/* yuvsplittoppm.c - construct a portable pixmap from 3 raw files:
** - basename.Y : The Luminance chunk at the size of the Image
** - basename.U : The Chrominance chunk U at 1/4
** - basename.V : The Chrominance chunk V at 1/4
** The subsampled U and V values are made by arithmetic mean.
**
** If ccir601 is defined, the produced YUV triples have been scaled again
** to fit into the smaller range of values for this standard.
**
** by Marcel Wijkstra <wijkstra@fwi.uva.nl>
**
** Based on ppmtoyuvsplit.c
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
*/

#include <string.h>
#include "ppm.h"

/* x must be signed for the following to work correctly */
#define limit(x) (((x>0xffffff)?0xff0000:((x<=0xffff)?0:x&0xff0000))>>16)

int
main(argc, argv)
    char **argv;
{
    FILE *vf,*uf,*yf;
    pixel          *pixelrow1,*pixelrow2;
    register pixel *pP1,*pP2;
    int             rows, cols, row;
    register int    col;
    const char     * const usage="<basename> <width> <height> [-ccir601]";
    long int  u,v,y0,y1,y2,y3,u0,u1,u2,u3,v0,v1,v2,v3;
    unsigned char  *y1buf,*y2buf,*ubuf,*vbuf;
    char        ufname[256],vfname[256],yfname[256];
    int     ccir601=0; 
        /* Whether to create YUV in JFIF(JPEG) or CCIR.601(MPEG) scale */



    ppm_init(&argc, argv);

    if ((argc>5) || (argc<4)) pm_usage(usage);

    if (argc==5) {
        if (strncmp(argv[4],"-c",2) == 0) ccir601 = 1;
        else pm_usage(usage);
    }

    strcpy(ufname,argv[1]);
    strcpy(vfname,argv[1]);
    strcpy(yfname,argv[1]);
 
    strcat(ufname,".U");
    strcat(vfname,".V");
    strcat(yfname,".Y");

    uf = fopen(ufname,"rb");
    vf = fopen(vfname,"rb");
    yf = fopen(yfname,"rb");

    if(!(uf && vf && yf)) {
     perror("error opening input files");
     exit(0);
    }

        cols = atoi(argv[2]);
        rows = atoi(argv[3]);
        if (cols <= 0 || rows <= 0)
                pm_usage(usage);

        ppm_writeppminit(stdout, cols, rows, (pixval) 255, 0);

        if(cols & 1) fprintf(stderr,
                             "%s: Warning: odd columns count, exceed ignored\n",
                             argv[0]);
        if(rows & 1) fprintf(stderr,
                             "%s: Warning: odd rows count, exceed ignored\n",
                             argv[0]);

    pixelrow1 = ((pixel*) pm_allocrow( cols, sizeof(pixel) ));
    pixelrow2 = ((pixel*) pm_allocrow( cols, sizeof(pixel) ));

    y1buf = (unsigned char *) pm_allocrow( cols, 1 );
    y2buf = (unsigned char *) pm_allocrow( cols, 1 );
    ubuf = (unsigned char *) pm_allocrow( cols, 1 );
        vbuf = (unsigned char *) pm_allocrow( cols, 1 );

        for (row = 0; row < (rows & ~1); row += 2) {
            unsigned char *y1ptr,*y2ptr,*uptr,*vptr;

            fread(y1buf, (cols & ~1), 1, yf);
            fread(y2buf, (cols & ~1), 1, yf);
            fread(ubuf, cols/2, 1, uf);
            fread(vbuf, cols/2, 1, vf);

            y1ptr = y1buf; y2ptr = y2buf; vptr = vbuf; uptr = ubuf;

            pP1 = pixelrow1; pP2 = pixelrow2;

            for (col = 0 ; col < (cols & ~1); col += 2) {
                long int r0,g0,b0,r1,g1,b1,r2,g2,b2,r3,g3,b3;

                y0 = (long int) *y1ptr++;
                y1 = (long int) *y1ptr++;
                y2 = (long int) *y2ptr++;
                y3 = (long int) *y2ptr++;

                u = (long int) ((*uptr++) - 128);
                v = (long int) ((*vptr++) - 128);

                if (ccir601) {
                    y0 = ((y0-16)*255)/219;
                    y1 = ((y1-16)*255)/219;
                    y2 = ((y2-16)*255)/219;
                    y3 = ((y3-16)*255)/219;

                    u  = (u*255)/224 ;
                    v  = (v*255)/224 ;
                }
                /* mean the chroma for subsampling */

                u0=u1=u2=u3=u;
                v0=v1=v2=v3=v;


/* The inverse of the JFIF RGB to YUV Matrix for $00010000 = 1.0

   [Y]   [65496        0   91880][R]
   [U] = [65533   -22580  -46799[G]
   [V]   [65537   116128      -8][B]

*/

                r0 = 65536 * y0               + 91880 * v0;
                g0 = 65536 * y0 -  22580 * u0 - 46799 * v0;
                b0 = 65536 * y0 + 116128 * u0             ;

                r1 = 65536 * y1               + 91880 * v1;
                g1 = 65536 * y1 -  22580 * u1 - 46799 * v1;
                b1 = 65536 * y1 + 116128 * u1             ;

                r2 = 65536 * y2               + 91880 * v2;
                g2 = 65536 * y2 -  22580 * u2 - 46799 * v2;
                b2 = 65536 * y2 + 116128 * u2             ;

                r3 = 65536 * y3               + 91880 * v3;
                g3 = 65536 * y3 -  22580 * u3 - 46799 * v3;
                b3 = 65536 * y3 + 116128 * u3             ;

                r0 = limit(r0);
                r1 = limit(r1);
                r2 = limit(r2);
                r3 = limit(r3);
                g0 = limit(g0);
                g1 = limit(g1);
                g2 = limit(g2);
                g3 = limit(g3);
                b0 = limit(b0);
                b1 = limit(b1);
                b2 = limit(b2);
                b3 = limit(b3);

                /* first pixel */
                PPM_ASSIGN(*pP1, (pixval)r0, (pixval)g0, (pixval)b0);
                pP1++;
                /* 2nd pixval */
                PPM_ASSIGN(*pP1, (pixval)r1, (pixval)g1, (pixval)b1);
                pP1++;
                /* 3rd pixval */
                PPM_ASSIGN(*pP2, (pixval)r2, (pixval)g2, (pixval)b2);
                pP2++;
                /* 4th pixval */
                PPM_ASSIGN(*pP2, (pixval)r3, (pixval)g3, (pixval)b3);
                pP2++;
            }
            ppm_writeppmrow(stdout, pixelrow1, cols, (pixval) 255, 0);
            ppm_writeppmrow(stdout, pixelrow2, cols, (pixval) 255, 0);
        }
    pm_close(stdout);

        fclose(yf);
    fclose(uf);
    fclose(vf);
    exit(0);
}