add WebAssembly for Kws (#648)

@@ -23,6 +23,7 @@ option(SHERPA_ONNX_ENABLE_GPU "Enable ONNX Runtime GPU support" OFF)
 option(SHERPA_ONNX_ENABLE_WASM "Whether to enable WASM" OFF)
 option(SHERPA_ONNX_ENABLE_WASM_TTS "Whether to enable WASM for TTS" OFF)
 option(SHERPA_ONNX_ENABLE_WASM_ASR "Whether to enable WASM for ASR" OFF)
+option(SHERPA_ONNX_ENABLE_WASM_KWS "Whether to enable WASM for KWS" OFF)
 option(SHERPA_ONNX_ENABLE_WASM_NODEJS "Whether to enable WASM for NodeJS" OFF)
 option(SHERPA_ONNX_ENABLE_BINARY "Whether to build binaries" ON)
 option(SHERPA_ONNX_LINK_LIBSTDCPP_STATICALLY "True to link libstdc++ statically. Used only when BUILD_SHARED_LIBS is OFF on Linux" ON)
@@ -135,6 +136,10 @@ if(SHERPA_ONNX_ENABLE_WASM)
   add_definitions(-DSHERPA_ONNX_ENABLE_WASM=1)
 endif()
 
+if(SHERPA_ONNX_ENABLE_WASM_KWS)
+  add_definitions(-DSHERPA_ONNX_ENABLE_WASM_KWS=1)
+endif()
+
 if(NOT CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_STANDARD 14 CACHE STRING "The C++ version to be used.")
 endif()

+#!/usr/bin/env  bash
+
+if [ x"$EMSCRIPTEN" == x"" ]; then
+  if ! command -v emcc &> /dev/null; then
+    echo "Please install emscripten first"
+    echo ""
+    echo "You can use the following commands to install it:"
+    echo ""
+    echo "git clone https://github.com/emscripten-core/emsdk.git"
+    echo "cd emsdk"
+    echo "git pull"
+    echo "./emsdk install latest"
+    echo "./emsdk activate latest"
+    echo "source ./emsdk_env.sh"
+    exit 1
+  else
+    EMSCRIPTEN=$(dirname $(realpath $(which emcc)))
+  fi
+fi
+
+export EMSCRIPTEN=$EMSCRIPTEN
+echo "EMSCRIPTEN: $EMSCRIPTEN"
+if [ ! -f $EMSCRIPTEN/cmake/Modules/Platform/Emscripten.cmake ]; then
+  echo "Cannot find $EMSCRIPTEN/cmake/Modules/Platform/Emscripten.cmake"
+  echo "Please make sure you have installed emsdk correctly"
+  exit 1
+fi
+
+mkdir -p build-wasm-simd-kws
+pushd build-wasm-simd-kws
+
+export SHERPA_ONNX_IS_USING_BUILD_WASM_SH=ON
+
+cmake \
+  -DCMAKE_INSTALL_PREFIX=./install \
+  -DCMAKE_BUILD_TYPE=Release \
+  -DCMAKE_TOOLCHAIN_FILE=$EMSCRIPTEN/cmake/Modules/Platform/Emscripten.cmake \
+  \
+  -DSHERPA_ONNX_ENABLE_PYTHON=OFF \
+  -DSHERPA_ONNX_ENABLE_TESTS=OFF \
+  -DSHERPA_ONNX_ENABLE_CHECK=OFF \
+  -DBUILD_SHARED_LIBS=OFF \
+  -DSHERPA_ONNX_ENABLE_PORTAUDIO=OFF \
+  -DSHERPA_ONNX_ENABLE_JNI=OFF \
+  -DSHERPA_ONNX_ENABLE_C_API=ON \
+  -DSHERPA_ONNX_ENABLE_WEBSOCKET=OFF \
+  -DSHERPA_ONNX_ENABLE_GPU=OFF \
+  -DSHERPA_ONNX_ENABLE_WASM=ON \
+  -DSHERPA_ONNX_ENABLE_WASM_KWS=ON \
+  -DSHERPA_ONNX_ENABLE_BINARY=OFF \
+  -DSHERPA_ONNX_LINK_LIBSTDCPP_STATICALLY=OFF \
+  ..
+make -j8
+make install
+
+ls -lh install/bin/wasm

