Atlas - SDL_diskaudio.c
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[FILE BEGIN]
1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2025 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#ifdef SDL_AUDIO_DRIVER_DISK
24
25// Output raw audio data to a file.
26
27#include "../SDL_sysaudio.h"
28#include "SDL_diskaudio.h"
29
30#define DISKDEFAULT_OUTFILE "sdlaudio.raw"
31#define DISKDEFAULT_INFILE  "sdlaudio-in.raw"
32
33static bool DISKAUDIO_WaitDevice(SDL_AudioDevice *device)
34{
35    SDL_Delay(device->hidden->io_delay);
36    return true;
37}
38
39static bool DISKAUDIO_PlayDevice(SDL_AudioDevice *device, const Uint8 *buffer, int buffer_size)
40{
41    const int written = (int)SDL_WriteIO(device->hidden->io, buffer, (size_t)buffer_size);
42    if (written != buffer_size) { // If we couldn't write, assume fatal error for now
43        return false;
44    }
45#ifdef DEBUG_AUDIO
46    SDL_Log("DISKAUDIO: Wrote %d bytes of audio data", (int) written);
47#endif
48    return true;
49}
50
51static Uint8 *DISKAUDIO_GetDeviceBuf(SDL_AudioDevice *device, int *buffer_size)
52{
53    return device->hidden->mixbuf;
54}
55
56static int DISKAUDIO_RecordDevice(SDL_AudioDevice *device, void *buffer, int buflen)
57{
58    struct SDL_PrivateAudioData *h = device->hidden;
59    const int origbuflen = buflen;
60
61    if (h->io) {
62        const int br = (int)SDL_ReadIO(h->io, buffer, (size_t)buflen);
63        buflen -= br;
64        buffer = ((Uint8 *)buffer) + br;
65        if (buflen > 0) { // EOF (or error, but whatever).
66            SDL_CloseIO(h->io);
67            h->io = NULL;
68        }
69    }
70
71    // if we ran out of file, just write silence.
72    SDL_memset(buffer, device->silence_value, buflen);
73
74    return origbuflen;
75}
76
77static void DISKAUDIO_FlushRecording(SDL_AudioDevice *device)
78{
79    // no op...we don't advance the file pointer or anything.
80}
81
82static void DISKAUDIO_CloseDevice(SDL_AudioDevice *device)
83{
84    if (device->hidden) {
85        if (device->hidden->io) {
86            SDL_CloseIO(device->hidden->io);
87        }
88        SDL_free(device->hidden->mixbuf);
89        SDL_free(device->hidden);
90        device->hidden = NULL;
91    }
92}
93
94static const char *get_filename(const bool recording)
95{
96    const char *devname = SDL_GetHint(recording ? SDL_HINT_AUDIO_DISK_INPUT_FILE : SDL_HINT_AUDIO_DISK_OUTPUT_FILE);
97    if (!devname) {
98        devname = recording ? DISKDEFAULT_INFILE : DISKDEFAULT_OUTFILE;
99    }
100    return devname;
101}
102
103static const char *AudioFormatString(SDL_AudioFormat fmt)
104{
105    const char *str = SDL_GetAudioFormatName(fmt);
106    SDL_assert(str);
107    if (SDL_strncmp(str, "SDL_AUDIO_", 10) == 0) {
108        str += 10;  // so we return "S8" instead of "SDL_AUDIO_S8", etc.
109    }
110    return str;
111}
112
113static bool DISKAUDIO_OpenDevice(SDL_AudioDevice *device)
114{
115    bool recording = device->recording;
116    const char *fname = get_filename(recording);
117
118    device->hidden = (struct SDL_PrivateAudioData *) SDL_calloc(1, sizeof(*device->hidden));
119    if (!device->hidden) {
120        return false;
121    }
122
123    device->hidden->io_delay = ((device->sample_frames * 1000) / device->spec.freq);
124
125    const char *hint = SDL_GetHint(SDL_HINT_AUDIO_DISK_TIMESCALE);
126    if (hint) {
127        double scale = SDL_atof(hint);
128        if (scale >= 0.0) {
129            device->hidden->io_delay = (Uint32)SDL_round(device->hidden->io_delay * scale);
130        }
131    }
132
133    // Open the "audio device"
134    device->hidden->io = SDL_IOFromFile(fname, recording ? "rb" : "wb");
135    if (!device->hidden->io) {
136        return false;
137    }
138
139    // Allocate mixing buffer
140    if (!recording) {
141        device->hidden->mixbuf = (Uint8 *)SDL_malloc(device->buffer_size);
142        if (!device->hidden->mixbuf) {
143            return false;
144        }
145        SDL_memset(device->hidden->mixbuf, device->silence_value, device->buffer_size);
146    }
147
148    SDL_LogCritical(SDL_LOG_CATEGORY_AUDIO, "You are using the SDL disk i/o audio driver!");
149    SDL_LogCritical(SDL_LOG_CATEGORY_AUDIO, " %s file [%s], format=%s channels=%d freq=%d.",
150                    recording ? "Reading from" : "Writing to", fname,
151                    AudioFormatString(device->spec.format), device->spec.channels, device->spec.freq);
152
153    return true;  // We're ready to rock and roll. :-)
154}
155
156static void DISKAUDIO_DetectDevices(SDL_AudioDevice **default_playback, SDL_AudioDevice **default_recording)
157{
158    *default_playback = SDL_AddAudioDevice(false, DEFAULT_PLAYBACK_DEVNAME, NULL, (void *)0x1);
159    *default_recording = SDL_AddAudioDevice(true, DEFAULT_RECORDING_DEVNAME, NULL, (void *)0x2);
160}
161
162static bool DISKAUDIO_Init(SDL_AudioDriverImpl *impl)
163{
164    impl->OpenDevice = DISKAUDIO_OpenDevice;
165    impl->WaitDevice = DISKAUDIO_WaitDevice;
166    impl->WaitRecordingDevice = DISKAUDIO_WaitDevice;
167    impl->PlayDevice = DISKAUDIO_PlayDevice;
168    impl->GetDeviceBuf = DISKAUDIO_GetDeviceBuf;
169    impl->RecordDevice = DISKAUDIO_RecordDevice;
170    impl->FlushRecording = DISKAUDIO_FlushRecording;
171    impl->CloseDevice = DISKAUDIO_CloseDevice;
172    impl->DetectDevices = DISKAUDIO_DetectDevices;
173
174    impl->HasRecordingSupport = true;
175
176    return true;
177}
178
179AudioBootStrap DISKAUDIO_bootstrap = {
180    "disk", "direct-to-disk audio", DISKAUDIO_Init, true, false
181};
182
183#endif // SDL_AUDIO_DRIVER_DISK
184
[FILE END]
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