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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 9565 | turbocat | 1 | /* |
| 2 | SDL_mixer: An audio mixer library based on the SDL library |
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| 3 | Copyright (C) 1997-2012 Sam Lantinga |
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| 4 | |||
| 5 | This software is provided 'as-is', without any express or implied |
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| 6 | warranty. In no event will the authors be held liable for any damages |
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| 7 | arising from the use of this software. |
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| 8 | |||
| 9 | Permission is granted to anyone to use this software for any purpose, |
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| 10 | including commercial applications, and to alter it and redistribute it |
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| 11 | freely, subject to the following restrictions: |
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| 12 | |||
| 13 | 1. The origin of this software must not be misrepresented; you must not |
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| 14 | claim that you wrote the original software. If you use this software |
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| 15 | in a product, an acknowledgment in the product documentation would be |
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| 16 | appreciated but is not required. |
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| 17 | 2. Altered source versions must be plainly marked as such, and must not be |
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| 18 | misrepresented as being the original software. |
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| 19 | 3. This notice may not be removed or altered from any source distribution. |
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| 20 | |||
| 21 | This file by Ryan C. Gordon (icculus@icculus.org) |
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| 22 | |||
| 23 | These are some helper functions for the internal mixer special effects. |
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| 24 | */ |
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| 25 | |||
| 26 | /* $Id$ */ |
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| 27 | |||
| 28 | |||
| 29 | /* ------ These are used internally only. Don't touch. ------ */ |
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| 30 | |||
| 31 | |||
| 32 | |||
| 33 | #include |
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| 34 | #include |
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| 35 | #include "SDL_mixer.h" |
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| 36 | |||
| 37 | #define __MIX_INTERNAL_EFFECT__ |
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| 38 | #include "effects_internal.h" |
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| 39 | |||
| 40 | /* Should we favor speed over memory usage and/or quality of output? */ |
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| 41 | int _Mix_effects_max_speed = 0; |
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| 42 | |||
| 43 | |||
| 44 | void _Mix_InitEffects(void) |
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| 45 | { |
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| 46 | _Mix_effects_max_speed = (SDL_getenv(MIX_EFFECTSMAXSPEED) != NULL); |
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| 47 | } |
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| 48 | |||
| 49 | void _Mix_DeinitEffects(void) |
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| 50 | { |
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| 51 | _Eff_PositionDeinit(); |
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| 52 | } |
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| 53 | |||
| 54 | |||
| 55 | void *_Eff_volume_table = NULL; |
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| 56 | |||
| 57 | |||
| 58 | /* Build the volume table for Uint8-format samples. |
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| 59 | * |
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| 60 | * Each column of the table is a possible sample, while each row of the |
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| 61 | * table is a volume. Volume is a Uint8, where 0 is silence and 255 is full |
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| 62 | * volume. So _Eff_volume_table[128][mysample] would be the value of |
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| 63 | * mysample, at half volume. |
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| 64 | */ |
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| 65 | void *_Eff_build_volume_table_u8(void) |
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| 66 | { |
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| 67 | int volume; |
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| 68 | int sample; |
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| 69 | Uint8 *rc; |
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| 70 | |||
| 71 | if (!_Mix_effects_max_speed) { |
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| 72 | return(NULL); |
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| 73 | } |
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| 74 | |||
| 75 | if (!_Eff_volume_table) { |
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| 76 | rc = SDL_malloc(256 * 256); |
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| 77 | if (rc) { |
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| 78 | _Eff_volume_table = (void *) rc; |
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| 79 | for (volume = 0; volume < 256; volume++) { |
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| 80 | for (sample = -128; sample < 128; sample ++) { |
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| 81 | *rc = (Uint8)(((float) sample) * ((float) volume / 255.0)) |
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| 82 | + 128; |
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| 83 | rc++; |
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| 84 | } |
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| 85 | } |
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| 86 | } |
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| 87 | } |
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| 88 | |||
| 89 | return(_Eff_volume_table); |
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| 90 | } |
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| 91 | |||
| 92 | |||
| 93 | /* Build the volume table for Sint8-format samples. |
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| 94 | * |
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| 95 | * Each column of the table is a possible sample, while each row of the |
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| 96 | * table is a volume. Volume is a Uint8, where 0 is silence and 255 is full |
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| 97 | * volume. So _Eff_volume_table[128][mysample+128] would be the value of |
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| 98 | * mysample, at half volume. |
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| 99 | */ |
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| 100 | void *_Eff_build_volume_table_s8(void) |
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| 101 | { |
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| 102 | int volume; |
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| 103 | int sample; |
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| 104 | Sint8 *rc; |
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| 105 | |||
| 106 | if (!_Eff_volume_table) { |
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| 107 | rc = SDL_malloc(256 * 256); |
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| 108 | if (rc) { |
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| 109 | _Eff_volume_table = (void *) rc; |
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| 110 | for (volume = 0; volume < 256; volume++) { |
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| 111 | for (sample = -128; sample < 128; sample ++) { |
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| 112 | *rc = (Sint8)(((float) sample) * ((float) volume / 255.0)); |
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| 113 | rc++; |
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| 114 | } |
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| 115 | } |
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| 116 | } |
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| 117 | } |
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| 118 | |||
| 119 | return(_Eff_volume_table); |
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| 120 | } |
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| 121 | |||
| 122 | |||
| 123 | /* end of effects.c ... */ |
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| 124 |