@@ -481,7 +481,7 @@ SherpaOnnxKeywordSpotter* CreateKeywordSpotter(
   SherpaOnnxKeywordSpotter* spotter = new SherpaOnnxKeywordSpotter;
 
   spotter->impl =
-    std::make_unique<sherpa_onnx::KeywordSpotter>(spotter_config);
+      std::make_unique<sherpa_onnx::KeywordSpotter>(spotter_config);
 
   return spotter;
 }
@@ -493,7 +493,7 @@ void DestroyKeywordSpotter(SherpaOnnxKeywordSpotter* spotter) {
 SherpaOnnxOnlineStream* CreateKeywordStream(
     const SherpaOnnxKeywordSpotter* spotter) {
   SherpaOnnxOnlineStream* stream =
-    new SherpaOnnxOnlineStream(spotter->impl->CreateStream());
+      new SherpaOnnxOnlineStream(spotter->impl->CreateStream());
   return stream;
 }
 
@@ -512,7 +512,7 @@ void DecodeMultipleKeywordStreams(
     int32_t n) {
   std::vector<sherpa_onnx::OnlineStream*> ss(n);
   for (int32_t i = 0; i != n; ++i) {
-      ss[i] = streams[i]->impl.get();
+    ss[i] = streams[i]->impl.get();
   }
   spotter->impl->DecodeStreams(ss.data(), n);
 }
@@ -593,7 +593,6 @@ void DestroyKeywordResult(const SherpaOnnxKeywordResult *r) {
   }
 }
 
-
 // ============================================================
 // For VAD
 // ============================================================

@@ -266,8 +266,14 @@ class KeywordSpotterTransducerImpl : public KeywordSpotterImpl {
   }
 
   void InitKeywords() {
+#ifdef SHERPA_ONNX_ENABLE_WASM_KWS
+    // Due to the limitations of the wasm file system,
+    // the keyword_file variable is directly parsed as a string of keywords
+    // if WASM KWS on
+    std::istringstream is(config_.keywords_file);
+    InitKeywords(is);
+#else
     // each line in keywords_file contains space-separated words
-
     std::ifstream is(config_.keywords_file);
     if (!is) {
       SHERPA_ONNX_LOGE("Open keywords file failed: %s",
@@ -275,6 +281,7 @@ class KeywordSpotterTransducerImpl : public KeywordSpotterImpl {
       exit(-1);
     }
     InitKeywords(is);
+#endif
   }
 
 #if __ANDROID_API__ >= 9

@@ -94,10 +94,17 @@ bool KeywordSpotterConfig::Validate() const {
     SHERPA_ONNX_LOGE("Please provide --keywords-file.");
     return false;
   }
+
+#ifndef SHERPA_ONNX_ENABLE_WASM_KWS
+  // due to the limitations of the wasm file system,
+  // keywords file will be packaged into the sherpa-onnx-wasm-kws-main.data file
+  // Solution: take keyword_file variable is directly
+  // parsed as a string of keywords
   if (!std::ifstream(keywords_file.c_str()).good()) {
     SHERPA_ONNX_LOGE("Keywords file %s does not exist.", keywords_file.c_str());
     return false;
   }
+#endif
 
   return model_config.Validate();
 }

@@ -2,16 +2,14 @@
 //
 // Copyright (c)  2023-2024  Xiaomi Corporation
 
-#include "sherpa-onnx/csrc/transducer-keyword-decoder.h"
-
 #include <algorithm>
 #include <cmath>
-#include <cstring>
 #include <utility>
 #include <vector>
 
 #include "sherpa-onnx/csrc/log.h"
 #include "sherpa-onnx/csrc/onnx-utils.h"
+#include "sherpa-onnx/csrc/transducer-keyword-decoder.h"
 
 namespace sherpa_onnx {
 

@@ -6,6 +6,10 @@ if(SHERPA_ONNX_ENABLE_WASM_ASR)
   add_subdirectory(asr)
 endif()
 
+if(SHERPA_ONNX_ENABLE_WASM_KWS)
+  add_subdirectory(kws)
+endif()
+
 if(SHERPA_ONNX_ENABLE_WASM_NODEJS)
   add_subdirectory(nodejs)
 endif()

