/*

    SDL - Simple DirectMedia Layer

    Copyright (C) 1997-2006 Sam Lantinga

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

    modify it under the terms of the GNU Lesser General Public

    License as published by the Free Software Foundation; either

    version 2.1 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

    Lesser General Public License for more details.

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

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

    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga

    slouken@libsdl.org

*/

#include "SDL_config.h"

/* Functions for audio drivers to perform runtime conversion of audio format */

#include "SDL_audio.h"

/* Effectively mix right and left channels into a single channel */

void SDL_ConvertMono(SDL_AudioCVT *cvt, Uint16 format)

{

	int i;

	Sint32 sample;

#ifdef DEBUG_CONVERT

	fprintf(stderr, "Converting to mono\n");

#endif

	switch (format&0x8018) {

		case AUDIO_U8: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			for ( i=cvt->len_cvt/2; i; --i ) {

				sample = src[0] + src[1];

				if ( sample > 255 ) {

					*dst = 255;

				} else {

					*dst = (Uint8)sample;

				}

				src += 2;

				dst += 1;

			}

		}

		break;

		case AUDIO_S8: {

			Sint8 *src, *dst;

			src = (Sint8 *)cvt->buf;

			dst = (Sint8 *)cvt->buf;

			for ( i=cvt->len_cvt/2; i; --i ) {

				sample = src[0] + src[1];

				if ( sample > 127 ) {

					*dst = 127;

				} else

				if ( sample < -128 ) {

					*dst = -128;

				} else {

					*dst = (Sint8)sample;

				}

				src += 2;

				dst += 1;

			}

		}

		break;

		case AUDIO_U16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/4; i; --i ) {

					sample = (Uint16)((src[0]<<8)|src[1])+

					         (Uint16)((src[2]<<8)|src[3]);

					if ( sample > 65535 ) {

						dst[0] = 0xFF;

						dst[1] = 0xFF;

					} else {

						dst[1] = (sample&0xFF);

						sample >>= 8;

						dst[0] = (sample&0xFF);

					}

					src += 4;

					dst += 2;

				}

			} else {

				for ( i=cvt->len_cvt/4; i; --i ) {

					sample = (Uint16)((src[1]<<8)|src[0])+

					         (Uint16)((src[3]<<8)|src[2]);

					if ( sample > 65535 ) {

						dst[0] = 0xFF;

						dst[1] = 0xFF;

					} else {

						dst[0] = (sample&0xFF);

						sample >>= 8;

						dst[1] = (sample&0xFF);

					}

					src += 4;

					dst += 2;

				}

			}

		}

		break;

		case AUDIO_S16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/4; i; --i ) {

					sample = (Sint16)((src[0]<<8)|src[1])+

					         (Sint16)((src[2]<<8)|src[3]);

					if ( sample > 32767 ) {

						dst[0] = 0x7F;

						dst[1] = 0xFF;

					} else

					if ( sample < -32768 ) {

						dst[0] = 0x80;

						dst[1] = 0x00;

					} else {

						dst[1] = (sample&0xFF);

						sample >>= 8;

						dst[0] = (sample&0xFF);

					}

					src += 4;

					dst += 2;

				}

			} else {

				for ( i=cvt->len_cvt/4; i; --i ) {

					sample = (Sint16)((src[1]<<8)|src[0])+

					         (Sint16)((src[3]<<8)|src[2]);

					if ( sample > 32767 ) {

						dst[1] = 0x7F;

						dst[0] = 0xFF;

					} else

					if ( sample < -32768 ) {

						dst[1] = 0x80;

						dst[0] = 0x00;

					} else {

						dst[0] = (sample&0xFF);

						sample >>= 8;

						dst[1] = (sample&0xFF);

					}

					src += 4;

					dst += 2;

				}

			}

		}

		break;

	}

	cvt->len_cvt /= 2;

	if ( cvt->filters[++cvt->filter_index] ) {

		cvt->filters[cvt->filter_index](cvt, format);

	}

}

/* Discard top 4 channels */

void SDL_ConvertStrip(SDL_AudioCVT *cvt, Uint16 format)

{

	int i;

	Sint32 lsample, rsample;

#ifdef DEBUG_CONVERT

	fprintf(stderr, "Converting down to stereo\n");

#endif

	switch (format&0x8018) {

		case AUDIO_U8: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			for ( i=cvt->len_cvt/6; i; --i ) {

				dst[0] = src[0];

				dst[1] = src[1];

				src += 6;

				dst += 2;

