mirror of
https://github.com/ZDoom/Raze.git
synced 2024-11-16 17:32:13 +00:00
48 lines
1.1 KiB
Lua
48 lines
1.1 KiB
Lua
|
|
||
|
|
-- "Bit array" module based on LuaJIT's BitOp.
|
||
|
|
|
||
|
|
local bit = require "bit"
|
||
|
|
|
||
|
|
local error = error
|
||
|
|
local type = type
|
||
|
|
|
||
|
|
module(...)
|
||
|
|
|
||
|
|
-- Create new bit array.
|
||
|
|
-- Returns a table p in which entries p[0] through p[floor((size+31)/32)]
|
||
|
|
-- are set to an initialization value: 0 if 0 has been passed, -1 if 1
|
||
|
|
-- has been passed.
|
||
|
|
function new(size, initval)
|
||
|
|
if (type(size) ~= "number" or size < 0) then
|
||
|
|
error("bad argument #1 to newarray (must be a nonnegative number)", 2)
|
||
|
|
end
|
||
|
|
|
||
|
|
if (initval ~= 0 and initval ~= 1) then
|
||
|
|
error("bad argument #2 to newarray (must be either 0 or 1)", 2)
|
||
|
|
end
|
||
|
|
|
||
|
|
local p = {}
|
||
|
|
for i=0,(size+31)/32 do
|
||
|
|
p[i] = -initval
|
||
|
|
end
|
||
|
|
|
||
|
|
return p
|
||
|
|
end
|
||
|
|
|
||
|
|
-- Is bit i set in bit array ar?
|
||
|
|
function isset(ar, i)
|
||
|
|
return bit.band(ar[bit.rshift(i, 5)], bit.lshift(1, i)) ~= 0
|
||
|
|
end
|
||
|
|
|
||
|
|
-- Set bit j in bit array ar.
|
||
|
|
function set0(ar, j)
|
||
|
|
local jx = bit.rshift(j, 5)
|
||
|
|
ar[jx] = bit.band(ar[jx], bit.rol(0xfffffffe, j))
|
||
|
|
end
|
||
|
|
|
||
|
|
-- Clear bit j in bit array ar.
|
||
|
|
function set1(ar, j)
|
||
|
|
local jx = bit.rshift(j, 5)
|
||
|
|
ar[jx] = bit.bor(ar[jx], bit.rol(0x00000001, j))
|
||
|
|
end
|