+if(NOT $ENV{SHERPA_ONNX_IS_USING_BUILD_WASM_SH})
+    message(FATAL_ERROR "Please use ./build-wasm-simd-kws.sh to build for wasm KWS")
+endif()
+
+if(NOT EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/assets/decoder-epoch-12-avg-2-chunk-16-left-64.onnx")
+    message(WARNING "${CMAKE_CURRENT_SOURCE_DIR}/assets/decoder-epoch-12-avg-2-chunk-16-left-64.onnx does not exist")
+    message(FATAL_ERROR "Please read ${CMAKE_CURRENT_SOURCE_DIR}/assets/README.md before you continue")
+endif()
+
+set(exported_functions
+        AcceptWaveform
+        CreateKeywordSpotter
+        DestroyKeywordSpotter
+        CreateKeywordStream
+        DecodeKeywordStream
+        GetKeywordResult
+        DestroyKeywordResult
+        IsKeywordStreamReady
+        InputFinished
+)
+set(mangled_exported_functions)
+foreach(x IN LISTS exported_functions)
+    list(APPEND mangled_exported_functions "_${x}")
+endforeach()
+
+list(JOIN mangled_exported_functions "," all_exported_functions)
+
+include_directories(${CMAKE_SOURCE_DIR})
+set(MY_FLAGS "-s FORCE_FILESYSTEM=1 -s INITIAL_MEMORY=512MB -s ALLOW_MEMORY_GROWTH=1")
+string(APPEND MY_FLAGS " -sSTACK_SIZE=10485760 ")
+string(APPEND MY_FLAGS " -sEXPORTED_FUNCTIONS=[_CopyHeap,_malloc,_free,${all_exported_functions}] ")
+string(APPEND MY_FLAGS "--preload-file ${CMAKE_CURRENT_SOURCE_DIR}/assets@. ")
+string(APPEND MY_FLAGS " -sEXPORTED_RUNTIME_METHODS=['ccall','stringToUTF8','setValue','getValue','lengthBytesUTF8','UTF8ToString'] ")
+message(STATUS "MY_FLAGS: ${MY_FLAGS}")
+
+set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${MY_FLAGS}")
+set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${MY_FLAGS}")
+set(CMAKE_EXECUTBLE_LINKER_FLAGS "${CMAKE_EXECUTBLE_LINKER_FLAGS} ${MY_FLAGS}")
+
+add_executable(sherpa-onnx-wasm-kws-main sherpa-onnx-wasm-main-kws.cc)
+target_link_libraries(sherpa-onnx-wasm-kws-main sherpa-onnx-c-api)
+install(TARGETS sherpa-onnx-wasm-kws-main DESTINATION bin/wasm)
+
+install(
+        FILES
+        "sherpa-onnx-kws.js"
+        "app.js"
+        "index.html"
+        "$<TARGET_FILE_DIR:sherpa-onnx-wasm-kws-main>/sherpa-onnx-wasm-kws-main.js"
+        "$<TARGET_FILE_DIR:sherpa-onnx-wasm-kws-main>/sherpa-onnx-wasm-kws-main.wasm"
+        "$<TARGET_FILE_DIR:sherpa-onnx-wasm-kws-main>/sherpa-onnx-wasm-kws-main.data"
+        DESTINATION
+        bin/wasm
+)
\ No newline at end of file

