src/audio/SDL_mixer.c
changeset 0 74212992fb08
child 1 cf2af46e9e2a
     1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/audio/SDL_mixer.c	Thu Apr 26 16:45:43 2001 +0000
     1.3 @@ -0,0 +1,217 @@
     1.4 +/*
     1.5 +    SDL - Simple DirectMedia Layer
     1.6 +    Copyright (C) 1997, 1998, 1999, 2000, 2001  Sam Lantinga
     1.7 +
     1.8 +    This library is free software; you can redistribute it and/or
     1.9 +    modify it under the terms of the GNU Library General Public
    1.10 +    License as published by the Free Software Foundation; either
    1.11 +    version 2 of the License, or (at your option) any later version.
    1.12 +
    1.13 +    This library is distributed in the hope that it will be useful,
    1.14 +    but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    1.16 +    Library General Public License for more details.
    1.17 +
    1.18 +    You should have received a copy of the GNU Library General Public
    1.19 +    License along with this library; if not, write to the Free
    1.20 +    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    1.21 +
    1.22 +    Sam Lantinga
    1.23 +    slouken@devolution.com
    1.24 +*/
    1.25 +
    1.26 +#ifdef SAVE_RCSID
    1.27 +static char rcsid =
    1.28 + "@(#) $Id$";
    1.29 +#endif
    1.30 +
    1.31 +/* This provides the default mixing callback for the SDL audio routines */
    1.32 +
    1.33 +#include <stdio.h>
    1.34 +#include <stdlib.h>
    1.35 +#include <string.h>
    1.36 +
    1.37 +#include "SDL_audio.h"
    1.38 +#include "SDL_mutex.h"
    1.39 +#include "SDL_timer.h"
    1.40 +#include "SDL_sysaudio.h"
    1.41 +
    1.42 +
    1.43 +/* This table is used to add two sound values together and pin
    1.44 + * the value to avoid overflow.  (used with permission from ARDI)
    1.45 + * Changed to use 0xFE instead of 0xFF for better sound quality.
    1.46 + */
    1.47 +static const Uint8 mix8[] =
    1.48 +{
    1.49 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.50 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.51 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.52 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.53 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.54 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.55 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.56 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.57 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.58 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.59 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    1.60 +  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03,
    1.61 +  0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
    1.62 +  0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
    1.63 +  0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24,
    1.64 +  0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
    1.65 +  0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A,
    1.66 +  0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45,
    1.67 +  0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50,
    1.68 +  0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B,
    1.69 +  0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66,
    1.70 +  0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71,
    1.71 +  0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C,
    1.72 +  0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    1.73 +  0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92,
    1.74 +  0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D,
    1.75 +  0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
    1.76 +  0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3,
    1.77 +  0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE,
    1.78 +  0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9,
    1.79 +  0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4,
    1.80 +  0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF,
    1.81 +  0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA,
    1.82 +  0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5,
    1.83 +  0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE,
