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(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-math/blob/88b29fa4/src/changes/changes.xml ---------------------------------------------------------------------- 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; + } } } }