+// This file copies and modifies code
+// from https://mdn.github.io/web-dictaphone/scripts/app.js
+// and https://gist.github.com/meziantou/edb7217fddfbb70e899e
+
+const startBtn = document.getElementById('startBtn');
+const stopBtn = document.getElementById('stopBtn');
+const clearBtn = document.getElementById('clearBtn');
+const hint = document.getElementById('hint');
+const soundClips = document.getElementById('sound-clips');
+
+let textArea = document.getElementById('results');
+
+let lastResult = '';
+let resultList = [];
+
+clearBtn.onclick = function() {
+  resultList = [];
+  textArea.value = getDisplayResult();
+  textArea.scrollTop = textArea.scrollHeight;  // auto scroll
+};
+
+function getDisplayResult() {
+  let i = 0;
+  let ans = '';
+  for (let s in resultList) {
+    if (resultList[s] == '') {
+      continue;
+    }
+
+    ans += '' + i + ': ' + resultList[s] + '\n';
+    i += 1;
+  }
+
+  return ans;
+}
+
+
+Module = {};
+Module.onRuntimeInitialized = function() {
+  console.log('inited!');
+  hint.innerText = 'Model loaded! Please click start';
+
+  startBtn.disabled = false;
+
+  recognizer = createKws(Module);
+  console.log('recognizer is created!', recognizer);
+};
+
+let audioCtx;
+let mediaStream;
+
+let expectedSampleRate = 16000;
+let recordSampleRate;  // the sampleRate of the microphone
+let recorder = null;   // the microphone
+let leftchannel = [];  // TODO: Use a single channel
+
+let recordingLength = 0;  // number of samples so far
+
+let recognizer = null;
+let recognizer_stream = null;
+
+if (navigator.mediaDevices.getUserMedia) {
+  console.log('getUserMedia supported.');
+
+  // see https://w3c.github.io/mediacapture-main/#dom-mediadevices-getusermedia
+  const constraints = {audio: true};
+
+  let onSuccess = function(stream) {
+    if (!audioCtx) {
+      audioCtx = new AudioContext({sampleRate: 16000});
+    }
+    console.log(audioCtx);
+    recordSampleRate = audioCtx.sampleRate;
+    console.log('sample rate ' + recordSampleRate);
+
+    // creates an audio node from the microphone incoming stream
+    mediaStream = audioCtx.createMediaStreamSource(stream);
+    console.log('media stream', mediaStream);
+
+    // https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/createScriptProcessor
+    // bufferSize: the onaudioprocess event is called when the buffer is full
+    var bufferSize = 4096;
+    var numberOfInputChannels = 1;
+    var numberOfOutputChannels = 2;
+    if (audioCtx.createScriptProcessor) {
+      recorder = audioCtx.createScriptProcessor(
+          bufferSize, numberOfInputChannels, numberOfOutputChannels);
+    } else {
+      recorder = audioCtx.createJavaScriptNode(
+          bufferSize, numberOfInputChannels, numberOfOutputChannels);
+    }
+    console.log('recorder', recorder);
+
+    recorder.onaudioprocess = function(e) {
+      let samples = new Float32Array(e.inputBuffer.getChannelData(0))
+      samples = downsampleBuffer(samples, expectedSampleRate);
+
+      if (recognizer_stream == null) {
+        recognizer_stream = recognizer.createStream();
+      }
+
+      recognizer_stream.acceptWaveform(expectedSampleRate, samples);
+      while (recognizer.isReady(recognizer_stream)) {
+        recognizer.decode(recognizer_stream);
+      }
+
+
+      let result = recognizer.getResult(recognizer_stream);
+      console.log(result)
+
+      if (result.keyword.length > 0) {
+        lastResult = result;
+        resultList.push(JSON.stringify(result));
+      }
+
+
+      textArea.value = getDisplayResult();
+      textArea.scrollTop = textArea.scrollHeight;  // auto scroll
+
+      let buf = new Int16Array(samples.length);
+      for (var i = 0; i < samples.length; ++i) {
+        let s = samples[i];
+        if (s >= 1)
+          s = 1;
+        else if (s <= -1)
+          s = -1;
+
+        samples[i] = s;
+        buf[i] = s * 32767;
+      }
+
+      leftchannel.push(buf);
+      recordingLength += bufferSize;
+    };
+
+    startBtn.onclick = function() {
+      mediaStream.connect(recorder);
+      recorder.connect(audioCtx.destination);
+
+      console.log('recorder started');
+
+      stopBtn.disabled = false;
+      startBtn.disabled = true;
+    };
+
+    stopBtn.onclick = function() {
+      console.log('recorder stopped');
+
+      // stopBtn recording
+      recorder.disconnect(audioCtx.destination);
+      mediaStream.disconnect(recorder);
+
+      startBtn.style.background = '';
+      startBtn.style.color = '';
+      // mediaRecorder.requestData();
+
+      stopBtn.disabled = true;
+      startBtn.disabled = false;
+
