2 files changed, 392 insertions, 0 deletions

diff --git a/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.c b/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.c
new file mode 100644
index 0000000..55fb5b4
--- /dev/null
+++ b/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.c
@@ -0,0 +1,359 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#ifdef SDL_AUDIO_DRIVER_EMSCRIPTEN
+
+#include "../SDL_sysaudio.h"
+#include "SDL_emscriptenaudio.h"
+
+#include <emscripten/emscripten.h>
+
+// just turn off clang-format for this whole file, this INDENT_OFF stuff on
+//  each EM_ASM section is ugly.
+/* *INDENT-OFF* */ // clang-format off
+
+static Uint8 *EMSCRIPTENAUDIO_GetDeviceBuf(SDL_AudioDevice *device, int *buffer_size)
+{
+    return device->hidden->mixbuf;
+}
+
+static bool EMSCRIPTENAUDIO_PlayDevice(SDL_AudioDevice *device, const Uint8 *buffer, int buffer_size)
+{
+    const int framelen = SDL_AUDIO_FRAMESIZE(device->spec);
+    MAIN_THREAD_EM_ASM({
+        /* Convert incoming buf pointer to a HEAPF32 offset. */
+        #ifdef __wasm64__
+        var buf = $0 / 4;
+        #else
+        var buf = $0 >>> 2;
+        #endif
+
+        var SDL3 = Module['SDL3'];
+        var numChannels = SDL3.audio_playback.currentPlaybackBuffer['numberOfChannels'];
+        for (var c = 0; c < numChannels; ++c) {
+            var channelData = SDL3.audio_playback.currentPlaybackBuffer['getChannelData'](c);
+            if (channelData.length != $1) {
+                throw 'Web Audio playback buffer length mismatch! Destination size: ' + channelData.length + ' samples vs expected ' + $1 + ' samples!';
+            }
+
+            for (var j = 0; j < $1; ++j) {
+                channelData[j] = HEAPF32[buf + (j*numChannels + c)];
+            }
+        }
+    }, buffer, buffer_size / framelen);
+    return true;
+}
+
+
+static void EMSCRIPTENAUDIO_FlushRecording(SDL_AudioDevice *device)
+{
+    // Do nothing, the new data will just be dropped.
+}
+
+static int EMSCRIPTENAUDIO_RecordDevice(SDL_AudioDevice *device, void *buffer, int buflen)
+{
+    MAIN_THREAD_EM_ASM({
+        var SDL3 = Module['SDL3'];
+        var numChannels = SDL3.audio_recording.currentRecordingBuffer.numberOfChannels;
+        for (var c = 0; c < numChannels; ++c) {
+            var channelData = SDL3.audio_recording.currentRecordingBuffer.getChannelData(c);
+            if (channelData.length != $1) {
+                throw 'Web Audio recording buffer length mismatch! Destination size: ' + channelData.length + ' samples vs expected ' + $1 + ' samples!';
+            }
+
+            if (numChannels == 1) {  // fastpath this a little for the common (mono) case.
