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SDL_diskaudio.c
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2013 Sam Lantinga <slouken@libsdl.org>
4 
5  This software is provided 'as-is', without any express or implied
6  warranty. In no event will the authors be held liable for any damages
7  arising from the use of this software.
8 
9  Permission is granted to anyone to use this software for any purpose,
10  including commercial applications, and to alter it and redistribute it
11  freely, subject to the following restrictions:
12 
13  1. The origin of this software must not be misrepresented; you must not
14  claim that you wrote the original software. If you use this software
15  in a product, an acknowledgment in the product documentation would be
16  appreciated but is not required.
17  2. Altered source versions must be plainly marked as such, and must not be
18  misrepresented as being the original software.
19  3. This notice may not be removed or altered from any source distribution.
20 */
21 #include "SDL_config.h"
22 
23 #if SDL_AUDIO_DRIVER_DISK
24 
25 /* Output raw audio data to a file. */
26 
27 #if HAVE_STDIO_H
28 #include <stdio.h>
29 #endif
30 
31 #include "SDL_rwops.h"
32 #include "SDL_timer.h"
33 #include "SDL_audio.h"
34 #include "../SDL_audiomem.h"
35 #include "../SDL_audio_c.h"
36 #include "SDL_diskaudio.h"
37 
38 /* environment variables and defaults. */
39 #define DISKENVR_OUTFILE "SDL_DISKAUDIOFILE"
40 #define DISKDEFAULT_OUTFILE "sdlaudio.raw"
41 #define DISKENVR_WRITEDELAY "SDL_DISKAUDIODELAY"
42 #define DISKDEFAULT_WRITEDELAY 150
43 
44 static const char *
45 DISKAUD_GetOutputFilename(const char *devname)
46 {
47  if (devname == NULL) {
48  devname = SDL_getenv(DISKENVR_OUTFILE);
49  if (devname == NULL) {
50  devname = DISKDEFAULT_OUTFILE;
51  }
52  }
53  return devname;
54 }
55 
56 /* This function waits until it is possible to write a full sound buffer */
57 static void
58 DISKAUD_WaitDevice(_THIS)
59 {
60  SDL_Delay(this->hidden->write_delay);
61 }
62 
63 static void
64 DISKAUD_PlayDevice(_THIS)
65 {
66  size_t written;
67 
68  /* Write the audio data */
69  written = SDL_RWwrite(this->hidden->output,
70  this->hidden->mixbuf, 1, this->hidden->mixlen);
71 
72  /* If we couldn't write, assume fatal error for now */
73  if (written != this->hidden->mixlen) {
74  this->enabled = 0;
75  }
76 #ifdef DEBUG_AUDIO
77  fprintf(stderr, "Wrote %d bytes of audio data\n", written);
78 #endif
79 }
80 
81 static Uint8 *
82 DISKAUD_GetDeviceBuf(_THIS)
83 {
84  return (this->hidden->mixbuf);
85 }
86 
87 static void
88 DISKAUD_CloseDevice(_THIS)
89 {
90  if (this->hidden != NULL) {
91  SDL_FreeAudioMem(this->hidden->mixbuf);
92  this->hidden->mixbuf = NULL;
93  if (this->hidden->output != NULL) {
94  SDL_RWclose(this->hidden->output);
95  this->hidden->output = NULL;
96  }
97  SDL_free(this->hidden);
98  this->hidden = NULL;
99  }
100 }
101 
102 static int
103 DISKAUD_OpenDevice(_THIS, const char *devname, int iscapture)
104 {
105  const char *envr = SDL_getenv(DISKENVR_WRITEDELAY);
106  const char *fname = DISKAUD_GetOutputFilename(devname);
107 
108  this->hidden = (struct SDL_PrivateAudioData *)
109  SDL_malloc(sizeof(*this->hidden));
110  if (this->hidden == NULL) {
111  return SDL_OutOfMemory();
112  }
113  SDL_memset(this->hidden, 0, sizeof(*this->hidden));
114 
115  this->hidden->mixlen = this->spec.size;
116  this->hidden->write_delay =
117  (envr) ? SDL_atoi(envr) : DISKDEFAULT_WRITEDELAY;
118 
119  /* Open the audio device */
120  this->hidden->output = SDL_RWFromFile(fname, "wb");
121  if (this->hidden->output == NULL) {
122  DISKAUD_CloseDevice(this);
123  return -1;
124  }
125 
126  /* Allocate mixing buffer */
127  this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
128  if (this->hidden->mixbuf == NULL) {
129  DISKAUD_CloseDevice(this);
130  return -1;
131  }
132  SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size);
133 
134 #if HAVE_STDIO_H
135  fprintf(stderr,
136  "WARNING: You are using the SDL disk writer audio driver!\n"
137  " Writing to file [%s].\n", fname);
138 #endif
139 
140  /* We're ready to rock and roll. :-) */
141  return 0;
142 }
143 
144 static int
145 DISKAUD_Init(SDL_AudioDriverImpl * impl)
146 {
147  /* Set the function pointers */
148  impl->OpenDevice = DISKAUD_OpenDevice;
149  impl->WaitDevice = DISKAUD_WaitDevice;
150  impl->PlayDevice = DISKAUD_PlayDevice;
151  impl->GetDeviceBuf = DISKAUD_GetDeviceBuf;
152  impl->CloseDevice = DISKAUD_CloseDevice;
153 
154  return 1; /* this audio target is available. */
155 }
156 
158  "disk", "direct-to-disk audio", DISKAUD_Init, 1
159 };
160 
161 #endif /* SDL_AUDIO_DRIVER_DISK */
162 
163 /* vi: set ts=4 sw=4 expandtab: */
AudioBootStrap DISKAUD_bootstrap
void(* CloseDevice)(_THIS)
Definition: SDL_sysaudio.h:45
void(* WaitDevice)(_THIS)
Definition: SDL_sysaudio.h:41
#define NULL
Definition: ftobjs.h:61
#define SDL_RWwrite(ctx, ptr, size, n)
Definition: SDL_rwops.h:188
GLenum GLsizei const GLuint GLboolean enabled
Definition: glew.h:2538
Uint8 *(* GetDeviceBuf)(_THIS)
Definition: SDL_sysaudio.h:43
#define SDL_FreeAudioMem
Definition: SDL_audiomem.h:24
DECLSPEC void SDLCALL SDL_free(void *mem)
int(* OpenDevice)(_THIS, const char *devname, int iscapture)
Definition: SDL_sysaudio.h:39
void(* PlayDevice)(_THIS)
Definition: SDL_sysaudio.h:42
#define _THIS
DECLSPEC void SDLCALL SDL_Delay(Uint32 ms)
Wait a specified number of milliseconds before returning.
Definition: SDL_systimer.c:70
DECLSPEC void *SDLCALL SDL_memset(void *dst, int c, size_t len)
Definition: SDL_string.c:261
DECLSPEC void *SDLCALL SDL_malloc(size_t size)
#define SDL_AllocAudioMem
Definition: SDL_audiomem.h:23
#define SDL_OutOfMemory()
Definition: SDL_error.h:52
#define SDL_RWclose(ctx)
Definition: SDL_rwops.h:189
uint8_t Uint8
An unsigned 8-bit integer type.
Definition: SDL_stdinc.h:129
DECLSPEC int SDLCALL SDL_atoi(const char *str)
Definition: SDL_string.c:774
DECLSPEC char *SDLCALL SDL_getenv(const char *name)
Definition: SDL_getenv.c:179
DECLSPEC SDL_RWops *SDLCALL SDL_RWFromFile(const char *file, const char *mode)
Definition: SDL_rwops.c:455