/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.lang;
import libcore.math.MathUtils;
final class RealToString {
private static final ThreadLocal<RealToString> INSTANCE = new ThreadLocal<RealToString>() {
@Override protected RealToString initialValue() {
return new RealToString();
}
};
private static final double invLogOfTenBaseTwo = Math.log(2.0) / Math.log(10.0);
private int firstK;
/**
* An array of decimal digits, filled by longDigitGenerator or bigIntDigitGenerator.
*/
private final int[] digits = new int[64];
/**
* Number of valid entries in 'digits'.
*/
private int digitCount;
private RealToString() {
}
public static RealToString getInstance() {
return INSTANCE.get();
}
private static String resultOrSideEffect(AbstractStringBuilder sb, String s) {
if (sb != null) {
sb.append0(s);
return null;
}
return s;
}
public String doubleToString(double d) {
return convertDouble(null, d);
}
public void appendDouble(AbstractStringBuilder sb, double d) {
convertDouble(sb, d);
}
private String convertDouble(AbstractStringBuilder sb, double inputNumber) {
long inputNumberBits = Double.doubleToRawLongBits(inputNumber);
boolean positive = (inputNumberBits & Double.SIGN_MASK) == 0;
int e = (int) ((inputNumberBits & Double.EXPONENT_MASK) >> Double.MANTISSA_BITS);
long f = inputNumberBits & Double.MANTISSA_MASK;
boolean mantissaIsZero = f == 0;
String quickResult = null;
if (e == 2047) {
if (mantissaIsZero) {
quickResult = positive ? "Infinity" : "-Infinity";
} else {
quickResult = "NaN";
}
} else if (e == 0) {
if (mantissaIsZero) {
quickResult = positive ? "0.0" : "-0.0";
} else if (f == 1) {
// special case to increase precision even though 2 * Double.MIN_VALUE is 1.0e-323
quickResult = positive ? "4.9E-324" : "-4.9E-324";
}
}
if (quickResult != null) {
return resultOrSideEffect(sb, quickResult);
}
int p = Double.EXPONENT_BIAS + Double.MANTISSA_BITS; // the power offset (precision)
int pow;
int numBits = Double.MANTISSA_BITS;
if (e == 0) {
pow = 1 - p; // a denormalized number
long ff = f;
while ((ff & 0x0010000000000000L) == 0) {
ff = ff << 1;
numBits--;
}
} else {
// 0 < e < 2047
// a "normalized" number
f = f | 0x0010000000000000L;
pow = e - p;
}
firstK = digitCount = 0;
if (-59 < pow && pow < 6 || (pow == -59 && !mantissaIsZero)) {
longDigitGenerator(f, pow, e == 0, mantissaIsZero, numBits);
} else {
bigIntDigitGenerator(f, pow, e == 0, numBits);
}
AbstractStringBuilder dst = (sb != null) ? sb : new StringBuilder(26);
if (inputNumber >= 1e7D || inputNumber <= -1e7D
|| (inputNumber > -1e-3D && inputNumber < 1e-3D)) {
freeFormatExponential(dst, positive);
} else {
freeFormat(dst, positive);
}
return (sb != null) ? null : dst.toString();
}
public String floatToString(float f) {
return convertFloat(null, f);
}
public void appendFloat(AbstractStringBuilder sb, float f) {
convertFloat(sb, f);
}
public String convertFloat(AbstractStringBuilder sb, float inputNumber) {
int inputNumberBits = Float.floatToRawIntBits(inputNumber);
boolean positive = (inputNumberBits & Float.SIGN_MASK) == 0;
int e = (inputNumberBits & Float.EXPONENT_MASK) >> Float.MANTISSA_BITS;
int f = inputNumberBits & Float.MANTISSA_MASK;
boolean mantissaIsZero = f == 0;
String quickResult = null;
if (e == 255) {
if (mantissaIsZero) {
quickResult = positive ? "Infinity" : "-Infinity";
} else {
quickResult = "NaN";
}
} else if (e == 0 && mantissaIsZero) {
