src/share/classes/java/lang/Long.java
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rev 7162 : 8007398: Peformance improvements to Integer and Long string formatting.
Reviewed-by: mdugiou, martin, darcy, briangoetz
Contributed-by: Steven Schlansker <stevenschlansker@gmail.com>, Mike Duigou <mike.duigou@oracle.com>
@@ -26,10 +26,11 @@
package java.lang;
import java.lang.annotation.Native;
import java.math.*;
+
/**
* The {@code Long} class wraps a value of the primitive type {@code
* long} in an object. An object of type {@code Long} contains a
* single field whose type is {@code long}.
*
@@ -342,22 +343,43 @@
public static String toBinaryString(long i) {
return toUnsignedString0(i, 1);
}
/**
- * Convert the integer to an unsigned number.
+ * Format a long (treated as unsigned) into a String.
+ * @param val the value to format
+ * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
+ */
+ static String toUnsignedString0(long val, int shift) {
+ // assert shift > 0 && shift <=5 : "Illegal shift value";
+ int mag = Long.SIZE - Long.numberOfLeadingZeros(val);
+ int chars = Math.max(((mag + (shift - 1)) / shift), 1);
+ char[] buf = new char[chars];
+
+ formatUnsignedLong(val, shift, buf, 0, chars);
+ return new String(buf, true);
+ }
+
+ /**
+ * Format a long (treated as unsigned) into a character buffer.
+ * @param val the unsigned long to format
+ * @param shift the log2 of the base to format in (4 for hex, 3 for octal, 1 for binary)
+ * @param buf the character buffer to write to
+ * @param offset the offset in the destination buffer to start at
+ * @param len the number of characters to write
+ * @return the lowest character location used
*/
- private static String toUnsignedString0(long i, int shift) {
- char[] buf = new char[64];
- int charPos = 64;
+ static int formatUnsignedLong(long val, int shift, char[] buf, int offset, int len) {
+ int charPos = len;
int radix = 1 << shift;
- long mask = radix - 1;
+ int mask = radix - 1;
do {
- buf[--charPos] = Integer.digits[(int)(i & mask)];
- i >>>= shift;
- } while (i != 0);
- return new String(buf, charPos, (64 - charPos));
+ buf[offset + --charPos] = Integer.digits[((int) val) & mask];
+ val >>>= shift;
+ } while (val != 0 && charPos > 0);
+
+ return charPos;
}
/**
* Returns a {@code String} object representing the specified
* {@code long}. The argument is converted to signed decimal