6935172: Optimize bit-twiddling in Bits.java
Summary: Transformations to reduce size of bytecode
Reviewed-by: sherman
Contributed-by: Based on an idea by Ulf Zibis <ulf.zibis@gmx.de>
--- a/jdk/src/share/classes/java/io/Bits.java Wed Jun 30 16:11:32 2010 -0700
+++ b/jdk/src/share/classes/java/io/Bits.java Wed Jun 30 16:11:32 2010 -0700
@@ -41,51 +41,39 @@
}
static char getChar(byte[] b, int off) {
- return (char) (((b[off + 1] & 0xFF) << 0) +
- ((b[off + 0]) << 8));
+ return (char) ((b[off + 1] & 0xFF) +
+ (b[off] << 8));
}
static short getShort(byte[] b, int off) {
- return (short) (((b[off + 1] & 0xFF) << 0) +
- ((b[off + 0]) << 8));
+ return (short) ((b[off + 1] & 0xFF) +
+ (b[off] << 8));
}
static int getInt(byte[] b, int off) {
- return ((b[off + 3] & 0xFF) << 0) +
- ((b[off + 2] & 0xFF) << 8) +
+ return ((b[off + 3] & 0xFF) ) +
+ ((b[off + 2] & 0xFF) << 8) +
((b[off + 1] & 0xFF) << 16) +
- ((b[off + 0]) << 24);
+ ((b[off ] ) << 24);
}
static float getFloat(byte[] b, int off) {
- int i = ((b[off + 3] & 0xFF) << 0) +
- ((b[off + 2] & 0xFF) << 8) +
- ((b[off + 1] & 0xFF) << 16) +
- ((b[off + 0]) << 24);
- return Float.intBitsToFloat(i);
+ return Float.intBitsToFloat(getInt(b, off));
}
static long getLong(byte[] b, int off) {
- return ((b[off + 7] & 0xFFL) << 0) +
- ((b[off + 6] & 0xFFL) << 8) +
+ return ((b[off + 7] & 0xFFL) ) +
+ ((b[off + 6] & 0xFFL) << 8) +
((b[off + 5] & 0xFFL) << 16) +
((b[off + 4] & 0xFFL) << 24) +
((b[off + 3] & 0xFFL) << 32) +
((b[off + 2] & 0xFFL) << 40) +
((b[off + 1] & 0xFFL) << 48) +
- (((long) b[off + 0]) << 56);
+ (((long) b[off]) << 56);
}
static double getDouble(byte[] b, int off) {
- long j = ((b[off + 7] & 0xFFL) << 0) +
- ((b[off + 6] & 0xFFL) << 8) +
- ((b[off + 5] & 0xFFL) << 16) +
- ((b[off + 4] & 0xFFL) << 24) +
- ((b[off + 3] & 0xFFL) << 32) +
- ((b[off + 2] & 0xFFL) << 40) +
- ((b[off + 1] & 0xFFL) << 48) +
- (((long) b[off + 0]) << 56);
- return Double.longBitsToDouble(j);
+ return Double.longBitsToDouble(getLong(b, off));
}
/*
@@ -98,50 +86,38 @@
}
static void putChar(byte[] b, int off, char val) {
- b[off + 1] = (byte) (val >>> 0);
- b[off + 0] = (byte) (val >>> 8);
+ b[off + 1] = (byte) (val );
+ b[off ] = (byte) (val >>> 8);
}
static void putShort(byte[] b, int off, short val) {
- b[off + 1] = (byte) (val >>> 0);
- b[off + 0] = (byte) (val >>> 8);
+ b[off + 1] = (byte) (val );
+ b[off ] = (byte) (val >>> 8);
}
static void putInt(byte[] b, int off, int val) {
- b[off + 3] = (byte) (val >>> 0);
- b[off + 2] = (byte) (val >>> 8);
+ b[off + 3] = (byte) (val );
+ b[off + 2] = (byte) (val >>> 8);
b[off + 1] = (byte) (val >>> 16);
- b[off + 0] = (byte) (val >>> 24);
+ b[off ] = (byte) (val >>> 24);
}
static void putFloat(byte[] b, int off, float val) {
- int i = Float.floatToIntBits(val);
- b[off + 3] = (byte) (i >>> 0);
- b[off + 2] = (byte) (i >>> 8);
- b[off + 1] = (byte) (i >>> 16);
- b[off + 0] = (byte) (i >>> 24);
+ putInt(b, off, Float.floatToIntBits(val));
}
static void putLong(byte[] b, int off, long val) {
- b[off + 7] = (byte) (val >>> 0);
- b[off + 6] = (byte) (val >>> 8);
+ b[off + 7] = (byte) (val );
+ b[off + 6] = (byte) (val >>> 8);
b[off + 5] = (byte) (val >>> 16);
b[off + 4] = (byte) (val >>> 24);
b[off + 3] = (byte) (val >>> 32);
b[off + 2] = (byte) (val >>> 40);
b[off + 1] = (byte) (val >>> 48);
- b[off + 0] = (byte) (val >>> 56);
+ b[off ] = (byte) (val >>> 56);
}
static void putDouble(byte[] b, int off, double val) {
- long j = Double.doubleToLongBits(val);
- b[off + 7] = (byte) (j >>> 0);
- b[off + 6] = (byte) (j >>> 8);
- b[off + 5] = (byte) (j >>> 16);
- b[off + 4] = (byte) (j >>> 24);
- b[off + 3] = (byte) (j >>> 32);
- b[off + 2] = (byte) (j >>> 40);
- b[off + 1] = (byte) (j >>> 48);
- b[off + 0] = (byte) (j >>> 56);
+ putLong(b, off, Double.doubleToLongBits(val));
}
}