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#[macro_export]
macro_rules! bits (
($i:expr, $submac:ident!( $($args:tt)* )) => (
bits_impl!($i, $submac!($($args)*));
);
($i:expr, $f:expr, $g:expr) => (
bits_impl!($i, call!($f));
);
);
#[macro_export]
macro_rules! bits_impl (
($i:expr, $submac:ident!( $($args:tt)* )) => (
{
let input = ($i, 0usize);
match $submac!( input, $($args)*) {
$crate::IResult::Error(e) => $crate::IResult::Error(e),
$crate::IResult::Incomplete($crate::Needed::Unknown) => $crate::IResult::Incomplete($crate::Needed::Unknown),
$crate::IResult::Incomplete($crate::Needed::Size(i)) => $crate::IResult::Incomplete($crate::Needed::Size(i)),
$crate::IResult::Done((i, bit_index), o) => {
let byte_index = if bit_index == 0 { 0 } else { 1 };
$crate::IResult::Done(&i[byte_index..], o)
}
}
}
);
);
#[macro_export]
macro_rules! take_bits (
($i:expr, $t:ty, $count:expr) => (
{
use std::ops::Div;
let (input, bit_offset) = $i;
if $count == 0 {
$crate::IResult::Done( (input, bit_offset), 0)
} else {
let cnt = ($count as usize + bit_offset).div(8);
if input.len() * 8 < $count as usize + bit_offset {
$crate::IResult::Incomplete($crate::Needed::Size(cnt+1))
} else {
let mut acc:$t = 0;
let mut offset: usize = bit_offset;
let mut remaining: usize = $count;
let mut end_offset: usize = 0;
for it in 0..cnt+1 {
if remaining == 0 {
break;
}
let val: $t = if offset == 0 {
input[it] as $t
} else {
((input[it] << offset) as u8 >> offset) as $t
};
if remaining < 8 - offset {
acc += val >> (8 - offset - remaining);
end_offset = remaining + offset;
break;
} else {
acc += val << remaining - (8 - offset);
remaining -= 8 - offset;
offset = 0;
}
}
$crate::IResult::Done( (&input[cnt..], end_offset) , acc)
}
}
}
);
);
#[cfg(test)]
mod tests {
use internal::{IResult,Needed};
#[test]
fn take_bits() {
let input = vec![0b10101010, 0b11110000, 0b00110011];
let sl = &input[..];
assert_eq!(take_bits!( (sl, 0), u8, 0 ), IResult::Done((sl, 0), 0));
assert_eq!(take_bits!( (sl, 0), u8, 8 ), IResult::Done((&sl[1..], 0), 170));
assert_eq!(take_bits!( (sl, 0), u8, 3 ), IResult::Done((&sl[0..], 3), 5));
assert_eq!(take_bits!( (sl, 0), u8, 6 ), IResult::Done((&sl[0..], 6), 42));
assert_eq!(take_bits!( (sl, 1), u8, 1 ), IResult::Done((&sl[0..], 2), 0));
assert_eq!(take_bits!( (sl, 1), u8, 2 ), IResult::Done((&sl[0..], 3), 1));
assert_eq!(take_bits!( (sl, 1), u8, 3 ), IResult::Done((&sl[0..], 4), 2));
assert_eq!(take_bits!( (sl, 6), u8, 3 ), IResult::Done((&sl[1..], 1), 5));
assert_eq!(take_bits!( (sl, 0), u16, 10 ), IResult::Done((&sl[1..], 2), 683));
assert_eq!(take_bits!( (sl, 0), u16, 8 ), IResult::Done((&sl[1..], 0), 170));
assert_eq!(take_bits!( (sl, 6), u16, 10 ), IResult::Done((&sl[2..], 0), 752));
assert_eq!(take_bits!( (sl, 6), u16, 11 ), IResult::Done((&sl[2..], 1), 1504));
assert_eq!(take_bits!( (sl, 0), u32, 20 ), IResult::Done((&sl[2..], 4), 700163));
assert_eq!(take_bits!( (sl, 4), u32, 20 ), IResult::Done((&sl[3..], 0), 716851));
assert_eq!(take_bits!( (sl, 4), u32, 22 ), IResult::Incomplete(Needed::Size(4)));
}
}