Mercurial > sdl-ios-xcode
annotate src/audio/SDL_mixer.c @ 4001:6831b8723a85 SDL-1.2
Don't initialize the audio buffer passed to the application's audio callback,
since they are expected to entirely fill it with data or silence.
For legacy apps that might expect the buffer to already have silence and thus
may not fill the buffer in the callback, there's an environment variable to
expose the old behaviour.
Fixes Bugzilla #416.
| author | Ryan C. Gordon <icculus@icculus.org> |
|---|---|
| date | Thu, 05 Jul 2007 02:24:36 +0000 |
| parents | e3242177fe4a |
| children | 782fd950bd46 c121d94672cb a1b03ba2fcd0 |
| rev | line source |
|---|---|
| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
|
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3 Copyright (C) 1997-2006 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
|
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6 modify it under the terms of the GNU Lesser General Public |
| 0 | 7 License as published by the Free Software Foundation; either |
|
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8 version 2.1 of the License, or (at your option) any later version. |
| 0 | 9 |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
|
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13 Lesser General Public License for more details. |
| 0 | 14 |
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15 You should have received a copy of the GNU Lesser General Public |
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16 License along with this library; if not, write to the Free Software |
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17 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| 0 | 18 |
| 19 Sam Lantinga | |
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20 slouken@libsdl.org |
| 0 | 21 */ |
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22 #include "SDL_config.h" |
| 0 | 23 |
| 24 /* This provides the default mixing callback for the SDL audio routines */ | |
| 25 | |
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26 #include "SDL_cpuinfo.h" |
| 0 | 27 #include "SDL_timer.h" |
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28 #include "SDL_audio.h" |
| 0 | 29 #include "SDL_sysaudio.h" |
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30 #include "SDL_mixer_MMX.h" |
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31 #include "SDL_mixer_MMX_VC.h" |
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32 #include "SDL_mixer_m68k.h" |
| 0 | 33 |
| 34 /* This table is used to add two sound values together and pin | |
| 35 * the value to avoid overflow. (used with permission from ARDI) | |
| 36 * Changed to use 0xFE instead of 0xFF for better sound quality. | |
| 37 */ | |
| 38 static const Uint8 mix8[] = | |
| 39 { | |
| 40 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 41 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 42 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 43 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 44 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 45 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 46 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 47 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 48 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 49 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 50 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, | |
| 51 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, | |
| 52 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, | |
| 53 0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, | |
| 54 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, | |
| 55 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, | |
| 56 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, | |
| 57 0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, | |
| 58 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, | |
| 59 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, | |
| 60 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, | |
| 61 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, | |
| 62 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, | |
| 63 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, | |
| 64 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92, | |
| 65 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, | |
| 66 0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, | |
| 67 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3, | |
| 68 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, | |
| 69 0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, | |
| 70 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4, | |
| 71 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF, | |
| 72 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, | |
| 73 0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, | |
| 74 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE, | |
| 75 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 76 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 77 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 78 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 79 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 80 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 81 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 82 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 83 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 84 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 85 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, | |
| 86 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE | |
| 87 }; | |
| 88 | |
| 89 /* The volume ranges from 0 - 128 */ | |
| 90 #define ADJUST_VOLUME(s, v) (s = (s*v)/SDL_MIX_MAXVOLUME) | |
| 91 #define ADJUST_VOLUME_U8(s, v) (s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128) | |
| 92 | |
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93 void SDL_MixAudio (Uint8 *dst, const Uint8 *src, Uint32 len, int volume) |
| 0 | 94 { |
| 95 Uint16 format; | |
| 96 | |
| 97 if ( volume == 0 ) { | |
| 98 return; | |
| 99 } | |
| 100 /* Mix the user-level audio format */ | |
| 101 if ( current_audio ) { | |
| 102 if ( current_audio->convert.needed ) { | |
| 103 format = current_audio->convert.src_format; | |
| 104 } else { | |
| 105 format = current_audio->spec.format; | |
| 106 } | |
| 107 } else { | |
| 108 /* HACK HACK HACK */ | |
| 109 format = AUDIO_S16; | |
| 110 } | |
| 111 switch (format) { | |
| 112 | |
| 113 case AUDIO_U8: { | |
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114 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES) |