+      var clipName = new Date().toISOString();
+
+      const clipContainer = document.createElement('article');
+      const clipLabel = document.createElement('p');
+      const audio = document.createElement('audio');
+      const deleteButton = document.createElement('button');
+      clipContainer.classList.add('clip');
+      audio.setAttribute('controls', '');
+      deleteButton.textContent = 'Delete';
+      deleteButton.className = 'delete';
+
+      clipLabel.textContent = clipName;
+
+      clipContainer.appendChild(audio);
+
+      clipContainer.appendChild(clipLabel);
+      clipContainer.appendChild(deleteButton);
+      soundClips.appendChild(clipContainer);
+
+      audio.controls = true;
+      let samples = flatten(leftchannel);
+      const blob = toWav(samples);
+
+      leftchannel = [];
+      const audioURL = window.URL.createObjectURL(blob);
+      audio.src = audioURL;
+      console.log('recorder stopped');
+
+      deleteButton.onclick = function(e) {
+        let evtTgt = e.target;
+        evtTgt.parentNode.parentNode.removeChild(evtTgt.parentNode);
+      };
+
+      clipLabel.onclick = function() {
+        const existingName = clipLabel.textContent;
+        const newClipName = prompt('Enter a new name for your sound clip?');
+        if (newClipName === null) {
+          clipLabel.textContent = existingName;
+        } else {
+          clipLabel.textContent = newClipName;
+        }
+      };
+    };
+  };
+
+  let onError = function(err) {
+    console.log('The following error occured: ' + err);
+  };
+
+  navigator.mediaDevices.getUserMedia(constraints).then(onSuccess, onError);
+} else {
+  console.log('getUserMedia not supported on your browser!');
+  alert('getUserMedia not supported on your browser!');
+}
+
+
+// this function is copied/modified from
+// https://gist.github.com/meziantou/edb7217fddfbb70e899e
+function flatten(listOfSamples) {
+  let n = 0;
+  for (let i = 0; i < listOfSamples.length; ++i) {
+    n += listOfSamples[i].length;
+  }
+  let ans = new Int16Array(n);
+
+  let offset = 0;
+  for (let i = 0; i < listOfSamples.length; ++i) {
+    ans.set(listOfSamples[i], offset);
+    offset += listOfSamples[i].length;
+  }
+  return ans;
+}
+
+// this function is copied/modified from
+// https://gist.github.com/meziantou/edb7217fddfbb70e899e
+function toWav(samples) {
+  let buf = new ArrayBuffer(44 + samples.length * 2);
+  var view = new DataView(buf);
+
+  // http://soundfile.sapp.org/doc/WaveFormat/
+  //                   F F I R
+  view.setUint32(0, 0x46464952, true);               // chunkID
+  view.setUint32(4, 36 + samples.length * 2, true);  // chunkSize
+  //                   E V A W
+  view.setUint32(8, 0x45564157, true);  // format
+                                        //
+  //                      t m f
+  view.setUint32(12, 0x20746d66, true);          // subchunk1ID
+  view.setUint32(16, 16, true);                  // subchunk1Size, 16 for PCM
+  view.setUint32(20, 1, true);                   // audioFormat, 1 for PCM
+  view.setUint16(22, 1, true);                   // numChannels: 1 channel
+  view.setUint32(24, expectedSampleRate, true);  // sampleRate
+  view.setUint32(28, expectedSampleRate * 2, true);  // byteRate
+  view.setUint16(32, 2, true);                       // blockAlign
+  view.setUint16(34, 16, true);                      // bitsPerSample
+  view.setUint32(36, 0x61746164, true);              // Subchunk2ID
+  view.setUint32(40, samples.length * 2, true);      // subchunk2Size
+
+  let offset = 44;
+  for (let i = 0; i < samples.length; ++i) {
+    view.setInt16(offset, samples[i], true);
+    offset += 2;
+  }
+
+  return new Blob([view], {type: 'audio/wav'});
+}
+
+// this function is copied from
+// https://github.com/awslabs/aws-lex-browser-audio-capture/blob/master/lib/worker.js#L46
+function downsampleBuffer(buffer, exportSampleRate) {
+  if (exportSampleRate === recordSampleRate) {
+    return buffer;
+  }
+  var sampleRateRatio = recordSampleRate / exportSampleRate;
+  var newLength = Math.round(buffer.length / sampleRateRatio);
+  var result = new Float32Array(newLength);
+  var offsetResult = 0;
+  var offsetBuffer = 0;
+  while (offsetResult < result.length) {
+    var nextOffsetBuffer = Math.round((offsetResult + 1) * sampleRateRatio);
+    var accum = 0, count = 0;
+    for (var i = offsetBuffer; i < nextOffsetBuffer && i < buffer.length; i++) {
+      accum += buffer[i];
+      count++;
+    }
+    result[offsetResult] = accum / count;
+    offsetResult++;
+    offsetBuffer = nextOffsetBuffer;
+  }
+  return result;
+};
\ No newline at end of file

