| 1 | /* |
| 2 | * (C) notaz, 2013 |
| 3 | * |
| 4 | * This work is licensed under the terms of any of these licenses |
| 5 | * (at your option): |
| 6 | * - GNU GPL, version 2 or later. |
| 7 | * - GNU LGPL, version 2.1 or later. |
| 8 | * - MAME license. |
| 9 | * See the COPYING file in the top-level directory. |
| 10 | */ |
| 11 | |
| 12 | #include <SDL.h> |
| 13 | #include "sndout_sdl.h" |
| 14 | |
| 15 | // ~1/3s at 44kHz |
| 16 | // set this to power of 2 |
| 17 | #define BUF_LEN 32768 |
| 18 | #define BUF_MASK (BUF_LEN - 1) |
| 19 | |
| 20 | static short buf[BUF_LEN]; |
| 21 | static int buf_w, buf_r; |
| 22 | static int started; |
| 23 | |
| 24 | static void callback(void *userdata, Uint8 *stream, int len) |
| 25 | { |
| 26 | int have = (buf_w - buf_r) & BUF_MASK; |
| 27 | int buf_left = BUF_LEN - buf_r; |
| 28 | |
| 29 | len /= 2; |
| 30 | if (have > len) |
| 31 | have = len; |
| 32 | if (have > 0) { |
| 33 | if (have > buf_left) { |
| 34 | memcpy(stream, buf + buf_r, buf_left * 2); |
| 35 | stream += buf_left * 2; |
| 36 | buf_r = 0; |
| 37 | have -= buf_left; |
| 38 | len -= buf_left; |
| 39 | } |
| 40 | memcpy(stream, buf + buf_r, have * 2); |
| 41 | stream += have * 2; |
| 42 | buf_r = (buf_r + have) & BUF_MASK; |
| 43 | len -= have; |
| 44 | } |
| 45 | |
| 46 | if (len > 0) { |
| 47 | // put in some silence.. |
| 48 | memset(stream, 0, len * 2); |
| 49 | } |
| 50 | } |
| 51 | |
| 52 | int sndout_sdl_init(void) |
| 53 | { |
| 54 | int ret; |
| 55 | |
| 56 | ret = SDL_InitSubSystem(SDL_INIT_AUDIO); |
| 57 | if (ret != 0) |
| 58 | return -1; |
| 59 | |
| 60 | return 0; |
| 61 | } |
| 62 | |
| 63 | int sndout_sdl_start(int rate, int stereo) |
| 64 | { |
| 65 | SDL_AudioSpec desired = { 0 }; |
| 66 | int samples, shift; |
| 67 | int ret; |
| 68 | |
| 69 | if (started) |
| 70 | sndout_sdl_stop(); |
| 71 | |
| 72 | desired.freq = rate; |
| 73 | desired.format = AUDIO_S16SYS; |
| 74 | desired.channels = stereo ? 2 : 1; |
| 75 | desired.callback = callback; |
| 76 | desired.userdata = NULL; |
| 77 | |
| 78 | samples = rate >> 6; |
| 79 | for (shift = 8; (1 << shift) < samples; shift++) |
| 80 | ; |
| 81 | desired.samples = 1 << shift; |
| 82 | |
| 83 | ret = SDL_OpenAudio(&desired, NULL); |
| 84 | if (ret != 0) { |
| 85 | fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError()); |
| 86 | return -1; |
| 87 | } |
| 88 | |
| 89 | buf_w = buf_r = 0; |
| 90 | |
| 91 | SDL_PauseAudio(0); |
| 92 | started = 1; |
| 93 | |
| 94 | return 0; |
| 95 | } |
| 96 | |
| 97 | void sndout_sdl_stop(void) |
| 98 | { |
| 99 | SDL_PauseAudio(1); |
| 100 | SDL_CloseAudio(); |
| 101 | started = 0; |
| 102 | } |
| 103 | |
| 104 | void sndout_sdl_wait(void) |
| 105 | { |
| 106 | int left; |
| 107 | |
| 108 | while (1) |
| 109 | { |
| 110 | left = (buf_r - buf_w - 2) & BUF_MASK; |
| 111 | if (left >= BUF_LEN / 2) |
| 112 | break; |
| 113 | |
| 114 | SDL_Delay(4); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | int sndout_sdl_write_nb(const void *samples, int len) |
| 119 | { |
| 120 | int maxlen = (buf_r - buf_w - 2) & BUF_MASK; |
| 121 | int buf_left = BUF_LEN - buf_w; |
| 122 | int retval; |
| 123 | |
| 124 | len /= 2; |
| 125 | if (len > maxlen) |
| 126 | // not enough space |
| 127 | len = maxlen; |
| 128 | if (len == 0) |
| 129 | // totally full |
| 130 | return 0; |
| 131 | |
| 132 | retval = len; |
| 133 | |
| 134 | if (len > buf_left) { |
| 135 | memcpy(buf + buf_w, samples, buf_left * 2); |
| 136 | samples = (const short *)samples + buf_left; |
| 137 | len -= buf_left; |
| 138 | buf_w = 0; |
| 139 | } |
| 140 | memcpy(buf + buf_w, samples, len * 2); |
| 141 | buf_w = (buf_w + len) & BUF_MASK; |
| 142 | |
| 143 | return retval; |
| 144 | } |
| 145 | |
| 146 | void sndout_sdl_exit(void) |
| 147 | { |
| 148 | if (started) |
| 149 | sndout_sdl_stop(); |
| 150 | SDL_QuitSubSystem(SDL_INIT_AUDIO); |
| 151 | } |