/* Copyright (c) 1993 Association of Universities for Research
 * in Astronomy. All rights reserved. Produced under National
 * Aeronautics and Space Administration Contract No. NAS5-26555.
 */
/* dodecode.c   Decode stream of characters on infile and return array
 *
 * This version encodes the different quadrants separately
 *
 * Programmer: R. White     Date: 9 May 1991
 *
 * Modified to read VMS fixed-length files, R. White, 16 June 1992
 */

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

#define input_nybble(infile)    input_nbits(infile,4)

extern void qtree_decode();
extern void start_inputing_bits();
extern int input_bit();
extern int input_nbits();

extern void
dodecode(infile,a,nx,ny,nbitplanes)
QFILE *infile;
int a[];                            /* Array of values to decode            */
int nx,ny;                          /* Array dimensions are [nx][ny]        */
unsigned char nbitplanes[3];        /* Number of bit planes in quadrants    */
{
int i, nel, nx2, ny2;

    nel = nx*ny;
    nx2 = (nx+1)/2;
    ny2 = (ny+1)/2;
    /*
     * initialize a to zero
     */
    for (i=0; i<nel; i++) a[i] = 0;
    /*
     * Initialize bit input
     */
    start_inputing_bits();
    /*
     * read bit planes for each quadrant
     */
    qtree_decode(infile, &a[0],          ny, nx2,  ny2,  nbitplanes[0]);
    qtree_decode(infile, &a[ny2],        ny, nx2,  ny/2, nbitplanes[1]);
    qtree_decode(infile, &a[ny*nx2],     ny, nx/2, ny2,  nbitplanes[1]);
    qtree_decode(infile, &a[ny*nx2+ny2], ny, nx/2, ny/2, nbitplanes[2]);
    /*
     * make sure there is an EOF symbol (nybble=0) at end
     */
    if (input_nybble(infile) != 0) {
        fprintf(stderr, "dodecode: bad bit plane values\n");
        exit(-1);
    }
    /*
     * now get the sign bits
     * Re-initialize bit input
     */
    start_inputing_bits();
    for (i=0; i<nel; i++) {
        if (a[i] != 0) {
            if (input_bit(infile) != 0) a[i] = -a[i];
        }
    }
}