$OpenBSD: patch-fast_snprintf_c,v 1.1 2002/08/10 01:14:04 naddy Exp $
--- fast_snprintf.c.orig	Fri Aug  2 22:15:44 2002
+++ fast_snprintf.c	Tue Mar  6 00:49:52 2001
@@ -0,0 +1,235 @@
+/* Copyright (C) 2000-1 drscholl@users.sourceforge.net
+   This is free software distributed under the terms of the
+   GNU Public License.  See the file COPYING for details.
+
+   fast_snprintf.c,v 1.12 2001/03/06 06:49:52 drscholl Exp */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdarg.h>
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <stdio.h>
+
+#define DIGIT(n,ui) \
+	if(ui>=(n)) { *out++ = '0' + (ui / (n)) % 10; if (--outsize == 0) break; }
+
+void fast_vsnprintf (char *out, size_t outsize, const char *fmt, va_list ap);
+void fast_snprintf (char *out, size_t outsize, const char *fmt, ...);
+
+void
+fast_vsnprintf (char *out, size_t outsize, const char *fmt, va_list ap)
+{
+    unsigned int ui;
+    unsigned short us;
+    int i, len;
+    char   *s;
+    char    c;
+
+    if (outsize == 0)
+	return;
+
+    outsize--;
+
+    while (*fmt && outsize > 0)
+    {
+	if ((c = *fmt++) != '%')
+	{
+	    *out++ = c;
+	    outsize--;
+	}
+	else
+	{
+	    c = *fmt++;
+	    if (c == 's')
+	    {
+		s = va_arg (ap, char *);
+
+		if (s == NULL)
+		{
+		    if (outsize < 6)
+			break;
+		    strcpy (out, "{null}");
+		    out+=6;
+		    outsize-=6;
+		}
+		else
+		    while (*s && outsize > 0)
+		    {
+			*out++ = *s++;
+			outsize--;
+		    }
+	    }
+	    else if (c == 'd')
+	    {
+		i = va_arg (ap, int);
+
+		if (i == 0)
+		{
+		    /* zero occurs often, so optimize for it */
+		    *out++ = '0';
+		    outsize--;
+		}
+		else
+		{
+		    /* optimized for small ints */
+		    if (i < 0)
+		    {
+			/* handle negative numbers */
+			*out++ = '-';
+			if (--outsize == 0)
+			    break;
+			i *= -1;
+		    }
+		    DIGIT (100000000, i);
+		    DIGIT (10000000, i);
+		    DIGIT (1000000, i);
+		    DIGIT (100000, i);
+		    DIGIT (10000, i);
+		    DIGIT (1000, i);
+		    DIGIT (100, i);
+		    DIGIT (10, i);
+		    *out++ = '0' + i % 10;
+		    outsize--;
+		}
+	    }
+	    else if (c == 'h' && *fmt == 'u')
+	    {
+		fmt++;
+		/* have to promote short to int */
+		us = (unsigned short) va_arg (ap, unsigned int);
+
+		DIGIT (10000, us);
+		DIGIT (1000, us);
+		DIGIT (100, us);
+		DIGIT (10, us);
+		*out++ = '0' + us % 10;
+		outsize--;
+	    }
+	    /* %u .  assume 10 digit number. this is typically used
+	     * to either print a time_t or an ip address.
+	     */
+	    else if (c == 'u')
+	    {
+		ui = va_arg (ap, unsigned int);
+
+#if 1
+		/* this appears to be faster than the other way.  my guess
+		 * is that the store of the leading 0's takes much longer
+		 * than doing ten if() evaluations.  The performance is only
+		 * slightly better, and solves the problem of those ugly
+		 * leading zeros
+		 */
+		DIGIT (1000000000, ui);
+		DIGIT (100000000, ui);
+		DIGIT (10000000, ui);
+		DIGIT (1000000, ui);
+		DIGIT (100000, ui);
+		DIGIT (10000, ui);
+		DIGIT (1000, ui);
+		DIGIT (100, ui);
+		DIGIT (10, ui);
+		*out++ = '0' + ui % 10;
+		outsize--;
+#else
+		if (outsize < 10)
+		    break;
+		*out++ = '0' + (ui / 1000000000) % 10;
+		*out++ = '0' + (ui / 100000000) % 10;
+		*out++ = '0' + (ui / 10000000) % 10;
+		*out++ = '0' + (ui / 1000000) % 10;
+		*out++ = '0' + (ui / 100000) % 10;
+		*out++ = '0' + (ui / 10000) % 10;
+		*out++ = '0' + (ui / 1000) % 10;
+		*out++ = '0' + (ui / 100) % 10;
+		*out++ = '0' + (ui / 10) % 10;
+		*out++ = '0' + ui % 10;
+		outsize -= 10;
+#endif
+	    }
+	    else if (c == 'c')
+	    {
+		/* va_arg only takes fully promoted types, so we need
+		 * a cast here
+		 */
+		c = (char) va_arg (ap, int);
+
+		*out++ = c;
+		outsize--;
+	    }
+	    /* %f is typically used to print an integer larger than a %u */
+	    else if (c == 'f')
+	    {
+		double f = va_arg (ap, double);
+
+		snprintf (out, outsize, "%.0f", f);
+		len = strlen (out);
+		out += len;
+		outsize -= len;
+	    }
+	    else
+		assert (0);	/* not supported */
+	}
+    }
+    *out = 0;
+}
+
+void
+fast_snprintf (char *out, size_t outsize, const char *fmt, ...)
+{
+    va_list ap;
+
+    va_start (ap, fmt);
+    fast_vsnprintf (out, outsize, fmt, ap);
+    va_end (ap);
+}
+
+#if TEST
+
+#if 1
+#define FUNC fast_snprintf
+#else
+#define FUNC snprintf
+#endif
+
+int
+main (int argc, char **argv)
+{
+    char    buf[1024];
+    char   *fmt1 = "The %s brown %s jumped %s the %s dogs.";
+    char   *fmt2 = "%d %d %d %d";
+    char   *fmt3 = "blah blah blah";
+    char *fmt4 = "%u %hu";
+    char *fmt5 = "%d";
+    char *fmt6 = "%u %u %u %u";
+    int     i;
+    struct timeval s, e;
+    char small[16];
+
+    memset(small,0xff,sizeof(small));
+    fast_snprintf(small,sizeof(small)-1,"this is a very long string");
+    memset(small,0xff,sizeof(small));
+    fast_snprintf(small,sizeof(small)-1,"this is a ver%d", 123456);
+    memset(small,0xff,sizeof(small));
+    fast_snprintf(small,sizeof(small)-1,"this is a ver%s", "blah blah blah");
+
+    gettimeofday (&s, 0);
+    for (i = 0; i < 10000; i++)
+    {
+	//FUNC (buf, sizeof (buf), fmt1, "quick", "fox", "over", "lazy");
+	//FUNC (buf, sizeof (buf), fmt2, 1, 11, 111, 1111);
+	//FUNC (buf, sizeof (buf), fmt3);
+	//FUNC (buf, sizeof (buf), fmt4, 0x7fffffff, 0xffff);
+	//FUNC (buf, sizeof (buf), fmt5, -10134);
+	FUNC(buf,sizeof(buf),fmt6,0x7fffffff,0x0fffffff,0x00ffffff,0x000fffff);
+	puts(buf);
+    }
+    gettimeofday (&e, 0);
+
+    printf ("%d\n",
+	    (e.tv_sec - s.tv_sec) * 1000000 + (e.tv_usec - s.tv_usec));
+}
+#endif