+# Introduction
+
+Please refer to
+https://www.modelscope.cn/models/pkufool/sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01/summary
+to download a model.
+
+# Kws
+
+The following is an example:
+```
+cd sherpa-onnx/wasm/kws
+git clone https://www.modelscope.cn/pkufool/sherpa-onnx-kws-zipformer-wenetspeech-3.3M-2024-01-01.git assets
+```
+
+You should have the following files in `assets` before you can run
+`build-wasm-simd-kws.sh`
+
+```
+├── decoder-epoch-12-avg-2-chunk-16-left-64.onnx
+├── encoder-epoch-12-avg-2-chunk-16-left-64.onnx
+├── joiner-epoch-12-avg-2-chunk-16-left-64.onnx
+├── keywords_raw.txt
+├── keywords.txt
+├── README.md
+└── tokens.txt
+
+```

+<html lang="en">
+
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width" />
+  <title>Next-gen Kaldi WebAssembly with sherpa-onnx for kws</title>
+  <style>
+    h1,div {
+      text-align: center;
+    }
+    textarea {
+      width:100%;
+    }
+  </style>
+</head>
+
+<body>
+  <h1>
+    WebAssembly<br/>
+    Kws Demo with <a href="https://github.com/k2-fsa/sherpa-onnx">sherpa-onnx</a>
+  </h1>
+  <div>
+    <span id="hint">Loading model ... ...</span>
+    <br/>
+    <br/>
+    <button id="startBtn" disabled>Start</button>
+    <button id="stopBtn" disabled>Stop</button>
+    <button id="clearBtn">Clear</button>
+    <br/>
+    <br/>
+    <textarea id="results" rows="10" readonly></textarea>
+  </div>
+
+  <section flex="1" overflow="auto" id="sound-clips">
+  </section>
+
+  <script src="sherpa-onnx-kws.js"></script>
+  <script src="app.js"></script>
+  <script src="sherpa-onnx-wasm-kws-main.js"></script>
+</body>
\ No newline at end of file

