ebiten/audio/internal/convert/stereo16.go

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// Copyright 2017 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"
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"github.com/hajimehoshi/ebiten/v2/audio"
)
type Stereo16 struct {
source audio.ReadSeekCloser
mono bool
eight bool
}
func NewStereo16(source audio.ReadSeekCloser, mono, eight bool) *Stereo16 {
return &Stereo16{
source: source,
mono: mono,
eight: eight,
}
}
func (s *Stereo16) Read(b []uint8) (int, error) {
l := len(b)
if s.mono {
l /= 2
}
if s.eight {
l /= 2
}
buf := make([]uint8, l)
n, err := s.source.Read(buf)
if err != nil && err != io.EOF {
return 0, err
}
switch {
case s.mono && s.eight:
for i := 0; i < n; i++ {
v := int16(int(buf[i])*0x101 - (1 << 15))
b[4*i] = uint8(v)
b[4*i+1] = uint8(v >> 8)
b[4*i+2] = uint8(v)
b[4*i+3] = uint8(v >> 8)
}
case s.mono && !s.eight:
for i := 0; i < n/2; i++ {
b[4*i] = buf[2*i]
b[4*i+1] = buf[2*i+1]
b[4*i+2] = buf[2*i]
b[4*i+3] = buf[2*i+1]
}
case !s.mono && s.eight:
for i := 0; i < n/2; i++ {
v0 := int16(int(buf[2*i])*0x101 - (1 << 15))
v1 := int16(int(buf[2*i+1])*0x101 - (1 << 15))
b[4*i] = uint8(v0)
b[4*i+1] = uint8(v0 >> 8)
b[4*i+2] = uint8(v1)
b[4*i+3] = uint8(v1 >> 8)
}
}
if s.mono {
n *= 2
}
if s.eight {
n *= 2
}
return n, err
}
func (s *Stereo16) Seek(offset int64, whence int) (int64, error) {
if s.mono {
offset /= 2
}
if s.eight {
offset /= 2
}
return s.source.Seek(offset, whence)
}
func (s *Stereo16) Close() error {
return s.source.Close()
}