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-- abstract different bit libraries in different lua versions
local require, error, assert, tonumber, tostring,
setmetatable, pairs, ipairs, unpack, rawget, rawset,
pcall, type, table, string =
require, error, assert, tonumber, tostring,
setmetatable, pairs, ipairs, unpack, rawget, rawset,
pcall, type, table, string
-- TODO add 64 bit operations here
local ffi = require "ffi"
local abi = require "syscall.abi"
local ok, bit
ok, bit = pcall(require, "bit")
if not ok then
ok, bit = pcall(require, "bit32")
local int32 = ffi.typeof("int32_t")
if not ok then error("no suitable bit library found") end
-- fixups to make compatible with luajit
bit.tobit = function(x) return tonumber(int32(x)) end
bit.bswap = function(x)
return bit.bor(bit.lshift(bit.extract(x, 0, 8), 24),
bit.lshift(bit.extract(x, 8, 8), 16),
bit.lshift(bit.extract(x, 16, 8), 8),
bit.extract(x, 24, 8))
end
end
-- 64 to 32 bit conversions via unions TODO use meth not object? tidy up
local mt
if abi.le then
mt = {
__index = {
to32 = function(u) return u.i32[1], u.i32[0] end,
from32 = function(u, a, b) u.i32[1], u.i32[0] = a, b end,
}
}
else
mt = {
__index = {
to32 = function(u) return u.i32[0], u.i32[1] end,
from32 = function(u, a, b) u.i32[0], u.i32[1] = a, b end,
}
}
end
mt.__new = function(tp, x)
local n = ffi.new(tp)
n.i64 = x or 0
return n
end
local i6432 = ffi.metatype("union {int64_t i64; int32_t i32[2];}", mt)
local u6432 = ffi.metatype("union {uint64_t i64; uint32_t i32[2];}", mt)
bit.i6432 = function(x) return i6432(x):to32() end
bit.u6432 = function(x) return u6432(x):to32() end
-- initial 64 bit ops. TODO for luajit 2.1 these are not needed, as accepts 64 bit cdata
function bit.bor64(a, b, ...)
local aa, bb, cc = i6432(a), i6432(b), i6432()
cc.i32[0], cc.i32[1] = bit.bor(aa.i32[0], bb.i32[0]), bit.bor(aa.i32[1], bb.i32[1])
if select('#', ...) > 0 then return bit.bor64(cc.i64, ...) end
return cc.i64
end
function bit.band64(a, b, ...)
local aa, bb, cc = i6432(a), i6432(b), i6432()
cc.i32[0], cc.i32[1] = bit.band(aa.i32[0], bb.i32[0]), bit.band(aa.i32[1], bb.i32[1])
if select('#', ...) > 0 then return bit.band64(cc.i64, ...) end
return cc.i64
end
function bit.lshift64(a, n)
if n == 0 then return a end
local aa, bb = i6432(a), i6432(0)
local ah, al = aa:to32()
local bl, bh = 0, 0
if n < 32 then
bh, bl = bit.lshift(ah, n), bit.lshift(al, n)
bh = bit.bor(bh, bit.rshift(al, 32 - n))
else
bh, bl = bit.lshift(al, n - 32), 0
end
bb:from32(bh, bl)
return bb.i64
end
function bit.rshift64(a, n)
if n == 0 then return a end
local aa, bb = i6432(a), i6432(0)
local ah, al = aa:to32()
local bl, bh = 0, 0
if n < 32 then
bh, bl = bit.rshift(ah, n), bit.rshift(al, n)
bl = bit.bor(bl, bit.lshift(ah, 32 - n))
else
bh, bl = 0, bit.rshift(ah, n - 32)
end
bb:from32(bh, bl)
return bb.i64
end
return bit
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