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Posted to commits@commons.apache.org by er...@apache.org on 2015/12/21 03:20:50 UTC
[math] MATH-1305
Repository: commons-math
Updated Branches:
refs/heads/master 813aa11d5 -> 88b29fa46
MATH-1305
Slight performance improvement of the "nextBytes" methods.
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo
Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/88b29fa4
Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/88b29fa4
Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/88b29fa4
Branch: refs/heads/master
Commit: 88b29fa46bcf6f56df4213e1ba7810735a28d755
Parents: 813aa11
Author: Gilles <er...@apache.org>
Authored: Mon Dec 21 03:14:32 2015 +0100
Committer: Gilles <er...@apache.org>
Committed: Mon Dec 21 03:14:32 2015 +0100
----------------------------------------------------------------------
src/changes/changes.xml | 5 +++
.../math4/random/AbstractRandomGenerator.java | 32 ++++++++++++--------
.../math4/random/BitsStreamGenerator.java | 32 ++++++++++++--------
3 files changed, 45 insertions(+), 24 deletions(-)
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http://git-wip-us.apache.org/repos/asf/commons-math/blob/88b29fa4/src/changes/changes.xml
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diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index 426d03c..c59d418 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -54,6 +54,11 @@ If the output is not quite correct, check for invisible trailing spaces!
</release>
<release version="4.0" date="XXXX-XX-XX" description="">
+ <action dev="erans" type="update" issue="MATH-1305" due-to="Rostislav Krasny">
+ "AbstractRandomGenerator" and "BitsStreamGenerator": Slight performance
+ improvement of the "nextBytes" method (particularly when the number of
+ requested bytes is a multiple of 4).
+ </action>
<action dev="erans" type="fix" issue="MATH-1300" due-to="Rostislav Krasny">
"AbstractRandomGenerator" and "BitsStreamGenerator": Remove a redundant call
to the random data provider.
http://git-wip-us.apache.org/repos/asf/commons-math/blob/88b29fa4/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java
----------------------------------------------------------------------
diff --git a/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java b/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java
index c31dc68..2115dbd 100644
--- a/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java
+++ b/src/main/java/org/apache/commons/math4/random/AbstractRandomGenerator.java
@@ -107,21 +107,29 @@ public abstract class AbstractRandomGenerator implements RandomGenerator {
*/
@Override
public void nextBytes(byte[] bytes) {
- int i = 0;
- final int iEnd = bytes.length - 3;
- while (i < iEnd) {
+ // Multiple 4 part of length (i.e. length with two least significant bits unset).
+ final int max = bytes.length & 0x7ffffffc;
+
+ int index = 0;
+ // Start filling in the byte array, 4 bytes at a time.
+ while (index < max) {
final int random = nextInt();
- bytes[i] = (byte) (random & 0xff);
- bytes[i + 1] = (byte) ((random >> 8) & 0xff);
- bytes[i + 2] = (byte) ((random >> 16) & 0xff);
- bytes[i + 3] = (byte) ((random >> 24) & 0xff);
- i += 4;
+ bytes[index++] = (byte) random;
+ bytes[index++] = (byte) (random >>> 8);
+ bytes[index++] = (byte) (random >>> 16);
+ bytes[index++] = (byte) (random >>> 24);
}
- if (i < bytes.length) {
+
+ // Fill in the remaining bytes.
+ if (index < bytes.length) {
int random = nextInt();
- while (i < bytes.length) {
- bytes[i++] = (byte) (random & 0xff);
- random >>= 8;
+ while (true) {
+ bytes[index++] = (byte) random;
+ if (index < bytes.length) {
+ random >>>= 8;
+ } else {
+ break;
+ }
}
}
}
http://git-wip-us.apache.org/repos/asf/commons-math/blob/88b29fa4/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
----------------------------------------------------------------------
diff --git a/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java b/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
index 7c89b60..4cf6823 100644
--- a/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
+++ b/src/main/java/org/apache/commons/math4/random/BitsStreamGenerator.java
@@ -72,21 +72,29 @@ public abstract class BitsStreamGenerator
/** {@inheritDoc} */
@Override
public void nextBytes(byte[] bytes) {
- int i = 0;
- final int iEnd = bytes.length - 3;
- while (i < iEnd) {
+ // Multiple 4 part of length (i.e. length with two least significant bits unset).
+ final int max = bytes.length & 0x7ffffffc;
+
+ int index = 0;
+ // Start filling in the byte array, 4 bytes at a time.
+ while (index < max) {
final int random = next(32);
- bytes[i] = (byte) (random & 0xff);
- bytes[i + 1] = (byte) ((random >> 8) & 0xff);
- bytes[i + 2] = (byte) ((random >> 16) & 0xff);
- bytes[i + 3] = (byte) ((random >> 24) & 0xff);
- i += 4;
+ bytes[index++] = (byte) random;
+ bytes[index++] = (byte) (random >>> 8);
+ bytes[index++] = (byte) (random >>> 16);
+ bytes[index++] = (byte) (random >>> 24);
}
- if (i < bytes.length) {
+
+ // Fill in the remaing bytes.
+ if (index < bytes.length) {
int random = next(32);
- while (i < bytes.length) {
- bytes[i++] = (byte) (random & 0xff);
- random >>= 8;
+ while (true) {
+ bytes[index++] = (byte) random;
+ if (index < bytes.length) {
+ random >>>= 8;
+ } else {
+ break;
+ }
}
}
}