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| Rev | Author | Line No. | Line |
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| 9169 | turbocat | 1 | /* |
| 2 | SDL - Simple DirectMedia Layer |
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| 3 | Copyright (C) 1997, 1998, 1999, 2000, 2001 Sam Lantinga |
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| 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 Library General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2 of the License, or (at your option) any later version. |
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| 9 | |||
| 10 | This library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Library General Public License for more details. |
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| 14 | |||
| 15 | You should have received a copy of the GNU Library General Public |
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| 16 | License along with this library; if not, write to the Free |
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| 17 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 18 | |||
| 19 | Sam Lantinga |
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| 20 | slouken@devolution.com |
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| 21 | */ |
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| 22 | |||
| 23 | #ifdef SAVE_RCSID |
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| 24 | static char rcsid = |
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| 25 | "@(#) $Id: SDL_mixer.c,v 1.2 2001/04/26 16:50:17 hercules Exp $"; |
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| 26 | #endif |
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| 27 | |||
| 28 | /* This provides the default mixing callback for the SDL audio routines */ |
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| 29 | |||
| 30 | #include |
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| 31 | #include |
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| 32 | #include |
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| 33 | |||
| 34 | #include "SDL_audio.h" |
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| 35 | #include "SDL_mutex.h" |
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| 36 | #include "SDL_timer.h" |
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| 37 | #include "SDL_sysaudio.h" |
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| 38 | |||
| 39 | SDL_AudioDevice *current_audio = NULL; |
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| 40 | |||
| 41 | /* This table is used to add two sound values together and pin |
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| 42 | * the value to avoid overflow. (used with permission from ARDI) |
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| 43 | * Changed to use 0xFE instead of 0xFF for better sound quality. |
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| 44 | */ |
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| 45 | static const Uint8 mix8[] = |
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| 46 | { |
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| 47 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 48 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 49 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 50 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 51 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 52 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 53 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 54 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 55 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 56 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 57 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, |
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| 58 | 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02, 0x03, |
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| 59 | 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, |
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| 60 | 0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, |
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| 61 | 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, |
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| 62 | 0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, |
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| 63 | 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, |
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| 64 | 0x3B, 0x3C, 0x3D, 0x3E, 0x3F, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, |
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| 65 | 0x46, 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, |
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| 66 | 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, |
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| 67 | 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, |
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| 68 | 0x67, 0x68, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6E, 0x6F, 0x70, 0x71, |
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| 69 | 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7A, 0x7B, 0x7C, |
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| 70 | 0x7D, 0x7E, 0x7F, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, |
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| 71 | 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F, 0x90, 0x91, 0x92, |
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| 72 | 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, |
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| 73 | 0x9E, 0x9F, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8, |
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| 74 | 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF, 0xB0, 0xB1, 0xB2, 0xB3, |
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| 75 | 0xB4, 0xB5, 0xB6, 0xB7, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, |
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| 76 | 0xBF, 0xC0, 0xC1, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8, 0xC9, |
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| 77 | 0xCA, 0xCB, 0xCC, 0xCD, 0xCE, 0xCF, 0xD0, 0xD1, 0xD2, 0xD3, 0xD4, |
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| 78 | 0xD5, 0xD6, 0xD7, 0xD8, 0xD9, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE, 0xDF, |
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| 79 | 0xE0, 0xE1, 0xE2, 0xE3, 0xE4, 0xE5, 0xE6, 0xE7, 0xE8, 0xE9, 0xEA, |
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| 80 | 0xEB, 0xEC, 0xED, 0xEE, 0xEF, 0xF0, 0xF1, 0xF2, 0xF3, 0xF4, 0xF5, |
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| 81 | 0xF6, 0xF7, 0xF8, 0xF9, 0xFA, 0xFB, 0xFC, 0xFD, 0xFE, 0xFE, 0xFE, |
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| 82 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 83 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 84 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 85 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 86 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 87 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 88 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 89 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 90 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 91 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 92 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, |
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| 93 | 0xFE, 0xFE, 0xFE, 0xFE, 0xFE, 0xFE |
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| 94 | }; |
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| 95 | |||
| 96 | /* The volume ranges from 0 - 128 */ |
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| 97 | #define ADJUST_VOLUME(s, v) (s = (s*v)/SDL_MIX_MAXVOLUME) |
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| 98 | #define ADJUST_VOLUME_U8(s, v) (s = (((s-128)*v)/SDL_MIX_MAXVOLUME)+128) |
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| 99 | |||
| 100 | void SDL_MixAudio (Uint8 *dst, const Uint8 *src, Uint32 len, int volume) |
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| 101 | { |
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| 102 | Uint16 format; |
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| 103 | |||
| 104 | if ( volume == 0 ) { |
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| 105 | return; |
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| 106 | } |
