == 0) {
+ if (m == 0) {
+ o.append("0x0.0p0");
+ } else {
+ o.append("0x0.");
+ String significand = Integer.toHexString(m);
+ o.append(significand.replaceFirst("0{2,}$", ""));
+ o.append("p-14");
+ }
+ } else {
+ o.append("0x1.");
+ String significand = Integer.toHexString(m);
+ o.append(significand.replaceFirst("0{2,}$", ""));
+ o.append('p');
+ o.append(Integer.toString(e - EXPONENT_BIAS));
+ }
+ }
+
+ return o.toString();
+ }
+}
diff --git a/mmodules/core_platform_api/api/platform/current-api.txt b/mmodules/core_platform_api/api/platform/current-api.txt
index c1f808f..1810c8a 100644
--- a/mmodules/core_platform_api/api/platform/current-api.txt
+++ b/mmodules/core_platform_api/api/platform/current-api.txt
@@ -1326,6 +1326,47 @@
field public static final String[] STRING;
}
+ public class FP16 {
+ method public static short ceil(short);
+ method public static int compare(short, short);
+ method public static boolean equals(short, short);
+ method public static short floor(short);
+ method public static boolean greater(short, short);
+ method public static boolean greaterEquals(short, short);
+ method public static boolean isInfinite(short);
+ method public static boolean isNaN(short);
+ method public static boolean isNormalized(short);
+ method public static boolean less(short, short);
+ method public static boolean lessEquals(short, short);
+ method public static short max(short, short);
+ method public static short min(short, short);
+ method public static short rint(short);
+ method public static float toFloat(short);
+ method public static short toHalf(float);
+ method public static String toHexString(short);
+ method public static short trunc(short);
+ field public static final short EPSILON = 5120; // 0x1400
+ field public static final int EXPONENT_BIAS = 15; // 0xf
+ field public static final int EXPONENT_SHIFT = 10; // 0xa
+ field public static final int EXPONENT_SIGNIFICAND_MASK = 32767; // 0x7fff
+ field public static final short LOWEST_VALUE = -1025; // 0xfffffbff
+ field public static final int MAX_EXPONENT = 15; // 0xf
+ field public static final short MAX_VALUE = 31743; // 0x7bff
+ field public static final int MIN_EXPONENT = -14; // 0xfffffff2
+ field public static final short MIN_NORMAL = 1024; // 0x400
+ field public static final short MIN_VALUE = 1; // 0x1
+ field public static final short NEGATIVE_INFINITY = -1024; // 0xfffffc00
+ field public static final short NEGATIVE_ZERO = -32768; // 0xffff8000
+ field public static final short NaN = 32256; // 0x7e00
+ field public static final short POSITIVE_INFINITY = 31744; // 0x7c00
+ field public static final short POSITIVE_ZERO = 0; // 0x0
+ field public static final int SHIFTED_EXPONENT_MASK = 31; // 0x1f
+ field public static final int SIGNIFICAND_MASK = 1023; // 0x3ff
+ field public static final int SIGN_MASK = 32768; // 0x8000
+ field public static final int SIGN_SHIFT = 15; // 0xf
+ field public static final int SIZE = 16; // 0x10
+ }
+
public class HexEncoding {
method public static byte[] decode(String) throws java.lang.IllegalArgumentException;
method public static byte[] decode(String, boolean) throws java.lang.IllegalArgumentException;
diff --git a/non_openjdk_java_files.bp b/non_openjdk_java_files.bp
index 2cbb946..77c56e4 100644
--- a/non_openjdk_java_files.bp
+++ b/non_openjdk_java_files.bp
@@ -194,6 +194,7 @@
"luni/src/main/java/libcore/util/CoreLibraryDebug.java",
"luni/src/main/java/libcore/util/DebugInfo.java",
"luni/src/main/java/libcore/util/EmptyArray.java",
+ "luni/src/main/java/libcore/util/FP16.java",
"luni/src/main/java/libcore/util/HexEncoding.java",
"luni/src/main/java/libcore/util/NativeAllocationRegistry.java",
"luni/src/main/java/libcore/util/NonNull.java",