/*
    This file is part of "psdparse"
    Copyright (C) 2004-9 Toby Thain, toby@telegraphics.com.au

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by  
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License  
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <stdio.h>
#include <string.h>

#include "psdparse.h"

int unpackbits(unsigned char *outp, unsigned char *inp,
			   psd_pixels_t outlen, psd_pixels_t inlen)
{
	psd_pixels_t i, len;
	int val;

	/* i counts output bytes; outlen = expected output size */
	for(i = 0; inlen > 1 && i < outlen;){
		/* get flag byte */
		len = *inp++;
		--inlen;

		if(len == 128) /* ignore this flag value */
			; // warn_msg("RLE flag byte=128 ignored");
		else{
			if(len > 128){
				len = 1+256-len;

				/* get value to repeat */
				val = *inp++;
				--inlen;

				if((i+len) <= outlen)
					memset(outp, val, len);
				else{
					memset(outp, val, outlen-i); // fill enough to complete row
					warn_msg("unpacked RLE data would overflow row (run)");
					len = 0; // effectively ignore this run, probably corrupt flag byte
				}
			}else{
				++len;
				if((i+len) <= outlen){
					if(len > inlen)
						break; // abort - ran out of input data
					/* copy verbatim run */
					memcpy(outp, inp, len);
					inp += len;
					inlen -= len;
				}else{
					memcpy(outp, inp, outlen-i); // copy enough to complete row
					warn_msg("unpacked RLE data would overflow row (copy)");
					len = 0; // effectively ignore
				}
			}
			outp += len;
			i += len;
		}
	}
	if(i < outlen)
		warn_msg("not enough RLE data for row");
	return i;
}