use crate::opaque::MemDecoder;
use crate::serialize::Decoder;
pub const fn max_leb128_len<T>() -> usize {
(std::mem::size_of::<T>() * 8 + 6) / 7
}
pub const fn largest_max_leb128_len() -> usize {
max_leb128_len::<u128>()
}
macro_rules! impl_write_unsigned_leb128 {
($fn_name:ident, $int_ty:ty) => {
#[inline]
pub fn $fn_name(out: &mut [u8; max_leb128_len::<$int_ty>()], mut value: $int_ty) -> usize {
let mut i = 0;
loop {
if value < 0x80 {
unsafe {
*out.get_unchecked_mut(i) = value as u8;
}
i += 1;
break;
} else {
unsafe {
*out.get_unchecked_mut(i) = ((value & 0x7f) | 0x80) as u8;
}
value >>= 7;
i += 1;
}
}
i
}
};
}
impl_write_unsigned_leb128!(write_u16_leb128, u16);
impl_write_unsigned_leb128!(write_u32_leb128, u32);
impl_write_unsigned_leb128!(write_u64_leb128, u64);
impl_write_unsigned_leb128!(write_u128_leb128, u128);
impl_write_unsigned_leb128!(write_usize_leb128, usize);
macro_rules! impl_read_unsigned_leb128 {
($fn_name:ident, $int_ty:ty) => {
#[inline]
pub fn $fn_name(decoder: &mut MemDecoder<'_>) -> $int_ty {
let byte = decoder.read_u8();
if (byte & 0x80) == 0 {
return byte as $int_ty;
}
let mut result = (byte & 0x7F) as $int_ty;
let mut shift = 7;
loop {
let byte = decoder.read_u8();
if (byte & 0x80) == 0 {
result |= (byte as $int_ty) << shift;
return result;
} else {
result |= ((byte & 0x7F) as $int_ty) << shift;
}
shift += 7;
}
}
};
}
impl_read_unsigned_leb128!(read_u16_leb128, u16);
impl_read_unsigned_leb128!(read_u32_leb128, u32);
impl_read_unsigned_leb128!(read_u64_leb128, u64);
impl_read_unsigned_leb128!(read_u128_leb128, u128);
impl_read_unsigned_leb128!(read_usize_leb128, usize);
macro_rules! impl_write_signed_leb128 {
($fn_name:ident, $int_ty:ty) => {
#[inline]
pub fn $fn_name(out: &mut [u8; max_leb128_len::<$int_ty>()], mut value: $int_ty) -> usize {
let mut i = 0;
loop {
let mut byte = (value as u8) & 0x7f;
value >>= 7;
let more = !(((value == 0) && ((byte & 0x40) == 0))
|| ((value == -1) && ((byte & 0x40) != 0)));
if more {
byte |= 0x80; }
unsafe {
*out.get_unchecked_mut(i) = byte;
}
i += 1;
if !more {
break;
}
}
i
}
};
}
impl_write_signed_leb128!(write_i16_leb128, i16);
impl_write_signed_leb128!(write_i32_leb128, i32);
impl_write_signed_leb128!(write_i64_leb128, i64);
impl_write_signed_leb128!(write_i128_leb128, i128);
impl_write_signed_leb128!(write_isize_leb128, isize);
macro_rules! impl_read_signed_leb128 {
($fn_name:ident, $int_ty:ty) => {
#[inline]
pub fn $fn_name(decoder: &mut MemDecoder<'_>) -> $int_ty {
let mut result = 0;
let mut shift = 0;
let mut byte;
loop {
byte = decoder.read_u8();
result |= <$int_ty>::from(byte & 0x7F) << shift;
shift += 7;
if (byte & 0x80) == 0 {
break;
}
}
if (shift < <$int_ty>::BITS) && ((byte & 0x40) != 0) {
result |= (!0 << shift);
}
result
}
};
}
impl_read_signed_leb128!(read_i16_leb128, i16);
impl_read_signed_leb128!(read_i32_leb128, i32);
impl_read_signed_leb128!(read_i64_leb128, i64);
impl_read_signed_leb128!(read_i128_leb128, i128);
impl_read_signed_leb128!(read_isize_leb128, isize);