Macro bit_fiddler::toggle

macro_rules! toggle {
    ($bitmap: tt, $ty: ty, [..]) => { ... };
    (in $bitmap: ident, $ty: ty, [..]) => { ... };
    ($bitmap: tt, $ty: ty, rev [..]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [..]) => { ... };
    ($bitmap: tt, $ty: ty, [$( $bit_pos: tt),*]) => { ... };
    (in $bitmap: ident, $ty: ty, [$( $bit_pos: tt),*]) => { ... };
    ($bitmap: tt, $ty: ty, rev [$( $bit_pos: tt),*]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [$( $bit_pos: tt),*]) => { ... };
    ($bitmap: tt, $ty: ty, [$start_pos: tt .. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, [.. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, [$start_pos: tt ..]) => { ... };
    (in $bitmap: ident, $ty: ty, [$start_pos: tt .. $end_pos: tt]) => { ... };
    (in $bitmap: ident, $ty: ty, [$start_pos: tt ..]) => { ... };
    (in $bitmap: ident, $ty: ty, [.. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, [start = $start_pos: tt, count = $count: tt]) => { ... };
    (in $bitmap: ident, $ty: ty, [start = $start_pos: tt, count = $count: tt]) => { ... };
    ($bitmap: tt, $ty: ty, rev [$start_pos: tt .. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, rev [.. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, rev [$start_pos: tt ..]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [$start_pos: tt .. $end_pos: tt]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [$start_pos: tt ..]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [.. $end_pos: tt]) => { ... };
    ($bitmap: tt, $ty: ty, rev [start = $start_pos: tt, count = $count: tt]) => { ... };
    (in $bitmap: ident, $ty: ty, rev [start = $start_pos: tt, count = $count: tt]) => { ... };
    ($bitmap: tt, $ty: ty, rev $bit_pos: tt) => { ... };
    (in $bitmap: ident, $ty: ty, rev $bit_pos: tt) => { ... };
    ($bitmap: tt, $ty: ty, $bit_pos: tt) => { ... };
    (in $bitmap: ident, $ty: ty, $bit_pos: tt) => { ... };
}

Macro for toggling single, multiple or range of bits. It accepts multiple patterns for different use cases. It doesn't do any overflow or underflow checks. Behaviour on passing invalid args is undefined.

For all patterns, first arg is the bitmap. Bitmap can be passed in 2 ways:

In first case, it will return the resultant bitmap after toggling bits without making any changes to the bitmap passed.

let bitmap: u8 = 0b_1010_1010;
let res = toggle!(bitmap, u8, ...);
assert_eq!(bitmap, 0b_1010_1010); // Stays same
println!("{:#b}", res); // new bitmap with bits unset

In this case, bitmap can also be a literal:

// bits will be toggled on 0b_0000_0101 and moved to res
let res = toggle!(0b_0000_0101, ...);

In the second case, we use in before the bitmap. This pattern will make changes to the bitmap itself and return nothing.

let mut bitmap = 0b_1111_1111;
toggle!(in bitmap, u8, ...);
// bits were toggled in bitmap

Another common thing in these patterns is rev. All patterns support this. Putting rev before the bits being toggled makes the macro toggle the bits from left hand side. Without rev, bits will be toggled from right hand side.

For example,

let mut bitmap: u8 = 0b_0010_0100;

// Toggling 2nd and 3rd bit from rhs
toggle!(in bitmap, u8, [2, 3]);
assert_eq!(bitmap, 0b_0010_1000);

// Unsetting 2nd and 3rd bit from lhs
toggle!(in bitmap, u8, rev [2, 3]);
assert_eq!(bitmap, 0b_0001_1000);

Examples

use bit_fiddler::toggle;

// Toggle third bit from the right and return the resulting bitmap.
let bitmap = 0b100;
let x = toggle!(bitmap, u8, 2);
assert_eq!(x, 0);

// Toggle third bit from the right in the passed bitmap itself.
let mut bitmap = 0b100;
toggle!(in bitmap, u8, 2);
assert_eq!(bitmap, 0);

// Toggle third bit from the left and return the resulting bitmap.
let bitmap: u8 = 0b_0010_0000;
let x = toggle!(bitmap, u8, rev 2);
assert_eq!(x, 0);

// Toggle third bit from the left in the passed bitmap itself.
let mut bitmap: u8 = 0b_0010_0000;
toggle!(in bitmap, u8, rev 2);
assert_eq!(bitmap, 0);

// Toggle second, third & fourth bit from the right and return the resulting bitmap.
let bitmap = 0b1010;
let x = toggle!(bitmap, u8, [1, 2, 3]);
assert_eq!(x, 0b0100);

// Toggle second, third & fourth bit from the right in the passed bitmap itself.
let mut bitmap = 0b1010;
toggle!(in bitmap, u8, [1, 2, 3]);
assert_eq!(bitmap, 0b0100);

// Toggle second, third & fourth bit from the left and return the resulting bitmap.
let bitmap: u8 = 0b0101_0000;
let x = toggle!(bitmap, u8, rev [1, 2, 3]);
assert_eq!(x, 0b0010_0000);

// Toggle second, third & fourth bit from the left in the passed bitmap itself.
let mut bitmap: u8 = 0b0101_0000;
toggle!(in bitmap, u8, rev [1, 2, 3]);
assert_eq!(bitmap, 0b0010_0000);

// Toggle second & third (1 and 2) bit from the right and return the resulting bitmap.
let bitmap = 0b100;
let x = toggle!(bitmap, u8, [1..3]);
assert_eq!(x, 0b010);

// Toggle second & third bit (1 and 2) from the right in the passed bitmap itself.
let mut bitmap = 0b100;
toggle!(in bitmap, u8, [1..3]);
assert_eq!(bitmap, 0b010);

// Starting from second bit, toggle 2 bits from the right and return the resulting bitmap.
let bitmap = 0b110;
let x = toggle!(bitmap, u8, [start = 1, count = 2]);
assert_eq!(x, 0);

// Starting from second bit, toggle 2 bits from the right in the passed bitmap itself.
let mut bitmap = 0b110;
toggle!(in bitmap, u8, [start = 1, count = 2]);
assert_eq!(bitmap, 0);

// Toggle second & third bit (1 and 2) from the left and return the resulting bitmap.
let bitmap: u8 = 0b_0110_0000;
let x = toggle!(bitmap, u8, rev [1..3]);
assert_eq!(x, 0);

// Toggle second & third bit (1 and 2) from the left in the passed bitmap itself.
let mut bitmap: u8 = 0b_0110_0000;
toggle!(in bitmap, u8, rev [1..3]);
assert_eq!(bitmap, 0);

// Starting from second bit, toggle 2 bits from the left and return the resulting bitmap.
let bitmap: u8 = 0b_0110_0000;
let x = toggle!(bitmap, u8, rev [start = 1, count = 2]);
assert_eq!(x, 0);

// Starting from second bit, toggle 2 bits from the left in the passed bitmap itself.
let mut bitmap: u8 = 0b_0110_0000;
toggle!(in bitmap, u8, rev [start = 1, count = 2]);
assert_eq!(bitmap, 0);