5 // (C) 2005-2018 Underground Software
7 // JLH = James Hammons <jlhamm@acm.org>
10 // --- ---------- -----------------------------------------------------------
11 // JLH 12/02/2005 Fixed a problem with sound callback thread signaling the
13 // JLH 12/03/2005 Fixed sound callback dropping samples when the sample
14 // buffer is shorter than the callback sample buffer
19 // - Figure out why it's losing samples (Bard's Tale) [DONE]
20 // - Figure out why it's playing too fast [DONE]
25 #include <string.h> // For memset, memcpy
34 #define SAMPLES_PER_FRAME (SAMPLE_RATE / 60.0)
35 #define CYCLES_PER_SAMPLE (1024000.0 / SAMPLE_RATE)
36 // 32K ought to be enough for anybody
37 #define SOUND_BUFFER_SIZE (32768)
44 static SDL_AudioSpec desired, obtained;
45 static SDL_AudioDeviceID device;
46 static bool soundInitialized = false;
47 static bool speakerState = false;
48 static uint16_t soundBuffer[SOUND_BUFFER_SIZE];
49 static uint32_t soundBufferPos;
50 static uint16_t sample;
51 static uint8_t ampPtr = 12; // Start with -2047 - +2047
52 static int16_t amplitude[17] = { 0, 1, 2, 3, 7, 15, 31, 63, 127, 255,
53 511, 1023, 2047, 4095, 8191, 16383, 32767 };
55 // Private function prototypes
57 static void SDLSoundCallback(void * userdata, Uint8 * buffer, int length);
61 N.B: We can convert this from the current callback model to a push model by using SDL_QueueAudio(SDL_AudioDeviceID id, const void * data, Uint32 len) where id is the audio device ID, data is a pointer to the sound buffer, and len is the size of the buffer in *bytes* (not samples!). To use this method, we need to set up things as usual but instead of putting the callback function pointer in desired.callback, we put a NULL there. The downside is that we can't tell if the buffer is being starved or not, which is why we haven't kicked it to the curb just yet--we want to know why we're still getting buffer starvation even if it's not as frequent as it used to be. :-/
62 You can get the size of the audio already queued with SDL_GetQueuedAudioSize(SDL_AudioDeviceID id), which will return the size of the buffer in bytes (again, *not* samples!).
65 // Initialize the SDL sound system
70 desired.freq = SAMPLE_RATE; // SDL will do conversion on the fly, if it can't get the exact rate. Nice!
71 desired.format = AUDIO_U16SYS; // This uses the native endian (for portability)...
73 desired.samples = 512; // Let's try a 1/2K buffer
74 desired.callback = SDLSoundCallback;
76 device = SDL_OpenAudioDevice(NULL, 0, &desired, &obtained, 0);
80 WriteLog("Sound: Failed to initialize SDL sound.\n");
85 sample = desired.silence; // ? wilwok ? yes
87 SDL_PauseAudioDevice(device, 0);// Start playback!
88 soundInitialized = true;
89 WriteLog("Sound: Successfully initialized.\n");
94 // Close down the SDL sound subsystem
100 SDL_PauseAudioDevice(device, 1);
101 SDL_CloseAudioDevice(device);
102 WriteLog("Sound: Done.\n");
107 void SoundPause(void)
109 if (soundInitialized)
110 SDL_PauseAudioDevice(device, 1);
114 void SoundResume(void)
116 if (soundInitialized)
117 SDL_PauseAudioDevice(device, 0);
122 // Sound card callback handler
124 static uint32_t sndFrmCnt = 0;
125 static uint32_t lastStarve = 0;
126 static void SDLSoundCallback(void * /*userdata*/, Uint8 * buffer8, int length8)
130 // Recast this as a 16-bit type...
131 uint16_t * buffer = (uint16_t *)buffer8;
132 uint32_t length = (uint32_t)length8 / 2;
134 if (soundBufferPos < length)
136 WriteLog("*** Sound buffer starved (%d short) *** [%d delta %d]\n", length - soundBufferPos, sndFrmCnt, sndFrmCnt - lastStarve);
137 lastStarve = sndFrmCnt;
139 for(uint32_t i=0; i<length; i++)
140 buffer[i] = desired.silence;
142 // The sound buffer is starved...
143 for(uint32_t i=0; i<soundBufferPos; i++)
144 buffer[i] = soundBuffer[i];
146 // Fill buffer with last value
147 for(uint32_t i=soundBufferPos; i<length; i++)
150 // Reset soundBufferPos to start of buffer...
156 // Fill sound buffer with frame buffered sound
157 for(uint32_t i=0; i<length; i++)
158 buffer[i] = soundBuffer[i];
160 soundBufferPos -= length;
162 // Move current buffer down to start
163 for(uint32_t i=0; i<soundBufferPos; i++)
164 soundBuffer[i] = soundBuffer[length + i];
170 // This is called by the main CPU thread every ~21.666 cycles.
172 void WriteSampleToBuffer(void)
174 #ifdef USE_NEW_AY8910
175 uint16_t s1 = AYGetSample(0);
176 uint16_t s2 = AYGetSample(1);
177 uint16_t adjustedMockingboard = s1 + s2;
179 int16_t s1, s2, s3, s4, s5, s6;
180 int16_t * bufPtrs[6] = { &s1, &s2, &s3, &s4, &s5, &s6 };
181 AY8910Update(0, bufPtrs, 1);
182 AY8910Update(1, &bufPtrs[3], 1);
183 int16_t adjustedMockingboard = (s1 / 8) + (s2 / 8) + (s3 / 8)
184 + (s4 / 8) + (s5 / 8) + (s6 / 8);
187 // This should almost never happen, but, if it does...
188 while (soundBufferPos >= (SOUND_BUFFER_SIZE - 1))
190 //WriteLog("WriteSampleToBuffer(): Waiting for sound thread. soundBufferPos=%i, SOUNDBUFFERSIZE-1=%i\n", soundBufferPos, SOUND_BUFFER_SIZE-1);
194 SDL_LockAudioDevice(device);
195 soundBuffer[soundBufferPos++] = sample + adjustedMockingboard;
196 SDL_UnlockAudioDevice(device);
200 void ToggleSpeaker(void)
202 if (!soundInitialized)
205 speakerState = !speakerState;
206 sample = (speakerState ? amplitude[ampPtr] : 0);
212 // Currently set for 16-bit samples
218 void VolumeDown(void)
225 uint8_t GetVolume(void)