    1.84 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.85 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.86 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.87 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.88 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.89 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.90 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.91 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.92 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.93 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.94 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE,
    1.95 +  0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE
    1.96 +};
    1.97 +
    1.98 +/* The volume ranges from 0 - 128 */
    1.99 +#define ADJUST_VOLUME(s, v)	(s = (s*v)/SDL_MIX_MAXVOLUME)
   1.100 +#define ADJUST_VOLUME_U8(s, v)	(s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128)
   1.101 +
   1.102 +void SDL_MixAudio (Uint8 *dst, Uint8 *src, Uint32 len, int volume)
   1.103 +{
   1.104 +	Uint16 format;
   1.105 +
   1.106 +	if ( volume == 0 ) {
   1.107 +		return;
   1.108 +	}
   1.109 +	/* Mix the user-level audio format */
   1.110 +	if ( current_audio ) {
   1.111 +		if ( current_audio->convert.needed ) {
   1.112 +			format = current_audio->convert.src_format;
   1.113 +		} else {
   1.114 +			format = current_audio->spec.format;
   1.115 +		}
   1.116 +	} else {
   1.117 +  		/* HACK HACK HACK */
   1.118 +		format = AUDIO_S16;
   1.119 +	}
   1.120 +	switch (format) {
   1.121 +
   1.122 +		case AUDIO_U8: {
   1.123 +			Uint8 src_sample;
   1.124 +
   1.125 +			while ( len-- ) {
   1.126 +				src_sample = *src;
   1.127 +				ADJUST_VOLUME_U8(src_sample, volume);
   1.128 +				*dst = mix8[*dst+src_sample];
   1.129 +				++dst;
   1.130 +				++src;
   1.131 +			}
   1.132 +		}
   1.133 +		break;
   1.134 +
   1.135 +		case AUDIO_S8: {
   1.136 +			Sint8 *dst8, *src8;
   1.137 +			Sint8 src_sample;
   1.138 +			int dst_sample;
   1.139 +			const int max_audioval = ((1<<(8-1))-1);
   1.140 +			const int min_audioval = -(1<<(8-1));
   1.141 +
   1.142 +			src8 = (Sint8 *)src;
   1.143 +			dst8 = (Sint8 *)dst;
   1.144 +			while ( len-- ) {
   1.145 +				src_sample = *src8;
   1.146 +				ADJUST_VOLUME(src_sample, volume);
   1.147 +				dst_sample = *dst8 + src_sample;
   1.148 +				if ( dst_sample > max_audioval ) {
   1.149 +					*dst8 = max_audioval;
   1.150 +				} else
   1.151 +				if ( dst_sample < min_audioval ) {
   1.152 +					*dst8 = min_audioval;
   1.153 +				} else {
   1.154 +					*dst8 = dst_sample;
   1.155 +				}
   1.156 +				++dst8;
   1.157 +				++src8;
   1.158 +			}
   1.159 +		}
   1.160 +		break;
   1.161 +
   1.162 +		case AUDIO_S16LSB: {
   1.163 +			Sint16 src1, src2;
   1.164 +			int dst_sample;
   1.165 +			const int max_audioval = ((1<<(16-1))-1);
   1.166 +			const int min_audioval = -(1<<(16-1));
   1.167 +
   1.168 +			len /= 2;
   1.169 +			while ( len-- ) {
   1.170 +				src1 = ((src[1])<<8|src[0]);
   1.171 +				ADJUST_VOLUME(src1, volume);
   1.172 +				src2 = ((dst[1])<<8|dst[0]);
   1.173 +				src += 2;
   1.174 +				dst_sample = src1+src2;
   1.175 +				if ( dst_sample > max_audioval ) {
   1.176 +					dst_sample = max_audioval;
   1.177 +				} else
   1.178 +				if ( dst_sample < min_audioval ) {
   1.179 +					dst_sample = min_audioval;
   1.180 +				}
   1.181 +				dst[0] = dst_sample&0xFF;
   1.182 +				dst_sample >>= 8;
   1.183 +				dst[1] = dst_sample&0xFF;
   1.184 +				dst += 2;
   1.185 +			}
   1.186 +		}
   1.187 +		break;
   1.188 +
   1.189 +		case AUDIO_S16MSB: {
   1.190 +			Sint16 src1, src2;
   1.191 +			int dst_sample;
   1.192 +			const int max_audioval = ((1<<(16-1))-1);
   1.193 +			const int min_audioval = -(1<<(16-1));
   1.194 +
   1.195 +			len /= 2;
   1.196 +			while ( len-- ) {
   1.197 +				src1 = ((src[0])<<8|src[1]);
   1.198 +				ADJUST_VOLUME(src1, volume);
   1.199 +				src2 = ((dst[0])<<8|dst[1]);
   1.200 +				src += 2;
   1.201 +				dst_sample = src1+src2;
   1.202 +				if ( dst_sample > max_audioval ) {
   1.203 +					dst_sample = max_audioval;
   1.204 +				} else
   1.205 +				if ( dst_sample < min_audioval ) {
   1.206 +					dst_sample = min_audioval;
   1.207 +				}
   1.208 +				dst[1] = dst_sample&0xFF;
   1.209 +				dst_sample >>= 8;
   1.210 +				dst[0] = dst_sample&0xFF;
   1.211 +				dst += 2;
   1.212 +			}
   1.213 +		}
   1.214 +		break;
   1.215 +
   1.216 +		default: /* If this happens... FIXME! */
   1.217 +			SDL_SetError("SDL_MixAudio(): unknown audio format");
   1.218 +			return;
   1.219 +	}
   1.220 +}