---

ccvt_c.c

/*
   Colour conversion routines (RGB <-> YUV) in plain C
   (C) 2000 Nemosoft Unv.    nemosoft@smcc.demon.nl
   
   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 "ccvt.h"

#define PUSH_RGB24      1
#define PUSH_BGR24      2
#define PUSH_RGB32      3
#define PUSH_BGR32      4

/* This is a really simplistic approach. Speedups are welcomed. */
static void ccvt_420i(int width, int height, unsigned char *src, unsigned char *dst, int push)
{
        int line, col, linewidth;
        int y, u, v, yy, vr, ug, vg, ub;
        int r, g, b;
        unsigned char *py, *pu, *pv;

        linewidth = width + (width >> 1);
        py = src;
        pu = py + 4;
        pv = pu + linewidth;

        y = *py++;
        yy = y << 8;
        u = *pu - 128;
        ug =   88 * u;
        ub =  454 * u;
        v = *pv - 128;
        vg =  183 * v;
        vr =  359 * v;

        /* The biggest problem is the interlaced data, and the fact that odd
           add even lines have V and U data, resp. 
         */
        for (line = 0; line < height; line++) {
                for (col = 0; col < width; col++) {
                        r = (yy +      vr) >> 8;
                        g = (yy - ug - vg) >> 8;
                        b = (yy + ub     ) >> 8;
                        
                        switch(push) {
                        case PUSH_RGB24:
                                *dst++ = r;
                                *dst++ = g;
                                *dst++ = b;
                                break;

                        case PUSH_BGR24:
                                *dst++ = b;
                                *dst++ = g;
                                *dst++ = r;
                                break;
                        
                        case PUSH_RGB32:
                                *dst++ = r;
                                *dst++ = g;
                                *dst++ = b;
                                *dst++ = 0;
                                break;

                        case PUSH_BGR32:
                                *dst++ = b;
                                *dst++ = g;
                                *dst++ = r;
                                *dst++ = 0;
                                break;
                        }
                        
                        y = *py++;
                        yy = y << 8;
                        if ((col & 3) == 3)
                                py += 2; // skip u/v
                        if (col & 1) {
                                if ((col & 3) == 3) {
                                        pu += 4; // skip y
                                        pv += 4;
                                }
                                else {
                                        pu++;
                                        pv++;
                                }
                                u = *pu - 128;
                                ug =   88 * u;
                                ub =  454 * u;
                                v = *pv - 128;
                                vg =  183 * v;
                                vr =  359 * v;
                        }
                } /* ..for col */
                if (line & 1) { // odd line: go to next band
                        pu += linewidth;
                        pv += linewidth;
                }
                else { // rewind u/v pointers
                        pu -= linewidth;
                        pv -= linewidth;
                }
        } /* ..for line */
}

void ccvt_420i_rgb24(int width, int height, void *src, void *dst)
{
        ccvt_420i(width, height, (unsigned char *)src, (unsigned char *)dst, PUSH_RGB24);
}

void ccvt_420i_bgr24(int width, int height, void *src, void *dst)
{
        ccvt_420i(width, height, (unsigned char *)src, (unsigned char *)dst, PUSH_BGR24);
}

void ccvt_420i_rgb32(int width, int height, void *src, void *dst)
{
        ccvt_420i(width, height, (unsigned char *)src, (unsigned char *)dst, PUSH_RGB32);
}

void ccvt_420i_bgr32(int width, int height, void *src, void *dst)
{
        ccvt_420i(width, height, (unsigned char *)src, (unsigned char *)dst, PUSH_BGR32);
}


void ccvt_420i_420p(int width, int height, void *src, void *dsty, void *dstu, void *dstv)
{
        short *s, *dy, *du, *dv;
        int line, col;

        s = (short *)src;
        dy = (short *)dsty;
        du = (short *)dstu;
        dv = (short *)dstv;
        for (line = 0; line < height; line++) {
                for (col = 0; col < width; col += 4) {
                        *dy++ = *s++;
                        *dy++ = *s++;
                        if (line & 1)
                                *dv++ = *s++;
                        else
                                *du++ = *s++;
                } /* ..for col */
        } /* ..for line */
}

void ccvt_420i_yuyv(int width, int height, void *src, void *dst)
{
        int line, col, linewidth;
        unsigned char *py, *pu, *pv, *d;

        linewidth = width + (width >> 1);
        py = (unsigned char *)src;
        pu = src + 4;
        pv = pu + linewidth;
        d = (unsigned char *)dst;

        for (line = 0; line < height; line++) {
                for (col = 0; col < width; col += 4) {
                        /* four pixels in one go */
                        *d++ = *py++;
                        *d++ = *pu++;
                        *d++ = *py++;
                        *d++ = *pv++;
                        
                        *d++ = *py++;
                        *d++ = *pu++;
                        *d++ = *py++;
                        *d++ = *pv++;

                        py += 2;
                        pu += 4;
                        pv += 4;
                } /* ..for col */
                if (line & 1) { // odd line: go to next band
                        pu += linewidth;
                        pv += linewidth;
                }
                else { // rewind u/v pointers
                        pu -= linewidth;
                        pv -= linewidth;
                }
        } /* ..for line */
}

---