csu3_am335x/EVSE/GPL/open-plc-utils-0.3/tools/hexdecode.c

/*====================================================================*
 *
 *   size_t hexdecode (void const * memory, size_t extent,  char buffer [], size_t length);
 *
 *   memory.h
 *
 *   decode a memory region as a string of hex octets separated with
 *   character HEX_EXTENDER;
 *
 *   allow three string characters for each memory byte; this means
 *   that the buffer must hold at least three characters or nothing
 *   will be decoded; the maximum number of bytes is the lesser of
 *   chars/3 and bytes;
 *
 *   Motley Tools by Charles Maier;
 *   Copyright (c) 2001-2006 by Charles Maier Associates;
 *   Licensed under the Internet Software Consortium License;
 *
 *--------------------------------------------------------------------*/

#ifndef HEXDECODE_SOURCE
#define HEXDECODE_SOURCE

#include "../tools/memory.h"
#include "../tools/number.h"

size_t hexdecode (void const * memory, register size_t extent, char buffer [], register size_t length)

{
	register char * string = (char *)(buffer);
	register byte * offset = (byte *)(memory);
	if (length)
	{
		length /= HEX_DIGITS + 1;
		while ((length--) && (extent--))
		{
			*string++ = DIGITS_HEX [(*offset >> 4) & 0x0F];
			*string++ = DIGITS_HEX [(*offset >> 0) & 0x0F];
			if ((length) && (extent))
			{
				*string++ = HEX_EXTENDER;
			}
			offset++;
		}
		*string = (char) (0);
	}
	return (string - buffer);
}


#endif