local bit32={}



local function fold(init,op,...)
local result=init
local args=table.pack(...)
for i=1,args.n do
result=op(result,args[i])
end
return result
end

local function trim(n)
return n&0xFFFFFFFF
end

local function mask(w)
return~(0xFFFFFFFF<<w)
end

function bit32.arshift(x,disp)
return x//(2^disp)
end

function bit32.band(...)
return fold(0xFFFFFFFF,function(a,b)return a&b end,...)
end

function bit32.bnot(x)
return~x
end

function bit32.bor(...)
return fold(0,function(a,b)return a|b end,...)
end

function bit32.btest(...)
return bit32.band(...)~=0
end

function bit32.bxor(...)
return fold(0,function(a,b)return a~b end,...)
end

local function fieldargs(f,w)
w=w or 1
assert(f>=0,"field cannot be negative")
assert(w>0,"width must be positive")
assert(f+w<=32,"trying to access non-existent bits")
return f,w
end

function bit32.extract(n,field,width)
local f,w=fieldargs(field,width)
return(n>>f)&mask(w)
end

function bit32.replace(n,v,field,width)
local f,w=fieldargs(field,width)
local m=mask(w)
return(n&~(m<<f))|((v&m)<<f)
end

function bit32.lrotate(x,disp)
if disp==0 then
return x
elseif disp<0 then
return bit32.rrotate(x,-disp)
else
disp=disp&31
x=trim(x)
return trim((x<<disp)|(x>>(32-disp)))
end
end

function bit32.lshift(x,disp)
return trim(x<<disp)
end

function bit32.rrotate(x,disp)
if disp==0 then
return x
elseif disp<0 then
return bit32.lrotate(x,-disp)
else
disp=disp&31
x=trim(x)
return trim((x>>disp)|(x<<(32-disp)))
end
end

function bit32.rshift(x,disp)
return trim(x>>disp)
end



return bit32