1 files changed, 87 insertions, 1 deletions
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index 74cbff1..fd16f88 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclUtil.c,v 1.120 2010/11/29 02:27:12 kennykb Exp $
+ * RCS: @(#) $Id: tclUtil.c,v 1.121 2010/11/30 18:17:26 hobbs Exp $
  */
 
 #include "tclInt.h"
@@ -2496,6 +2496,92 @@ TclNeedSpace(
 /*
  *----------------------------------------------------------------------
  *
+ * TclFormatInt --
+ *
+ *	This procedure formats an integer into a sequence of decimal digit
+ *	characters in a buffer. If the integer is negative, a minus sign is
+ *	inserted at the start of the buffer. A null character is inserted at
+ *	the end of the formatted characters. It is the caller's
+ *	responsibility to ensure that enough storage is available. This
+ *	procedure has the effect of sprintf(buffer, "%ld", n) but is faster
+ *	as proven in benchmarks.  This is key to UpdateStringOfInt, which
+ *	is a common path for a lot of code (e.g. int-indexed arrays).
+ *
+ * Results:
+ *	An integer representing the number of characters formatted, not
+ *	including the terminating \0.
+ *
+ * Side effects:
+ *	The formatted characters are written into the storage pointer to
+ *	by the "buffer" argument.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclFormatInt(buffer, n)
+    char *buffer;		/* Points to the storage into which the
+				 * formatted characters are written. */
+    long n;			/* The integer to format. */
+{
+    long intVal;
+    int i;
+    int numFormatted, j;
+    char *digits = "0123456789";
+
+    /*
+     * Check first whether "n" is zero.
+     */
+
+    if (n == 0) {
+	buffer[0] = '0';
+	buffer[1] = 0;
+	return 1;
+    }
+
+    /*
+     * Check whether "n" is the maximum negative value. This is
+     * -2^(m-1) for an m-bit word, and has no positive equivalent;
+     * negating it produces the same value.
+     */
+
+    if (n == -n) {
+	return sprintf(buffer, "%ld", n);
+    }
+
+    /*
+     * Generate the characters of the result backwards in the buffer.
+     */
+
+    intVal = (n < 0? -n : n);
+    i = 0;
+    buffer[0] = '\0';
+    do {
+	i++;
+	buffer[i] = digits[intVal % 10];
+	intVal = intVal/10;
+    } while (intVal > 0);
+    if (n < 0) {
+	i++;
+	buffer[i] = '-';
+    }
+    numFormatted = i;
+
+    /*
+     * Now reverse the characters.
+     */
+
+    for (j = 0;  j < i;  j++, i--) {
+	char tmp = buffer[i];
+	buffer[i] = buffer[j];
+	buffer[j] = tmp;
+    }
+    return numFormatted;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TclGetIntForIndex --
  *
  *	This function returns an integer corresponding to the list index held