Atlas - SDL_diskaudio.c
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[FILE BEGIN]
1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2018 Sam Lantinga <[email protected]>
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_internal.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_audio_c.h"
35#include "SDL_diskaudio.h"
36#include "SDL_log.h"
37
38/* !!! FIXME: these should be SDL hints, not environment variables. */
39/* environment variables and defaults. */
40#define DISKENVR_OUTFILE         "SDL_DISKAUDIOFILE"
41#define DISKDEFAULT_OUTFILE      "sdlaudio.raw"
42#define DISKENVR_INFILE         "SDL_DISKAUDIOFILEIN"
43#define DISKDEFAULT_INFILE      "sdlaudio-in.raw"
44#define DISKENVR_IODELAY      "SDL_DISKAUDIODELAY"
45
46/* This function waits until it is possible to write a full sound buffer */
47static void
48DISKAUDIO_WaitDevice(_THIS)
49{
50    SDL_Delay(this->hidden->io_delay);
51}
52
53static void
54DISKAUDIO_PlayDevice(_THIS)
55{
56    const size_t written = SDL_RWwrite(this->hidden->io,
57                                       this->hidden->mixbuf,
58                                       1, this->spec.size);
59
60    /* If we couldn't write, assume fatal error for now */
61    if (written != this->spec.size) {
62        SDL_OpenedAudioDeviceDisconnected(this);
63    }
64#ifdef DEBUG_AUDIO
65    fprintf(stderr, "Wrote %d bytes of audio data\n", written);
66#endif
67}
68
69static Uint8 *
70DISKAUDIO_GetDeviceBuf(_THIS)
71{
72    return (this->hidden->mixbuf);
73}
74
75static int
76DISKAUDIO_CaptureFromDevice(_THIS, void *buffer, int buflen)
77{
78    struct SDL_PrivateAudioData *h = this->hidden;
79    const int origbuflen = buflen;
80
81    SDL_Delay(h->io_delay);
82
83    if (h->io) {
84        const size_t br = SDL_RWread(h->io, buffer, 1, buflen);
85        buflen -= (int) br;
86        buffer = ((Uint8 *) buffer) + br;
87        if (buflen > 0) {  /* EOF (or error, but whatever). */
88            SDL_RWclose(h->io);
89            h->io = NULL;
90        }
91    }
92
93    /* if we ran out of file, just write silence. */
94    SDL_memset(buffer, this->spec.silence, buflen);
95
96    return origbuflen;
97}
98
99static void
100DISKAUDIO_FlushCapture(_THIS)
101{
102    /* no op...we don't advance the file pointer or anything. */
103}
104
105
106static void
107DISKAUDIO_CloseDevice(_THIS)
108{
109    if (this->hidden->io != NULL) {
110        SDL_RWclose(this->hidden->io);
111    }
112    SDL_free(this->hidden->mixbuf);
113    SDL_free(this->hidden);
114}
115
116
117static const char *
118get_filename(const int iscapture, const char *devname)
119{
120    if (devname == NULL) {
121        devname = SDL_getenv(iscapture ? DISKENVR_INFILE : DISKENVR_OUTFILE);
122        if (devname == NULL) {
123            devname = iscapture ? DISKDEFAULT_INFILE : DISKDEFAULT_OUTFILE;
124        }
125    }
126    return devname;
127}
128
129static int
130DISKAUDIO_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
131{
132    /* handle != NULL means "user specified the placeholder name on the fake detected device list" */
133    const char *fname = get_filename(iscapture, handle ? NULL : devname);
134    const char *envr = SDL_getenv(DISKENVR_IODELAY);
135
136    this->hidden = (struct SDL_PrivateAudioData *)
137        SDL_malloc(sizeof(*this->hidden));
138    if (this->hidden == NULL) {
139        return SDL_OutOfMemory();
140    }
141    SDL_zerop(this->hidden);
142
143    if (envr != NULL) {
144        this->hidden->io_delay = SDL_atoi(envr);
145    } else {
146        this->hidden->io_delay = ((this->spec.samples * 1000) / this->spec.freq);
147    }
148
149    /* Open the audio device */
150    this->hidden->io = SDL_RWFromFile(fname, iscapture ? "rb" : "wb");
151    if (this->hidden->io == NULL) {
152        return -1;
153    }
154
155    /* Allocate mixing buffer */
156    if (!iscapture) {
157        this->hidden->mixbuf = (Uint8 *) SDL_malloc(this->spec.size);
158        if (this->hidden->mixbuf == NULL) {
159            return SDL_OutOfMemory();
160        }
161        SDL_memset(this->hidden->mixbuf, this->spec.silence, this->spec.size);
162    }
163
164    SDL_LogCritical(SDL_LOG_CATEGORY_AUDIO,
165                "You are using the SDL disk i/o audio driver!\n");
166    SDL_LogCritical(SDL_LOG_CATEGORY_AUDIO,
167                " %s file [%s].\n", iscapture ? "Reading from" : "Writing to",
168                fname);
169
170    /* We're ready to rock and roll. :-) */
171    return 0;
172}
173
174static void
175DISKAUDIO_DetectDevices(void)
176{
177    SDL_AddAudioDevice(SDL_FALSE, DEFAULT_OUTPUT_DEVNAME, (void *) 0x1);
178    SDL_AddAudioDevice(SDL_TRUE, DEFAULT_INPUT_DEVNAME, (void *) 0x2);
179}
180
181static int
182DISKAUDIO_Init(SDL_AudioDriverImpl * impl)
183{
184    /* Set the function pointers */
185    impl->OpenDevice = DISKAUDIO_OpenDevice;
186    impl->WaitDevice = DISKAUDIO_WaitDevice;
187    impl->PlayDevice = DISKAUDIO_PlayDevice;
188    impl->GetDeviceBuf = DISKAUDIO_GetDeviceBuf;
189    impl->CaptureFromDevice = DISKAUDIO_CaptureFromDevice;
190    impl->FlushCapture = DISKAUDIO_FlushCapture;
191
192    impl->CloseDevice = DISKAUDIO_CloseDevice;
193    impl->DetectDevices = DISKAUDIO_DetectDevices;
194
195    impl->AllowsArbitraryDeviceNames = 1;
196    impl->HasCaptureSupport = SDL_TRUE;
197
198    return 1;   /* this audio target is available. */
199}
200
201AudioBootStrap DISKAUDIO_bootstrap = {
202    "disk", "direct-to-disk audio", DISKAUDIO_Init, 1
203};
204
205#endif /* SDL_AUDIO_DRIVER_DISK */
206
207/* vi: set ts=4 sw=4 expandtab: */
208
[FILE END]
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