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if not modules then modules = { } end modules ['l-number'] = {
version = 1.001,
comment = "companion to luat-lib.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local tostring = tostring
local format, floor, insert, match = string.format, math.floor, table.insert, string.match
local lpegmatch = lpeg.match
number = number or { }
local number = number
-- a,b,c,d,e,f = number.toset(100101)
function number.toset(n)
return match(tostring(n),"(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)")
end
function number.toevenhex(n)
local s = format("%X",n)
if #s % 2 == 0 then
return s
else
return "0" .. s
end
end
-- the lpeg way is slower on 8 digits, but faster on 4 digits, some 7.5%
-- on
--
-- for i=1,1000000 do
-- local a,b,c,d,e,f,g,h = number.toset(12345678)
-- local a,b,c,d = number.toset(1234)
-- local a,b,c = number.toset(123)
-- end
--
-- of course dedicated "(.)(.)(.)(.)" matches are even faster
local one = lpeg.C(1-lpeg.S(''))^1
function number.toset(n)
return lpegmatch(one,tostring(n))
end
function number.bits(n,zero)
local t, i = { }, (zero and 0) or 1
while n > 0 do
local m = n % 2
if m > 0 then
insert(t,1,i)
end
n = floor(n/2)
i = i + 1
end
return t
end
--~ http://ricilake.blogspot.com/2007/10/iterating-bits-in-lua.html
function number.bit(p)
return 2 ^ (p - 1) -- 1-based indexing
end
function number.hasbit(x, p) -- typical call: if hasbit(x, bit(3)) then ...
return x % (p + p) >= p
end
function number.setbit(x, p)
return hasbit(x, p) and x or x + p
end
function number.clearbit(x, p)
return hasbit(x, p) and x - p or x
end
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