nodemcu-firmware/docs/modules/bit.md

# bit Module
| Since  | Origin / Contributor  | Maintainer  | Source  |
| :----- | :-------------------- | :---------- | :------ |
| 2014-12-24 | [https://github.com/LuaDist/bitlib](https://github.com/LuaDist/bitlib), [Zeroday](https://github.com/funshine) | [Zeroday](https://github.com/funshine) | [bit.c](../../app/modules/bit.c)|


Bit manipulation support, on 32bit integers.

## bit.arshift()
Arithmetic right shift a number equivalent to `value >> shift` in C.

#### Syntax
`bit.arshift(value, shift)`

#### Parameters
- `value` the value to shift
- `shift` positions to shift

#### Returns
the number shifted right (arithmetically)

#### Example
```lua
bit.arshift(3, 1) -- returns 1
-- Using a 4 bits representation: 0011 >> 1 == 0001
```

## bit.band()

Bitwise AND, equivalent to `val1 & val2 & ... & valn` in C.

#### Syntax
`bit.band(val1, val2 [, ... valn])`

#### Parameters
 - `val1` first AND argument
 - `val2` second AND argument
 - `...valn` ...nth AND argument

#### Returns
the bitwise AND of all the arguments (number)

### Example
```lua
bit.band(3, 2) -- returns 2
-- Using a 4 bits representation: 0011 & 0010 == 0010
```

## bit.bit()

Generate a number with a 1 bit (used for mask generation). Equivalent to `1 << position` in C.

#### Syntax
`bit.bit(position)`

#### Parameters
`position` position of the bit that will be set to 1

#### Returns
a number with only one 1 bit at position (the rest are set to 0)

### Example
```lua
bit.bit(4) -- returns 16
```

## bit.bnot()

Bitwise negation, equivalent to `~value in C.`

#### Syntax
`bit.bnot(value)`

#### Parameters
`value` the number to negate

#### Returns
the bitwise negated value of the number

## bit.bor()
Bitwise OR, equivalent to `val1 | val2 | ... | valn` in C.

#### Syntax
`bit.bor(val1, val2 [, ... valn])`

#### Parameters
- `val1` first OR argument.
- `val2` second OR argument.
- `...valn` ...nth OR argument

#### Returns
the bitwise OR of all the arguments (number)

### Example
```lua
bit.bor(3, 2) -- returns 3
-- Using a 4 bits representation: 0011 | 0010 == 0011
```

## bit.bxor()

Bitwise XOR, equivalent to `val1 ^ val2 ^ ... ^ valn` in C.

#### Syntax
`bit.bxor(val1, val2 [, ... valn])`

#### Parameters
- `val1` first XOR argument
- `val2` second XOR argument
- `...valn` ...nth XOR argument

#### Returns
the bitwise XOR of all the arguments (number)

### Example
```lua
bit.bxor(3, 2) -- returns 1
-- Using a 4 bits representation: 0011 ^ 0010 == 0001
```

## bit.clear()
Clear bits in a number.

#### Syntax
`bit.clear(value, pos1 [, ... posn])`

#### Parameters
- `value` the base number
- `pos1` position of the first bit to clear
- `...posn` position of thet nth bit to clear

#### Returns
the number with the bit(s) cleared in the given position(s)

### Example
```lua
bit.clear(3, 0) -- returns 2
```

## bit.isclear()
Test if a given bit is cleared.

#### Syntax
`bit.isclear(value, position)`

#### Parameters
- `value` the value to test
- `position` bit position to test

#### Returns
true if the bit at the given position is 0, false otherwise

### Example
```lua
bit.isclear(2, 0) -- returns true
```

## bit.isset()

Test if a given bit is set.

#### Syntax
`bit.isset(value, position)`

#### Parameters
- `value` the value to test
- `position` bit position to test

#### Returns
true if the bit at the given position is 1, false otherwise

### Example
```lua
bit.isset(2, 0) -- returns false
```

## bit.lshift()
Left-shift a number, equivalent to `value << shift` in C.

#### Syntax
`bit.lshift(value, shift)`

#### Parameters
- `value` the value to shift
- `shift` positions to shift

#### Returns
the number shifted left

### Example
```lua
bit.lshift(2, 2) -- returns 8
-- Using a 4 bits representation: 0010 << 2 == 1000
```

## bit.rshift()

Logical right shift a number, equivalent to `( unsigned )value >> shift` in C.

#### Syntax
`bit.rshift(value, shift)`

#### Parameters
- `value` the value to shift.
- `shift` positions to shift.

#### Returns
the number shifted right (logically)

### Example
```lua
bit.rshift(2, 1) -- returns 1
-- Using a 4 bits representation: 0010 >> 1 == 0001
```

## bit.set()

Set bits in a number.

#### Syntax
`bit.set(value, pos1 [, ... posn ])`

#### Parameters
- `value` the base number.
- `pos1` position of the first bit to set.
- `...posn` position of the nth bit to set.

#### Returns
the number with the bit(s) set in the given position(s)

### Example
```lua
bit.set(2, 0) -- returns 3
```