			}

		}

		break;

		case AUDIO_S8: {

			Sint8 *src, *dst;

			src = (Sint8 *)cvt->buf;

			dst = (Sint8 *)cvt->buf;

			for ( i=cvt->len_cvt/6; i; --i ) {

				dst[0] = src[0];

				dst[1] = src[1];

				src += 6;

				dst += 2;

			}

		}

		break;

		case AUDIO_U16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/12; i; --i ) {

					lsample = (Uint16)((src[0]<<8)|src[1]);

					rsample = (Uint16)((src[2]<<8)|src[3]);

						dst[1] = (lsample&0xFF);

						lsample >>= 8;

						dst[0] = (lsample&0xFF);

						dst[3] = (rsample&0xFF);

						rsample >>= 8;

						dst[2] = (rsample&0xFF);

					src += 12;

					dst += 4;

				}

			} else {

				for ( i=cvt->len_cvt/12; i; --i ) {

					lsample = (Uint16)((src[1]<<8)|src[0]);

					rsample = (Uint16)((src[3]<<8)|src[2]);

						dst[0] = (lsample&0xFF);

						lsample >>= 8;

						dst[1] = (lsample&0xFF);

						dst[2] = (rsample&0xFF);

						rsample >>= 8;

						dst[3] = (rsample&0xFF);

					src += 12;

					dst += 4;

				}

			}

		}

		break;

		case AUDIO_S16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/12; i; --i ) {

					lsample = (Sint16)((src[0]<<8)|src[1]);

					rsample = (Sint16)((src[2]<<8)|src[3]);

						dst[1] = (lsample&0xFF);

						lsample >>= 8;

						dst[0] = (lsample&0xFF);

						dst[3] = (rsample&0xFF);

						rsample >>= 8;

						dst[2] = (rsample&0xFF);

					src += 12;

					dst += 4;

				}

			} else {

				for ( i=cvt->len_cvt/12; i; --i ) {

					lsample = (Sint16)((src[1]<<8)|src[0]);

					rsample = (Sint16)((src[3]<<8)|src[2]);

						dst[0] = (lsample&0xFF);

						lsample >>= 8;

						dst[1] = (lsample&0xFF);

						dst[2] = (rsample&0xFF);

						rsample >>= 8;

						dst[3] = (rsample&0xFF);

					src += 12;

					dst += 4;

				}

			}

		}

		break;

	}

	cvt->len_cvt /= 3;

	if ( cvt->filters[++cvt->filter_index] ) {

		cvt->filters[cvt->filter_index](cvt, format);

	}

}

/* Discard top 2 channels of 6 */

void SDL_ConvertStrip_2(SDL_AudioCVT *cvt, Uint16 format)

{

	int i;

	Sint32 lsample, rsample;

#ifdef DEBUG_CONVERT

	fprintf(stderr, "Converting 6 down to quad\n");

#endif

	switch (format&0x8018) {

		case AUDIO_U8: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			for ( i=cvt->len_cvt/4; i; --i ) {

				dst[0] = src[0];

				dst[1] = src[1];

				src += 4;

				dst += 2;

			}

		}

		break;

		case AUDIO_S8: {

			Sint8 *src, *dst;

			src = (Sint8 *)cvt->buf;

			dst = (Sint8 *)cvt->buf;

			for ( i=cvt->len_cvt/4; i; --i ) {

				dst[0] = src[0];

				dst[1] = src[1];

				src += 4;

				dst += 2;

			}

		}

		break;

		case AUDIO_U16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/8; i; --i ) {

					lsample = (Uint16)((src[0]<<8)|src[1]);

					rsample = (Uint16)((src[2]<<8)|src[3]);

						dst[1] = (lsample&0xFF);

						lsample >>= 8;

						dst[0] = (lsample&0xFF);

						dst[3] = (rsample&0xFF);

						rsample >>= 8;

						dst[2] = (rsample&0xFF);

					src += 8;

					dst += 4;

				}

			} else {

				for ( i=cvt->len_cvt/8; i; --i ) {

					lsample = (Uint16)((src[1]<<8)|src[0]);

					rsample = (Uint16)((src[3]<<8)|src[2]);

						dst[0] = (lsample&0xFF);

						lsample >>= 8;

						dst[1] = (lsample&0xFF);

						dst[2] = (rsample&0xFF);

						rsample >>= 8;

						dst[3] = (rsample&0xFF);

					src += 8;

					dst += 4;

