ebiten/audio/vorbis/internal/stb/decode.go

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// Copyright 2018 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package stb
import (
"fmt"
"io"
"github.com/gopherjs/gopherwasm/js"
)
var flatten = js.Global().Get("window").Call("eval", `(function(arr) {
var ch = arr.length;
var len = arr[0].length;
var result = new Float32Array(ch * len);
for (var j = 0; j < len; j++) {
for (var i = 0; i < ch; i++) {
result[j*ch+i] = arr[i][j];
}
}
return result;
})`)
func init() {
// Eval wasm.js first to set the Wasm binary to Module.
js.Global().Get("window").Call("eval", string(stbvorbis_js))
}
type Samples struct {
samples [][]float32
length int64
}
func (s *Samples) Read(buf []float32) (int, error) {
if len(s.samples) == 0 {
return 0, io.EOF
}
n := copy(buf, s.samples[0])
s.samples[0] = s.samples[0][n:]
if len(s.samples[0]) == 0 {
s.samples = s.samples[1:]
}
return n, nil
}
func (s *Samples) Length() int64 {
return s.length
}
func DecodeVorbis(buf []byte) (*Samples, int, int, error) {
ch := make(chan error)
samples := &Samples{}
channels := 0
sampleRate := 0
var f js.Callback
f = js.NewCallback(func(args []js.Value) {
r := args[0]
if e := r.Get("error"); e != js.Null() {
ch <- fmt.Errorf("audio/vorbis/internal/stb: decode error: %s", e.String())
close(ch)
f.Release()
return
}
if r.Get("eof").Bool() {
close(ch)
f.Release()
return
}
if channels == 0 {
channels = r.Get("data").Length()
}
if sampleRate == 0 {
sampleRate = r.Get("sampleRate").Int()
}
flattened := flatten.Invoke(r.Get("data"))
s := make([]float32, flattened.Length())
arr := js.TypedArrayOf(s)
arr.Call("set", flattened)
arr.Release()
samples.samples = append(samples.samples, s)
samples.length += int64(len(s)) / int64(channels)
})
arr := js.TypedArrayOf(buf)
js.Global().Get("stbvorbis").Call("decode", arr, f)
arr.Release()
if err := <-ch; err != nil {
return nil, 0, 0, err
}
return samples, channels, sampleRate, nil
}