+
+
+function freeConfig(config, Module) {
+  if ('buffer' in config) {
+    Module._free(config.buffer);
+  }
+  Module._free(config.ptr);
+}
+
+
+function initSherpaOnnxOnlineTransducerModelConfig(config, Module) {
+  const encoderLen = Module.lengthBytesUTF8(config.encoder) + 1;
+  const decoderLen = Module.lengthBytesUTF8(config.decoder) + 1;
+  const joinerLen = Module.lengthBytesUTF8(config.joiner) + 1;
+
+  const n = encoderLen + decoderLen + joinerLen;
+
+  const buffer = Module._malloc(n);
+
+  const len = 3 * 4;  // 3 pointers
+  const ptr = Module._malloc(len);
+
+  let offset = 0;
+  Module.stringToUTF8(config.encoder, buffer + offset, encoderLen);
+  offset += encoderLen;
+
+  Module.stringToUTF8(config.decoder, buffer + offset, decoderLen);
+  offset += decoderLen;
+
+  Module.stringToUTF8(config.joiner, buffer + offset, joinerLen);
+
+  offset = 0;
+  Module.setValue(ptr, buffer + offset, 'i8*');
+  offset += encoderLen;
+
+  Module.setValue(ptr + 4, buffer + offset, 'i8*');
+  offset += decoderLen;
+
+  Module.setValue(ptr + 8, buffer + offset, 'i8*');
+
+  return {
+    buffer: buffer, ptr: ptr, len: len,
+  }
+}
+
+// The user should free the returned pointers
+function initModelConfig(config, Module) {
+  const transducer =
+      initSherpaOnnxOnlineTransducerModelConfig(config.transducer, Module);
+  const paraformer_len = 2 * 4
+  const ctc_len = 1 * 4
+
+  const len = transducer.len + paraformer_len + ctc_len + 5 * 4;
+  const ptr = Module._malloc(len);
+
+  let offset = 0;
+  Module._CopyHeap(transducer.ptr, transducer.len, ptr + offset);
+
+  const tokensLen = Module.lengthBytesUTF8(config.tokens) + 1;
+  const providerLen = Module.lengthBytesUTF8(config.provider) + 1;
+  const modelTypeLen = Module.lengthBytesUTF8(config.modelType) + 1;
+  const bufferLen = tokensLen + providerLen + modelTypeLen;
+  const buffer = Module._malloc(bufferLen);
+
+  offset = 0;
+  Module.stringToUTF8(config.tokens, buffer, tokensLen);
+  offset += tokensLen;
+
+  Module.stringToUTF8(config.provider, buffer + offset, providerLen);
+  offset += providerLen;
+
+  Module.stringToUTF8(config.modelType, buffer + offset, modelTypeLen);
+
+  offset = transducer.len + paraformer_len + ctc_len;
+  Module.setValue(ptr + offset, buffer, 'i8*');  // tokens
+  offset += 4;
+
+  Module.setValue(ptr + offset, config.numThreads, 'i32');
+  offset += 4;
+
+  Module.setValue(ptr + offset, buffer + tokensLen, 'i8*');  // provider
+  offset += 4;
+
+  Module.setValue(ptr + offset, config.debug, 'i32');
+  offset += 4;
+
+  Module.setValue(
+      ptr + offset, buffer + tokensLen + providerLen, 'i8*');  // modelType
+  offset += 4;
+
+  return {
+    buffer: buffer, ptr: ptr, len: len,
+  }
+}
+
+function initFeatureExtractorConfig(config, Module) {
+  let ptr = Module._malloc(4 * 2);
+  Module.setValue(ptr, config.samplingRate, 'i32');
+  Module.setValue(ptr + 4, config.featureDim, 'i32');
+  return {
+    ptr: ptr, len: 8,
+  }
+}
+
+function initKwsConfig(config, Module) {
+  let featConfig =
+      initFeatureExtractorConfig(config.featConfig, Module);
+
+  let modelConfig = initModelConfig(config.modelConfig, Module);
+  let numBytes =
+      featConfig.len + modelConfig.len + 4 * 5;
+
+  let ptr = Module._malloc(numBytes);
+  let offset = 0;
+  Module._CopyHeap(featConfig.ptr, featConfig.len, ptr + offset);
+  offset += featConfig.len;
+
+  Module._CopyHeap(modelConfig.ptr, modelConfig.len, ptr + offset)
+  offset += modelConfig.len;
+
+
+  Module.setValue(ptr + offset, config.maxActivePaths, 'i32');
+  offset += 4;
+
+  Module.setValue(ptr + offset, config.numTrailingBlanks, 'i32');
+  offset += 4;
+
+  Module.setValue(ptr + offset, config.keywordsScore, 'float');
+  offset += 4;
+
+  Module.setValue(ptr + offset, config.keywordsThreshold, 'float');
+  offset += 4;
+
+  let keywordsLen = Module.lengthBytesUTF8(config.keywords) + 1;
+  let keywordsBuffer = Module._malloc(keywordsLen);
+  Module.stringToUTF8(config.keywords, keywordsBuffer, keywordsLen);
+  Module.setValue(ptr + offset, keywordsBuffer, 'i8*');
+  offset += 4;
+
+  return {
+    ptr: ptr, len: numBytes, featConfig: featConfig, modelConfig: modelConfig
+  }
+}
+
+class Stream {
+  constructor(handle, Module) {
+    this.handle = handle;
+    this.pointer = null;
+    this.n = 0;
+    this.Module = Module;
+  }
+
+  free() {
+    if (this.handle) {
+      this.Module._DestroyOnlineKwsStream(this.handle);
+      this.handle = null;
+      this.Module._free(this.pointer);
+      this.pointer = null;
+      this.n = 0;
+    }
+  }
+
+  /**
+   * @param sampleRate {Number}
+   * @param samples {Float32Array} Containing samples in the range [-1, 1]
+   */
+  acceptWaveform(sampleRate, samples) {
+    if (this.n < samples.length) {
+      this.Module._free(this.pointer);
+      this.pointer =
+          this.Module._malloc(samples.length * samples.BYTES_PER_ELEMENT);
+      this.n = samples.length
+    }
+
+    this.Module.HEAPF32.set(samples, this.pointer / samples.BYTES_PER_ELEMENT);
+    this.Module._AcceptWaveform(
+        this.handle, sampleRate, this.pointer, samples.length);
+  }
+
+  inputFinished() {
+    _InputFinished(this.handle);
+  }
+};
+
+class Kws {
+  constructor(configObj, Module) {
+    this.config = configObj;
+    let config = initKwsConfig(configObj, Module)
+    let handle = Module._CreateKeywordSpotter(config.ptr);
+
+
+    freeConfig(config.featConfig, Module);
+    freeConfig(config.modelConfig, Module);
+    freeConfig(config, Module);
+
+    this.handle = handle;
+    this.Module = Module;
+  }
+
+  free() {
+    this.Module._DestroyKeywordSpotter(this.handle);
+    this.handle = 0
+  }
+
+  createStream() {
+    let handle = this.Module._CreateKeywordStream(this.handle);
+    return new Stream(handle, this.Module);
+  }
+
+  isReady(stream) {
+    return this.Module._IsKeywordStreamReady(this.handle, stream.handle) === 1;
+  }
+
+
+  decode(stream) {
+    return this.Module._DecodeKeywordStream(this.handle, stream.handle);
+  }
+
+  getResult(stream) {
+    let r = this.Module._GetKeywordResult(this.handle, stream.handle);
+    let jsonPtr = this.Module.getValue(r + 24, 'i8*');
+    let json = this.Module.UTF8ToString(jsonPtr);
+    this.Module._DestroyKeywordResult(r);
+    return JSON.parse(json);
+  }
+}
+
+function createKws(Module, myConfig) {
+  let transducerConfig = {
+    encoder: './encoder-epoch-12-avg-2-chunk-16-left-64.onnx',
+    decoder: './decoder-epoch-12-avg-2-chunk-16-left-64.onnx',
+    joiner: './joiner-epoch-12-avg-2-chunk-16-left-64.onnx',
+  }
+  let modelConfig = {
+    transducer: transducerConfig,
+    tokens: './tokens.txt',
+    provider: 'cpu',
+    modelType: "",
+    numThreads: 1,
+    debug: 1
+  };
+
+  let featConfig = {
+    samplingRate: 16000,
+    featureDim: 80,
+  };
+
+  let configObj = {
+    featConfig: featConfig,
+    modelConfig: modelConfig,
+    maxActivePaths: 4,
+    numTrailingBlanks: 1,
+    keywordsScore: 1.0,
+    keywordsThreshold: 0.25,
+    keywords: "x iǎo ài t óng x ué @小爱同学\n" +
+        "j ūn g ē n iú b ī @军哥牛逼"
+  };
+
+  if (myConfig) {
+    configObj = myConfig;
+  }
+  return new Kws(configObj, Module);
+}
+
+if (typeof process == 'object' && typeof process.versions == 'object' &&
+    typeof process.versions.node == 'string') {
+  module.exports = {
+    createKws,
+  };
+}
\ No newline at end of file