				}

			}

		}

		break;

		case AUDIO_S16: {

			Uint8 *src, *dst;

			src = cvt->buf;

			dst = cvt->buf;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/8; i; --i ) {

					lsample = (Sint16)((src[0]<<8)|src[1]);

					rsample = (Sint16)((src[2]<<8)|src[3]);

						dst[1] = (lsample&0xFF);

						lsample >>= 8;

						dst[0] = (lsample&0xFF);

						dst[3] = (rsample&0xFF);

						rsample >>= 8;

						dst[2] = (rsample&0xFF);

					src += 8;

					dst += 4;

				}

			} else {

				for ( i=cvt->len_cvt/8; i; --i ) {

					lsample = (Sint16)((src[1]<<8)|src[0]);

					rsample = (Sint16)((src[3]<<8)|src[2]);

						dst[0] = (lsample&0xFF);

						lsample >>= 8;

						dst[1] = (lsample&0xFF);

						dst[2] = (rsample&0xFF);

						rsample >>= 8;

						dst[3] = (rsample&0xFF);

					src += 8;

					dst += 4;

				}

			}

		}

		break;

	}

	cvt->len_cvt /= 2;

	if ( cvt->filters[++cvt->filter_index] ) {

		cvt->filters[cvt->filter_index](cvt, format);

	}

}

/* Duplicate a mono channel to both stereo channels */

void SDL_ConvertStereo(SDL_AudioCVT *cvt, Uint16 format)

{

	int i;

#ifdef DEBUG_CONVERT

	fprintf(stderr, "Converting to stereo\n");

#endif

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

		Uint16 *src, *dst;

		src = (Uint16 *)(cvt->buf+cvt->len_cvt);

		dst = (Uint16 *)(cvt->buf+cvt->len_cvt*2);

		for ( i=cvt->len_cvt/2; i; --i ) {

			dst -= 2;

			src -= 1;

			dst[0] = src[0];

			dst[1] = src[0];

		}

	} else {

		Uint8 *src, *dst;

		src = cvt->buf+cvt->len_cvt;

		dst = cvt->buf+cvt->len_cvt*2;

		for ( i=cvt->len_cvt; i; --i ) {

			dst -= 2;

			src -= 1;

			dst[0] = src[0];

			dst[1] = src[0];

		}

	}

	cvt->len_cvt *= 2;

	if ( cvt->filters[++cvt->filter_index] ) {

		cvt->filters[cvt->filter_index](cvt, format);

	}

}

/* Duplicate a stereo channel to a pseudo-5.1 stream */

void SDL_ConvertSurround(SDL_AudioCVT *cvt, Uint16 format)

{

	int i;

#ifdef DEBUG_CONVERT

	fprintf(stderr, "Converting stereo to surround\n");

#endif

	switch (format&0x8018) {

		case AUDIO_U8: {

			Uint8 *src, *dst, lf, rf, ce;

			src = (Uint8 *)(cvt->buf+cvt->len_cvt);

			dst = (Uint8 *)(cvt->buf+cvt->len_cvt*3);

			for ( i=cvt->len_cvt; i; --i ) {

				dst -= 6;

				src -= 2;

				lf = src[0];

				rf = src[1];

				ce = (lf/2) + (rf/2);

				dst[0] = lf;

				dst[1] = rf;

				dst[2] = lf - ce;

				dst[3] = rf - ce;

				dst[4] = ce;

				dst[5] = ce;

			}

		}

		break;

		case AUDIO_S8: {

			Sint8 *src, *dst, lf, rf, ce;

			src = (Sint8 *)cvt->buf+cvt->len_cvt;

			dst = (Sint8 *)cvt->buf+cvt->len_cvt*3;

			for ( i=cvt->len_cvt; i; --i ) {

				dst -= 6;

				src -= 2;

				lf = src[0];

				rf = src[1];

				ce = (lf/2) + (rf/2);

				dst[0] = lf;

				dst[1] = rf;

				dst[2] = lf - ce;

				dst[3] = rf - ce;

				dst[4] = ce;

				dst[5] = ce;

			}

		}

		break;

		case AUDIO_U16: {

			Uint8 *src, *dst;

			Uint16 lf, rf, ce, lr, rr;

			src = cvt->buf+cvt->len_cvt;

			dst = cvt->buf+cvt->len_cvt*3;

			if ( (format & 0x1000) == 0x1000 ) {

				for ( i=cvt->len_cvt/4; i; --i ) {

					dst -= 12;

					src -= 4;

					lf = (Uint16)((src[0]<<8)|src[1]);

					rf = (Uint16)((src[2]<<8)|src[3]);

					ce = (lf/2) + (rf/2);

					rr = lf - ce;