+                for (var j = 0; j < $1; ++j) {
+                    setValue($0 + (j * 4), channelData[j], 'float');
+                }
+            } else {
+                for (var j = 0; j < $1; ++j) {
+                    setValue($0 + (((j * numChannels) + c) * 4), channelData[j], 'float');
+                }
+            }
+        }
+    }, buffer, (buflen / sizeof(float)) / device->spec.channels);
+
+    return buflen;
+}
+
+static void EMSCRIPTENAUDIO_CloseDevice(SDL_AudioDevice *device)
+{
+    if (!device->hidden) {
+        return;
+    }
+
+    MAIN_THREAD_EM_ASM({
+        var SDL3 = Module['SDL3'];
+        if ($0) {
+            if (SDL3.audio_recording.silenceTimer !== undefined) {
+                clearInterval(SDL3.audio_recording.silenceTimer);
+            }
+            if (SDL3.audio_recording.stream !== undefined) {
+                var tracks = SDL3.audio_recording.stream.getAudioTracks();
+                for (var i = 0; i < tracks.length; i++) {
+                    SDL3.audio_recording.stream.removeTrack(tracks[i]);
+                }
+            }
+            if (SDL3.audio_recording.scriptProcessorNode !== undefined) {
+                SDL3.audio_recording.scriptProcessorNode.onaudioprocess = function(audioProcessingEvent) {};
+                SDL3.audio_recording.scriptProcessorNode.disconnect();
+            }
+            if (SDL3.audio_recording.mediaStreamNode !== undefined) {
+                SDL3.audio_recording.mediaStreamNode.disconnect();
+            }
+            SDL3.audio_recording = undefined;
+        } else {
+            if (SDL3.audio_playback.scriptProcessorNode != undefined) {
+                SDL3.audio_playback.scriptProcessorNode.disconnect();
+            }
+            if (SDL3.audio_playback.silenceTimer !== undefined) {
+                clearInterval(SDL3.audio_playback.silenceTimer);
+            }
+            SDL3.audio_playback = undefined;
+        }
+        if ((SDL3.audioContext !== undefined) && (SDL3.audio_playback === undefined) && (SDL3.audio_recording === undefined)) {
+            SDL3.audioContext.close();
+            SDL3.audioContext = undefined;
+        }
+    }, device->recording);
+
+    SDL_free(device->hidden->mixbuf);
+    SDL_free(device->hidden);
+    device->hidden = NULL;
+
+    SDL_AudioThreadFinalize(device);
+}
+
+EM_JS_DEPS(sdlaudio, "$autoResumeAudioContext,$dynCall");
+
+static bool EMSCRIPTENAUDIO_OpenDevice(SDL_AudioDevice *device)
+{
+    // based on parts of library_sdl.js
+
+    // create context
+    const bool result = MAIN_THREAD_EM_ASM_INT({
+        if (typeof(Module['SDL3']) === 'undefined') {
+            Module['SDL3'] = {};
+        }
+        var SDL3 = Module['SDL3'];
+        if (!$0) {
+            SDL3.audio_playback = {};
+        } else {
+            SDL3.audio_recording = {};
+        }
+
+        if (!SDL3.audioContext) {
+            if (typeof(AudioContext) !== 'undefined') {
+                SDL3.audioContext = new AudioContext();
+            } else if (typeof(webkitAudioContext) !== 'undefined') {
+                SDL3.audioContext = new webkitAudioContext();
+            }
+            if (SDL3.audioContext) {
+                if ((typeof navigator.userActivation) === 'undefined') {
+                    autoResumeAudioContext(SDL3.audioContext);
+                }
+            }
+        }
+        return (SDL3.audioContext !== undefined);
+    }, device->recording);
+
+    if (!result) {
+        return SDL_SetError("Web Audio API is not available!");
+    }
+
+    device->spec.format = SDL_AUDIO_F32;  // web audio only supports floats
+
+    // Initialize all variables that we clean on shutdown
+    device->hidden = (struct SDL_PrivateAudioData *)SDL_calloc(1, sizeof(*device->hidden));
+    if (!device->hidden) {
+        return false;
+    }
+
+    // limit to native freq
+    device->spec.freq = EM_ASM_INT({ return Module['SDL3'].audioContext.sampleRate; });
+    device->sample_frames = SDL_GetDefaultSampleFramesFromFreq(device->spec.freq) * 2;  // double the buffer size, some browsers need more, and we'll just have to live with the latency.
+
+    SDL_UpdatedAudioDeviceFormat(device);
+
+    if (!device->recording) {
+        device->hidden->mixbuf = (Uint8 *)SDL_malloc(device->buffer_size);
+        if (!device->hidden->mixbuf) {
+            return false;
+        }
+        SDL_memset(device->hidden->mixbuf, device->silence_value, device->buffer_size);
+    }
+
+    if (device->recording) {
+        /* The idea is to take the recording media stream, hook it up to an
+           audio graph where we can pass it through a ScriptProcessorNode
+           to access the raw PCM samples and push them to the SDL app's
+           callback. From there, we "process" the audio data into silence
+           and forget about it.
+
+           This should, strictly speaking, use MediaRecorder for recording, but
+           this API is cleaner to use and better supported, and fires a
+           callback whenever there's enough data to fire down into the app.