+// wasm/sherpa-onnx-wasm-main-kws.cc
+//
+// Copyright (c)  2024  lovemefan
+#include <stdio.h>
+
+#include <algorithm>
+#include <memory>
+
+#include "sherpa-onnx/c-api/c-api.h"
+
+// see also
+// https://emscripten.org/docs/porting/connecting_cpp_and_javascript/Interacting-with-code.html
+
+extern "C" {
+
+static_assert(sizeof(SherpaOnnxOnlineTransducerModelConfig) == 3 * 4, "");
+static_assert(sizeof(SherpaOnnxOnlineParaformerModelConfig) == 2 * 4, "");
+static_assert(sizeof(SherpaOnnxOnlineZipformer2CtcModelConfig) == 1 * 4, "");
+static_assert(sizeof(SherpaOnnxOnlineModelConfig) ==
+                  sizeof(SherpaOnnxOnlineTransducerModelConfig) +
+                      sizeof(SherpaOnnxOnlineParaformerModelConfig) +
+                      sizeof(SherpaOnnxOnlineZipformer2CtcModelConfig) + 5 * 4,
+              "");
+static_assert(sizeof(SherpaOnnxFeatureConfig) == 2 * 4, "");
+static_assert(sizeof(SherpaOnnxKeywordSpotterConfig) ==
+                  sizeof(SherpaOnnxFeatureConfig) +
+                      sizeof(SherpaOnnxOnlineModelConfig) + 5 * 4,
+              "");
+
+void CopyHeap(const char *src, int32_t num_bytes, char *dst) {
+  std::copy(src, src + num_bytes, dst);
+}
+}

@@ -37,6 +37,14 @@ set(exported_functions
   DecodeMultipleOfflineStreams
   GetOfflineStreamResult
   DestroyOfflineRecognizerResult
+  # online kws
+  CreateKeywordSpotter
+  DestroyKeywordSpotter
+  CreateKeywordStream
+  DecodeKeywordStream
+  GetKeywordResult
+  DestroyKeywordResult
+  IsKeywordStreamReady
 )
 
 
@@ -69,6 +77,7 @@ install(
   FILES
   ${CMAKE_SOURCE_DIR}/wasm/asr/sherpa-onnx-asr.js
   ${CMAKE_SOURCE_DIR}/wasm/tts/sherpa-onnx-tts.js
+  ${CMAKE_SOURCE_DIR}/wasm/kws/sherpa-onnx-kws.js
     "$<TARGET_FILE_DIR:sherpa-onnx-wasm-nodejs>/sherpa-onnx-wasm-nodejs.js"
     "$<TARGET_FILE_DIR:sherpa-onnx-wasm-nodejs>/sherpa-onnx-wasm-nodejs.wasm"
   DESTINATION