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comparison src/audio/dummy/SDL_dummyaudio.c @ 3798:c8b3d3d13ed1 SDL-ryan-multiple-audio-device

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Audio bootstraps can now specify that a driver is only to be used if explicitly requested (for things like the "disk" driver that is always available but you would never want to default to using). Trimmed out code that can be handled by stubs in the core. The "dummy" driver is pretty damned small now. :)
author Ryan C. Gordon <icculus@icculus.org>
date Wed, 04 Oct 2006 21:27:53 +0000
parents b19680c84cdf
children 7852b5b78af5
comparison
equal deleted inserted replaced
3797:9dc81c6acaf5 3798:c8b3d3d13ed1
45 45
46 /* Audio driver bootstrap functions */ 46 /* Audio driver bootstrap functions */
47 static int 47 static int
48 DUMMYAUD_Available(void) 48 DUMMYAUD_Available(void)
49 { 49 {
50 /* !!! FIXME: check this at a higher level... */ 50 return 1; /* always available. */
51 /* only ever use this driver if explicitly requested. */
52 const char *envr = SDL_getenv("SDL_AUDIODRIVER");
53 if (envr && (SDL_strcmp(envr, DUMMYAUD_DRIVER_NAME) == 0)) {
54 return (1);
55 }
56 return (0);
57 } 51 }
58 52
59 static int 53 static int
60 DUMMYAUD_Init(SDL_AudioDriverImpl *impl) 54 DUMMYAUD_Init(SDL_AudioDriverImpl *impl)
61 { 55 {
62 /* Set the function pointers */ 56 /* Set the function pointers */
63 impl->OpenDevice = DUMMYAUD_OpenDevice; 57 impl->OpenDevice = DUMMYAUD_OpenDevice;
64 impl->WaitDevice = DUMMYAUD_WaitDevice;
65 impl->PlayDevice = DUMMYAUD_PlayDevice;
66 impl->GetDeviceBuf = DUMMYAUD_GetDeviceBuf;
67 impl->CloseDevice = DUMMYAUD_CloseDevice;
68 impl->OnlyHasDefaultOutputDevice = 1; 58 impl->OnlyHasDefaultOutputDevice = 1;
69 59
70 return 1; 60 return 1;
71 } 61 }
72 62
73 AudioBootStrap DUMMYAUD_bootstrap = { 63 AudioBootStrap DUMMYAUD_bootstrap = {
74 DUMMYAUD_DRIVER_NAME, "SDL dummy audio driver", 64 DUMMYAUD_DRIVER_NAME, "SDL dummy audio driver",
75 DUMMYAUD_Available, DUMMYAUD_Init 65 DUMMYAUD_Available, DUMMYAUD_Init, 1
76 }; 66 };
77
78 /* This function waits until it is possible to write a full sound buffer */
79 static void
80 DUMMYAUD_WaitDevice(_THIS)
81 {
82 /* Don't block on first calls to simulate initial fragment filling. */
83 if (this->hidden->initial_calls)
84 this->hidden->initial_calls--;
85 else
86 SDL_Delay(this->hidden->write_delay);
87 }
88
89 static void
90 DUMMYAUD_PlayDevice(_THIS)
91 {
92 /* no-op...this is a null driver. */
93 }
94
95 static Uint8 *
96 DUMMYAUD_GetDeviceBuf(_THIS)
97 {
98 return (this->hidden->mixbuf);
99 }
100
101 static void
102 DUMMYAUD_CloseDevice(_THIS)
103 {
104 if (this->hidden->mixbuf != NULL) {
105 SDL_FreeAudioMem(this->hidden->mixbuf);
106 this->hidden->mixbuf = NULL;
107 }
108 SDL_free(this->hidden);
109 this->hidden = NULL;
110 }
111 67
112 static int 68 static int
113 DUMMYAUD_OpenDevice(_THIS, const char *devname, int iscapture) 69 DUMMYAUD_OpenDevice(_THIS, const char *devname, int iscapture)
114 { 70 {
115 float bytes_per_sec = 0.0f; 71 return 1; /* always succeeds. */
116
117 /* Initialize all variables that we clean on shutdown */
118 this->hidden = (struct SDL_PrivateAudioData *)
119 SDL_malloc((sizeof *this->hidden));
120 if (this->hidden == NULL) {
121 SDL_OutOfMemory();
122 return 0;
123 }
124 SDL_memset(this->hidden, 0, (sizeof *this->hidden));
125
126 /* Allocate mixing buffer */
127 this->hidden->mixlen = this->spec.size;
128 this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
129 if (this->hidden->mixbuf == NULL) {
130 DUMMYAUD_CloseDevice(this);
131 return 0;
132 }
133 SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size);
134
135 bytes_per_sec = (float) (SDL_AUDIO_BITSIZE(this->spec.format) / 8) *
136 this->spec.channels * this->spec.freq;
137
138 /*
139 * We try to make this request more audio at the correct rate for
140 * a given audio spec, so timing stays fairly faithful.
141 * Also, we have it not block at all for the first two calls, so
142 * it seems like we're filling two audio fragments right out of the
143 * gate, like other SDL drivers tend to do.
144 */
145 this->hidden->initial_calls = 2;
146 this->hidden->write_delay =
147 (Uint32) ((((float) this->spec.size) / bytes_per_sec) * 1000.0f);
148
149 /* We're ready to rock and roll. :-) */
150 return 1;
151 } 72 }
152 73
153 /* vi: set ts=4 sw=4 expandtab: */ 74 /* vi: set ts=4 sw=4 expandtab: */