add new fields to math library

1 files changed, 73 insertions, 4 deletions

diff --git a/compat53.lua b/compat53.lua
index 98e1a3d..0346cb7 100644
--- a/compat53.lua
+++ b/compat53.lua
@@ -3,10 +3,13 @@ local lua_version = _VERSION:sub(-3)
 if lua_version ~= "5.3" then
 
    -- load utf8 library
-   utf8 = require("compat53.utf8")
-   package.loaded["utf8"] = utf8
-   if lua_version == "5.1" then
-      utf8.charpattern = "[%z\1-\127\194-\244][\128-\191]*"
+   local ok, utf8lib = pcall(require, "compat53.utf8")
+   if ok then
+      utf8 = utf8lib
+      package.loaded["utf8"] = utf8lib
+      if lua_version == "5.1" then
+         utf8lib.charpattern = "[%z\1-\127\194-\244][\128-\191]*"
+      end
    end
 
    -- use Roberto's struct module for string packing/unpacking for now
@@ -20,5 +23,71 @@ if lua_version ~= "5.3" then
       string.unpack = struct.unpack
    end
 
+
+   -- update math library
+   do
+      local maxint, minint = 1, 0
+
+      while maxint+1 > maxint and 2*maxint > maxint do
+         maxint = maxint * 2
+      end
+      if 2*maxint <= maxint then
+         maxint = 2*maxint-1
+         minint = -maxint-1
+      else
+         maxint = maxint
+         minint = -maxint
+      end
+      math.maxinteger = maxint
+      math.mininteger = minint
+
+      local _type = type
+      function math.tointeger(n)
+         if _type(n) == "number" and n <= maxint and n >= minint and n % 1 == 0 then
+            return n
+         end
+         return nil
+      end
+
+      function math.type(n)
+         if _type(n) == "number" then
+            if n <= maxint and n >= minint and n % 1 == 0 then
+               return "integer"
+            else
+               return "float"
+            end
+         else
+            return nil
+         end
+      end
+
+      local _error = error
+      local function checkinteger(x, i, f)
+         local t = _type(x)
+         if t ~= "number" then
+            _error("bad argument #"..i.." to '"..f..
+                   "' (number expected, got "..t..")", 0)
+         elseif x > maxint or x < minint or x % 1 ~= 0 then
+            _error("bad argument #"..i.." to '"..f..
+                   "' (number has no integer representation)", 0)
+         else
+            return x
+         end
+      end
+
+      function math.ult(m, n)
+         m = checkinteger(m, "1", "math.ult")
+         n = checkinteger(n, "2", "math.ult")
+         if m >= 0 and n < 0 then
+            return true
+         elseif m < 0 and n >= 0 then
+            return false
+         else
+            return m < n
+         end
+      end
+   end
+
 end
 
+-- vi: set expandtab softtabstop=3 shiftwidth=3 :