/*

     MIXERLIB:  An audio mixer library based on the SDL library

     Copyright (C) 1997-1999  Sam Lantinga

     This library is free software; you can redistribute it and/or

     modify it under the terms of the GNU Library General Public

     License as published by the Free Software Foundation; either

     version 2 of the License, or (at your option) any later version.

     This library 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

     Library General Public License for more details.

     You should have received a copy of the GNU Library General Public

     License along with this library; if not, write to the Free

     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

     This file by Ryan C. Gordon (icculus@linuxgames.com)

     These are some internally supported special effects that use SDL_mixer's

     effect callback API. They are meant for speed over quality.  :)

 */

 /* $Id$ */

 #include <stdio.h>

 #include <stdlib.h>

 #include <sys/time.h>

 #include <unistd.h>

 #include "SDL.h"

 #include "SDL_mixer.h"

 #define __MIX_INTERNAL_EFFECT__

 #include "effects_internal.h"

 /* profile code:

     #include <sys/time.h>

     #include <unistd.h>

     struct timeval tv1;

     struct timeval tv2;

     gettimeofday(&tv1, NULL);

         ... do your thing here ...

     gettimeofday(&tv2, NULL);

     printf("%ld\n", tv2.tv_usec - tv1.tv_usec);

 */

 /*

  * Stereo reversal effect...this one's pretty straightforward...

  */

 static void _Eff_reversestereo16(int chan, void *stream, int len, void *udata)

 {

     /* 16 bits * 2 channels. */

     Uint32 *ptr = (Uint32 *) stream;

     int i;

     for (i = 0; i < len; i += sizeof (Uint32), ptr++) {

         *ptr = (((*ptr) & 0xFFFF0000) >> 16) | (((*ptr) & 0x0000FFFF) << 16);

     }

 }

 static void _Eff_reversestereo8(int chan, void *stream, int len, void *udata)

 {

     /* 8 bits * 2 channels. */

     Uint32 *ptr = (Uint32 *) stream;

     int i;

     /* get the last two bytes if len is not divisible by four... */

     if (len % sizeof (Uint32) != 0) {

         Uint16 *p = (Uint16 *) (((Uint8 *) stream) + (len - 2));

         *p = (((*p) & 0xFF00) >> 8) | (((*ptr) & 0x00FF) << 8);

         len -= 2;

     }

     for (i = 0; i < len; i += sizeof (Uint32), ptr++) {

         *ptr = (((*ptr) & 0x0000FF00) >> 8) | (((*ptr) & 0x000000FF) << 8) |

                (((*ptr) & 0xFF000000) >> 8) | (((*ptr) & 0x00FF0000) << 8);

     }

 }

 int Mix_SetReverseStereo(int channel, int flip)

 {

     Mix_EffectFunc_t f = NULL;

     int channels;

     Uint16 format;

     Mix_QuerySpec(NULL, &format, &channels);

     if (channels == 2) {

         if ((format & 0xFF) == 16)

             f = _Eff_reversestereo16;

         else if ((format & 0xFF) == 8)

             f = _Eff_reversestereo8;

         else {

             Mix_SetError("Unsupported audio format");

             return(0);

         }

         if (!flip) {

             return(Mix_UnregisterEffect(channel, f));

         } else {

             return(Mix_RegisterEffect(channel, f, NULL, NULL));

         }

     }

     return(1);

 }

 /* end of effect_stereoreverse.c ... */