math.bits

count, test, set, rotate and swap bits

Example results generated on 2026-10-08. Ones using now, today or randomness will differ when you run them: press Run on any example to run it in your browser, after editing it if you like.

conversions

# to bits
0xf0 to bits
# → "0b1111_0000"

Functions

popcount

popcount(n: int): number of 1 bits (two’s complement for negatives)

popcount(0b1011)
# → 3
popcount(-1)
# → 64

See also: bit

bit

bit(n: int, i: int): bit i of n (0 is the lowest), as 0 or 1

bit(0b100, 2)
# → 1

See also: set_bit, clear_bit, popcount

set_bit

set_bit(n: int, i: int): n with bit i set

set_bit(0b1, 4)
# → 0b10001

See also: clear_bit, bit

clear_bit

clear_bit(n: int, i: int): n with bit i cleared

clear_bit(0xff, 0)
# → 0xfe

See also: set_bit, bit

rotl

rotl(n: int, k: int, width: int): rotate the low width bits left by k

rotl(0x81, 1, 8)
# → 0x3
rotl(0x80000000, 1, 32)
# → 0x1

See also: rotr

rotr

rotr(n: int, k: int, width: int): rotate the low width bits right by k

rotr(0x81, 1, 8)
# → 0xc0

See also: rotl

byteswap

byteswap(n: int, width: int): reverse the bytes of a width-bit number

byteswap(0x1234, 16)
# → 0x3412
byteswap(0x12345678, 32)
# → 0x78563412

See also: rotl

More examples

bits

# see the bits
0xf0 to bits
# → "0b1111_0000"
# xor
0b1010 ^ 0b0110
# → 0b1100
# count set bits
popcount(0xff)
# → 8
# rotate within 8 bits
rotr(1, 1, 8)
# → 128
# swap byte order
byteswap(0x1234, 16)
# → 0x3412
# clear a bit
clear_bit(0xff, 0)
# → 0xfe