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synchronization cache of roots #72

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synchronization cache of roots #72

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1ab6b10
synchronization cache of roots
antonin-janec Jun 12, 2023
1a7d142
Merge branch 'wrandelshofer:main' into CONCURRENT_MAP
antonin-janec Jun 16, 2023
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21 changes: 11 additions & 10 deletions ...java/ch.randelshofer.fastdoubleparser/ch/randelshofer/fastdoubleparser/FftMultiplier.java
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
package ch.randelshofer.fastdoubleparser;

import java.math.BigInteger;
import java.util.concurrent.atomic.AtomicReferenceArray;

import static ch.randelshofer.fastdoubleparser.FastDoubleMath.fastScalb;
import static ch.randelshofer.fastdoubleparser.FastDoubleSwar.fma;
Expand Down Expand Up @@ -48,7 +49,7 @@ class FftMultiplier {
/**
* for FFTs of length up to 2^19
*/
private static final int ROOTS_CACHE2_SIZE = 20;
private static final int ROOTS2_CACHE_SIZE = 20;
/**
* The threshold value for using 3-way Toom-Cook multiplication.
*/
Expand All @@ -58,13 +59,13 @@ class FftMultiplier {
* elements representing all (2^(k+2))-th roots between 0 and pi/2.
* Used for FFT multiplication.
*/
private volatile static ComplexVector[] ROOTS2_CACHE = new ComplexVector[ROOTS_CACHE2_SIZE];
private final static AtomicReferenceArray<ComplexVector> ROOTS2_CACHE = new AtomicReferenceArray<>(ROOTS2_CACHE_SIZE);
/**
* Sets of complex roots of unity. The set at index k contains 3*2^k
* elements representing all (3*2^(k+2))-th roots between 0 and pi/2.
* Used for FFT multiplication.
*/
private volatile static ComplexVector[] ROOTS3_CACHE = new ComplexVector[ROOTS3_CACHE_SIZE];
private final static AtomicReferenceArray<ComplexVector> ROOTS3_CACHE = new AtomicReferenceArray<>(ROOTS3_CACHE_SIZE);

/**
* Returns the maximum number of bits that one double precision number can fit without
Expand Down Expand Up @@ -351,11 +352,11 @@ static BigInteger fromFftVector(ComplexVector fftVec, int signum, int bitsPerFft
private static ComplexVector[] getRootsOfUnity2(int logN) {
ComplexVector[] roots = new ComplexVector[logN + 1];
for (int i = logN; i >= 0; i -= 2) {
if (i < ROOTS_CACHE2_SIZE) {
if (ROOTS2_CACHE[i] == null) {
ROOTS2_CACHE[i] = calculateRootsOfUnity(1 << i);
if (i < ROOTS2_CACHE_SIZE) {
if (ROOTS2_CACHE.get(i) == null) {
ROOTS2_CACHE.set(i, calculateRootsOfUnity(1 << i));
}
roots[i] = ROOTS2_CACHE[i];
roots[i] = ROOTS2_CACHE.get(i);
} else {
roots[i] = calculateRootsOfUnity(1 << i);
}
Expand All @@ -371,10 +372,10 @@ private static ComplexVector[] getRootsOfUnity2(int logN) {
*/
private static ComplexVector getRootsOfUnity3(int logN) {
if (logN < ROOTS3_CACHE_SIZE) {
if (ROOTS3_CACHE[logN] == null) {
ROOTS3_CACHE[logN] = calculateRootsOfUnity(3 << logN);
if (ROOTS3_CACHE.get(logN) == null) {
ROOTS3_CACHE.set(logN, calculateRootsOfUnity(3 << logN));
}
return ROOTS3_CACHE[logN];
return ROOTS3_CACHE.get(logN);
} else {
return calculateRootsOfUnity(3 << logN);
}
Expand Down