bundle a fftw-js compiled with latest emscripten for any files length…

… analysis

due to the latest emscripten the library interface was slightly updated with promise based initialization

README.md

@@ -38,14 +38,14 @@ Run the demo in default browser (which will use `http-server` to avoid CORS issu
 `npm install ccwt.js --save`
 
 ```js
-let CCWT = require('ccwt.js')
+const CCWT = require('ccwt.js')
 
-CCWT.onReady = function () {
-    // CCWT.frequencyBand
-    // CCWT.fft1d
-    // CCWT.numericOutput
+CCWT.then((ccwt_lib) => {
+    // ccwt_lib.frequencyBand
+    // ccwt_lib.fft1d
+    // ccwt_lib.numericOutput
     // see demo/index.html :)
-}
+});
 ```
 
 ## Browser
@@ -54,7 +54,7 @@ See `demo/index.html`
 
 ## Documentation
 
-First register a ready callback to `CCWT.onReady`, it will fire once the library is initialized
+Include the library file `ccwt.js`, the web version define a `CCWT` symbol globally which is a promise (which load the FFTW .wasm file) which when resolved return the CCWT library object where all functions are defined.
 
 Then there is only 3 functions needed :
 
@@ -71,3 +71,29 @@ The provided example `demo/index.html` has everything needed to generate a linea
 All usable CCWT functions in `src/ccwt.js` are documented using JSDoc
 
 The [original tutorial](https://github.com/Lichtso/CCWT/wiki/Tutorial) can also help (note : functions name are the same but arguments orders aren't)
+
+## fftw-js
+
+This library use a modified [fftw-js](https://github.com/dean-shaff/fftw-js) library which is a Javascript port via Emscripten of the FFTW library.
+
+The modifications include :
+
+* compiled with Emscripten 1.39.17 (latest right now)
+* compiled with `-s ALLOW_MEMORY_GROWTH=1` to allow arbitrary files length analysis
+
+There is also a small modification of the glue code to silence warnings related to errno.
+
+Note : The original `Makefile.emscripten` of the fftw-js library had to be modified a bit to produce a correct build, here are the options used : 
+
+```bash
+OPTIONS=--memory-init-file 0 \
+                                 -s FILESYSTEM=0 \
+                                 -s PRECISE_F32=1 \
+                                 -s MODULARIZE=1 \
+                                 -s WASM=1 \
+                                 -s ALLOW_MEMORY_GROWTH=1 \
+                                 -s EXPORT_NAME="'FFTWModule'" \
+                                 -s EXPORTED_FUNCTIONS=$(EXPORTED_FUNCTIONS) \
+                                 -s "EXTRA_EXPORTED_RUNTIME_METHODS=['ccall', 'cwrap']"
+
+```

demo/index.html

@@ -20,7 +20,7 @@
       canvas_ctx.fillStyle = "#000000"
       canvas_ctx.fillRect(0, 0, canvas.width, canvas.height)
 
-      CCWT.onReady = function () {
+      CCWT.then((ccwt_lib) => {
         // load audio
         const audio_context = new window.AudioContext({
           sampleRate: 44100
@@ -56,15 +56,15 @@
             const frequency_offset_log = minimum_octave
 
             // linear
-            //CCWT.frequencyBand(frequencies, height, frequency_range_linear, frequency_offset_linear, frequency_basis_linear, deviation)
+            //ccwt_lib.frequencyBand(frequencies, height, frequency_range_linear, frequency_offset_linear, frequency_basis_linear, deviation)
 
             // logarithmic
-            const frequencies = CCWT.frequencyBand(height, frequency_range_log, frequency_offset_log, frequency_basis_log, deviation)
+            const frequencies = ccwt_lib.frequencyBand(height, frequency_range_log, frequency_offset_log, frequency_basis_log, deviation)
 
             // add some padding to avoid start / end oddities (when there is data at one/both end of the signal)
             const padding = 0
             const gain_factor = 30
-            const fourier_transformed_signal = CCWT.fft1d(pcmf32_buffer, padding, gain_factor)
+            const fourier_transformed_signal = ccwt_lib.fft1d(pcmf32_buffer, padding, gain_factor)
 
             const pixels_per_second = 60
             const output_width = Math.floor(length_in_seconds * pixels_per_second)
@@ -116,14 +116,14 @@
             canvas.width = output_width
             canvas.height = height
 
-            CCWT.numericOutput(fourier_transformed_signal, padding, frequencies, 0, frequencies.length / 2, output_width, row_callback)
+            ccwt_lib.numericOutput(fourier_transformed_signal, padding, frequencies, 0, frequencies.length / 2, output_width, row_callback)
           }, function () {
             window.alert('Could not load audio file.')
           })
 
         }
         request.send()
-      }
+      })
     }
     </script>
   </body>

src/ccwt.js

@@ -12,11 +12,11 @@ const FFTW_BACKWARD = 1
 const FFTW_MEASURE = 0
 const FFTW_ESTIMATE = (1 << 6)
 
-const CCWT = {
-    onReady: null
-}
+const CCWT_obj = fftw_runtime.then((fftw_runtime) => {
+    const CCWT = {
+
+    };
 
-fftw_runtime.onRuntimeInitialized = () => {
     // initialize fftw functions
     const fftwf_plan_dft_r2c_1d = fftw_runtime.cwrap('fftwf_plan_dft_r2c_1d', 'number', ['number', 'number', 'number', 'number'])
 
@@ -74,7 +74,10 @@ fftw_runtime.onRuntimeInitialized = () => {
         fftwf_free(input_ptr)
         fftwf_free(output_ptr)
 
-        return output.slice()
+        // due to memory growth build a new buffer view
+        const output_data = new Float32Array(fftw_runtime.HEAPU8.buffer, output_ptr, input_sample_count * 2)
+
+        return output_data
     }
 
     /**
@@ -243,11 +246,7 @@ fftw_runtime.onRuntimeInitialized = () => {
         return 0
     }
 
-    if (CCWT.onReady !== null) {
-        CCWT.onReady()
-    } else {
-        console.log("ccwt.js : unregistered onReady callback")
-    }
-}
+    return CCWT;
+});
 
-module.exports = CCWT
+module.exports = CCWT_obj