Merge "Move Half implementations to libcore to allow ART optimizations"
am: f54cb9109c
Change-Id: I9d03803ae3e39bd52afa7d6ee3bd84e8dbff0034
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 cc59804..b4912a1 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 0d274ed..c1b3511 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",