70 lines
2.1 KiB
Rust
70 lines
2.1 KiB
Rust
use crate::{config::Endian, de::read::Reader, error::DecodeError};
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pub fn varint_decode_i16<R: Reader>(read: &mut R, endian: Endian) -> Result<i16, DecodeError> {
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let n = super::varint_decode_u16(read, endian)?;
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Ok(if n % 2 == 0 {
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// positive number
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(n / 2) as _
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} else {
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// negative number
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// !m * 2 + 1 = n
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// !m * 2 = n - 1
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// !m = (n - 1) / 2
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// m = !((n - 1) / 2)
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// since we have n is odd, we have floor(n / 2) = floor((n - 1) / 2)
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!(n / 2) as _
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})
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}
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pub fn varint_decode_i32<R: Reader>(read: &mut R, endian: Endian) -> Result<i32, DecodeError> {
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let n = super::varint_decode_u32(read, endian)?;
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Ok(if n % 2 == 0 {
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// positive number
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(n / 2) as _
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} else {
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// negative number
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// !m * 2 + 1 = n
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// !m * 2 = n - 1
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// !m = (n - 1) / 2
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// m = !((n - 1) / 2)
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// since we have n is odd, we have floor(n / 2) = floor((n - 1) / 2)
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!(n / 2) as _
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})
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}
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pub fn varint_decode_i64<R: Reader>(read: &mut R, endian: Endian) -> Result<i64, DecodeError> {
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let n = super::varint_decode_u64(read, endian)?;
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Ok(if n % 2 == 0 {
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// positive number
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(n / 2) as _
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} else {
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// negative number
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// !m * 2 + 1 = n
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// !m * 2 = n - 1
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// !m = (n - 1) / 2
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// m = !((n - 1) / 2)
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// since we have n is odd, we have floor(n / 2) = floor((n - 1) / 2)
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!(n / 2) as _
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})
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}
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pub fn varint_decode_i128<R: Reader>(read: &mut R, endian: Endian) -> Result<i128, DecodeError> {
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let n = super::varint_decode_u128(read, endian)?;
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Ok(if n % 2 == 0 {
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// positive number
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(n / 2) as _
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} else {
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// negative number
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// !m * 2 + 1 = n
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// !m * 2 = n - 1
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// !m = (n - 1) / 2
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// m = !((n - 1) / 2)
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// since we have n is odd, we have floor(n / 2) = floor((n - 1) / 2)
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!(n / 2) as _
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})
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}
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pub fn varint_decode_isize<R: Reader>(read: &mut R, endian: Endian) -> Result<isize, DecodeError> {
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varint_decode_i64(read, endian).map(|v| v as isize)
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}
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