func (editor *FlacTagEditor) getSizesAndPositions() (int, int, int, int) {
commentPosition := 0
commentSize := 0
picturePosition := 0
pictureSize := 0
data := editor.file[4:]
lastBlock := false
currentPosition := 4
for len(data) > 3 && !lastBlock {
blockType := data[0] & (^lastMetaBlockFlag)
blockSize := utils.ReadInt24Be(data[1:4]) + 4
switch blockType {
case commentBlockType:
commentPosition = currentPosition
commentSize = blockSize
case pictureBlockType:
if blockSize > pictureSize {
picturePosition = currentPosition
pictureSize = blockSize
}
}
lastBlock = data[0]&lastMetaBlockFlag == lastMetaBlockFlag
currentPosition += blockSize
data = data[blockSize:]
}
return commentPosition, commentSize, picturePosition, pictureSize
}
func (editor *FlacTagEditor) findAndRemoveLastMetaBlockFlag(blocks []byte) bool {
for len(blocks) > 3 {
if blocks[0]&lastMetaBlockFlag == lastMetaBlockFlag {
blocks[0] &= (^lastMetaBlockFlag)
return true
}
blockSize := utils.ReadInt24Be(blocks[1:4]) + 4
blocks = blocks[blockSize:]
}
return false
}