+           The downside is that we are spending CPU time silencing a buffer
+           that the audiocontext uselessly mixes into any playback. On the
+           upside, both of those things are not only run in native code in
+           the browser, they're probably SIMD code, too. MediaRecorder
+           feels like it's a pretty inefficient tapdance in similar ways,
+           to be honest. */
+
+        MAIN_THREAD_EM_ASM({
+            var SDL3 = Module['SDL3'];
+            var have_microphone = function(stream) {
+                //console.log('SDL audio recording: we have a microphone! Replacing silence callback.');
+                if (SDL3.audio_recording.silenceTimer !== undefined) {
+                    clearInterval(SDL3.audio_recording.silenceTimer);
+                    SDL3.audio_recording.silenceTimer = undefined;
+                    SDL3.audio_recording.silenceBuffer = undefined
+                }
+                SDL3.audio_recording.mediaStreamNode = SDL3.audioContext.createMediaStreamSource(stream);
+                SDL3.audio_recording.scriptProcessorNode = SDL3.audioContext.createScriptProcessor($1, $0, 1);
+                SDL3.audio_recording.scriptProcessorNode.onaudioprocess = function(audioProcessingEvent) {
+                    if ((SDL3 === undefined) || (SDL3.audio_recording === undefined)) { return; }
+                    audioProcessingEvent.outputBuffer.getChannelData(0).fill(0.0);
+                    SDL3.audio_recording.currentRecordingBuffer = audioProcessingEvent.inputBuffer;
+                    dynCall('ip', $2, [$3]);
+                };
+                SDL3.audio_recording.mediaStreamNode.connect(SDL3.audio_recording.scriptProcessorNode);
+                SDL3.audio_recording.scriptProcessorNode.connect(SDL3.audioContext.destination);
+                SDL3.audio_recording.stream = stream;
+            };
+
+            var no_microphone = function(error) {
+                //console.log('SDL audio recording: we DO NOT have a microphone! (' + error.name + ')...leaving silence callback running.');
+            };
+
+            // we write silence to the audio callback until the microphone is available (user approves use, etc).
+            SDL3.audio_recording.silenceBuffer = SDL3.audioContext.createBuffer($0, $1, SDL3.audioContext.sampleRate);
+            SDL3.audio_recording.silenceBuffer.getChannelData(0).fill(0.0);
+            var silence_callback = function() {
+                SDL3.audio_recording.currentRecordingBuffer = SDL3.audio_recording.silenceBuffer;
+                dynCall('ip', $2, [$3]);
+            };
+
+            SDL3.audio_recording.silenceTimer = setInterval(silence_callback, ($1 / SDL3.audioContext.sampleRate) * 1000);
+
+            if ((navigator.mediaDevices !== undefined) && (navigator.mediaDevices.getUserMedia !== undefined)) {
+                navigator.mediaDevices.getUserMedia({ audio: true, video: false }).then(have_microphone).catch(no_microphone);
+            } else if (navigator.webkitGetUserMedia !== undefined) {
+                navigator.webkitGetUserMedia({ audio: true, video: false }, have_microphone, no_microphone);
+            }
+        }, device->spec.channels, device->sample_frames, SDL_RecordingAudioThreadIterate, device);
+    } else {
+        // setup a ScriptProcessorNode
+        MAIN_THREAD_EM_ASM({
+            var SDL3 = Module['SDL3'];
+            SDL3.audio_playback.scriptProcessorNode = SDL3.audioContext['createScriptProcessor']($1, 0, $0);
+            SDL3.audio_playback.scriptProcessorNode['onaudioprocess'] = function (e) {
+                if ((SDL3 === undefined) || (SDL3.audio_playback === undefined)) { return; }
+                // if we're actually running the node, we don't need the fake callback anymore, so kill it.
+                if (SDL3.audio_playback.silenceTimer !== undefined) {
+                    clearInterval(SDL3.audio_playback.silenceTimer);
+                    SDL3.audio_playback.silenceTimer = undefined;
+                    SDL3.audio_playback.silenceBuffer = undefined;
+                }
+                SDL3.audio_playback.currentPlaybackBuffer = e['outputBuffer'];
+                dynCall('ip', $2, [$3]);
+            };
+
+            SDL3.audio_playback.scriptProcessorNode['connect'](SDL3.audioContext['destination']);
+
+            if (SDL3.audioContext.state === 'suspended') {  // uhoh, autoplay is blocked.