quickResult = positive ? "0.0" : "-0.0";
}
if (quickResult != null) {
return resultOrSideEffect(sb, quickResult);
}
int p = Float.EXPONENT_BIAS + Float.MANTISSA_BITS; // the power offset (precision)
int pow;
int numBits = Float.MANTISSA_BITS;
if (e == 0) {
pow = 1 - p; // a denormalized number
if (f < 8) { // want more precision with smallest values
f = f << 2;
pow -= 2;
}
int ff = f;
while ((ff & 0x00800000) == 0) {
ff = ff << 1;
numBits--;
}
} else {
// 0 < e < 255
// a "normalized" number
f = f | 0x00800000;
pow = e - p;
}
firstK = digitCount = 0;
if (-59 < pow && pow < 35 || (pow == -59 && !mantissaIsZero)) {
longDigitGenerator(f, pow, e == 0, mantissaIsZero, numBits);
} else {
bigIntDigitGenerator(f, pow, e == 0, numBits);
}
AbstractStringBuilder dst = (sb != null) ? sb : new StringBuilder(26);
if (inputNumber >= 1e7f || inputNumber <= -1e7f
|| (inputNumber > -1e-3f && inputNumber < 1e-3f)) {
freeFormatExponential(dst, positive);
} else {
freeFormat(dst, positive);
}
return (sb != null) ? null : dst.toString();
}
private void freeFormatExponential(AbstractStringBuilder sb, boolean positive) {
int digitIndex = 0;
if (!positive) {
sb.append0('-');
}
sb.append0((char) ('0' + digits[digitIndex++]));
sb.append0('.');
int k = firstK;
int exponent = k;
while (true) {
k--;
if (digitIndex >= digitCount) {
break;
}
sb.append0((char) ('0' + digits[digitIndex++]));
}
if (k == exponent - 1) {
sb.append0('0');
}
sb.append0('E');
IntegralToString.appendInt(sb, exponent);
}
private void freeFormat(AbstractStringBuilder sb, boolean positive) {
int digitIndex = 0;
if (!positive) {
sb.append0('-');
}
int k = firstK;
if (k < 0) {
sb.append0('0');
sb.append0('.');
for (int i = k + 1; i < 0; ++i) {
sb.append0('0');
}
}
int U = digits[digitIndex++];
do {
if (U != -1) {
sb.append0((char) ('0' + U));
} else if (k >= -1) {
sb.append0('0');
}
if (k == 0) {
sb.append0('.');
}
k--;
U = digitIndex < digitCount ? digits[digitIndex++] : -1;
} while (U != -1 || k >= -1);
}
private native void bigIntDigitGenerator(long f, int e, boolean isDenormalized, int p);
private void longDigitGenerator(long f, int e, boolean isDenormalized,
boolean mantissaIsZero, int p) {
long R, S, M;
if (e >= 0) {
M = 1l << e;
if (!mantissaIsZero) {
R = f << (e + 1);
S = 2;
} else {
R = f << (e + 2);
S = 4;
}
} else {
M = 1;
if (isDenormalized || !mantissaIsZero) {
R = f << 1;
S = 1l << (1 - e);
} else {
R = f << 2;
S = 1l << (2 - e);
}
}
int k = (int) Math.ceil((e + p - 1) * invLogOfTenBaseTwo - 1e-10);
if (k > 0) {
S = S * MathUtils.LONG_POWERS_OF_TEN[k];
} else if (k < 0) {
long scale = MathUtils.LONG_POWERS_OF_TEN[-k];
R = R * scale;
M = M == 1 ? scale : M * scale;
}
if (R + M > S) { // was M_plus
firstK = k;
} else {
firstK = k - 1;
R = R * 10;
M = M * 10;
}
boolean low, high;
int U;
while (true) {
// Set U to floor(R/S) and R to the remainder, using *unsigned* 64-bit division
U = 0;
for (int i = 3; i >= 0; i--) {
long remainder = R - (S << i);
if (remainder >= 0) {
R = remainder;
U += 1 << i;
}
}
low = R < M; // was M_minus
high = R + M > S; // was M_plus
if (low || high) {
break;
}
R = R * 10;
M = M * 10;
digits[digitCount++] = U;
}
if (low && !high) {
digits[digitCount++] = U;
} else if (high && !low) {
digits[digitCount++] = U + 1;
} else if ((R << 1) < S) {
digits[digitCount++] = U;
} else {
digits[digitCount++] = U + 1;
}
}
}