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use crate::{BitBuf, Error, Result, Storage};
impl<S: Storage> BitBuf<S> {
/// Read a BE-bit-order [`u8`] from `byte_offset` without performing bound checks
///
/// # Safety
///
/// * This is UB if [`byte_offset >= self.bytes().len()`][Self::bytes]
///
/// # Panics
///
/// * Panics in debug mode if [`byte_offset >= self.bytes().len()`][Self::bytes]
#[inline(always)]
#[must_use]
pub unsafe fn read_u8_be_aligned_full_at_unchecked(&self, byte_offset: usize) -> u8 {
let bytes = self.bytes();
debug_assert!(
byte_offset < bytes.len(),
"BitBuf::read_u8_be_aligned_full_at_unchecked: index out of bounds! len is {}, offset is {}",
bytes.len(),
byte_offset,
);
unsafe { *bytes.get_unchecked(byte_offset) }
}
/// Read the next BE-bit-order [`u8`] without performing bound checks, advancing the internal cursor
///
/// # Safety
///
/// * The internal cursor must be byte-aligned ([`self.is_aligned()`][Self::is_aligned])
/// * This is UB if the internal cursor points past the end of storage (<code>[self.byte_pos()][Self::byte_pos] >= [self.bytes().len()][Self::bytes]</code>)
///
/// # Panics
///
/// * Panics in debug mode if the internal cursor is not byte-aligned ([`!self.is_aligned()`][Self::is_aligned])
/// * Panics in debug mode if the internal cursor points past the end of storage (<code>[self.byte_pos()][Self::byte_pos] >= [self.bytes().len()][Self::bytes]</code>)
#[inline(always)]
#[must_use]
pub unsafe fn read_u8_be_aligned_full_unchecked(&mut self) -> u8 {
debug_assert!(
self.is_aligned(),
"BitBuf::read_u8_be_aligned_full_unchecked called at unaligned bit position: {}",
self.pos(),
);
let b = unsafe { self.read_u8_be_aligned_full_at_unchecked(self.byte_pos()) };
self.advance_bytes(1);
b
}
/// Read a BE-bit-order [`u8`] from `offset` without performing bound checks
///
/// # Safety
///
/// * This is UB if <code>(offset / 8) >= [`self.bytes().len()`][Self::bytes]</code>
/// * This is UB if <code>(offset % 8 != 0) && (offset / 8) + 1 >= [`self.bytes().len()`][Self::bytes]</code>
///
/// # Panics
///
/// * Panics in debug mode if <code>(offset / 8) >= [`self.bytes().len()`][Self::bytes]</code>
/// * Panics in debug mode if <code>(offset % 8 != 0) && (offset / 8) + 1 >= [`self.bytes().len()`][Self::bytes]</code>
#[inline(always)]
#[must_use]
pub unsafe fn read_u8_be_full_at_unchecked(&self, offset: usize) -> u8 {
let byte_idx = offset / 8;
let shift = offset % 8;
let bytes = self.bytes();
debug_assert!(
byte_idx < bytes.len(),
"BitBuf::read_u8_be_full_at_unchecked: index out of bounds! len is {}, byte_idx is {}",
bytes.len(),
byte_idx,
);
if shift == 0 {
unsafe { self.read_u8_be_aligned_full_at_unchecked(byte_idx) }
} else {
let next_idx = byte_idx + 1;
debug_assert!(
next_idx < bytes.len(),
"BitBuf::read_u8_be_full_at_unchecked: lookahead index out of bounds! len is {}, lookahead byte_idx is {}",
bytes.len(),
next_idx,
);
let (high, low) = unsafe {
(
*bytes.get_unchecked(byte_idx),
*bytes.get_unchecked(next_idx),
)
};
(high << shift) | (low >> (8 - shift))
}
}
/// Read a BE-bit-order [`u8`] from `offset` while performing bound checks
///
/// # Errors
///
/// * Returns [`Error::OutOfBounds`]
/// * if <code>(offset / 8) >= [`self.bytes().len()`][Self::bytes]</code>
/// * if <code>(offset % 8 != 0) && (offset / 8) + 1 >= [`self.bytes().len()`][Self::bytes]</code>
#[inline(always)]
pub fn try_read_u8_be_full_at(&self, offset: usize) -> Result<u8> {
let byte_idx = offset / 8;
let shift = offset % 8;
let len = self.bytes().len();
if byte_idx >= len {
return Err(Error::OutOfBounds);
}
if shift != 0 && byte_idx + 1 >= len {
return Err(Error::OutOfBounds);
}
Ok(unsafe { self.read_u8_be_full_at_unchecked(offset) })
}
/// Read a BE-bit-order [`u8`] from `offset`, panicking on out of bounds
///
/// # Panics
///
/// * Panics if <code>(offset / 8) >= [`self.bytes().len()`][Self::bytes]</code>
/// * Panics if <code>(offset % 8 != 0) && (offset / 8) + 1 >= [`self.bytes().len()`][Self::bytes]</code>
#[inline(always)]
#[must_use]
pub fn read_u8_be_full_at(&self, offset: usize) -> u8 {
self
.try_read_u8_be_full_at(offset)
.expect("BitBuf::read_u8_be_full_at out of bounds")
}
}