1 files changed, 58 insertions, 0 deletions
diff --git a/lualibs-number.lua b/lualibs-number.lua
new file mode 100644
index 0000000..a1249f0
--- /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