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| 107 | /* Mix the user-level audio format */ |
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| 108 | if ( current_audio ) { |
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| 109 | if ( current_audio->convert.needed ) { |
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| 110 | format = current_audio->convert.src_format; |
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| 111 | } else { |
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| 112 | format = current_audio->spec.format; |
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| 113 | } |
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| 114 | } else { |
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| 115 | format = AUDIO_S16; |
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| 116 | } |
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| 117 | format = AUDIO_S16; |
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| 118 | switch (format) { |
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| 119 | |||
| 120 | case AUDIO_U8: { |
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| 121 | Uint8 src_sample; |
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| 122 | |||
| 123 | while ( len-- ) { |
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| 124 | src_sample = *src; |
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| 125 | ADJUST_VOLUME_U8(src_sample, volume); |
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| 126 | *dst = mix8[*dst+src_sample]; |
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| 127 | ++dst; |
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| 128 | ++src; |
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| 129 | } |
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| 130 | } |
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| 131 | break; |
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| 132 | |||
| 133 | case AUDIO_S8: { |
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| 134 | Sint8 *dst8, *src8; |
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| 135 | Sint8 src_sample; |
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| 136 | int dst_sample; |
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| 137 | const int max_audioval = ((1<<(8-1))-1); |
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| 138 | const int min_audioval = -(1<<(8-1)); |
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| 139 | |||
| 140 | src8 = (Sint8 *)src; |
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| 141 | dst8 = (Sint8 *)dst; |
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| 142 | while ( len-- ) { |
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| 143 | src_sample = *src8; |
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| 144 | ADJUST_VOLUME(src_sample, volume); |
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| 145 | dst_sample = *dst8 + src_sample; |
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| 146 | if ( dst_sample > max_audioval ) { |
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| 147 | *dst8 = max_audioval; |
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| 148 | } else |
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| 149 | if ( dst_sample < min_audioval ) { |
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| 150 | *dst8 = min_audioval; |
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| 151 | } else { |
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| 152 | *dst8 = dst_sample; |
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| 153 | } |
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| 154 | ++dst8; |
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| 155 | ++src8; |
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| 156 | } |
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| 157 | } |
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| 158 | break; |
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| 159 | |||
| 160 | case AUDIO_S16LSB: { |
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| 161 | Sint16 src1, src2; |
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| 162 | int dst_sample; |
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| 163 | const int max_audioval = ((1<<(16-1))-1); |
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| 164 | const int min_audioval = -(1<<(16-1)); |
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| 165 | |||
| 166 | len /= 2; |
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| 167 | while ( len-- ) { |
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| 168 | src1 = ((src[1])<<8|src[0]); |
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| 169 | ADJUST_VOLUME(src1, volume); |
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| 170 | src2 = ((dst[1])<<8|dst[0]); |
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| 171 | src += 2; |
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| 172 | dst_sample = src1+src2; |
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| 173 | if ( dst_sample > max_audioval ) { |
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| 174 | dst_sample = max_audioval; |
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| 175 | } else |
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| 176 | if ( dst_sample < min_audioval ) { |
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| 177 | dst_sample = min_audioval; |
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| 178 | } |
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| 179 | dst[0] = dst_sample&0xFF; |
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| 180 | dst_sample >>= 8; |
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| 181 | dst[1] = dst_sample&0xFF; |
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| 182 | dst += 2; |
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| 183 | } |
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| 184 | } |
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| 185 | break; |
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| 186 | |||
| 187 | case AUDIO_S16MSB: { |
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| 188 | Sint16 src1, src2; |
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| 189 | int dst_sample; |
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| 190 | const int max_audioval = ((1<<(16-1))-1); |
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| 191 | const int min_audioval = -(1<<(16-1)); |
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| 192 | |||
| 193 | len /= 2; |
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| 194 | while ( len-- ) { |
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| 195 | src1 = ((src[0])<<8|src[1]); |
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| 196 | ADJUST_VOLUME(src1, volume); |
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| 197 | src2 = ((dst[0])<<8|dst[1]); |
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| 198 | src += 2; |
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| 199 | dst_sample = src1+src2; |
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| 200 | if ( dst_sample > max_audioval ) { |
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| 201 | dst_sample = max_audioval; |
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| 202 | } else |
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| 203 | if ( dst_sample < min_audioval ) { |
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| 204 | dst_sample = min_audioval; |
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| 205 | } |
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| 206 | dst[1] = dst_sample&0xFF; |
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| 207 | dst_sample >>= 8; |
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| 208 | dst[0] = dst_sample&0xFF; |
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| 209 | dst += 2; |
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| 210 | } |
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| 211 | } |
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| 212 | break; |
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| 213 | |||
| 214 | default: /* If this happens... FIXME! */ |
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| 215 | SDL_SetError("SDL_MixAudio(): unknown audio format"); |
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| 216 | return; |
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| 217 | } |
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| 218 | } |