Bitwise operations API documentation
Version: alpha
| FUNCTION | |
|---|---|
| bit.arshift() | bitwise arithmetic right-shift |
| bit.band() | bitwise and |
| bit.bnot() | bitwise not |
| bit.bor() | bitwise or |
| bit.bswap() | bitwise swap |
| bit.bxor() | bitwise xor |
| bit.lshift() | bitwise logical left-shift |
| bit.rol() | bitwise left rotation |
| bit.ror() | bitwise right rotation |
| bit.rshift() | bitwise logical right-shift |
| bit.tobit() | normalize number to the numeric range for bit operations |
| bit.tohex() | convert number to a hex string |
bit.arshift(x,n)
Returns the bitwise arithmetic right-shift of its first argument by the number of bits given by the second argument. Arithmetic right-shift treats the most-significant bit as a sign bit and replicates it. Only the lower 5 bits of the shift count are used (reduces to the range [0..31]).
PARAMETERS
x |
number number |
n |
number number of bits |
RETURNS
y |
number bitwise arithmetic right-shifted number |
EXAMPLES
print(bit.arshift(256, 8)) --> 1 print(bit.arshift(-256, 8)) --> -1 printx(bit.arshift(0x87654321, 12)) --> 0xfff87654
bit.band(x1,[x2...])
Returns the bitwise and of all of its arguments. Note that more than two arguments are allowed.
PARAMETERS
x1 |
number number |
[x2...] |
number number(s) |
RETURNS
y |
number bitwise and of the provided arguments |
EXAMPLES
printx(bit.band(0x12345678, 0xff)) --> 0x00000078
bit.bnot(x)
Returns the bitwise not of its argument.
PARAMETERS
x |
number number |
RETURNS
y |
number bitwise not of number x |
EXAMPLES
print(bit.bnot(0)) --> -1 printx(bit.bnot(0)) --> 0xffffffff print(bit.bnot(-1)) --> 0 print(bit.bnot(0xffffffff)) --> 0 printx(bit.bnot(0x12345678)) --> 0xedcba987
bit.bor(x1,[x2...])
Returns the bitwise or of all of its arguments. Note that more than two arguments are allowed.
PARAMETERS
x1 |
number number |
[x2...] |
number number(s) |
RETURNS
y |
number bitwise or of the provided arguments |
EXAMPLES
print(bit.bor(1, 2, 4, 8)) --> 15
bit.bswap(x)
Swaps the bytes of its argument and returns it. This can be used to convert little-endian 32 bit numbers to big-endian 32 bit numbers or vice versa.
PARAMETERS
x |
number number |
RETURNS
y |
number bitwise swapped number |
EXAMPLES
printx(bit.bswap(0x12345678)) --> 0x78563412 printx(bit.bswap(0x78563412)) --> 0x12345678
bit.bxor(x1,[x2...])
Returns the bitwise xor of all of its arguments. Note that more than two arguments are allowed.
PARAMETERS
x1 |
number number |
[x2...] |
number number(s) |
RETURNS
y |
number bitwise xor of the provided arguments |
EXAMPLES
printx(bit.bxor(0xa5a5f0f0, 0xaa55ff00)) --> 0x0ff00ff0
bit.lshift(x,n)
Returns the bitwise logical left-shift of its first argument by the number of bits given by the second argument. Logical shifts treat the first argument as an unsigned number and shift in 0-bits. Only the lower 5 bits of the shift count are used (reduces to the range [0..31]).
PARAMETERS
x |
number number |
n |
number number of bits |
RETURNS
y |
number bitwise logical left-shifted number |
EXAMPLES
print(bit.lshift(1, 0)) --> 1 print(bit.lshift(1, 8)) --> 256 print(bit.lshift(1, 40)) --> 256 printx(bit.lshift(0x87654321, 12)) --> 0x54321000
bit.rol(x,n)
Returns the bitwise left rotation of its first argument by the number of bits given by the second argument. Bits shifted out on one side are shifted back in on the other side. Only the lower 5 bits of the rotate count are used (reduces to the range [0..31]).
PARAMETERS
x |
number number |
n |
number number of bits |
RETURNS
y |
number bitwise left-rotated number |
EXAMPLES
printx(bit.rol(0x12345678, 12)) --> 0x45678123
bit.ror(x,n)
Returns the bitwise right rotation of its first argument by the number of bits given by the second argument. Bits shifted out on one side are shifted back in on the other side. Only the lower 5 bits of the rotate count are used (reduces to the range [0..31]).
PARAMETERS
x |
number number |
n |
number number of bits |
RETURNS
y |
number bitwise right-rotated number |
EXAMPLES
printx(bit.ror(0x12345678, 12)) --> 0x67812345
bit.rshift(x,n)
Returns the bitwise logical right-shift of its first argument by the number of bits given by the second argument. Logical shifts treat the first argument as an unsigned number and shift in 0-bits. Only the lower 5 bits of the shift count are used (reduces to the range [0..31]).
PARAMETERS
x |
number number |
n |
number number of bits |
RETURNS
y |
number bitwise logical right-shifted number |
EXAMPLES
print(bit.rshift(256, 8)) --> 1 print(bit.rshift(-256, 8)) --> 16777215 printx(bit.rshift(0x87654321, 12)) --> 0x00087654
bit.tobit(x)
Normalizes a number to the numeric range for bit operations and returns it. This function is usually not needed since all bit operations already normalize all of their input arguments.
PARAMETERS
x |
number number to normalize |
RETURNS
y |
number normalized number |
EXAMPLES
print(0xffffffff) --> 4294967295 (*) print(bit.tobit(0xffffffff)) --> -1 printx(bit.tobit(0xffffffff)) --> 0xffffffff print(bit.tobit(0xffffffff + 1)) --> 0 print(bit.tobit(2^40 + 1234)) --> 1234
(*) See the treatment of hex literals for an explanation why the printed numbers in the first two lines differ (if your Lua installation uses a double number type).
bit.tohex(x,n)
Converts its first argument to a hex string. The number of hex digits is given by the absolute value of the optional second argument. Positive numbers between 1 and 8 generate lowercase hex digits. Negative numbers generate uppercase hex digits. Only the least-significant 4*|n| bits are used. The default is to generate 8 lowercase hex digits.
PARAMETERS
x |
number number to convert |
n |
number number of hex digits to return |
RETURNS
s |
string hexadecimal string |
EXAMPLES
print(bit.tohex(1)) --> 00000001 print(bit.tohex(-1)) --> ffffffff print(bit.tohex(0xffffffff)) --> ffffffff print(bit.tohex(-1, -8)) --> FFFFFFFF print(bit.tohex(0x21, 4)) --> 0021 print(bit.tohex(0x87654321, 4)) --> 4321