/*
	File       : PACK.C
	Description:
	Author     : Peter H. Michalicka
	Environment: HP-UX 8.05
*/

#include <stdio.h>
#include "tiff.h"

#ifdef ANSI
void getbuf(int count, BYTE *ptr);
#endif

/* Unpack a line of data compressed with the PackBits scheme.  */

void unpackbits(des_byts, des)
int des_byts;
BYTE *des;
{
	int i, count, ch;
	BYTE src[128];

	while(des_byts > 0) {
		getbuf(1, src);
		ch = *src;
		if(ch & 0x80) { /* ch = 128 -> 255: write the following byte 257-ch times */
			count = 257 - ch;
			getbuf(1, src);
			ch = *src;
			for (i = 0; i < count; i++)
				*des++ = (BYTE)ch;
		} else { /* ch = 0 -> 127: copy the following ch+1 bytes literally */
			count = ch + 1;
			getbuf(count, des);
			des += count;			/* and where to write them */
		}
		des_byts -= count;	/* Update bytes left to write */
	}
}