+                SDL3.audio_playback.silenceBuffer = SDL3.audioContext.createBuffer($0, $1, SDL3.audioContext.sampleRate);
+                SDL3.audio_playback.silenceBuffer.getChannelData(0).fill(0.0);
+                var silence_callback = function() {
+                    if ((typeof navigator.userActivation) !== 'undefined') {
+                        if (navigator.userActivation.hasBeenActive) {
+                            SDL3.audioContext.resume();
+                        }
+                    }
+
+                    // the buffer that gets filled here just gets ignored, so the app can make progress
+                    //  and/or avoid flooding audio queues until we can actually play audio.
+                    SDL3.audio_playback.currentPlaybackBuffer = SDL3.audio_playback.silenceBuffer;
+                    dynCall('ip', $2, [$3]);
+                    SDL3.audio_playback.currentPlaybackBuffer = undefined;
+                };
+
+                SDL3.audio_playback.silenceTimer = setInterval(silence_callback, ($1 / SDL3.audioContext.sampleRate) * 1000);
+            }
+        }, device->spec.channels, device->sample_frames, SDL_PlaybackAudioThreadIterate, device);
+    }
+
+    return true;
+}
+
+static bool EMSCRIPTENAUDIO_Init(SDL_AudioDriverImpl *impl)
+{
+    bool available, recording_available;
+
+    impl->OpenDevice = EMSCRIPTENAUDIO_OpenDevice;
+    impl->CloseDevice = EMSCRIPTENAUDIO_CloseDevice;
+    impl->GetDeviceBuf = EMSCRIPTENAUDIO_GetDeviceBuf;
+    impl->PlayDevice = EMSCRIPTENAUDIO_PlayDevice;
+    impl->FlushRecording = EMSCRIPTENAUDIO_FlushRecording;
+    impl->RecordDevice = EMSCRIPTENAUDIO_RecordDevice;
+
+    impl->OnlyHasDefaultPlaybackDevice = true;
+
+    // technically, this is just runs in idle time in the main thread, but it's close enough to a "thread" for our purposes.
+    impl->ProvidesOwnCallbackThread = true;
+
+    // check availability
+    available = MAIN_THREAD_EM_ASM_INT({
+        if (typeof(AudioContext) !== 'undefined') {
+            return true;
+        } else if (typeof(webkitAudioContext) !== 'undefined') {
+            return true;
+        }
+        return false;
+    });
+
+    if (!available) {
+        SDL_SetError("No audio context available");
+    }
+
+    recording_available = available && MAIN_THREAD_EM_ASM_INT({
+        if ((typeof(navigator.mediaDevices) !== 'undefined') && (typeof(navigator.mediaDevices.getUserMedia) !== 'undefined')) {
+            return true;
+        } else if (typeof(navigator.webkitGetUserMedia) !== 'undefined') {
+            return true;
+        }
+        return false;
+    });
+
+    impl->HasRecordingSupport = recording_available;
+    impl->OnlyHasDefaultRecordingDevice = recording_available;
+
+    return available;
+}
+
+AudioBootStrap EMSCRIPTENAUDIO_bootstrap = {
+    "emscripten", "SDL emscripten audio driver", EMSCRIPTENAUDIO_Init, false, false
+};
+
+/* *INDENT-ON* */ // clang-format on
+
+#endif // SDL_AUDIO_DRIVER_EMSCRIPTEN
diff --git a/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.h b/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.h
new file mode 100644
index 0000000..aaf761b
--- /dev/null
+++ b/contrib/SDL-3.2.8/src/audio/emscripten/SDL_emscriptenaudio.h
@@ -0,0 +1,33 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "SDL_internal.h"
+
+#ifndef SDL_emscriptenaudio_h_
+#define SDL_emscriptenaudio_h_
+
+#include "../SDL_sysaudio.h"
+
+struct SDL_PrivateAudioData
+{
+    Uint8 *mixbuf;
+};
+
+#endif // SDL_emscriptenaudio_h_