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use std::mem;
use futures::{AsyncSeek, AsyncSeekExt};
use std::io::SeekFrom;
use crate::error::MP4Error;
#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
pub enum BoxSize {
Known(usize),
Unknown
}
impl BoxSize {
pub fn from_size_without_self(size: usize) -> Self {
Self::Known(size + if cfg!(target_pointer_width = "64") {
mem::size_of::<u32>() + if size + mem::size_of::<u32>() > u32::MAX as usize {
mem::size_of::<u64>()
} else {
0
}
} else {
mem::size_of::<u32>()
})
}
pub fn byte_size(&self) -> usize {
match self {
BoxSize::Known(size) => {
if cfg!(target_pointer_width = "64") {
mem::size_of::<u32>() + if size > &(u32::MAX as usize) {
mem::size_of::<u64>()
} else {
0
}
} else {
mem::size_of::<u32>()
}
}
BoxSize::Unknown => mem::size_of::<u32>()
}
}
pub async fn ended<R: AsyncSeek + Unpin>(&self, start: u64, reader: &mut R) -> Result<bool, MP4Error> {
Ok(match self {
BoxSize::Known(size) => {
let size = *size as i64;
let mut pos = reader.seek(SeekFrom::Current(0)).await?;
let read = (pos - start) as i64;
if read > size {
reader.seek(SeekFrom::Current(size - read)).await?;
}
read >= size
}
BoxSize::Unknown => false
})
}
}