[Redbutton-devel] SF.net SVN: redbutton: [408] redbutton-author/trunk/der_encode.c

[<ski...@us...>]

Revision: 408
          http://redbutton.svn.sourceforge.net/redbutton/?rev=408&view=rev
Author:   skilvington
Date:     2007-09-21 09:17:21 -0700 (Fri, 21 Sep 2007)

Log Message:
-----------
use as few bytes as possible to store -ve ints

Modified Paths:
--------------
    redbutton-author/trunk/der_encode.c

Modified: redbutton-author/trunk/der_encode.c
===================================================================
--- redbutton-author/trunk/der_encode.c	2007-09-21 15:52:33 UTC (rev 407)
+++ redbutton-author/trunk/der_encode.c	2007-09-21 16:17:21 UTC (rev 408)
@@ -56,15 +56,21 @@
 	}
 	else
 	{
+		/* work with an unsigned value */
+		uval = (unsigned int) val;
 		/*
-		 * TODO
-		 * should really use as few bytes as possible
+		 * use as few bytes as possible
 		 * ie chop off leading 0xff's while the next byte has its top bit set
 		 */
 		*len = sizeof(unsigned int);
+		while((*len) > 1
+		   && ((uval >> (((*len) - 1) * 8)) & 0xff) == 0xff
+		   && ((uval >> (((*len) - 2) * 8)) & 0x80) == 0x80)
+		{
+			(*len) --;
+		}
 		*out = safe_malloc(*len);
 		/* big endian */
-		uval = (unsigned int) val;
 		for(i=1; i<=(*len); i++)
 			(*out)[i - 1] = (uval >> (((*len) - i) * 8)) & 0xff;
 	}


This was sent by the SourceForge.net collaborative development platform, the world's largest Open Source development site.