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--- useful_programs [2020/07/30 15:07] – atolstov
+++ useful_programs [2021/02/12 10:15] – [Curve handler] emozolyak
@@ Line 914: / Line 914: @@
 </code>
 Example of usage:
-<code lua - Getter>
+<code lua - curves getter>
 include "curves.lib"
@@ Line 925: / Line 925: @@
 end
+</code>
+===== Processing double float numbers =====
+<code lua>
+function d2float(n)  ----------------------- CONVERT DOUBLE FLOAT TO FLOAT -------------------------------------------
+	local function getBits(input_num, length)  			-- get number as table of bits
+														-- works with number and len
+		local tab = {}
+		local max_i = length - 1
+		local remainder = input_num       	   			-- rem of bitwise weighing
+		for i = max_i, 0, -1 do
+			 local bit_ = (remainder - 2^i >= 0) and '1' or '0'
+			 table.insert(tab, bit_)
+		end
+		return tab
+	end
+	local function getNumberFromTab(tab, start, length)  -- get a number from table
+		local result_str = ""
+		for i = start, (start + length - 1) do
+			result_str = result_str .. tostring(tab[i])
+		end
+		return tonumber(result_str,2)
+	end
+	local NaN = tonumber("11111111111111111111111111111111", 2)
+	local result_tab = {}
+				-- get a table of "0" & "1"
+	  if (type(n) == "number") then
+	 		 result_tab = getBits(n, 64)
+	  elseif (type(n) == "table") then
+		 local tmpS = ''
+		 for i = 1, #n do
+			 tmpS = tmpS .. table.concat(getBits(n[i],8))
+		 end
+		 for j=1, #tmpS do
+			 table.insert(result_tab, string.sub(tmpS, j, j))
+		 end
+	 else
+		 ERROR("Unknown type for the d2float!")
+	 end
+	local sign, exp, mantissa = 0, 0, 0
+	local fraction_table = {} 						-- fraction part table
+	sign = ((result_tab[1] == "1") and -1) or 1     -- get sign
+	exp = getNumberFromTab(result_tab, 2, 11)       -- get exp
+	for i = 13, 64 do
+		table.insert(fraction_table, result_tab[i]) -- mantissa
+	end
+	for j = 1, 52 do
+		if (fraction_table[j]== "1") then
+		mantissa = mantissa +(2 ^(-1 * j))   		-- calc. mantissa by summing individual bits
+		end
+	end
+	mantissa = mantissa + 1
+	local result_num = sign * (2 ^ (exp - 1023)) * mantissa
+	----------------------------------------- exceptions ----------------------------------
+	if exp == 0 then -- subnormals
+	   result_num = sign*(2^(-1022))*(mantissa-1)
+	end
+	if exp == 0x7ff then -- nan
+	   result_num = NaN;
+	end
+   return result_num
+end
 </code>