-#[inline]
-pub fn write_to_vec(vec: &mut Vec<u8>, byte: u8) {
- vec.push(byte);
-}
-
-#[cfg(target_pointer_width = "32")]
-const USIZE_LEB128_SIZE: usize = 5;
-#[cfg(target_pointer_width = "64")]
-const USIZE_LEB128_SIZE: usize = 10;
-
-macro_rules! leb128_size {
- (u16) => {
- 3
- };
- (u32) => {
- 5
- };
- (u64) => {
- 10
- };
- (u128) => {
- 19
- };
- (usize) => {
- USIZE_LEB128_SIZE
- };
-}
-
macro_rules! impl_write_unsigned_leb128 {
($fn_name:ident, $int_ty:ident) => {
#[inline]
pub fn $fn_name(out: &mut Vec<u8>, mut value: $int_ty) {
- for _ in 0..leb128_size!($int_ty) {
- let mut byte = (value & 0x7F) as u8;
- value >>= 7;
- if value != 0 {
- byte |= 0x80;
- }
-
- write_to_vec(out, byte);
-
- if value == 0 {
+ loop {
+ if value < 0x80 {
+ out.push(value as u8);
break;
+ } else {
+ out.push(((value & 0x7f) | 0x80) as u8);
+ value >>= 7;
}
}
}
($fn_name:ident, $int_ty:ident) => {
#[inline]
pub fn $fn_name(slice: &[u8]) -> ($int_ty, usize) {
- let mut result: $int_ty = 0;
+ let mut result = 0;
let mut shift = 0;
let mut position = 0;
-
- for _ in 0..leb128_size!($int_ty) {
- let byte = unsafe { *slice.get_unchecked(position) };
+ loop {
+ let byte = slice[position];
position += 1;
- result |= ((byte & 0x7F) as $int_ty) << shift;
if (byte & 0x80) == 0 {
- break;
+ result |= (byte as $int_ty) << shift;
+ return (result, position);
+ } else {
+ result |= ((byte & 0x7F) as $int_ty) << shift;
}
shift += 7;
}
-
- // Do a single bounds check at the end instead of for every byte.
- assert!(position <= slice.len());
-
- (result, position)
}
};
}
#[inline]
pub fn write_signed_leb128(out: &mut Vec<u8>, value: i128) {
- write_signed_leb128_to(value, |v| write_to_vec(out, v))
+ write_signed_leb128_to(value, |v| out.push(v))
}
#[inline]