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115 SDL_MixAudio_m68k_U8((char*)dst,(char*)src,(unsigned long)len,(long)volume,(char *)mix8); |
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116 #else |
| 0 | 117 Uint8 src_sample; |
| 118 | |
| 119 while ( len-- ) { | |
| 120 src_sample = *src; | |
| 121 ADJUST_VOLUME_U8(src_sample, volume); | |
| 122 *dst = mix8[*dst+src_sample]; | |
| 123 ++dst; | |
| 124 ++src; | |
| 125 } | |
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126 #endif |
| 0 | 127 } |
| 128 break; | |
| 129 | |
| 130 case AUDIO_S8: { | |
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131 #if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES) |
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132 if (SDL_HasMMX()) |
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133 { |
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134 SDL_MixAudio_MMX_S8((char*)dst,(char*)src,(unsigned int)len,(int)volume); |
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135 } |
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136 else |
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137 #elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES) |
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138 if (SDL_HasMMX()) |
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139 { |
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140 SDL_MixAudio_MMX_S8_VC((char*)dst,(char*)src,(unsigned int)len,(int)volume); |
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141 } |
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142 else |
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143 #endif |
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144 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES) |
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145 SDL_MixAudio_m68k_S8((char*)dst,(char*)src,(unsigned long)len,(long)volume); |
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146 #else |
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147 { |
| 0 | 148 Sint8 *dst8, *src8; |
| 149 Sint8 src_sample; | |
| 150 int dst_sample; | |
| 151 const int max_audioval = ((1<<(8-1))-1); | |
| 152 const int min_audioval = -(1<<(8-1)); | |
| 153 | |
| 154 src8 = (Sint8 *)src; | |
| 155 dst8 = (Sint8 *)dst; | |
| 156 while ( len-- ) { | |
| 157 src_sample = *src8; | |
| 158 ADJUST_VOLUME(src_sample, volume); | |
| 159 dst_sample = *dst8 + src_sample; | |
| 160 if ( dst_sample > max_audioval ) { | |
| 161 *dst8 = max_audioval; | |
| 162 } else | |
| 163 if ( dst_sample < min_audioval ) { | |
| 164 *dst8 = min_audioval; | |
| 165 } else { | |
| 166 *dst8 = dst_sample; | |
| 167 } | |
| 168 ++dst8; | |
| 169 ++src8; | |
| 170 } | |
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171 } |
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172 #endif |
| 0 | 173 } |
| 174 break; | |
| 175 | |
| 176 case AUDIO_S16LSB: { | |
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177 #if defined(__GNUC__) && defined(__i386__) && defined(SDL_ASSEMBLY_ROUTINES) |
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178 if (SDL_HasMMX()) |
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179 { |
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180 SDL_MixAudio_MMX_S16((char*)dst,(char*)src,(unsigned int)len,(int)volume); |
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181 } |
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182 else |
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183 #elif ((defined(_MSC_VER) && defined(_M_IX86)) || defined(__WATCOMC__)) && defined(SDL_ASSEMBLY_ROUTINES) |
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184 if (SDL_HasMMX()) |
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185 { |
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186 SDL_MixAudio_MMX_S16_VC((char*)dst,(char*)src,(unsigned int)len,(int)volume); |
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187 } |
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188 else |
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189 #endif |
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190 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES) |
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191 SDL_MixAudio_m68k_S16LSB((short*)dst,(short*)src,(unsigned long)len,(long)volume); |
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192 #else |
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193 { |
| 0 | 194 Sint16 src1, src2; |
| 195 int dst_sample; | |
| 196 const int max_audioval = ((1<<(16-1))-1); | |
| 197 const int min_audioval = -(1<<(16-1)); | |
| 198 | |
| 199 len /= 2; | |
| 200 while ( len-- ) { | |
| 201 src1 = ((src[1])<<8|src[0]); | |
| 202 ADJUST_VOLUME(src1, volume); | |
| 203 src2 = ((dst[1])<<8|dst[0]); | |
| 204 src += 2; | |
| 205 dst_sample = src1+src2; | |
| 206 if ( dst_sample > max_audioval ) { | |
| 207 dst_sample = max_audioval; | |
| 208 } else | |
| 209 if ( dst_sample < min_audioval ) { | |
| 210 dst_sample = min_audioval; | |
| 211 } | |
| 212 dst[0] = dst_sample&0xFF; | |
| 213 dst_sample >>= 8; | |
| 214 dst[1] = dst_sample&0xFF; | |
| 215 dst += 2; | |
| 216 } | |
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217 } |
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218 #endif |
| 0 | 219 } |
| 220 break; | |
| 221 | |
| 222 case AUDIO_S16MSB: { | |
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223 #if defined(__GNUC__) && defined(__M68000__) && defined(SDL_ASSEMBLY_ROUTINES) |
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224 SDL_MixAudio_m68k_S16MSB((short*)dst,(short*)src,(unsigned long)len,(long)volume); |
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225 #else |
| 0 | 226 Sint16 src1, src2; |
| 227 int dst_sample; | |
| 228 const int max_audioval = ((1<<(16-1))-1); | |
| 229 const int min_audioval = -(1<<(16-1)); | |
| 230 | |
| 231 len /= 2; | |
| 232 while ( len-- ) { | |
| 233 src1 = ((src[0])<<8|src[1]); | |
| 234 ADJUST_VOLUME(src1, volume); | |
| 235 src2 = ((dst[0])<<8|dst[1]); | |
| 236 src += 2; | |
| 237 dst_sample = src1+src2; | |
| 238 if ( dst_sample > max_audioval ) { | |
| 239 dst_sample = max_audioval; | |
| 240 } else | |
| 241 if ( dst_sample < min_audioval ) { | |
| 242 dst_sample = min_audioval; | |
| 243 } | |
| 244 dst[1] = dst_sample&0xFF; | |
| 245 dst_sample >>= 8; | |
| 246 dst[0] = dst_sample&0xFF; | |
| 247 dst += 2; | |
| 248 } | |
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249 #endif |
| 0 | 250 } |
| 251 break; | |
| 252 | |
| 253 default: /* If this happens... FIXME! */ | |
| 254 SDL_SetError("SDL_MixAudio(): unknown audio format"); | |
| 255 return; | |
| 256 } | |
| 257 } | |
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258 |