moonledger

commit 9b6ef07fc1867b47fbeb55356486e55bb12c98ab
Author: Nihal Jere <nihal@nihaljere.xyz>
Date:   Tue, 16 Aug 2022 22:57:16 -0500

add decmath

Diffstat:
A
decmath.lua
 | 
35
+++++++++++++++++++++++++++++++++++

1 file changed, 35 insertions(+), 0 deletions(-)
diff --git a/decmath.lua b/decmath.lua
@@ -0,0 +1,35 @@
+-- decimal arithmetic using limath
+
+local imath = require "imath"
+
+local meta = {
+	__tostring = function(val)
+		local str = tostring(val.sig)
+		return string.sub(str, 1, #str + val.exp) .. "." .. string.sub(str, #str + val.exp + 1, #str)
+	end,
+	__add = function(a, b)
+		if a.exp < b.exp then
+			a, b = b, a
+		end
+
+		if a.exp > b.exp then
+			return {sig = b.sig * 10^(b.exp - a.exp), exp = a.exp}
+		end
+
+		return {sig = a.sig + b.sig, exp = a.exp}
+	end
+}
+
+return {
+	new = function (val)
+		if type(val) == "string" then
+			-- todo normalize
+			local asint, count = string.gsub(val, "%.", "")
+			local pos = string.find(val, "%.")
+			assert(count == 1)
+			local dec = {sig=imath.new(asint), exp=pos-#val}
+			setmetatable(dec, meta)
+			return dec
+		end
+	end
+}