ebiten/audio/internal/convert/float32.go

92 lines
1.6 KiB
Go

// Copyright 2019 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 convert
import (
"io"
)
type Float32Reader interface {
Read([]float32) (int, error)
}
func NewReaderFromFloat32Reader(r Float32Reader) io.Reader {
return &f32Reader{r: r}
}
type f32Reader struct {
r Float32Reader
eof bool
buf *byte
fbuf []float32
}
func max(a, b int) int {
if a < b {
return b
}
return a
}
func (f *f32Reader) Read(buf []byte) (int, error) {
if f.eof {
return 0, io.EOF
}
if len(buf) == 0 {
return 0, nil
}
if f.buf != nil {
buf[0] = *f.buf
f.buf = nil
return 1, nil
}
l := max(len(buf)/2, 1)
ll := len(f.fbuf)
if ll < 16 {
ll = 16
}
for ll < l {
ll *= 2
}
f.fbuf = make([]float32, ll)
n, err := f.r.Read(f.fbuf[:l])
if err != nil && err != io.EOF {
return 0, err
}
if err == io.EOF {
f.eof = true
}
b := buf
if len(buf) == 1 && n > 0 {
b = make([]byte, 2)
}
for i := 0; i < n; i++ {
f := f.fbuf[i]
s := int16(f * (1<<15 - 1))
b[2*i] = uint8(s)
b[2*i+1] = uint8(s >> 8)
}
if len(buf) == 1 && len(b) == 2 {
buf[0] = b[0]
f.buf = &b[1]
return 1, err
}
return n * 2, err
}