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-rw-r--r--lualibs-number.lua58
1 files changed, 58 insertions, 0 deletions
diff --git a/lualibs-number.lua b/lualibs-number.lua
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--- /dev/null
+++ b/lualibs-number.lua
@@ -0,0 +1,58 @@
+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 { }
+
+-- 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