files/examples/vstruct/fp-littleendian.lua
package.path = "./?/init.lua;".. package.path 
local vstruct = require"vstruct"
local inf = math.huge

-- work around a bug in the Lua constant table optimizer
local z = 0
local nz = -z

function to_hex(bytes, sep)
   local hexes = {}
   local append = table.insert
   for b in bytes:gmatch"." do
      append(hexes, ("%02x"):format(b:byte()))
   end
   return table.concat(hexes, sep)
end

function test(num, bytes)
   local packed_bytes = assert(vstruct.pack("< f8", { num }))
   local status = packed_bytes == bytes and "PASS" or "FAIL"

   io.write(("%s   packing %-30.20g"):format(status, num))
   if status == "FAIL" then
      io.write(("\twanted %-30s got %-30s"):format(
		  to_hex(bytes), to_hex(packed_bytes)))
   end
   io.write"\n"

   local unpacked_num = unpack((assert(vstruct.unpack("< f8", bytes))))
   local status = unpacked_num == num and "PASS" or "FAIL"

   io.write(("%s unpacking %-30s"):format(status, to_hex(bytes)))
   if status == "FAIL" then
      io.write(("\twanted %-30.20g got %-30.20g"):format(
		  num, unpacked_num))
   end
   io.write"\n"
end

test(0, "\000\000\000\000\000\000\000\000")
test(4.9406564584124654418e-324, "\001\000\000\000\000\000\000\000")
test(7.4169128616906696301e-309, "\085\085\085\085\085\085\005\000")
test(1.483382572338133926e-308, "\170\170\170\170\170\170\010\000")
test(2.225073858507200889e-308, "\255\255\255\255\255\255\015\000")
test(2.2250738585072013831e-308, "\000\000\000\000\000\000\016\000")
test(2.2250738585072018772e-308, "\001\000\000\000\000\000\016\000")
test(2.9667651446762683461e-308, "\085\085\085\085\085\085\021\000")
test(3.7084564308453353091e-308, "\170\170\170\170\170\170\026\000")
test(4.4501477170144022721e-308, "\255\255\255\255\255\255\031\000")
test(8.9884656743115795386e+307, "\000\000\000\000\000\000\224\127")
test(8.9884656743115815345e+307, "\001\000\000\000\000\000\224\127")
test(1.1984620899082105386e+308, "\085\085\085\085\085\085\229\127")
test(1.4980776123852631234e+308, "\170\170\170\170\170\170\234\127")
test(1.7976931348623157081e+308, "\255\255\255\255\255\255\239\127")
test(4.9406564584124654418e-324, "\001\000\000\000\000\000\000\000")
test(2.225073858507200889e-308, "\255\255\255\255\255\255\015\000")
test(2.2250738585072013831e-308, "\000\000\000\000\000\000\016\000")
test(1.7976931348623157081e+308, "\255\255\255\255\255\255\239\127")
test(inf, "\000\000\000\000\000\000\240\127")
test(0, "\000\000\000\000\000\000\000\000")
test(nz, "\000\000\000\000\000\000\000\128")
test(-4.9406564584124654418e-324, "\001\000\000\000\000\000\000\128")
test(-7.4169128616906696301e-309, "\085\085\085\085\085\085\005\128")
test(-1.483382572338133926e-308, "\170\170\170\170\170\170\010\128")
test(-2.225073858507200889e-308, "\255\255\255\255\255\255\015\128")
test(-2.2250738585072013831e-308, "\000\000\000\000\000\000\016\128")
test(-2.2250738585072018772e-308, "\001\000\000\000\000\000\016\128")
test(-2.9667651446762683461e-308, "\085\085\085\085\085\085\021\128")
test(-3.7084564308453353091e-308, "\170\170\170\170\170\170\026\128")
test(-4.4501477170144022721e-308, "\255\255\255\255\255\255\031\128")
test(-8.9884656743115795386e+307, "\000\000\000\000\000\000\224\255")
test(-8.9884656743115815345e+307, "\001\000\000\000\000\000\224\255")
test(-1.1984620899082105386e+308, "\085\085\085\085\085\085\229\255")
test(-1.4980776123852631234e+308, "\170\170\170\170\170\170\234\255")
test(-1.7976931348623157081e+308, "\255\255\255\255\255\255\239\255")
test(-4.9406564584124654418e-324, "\001\000\000\000\000\000\000\128")
test(-2.225073858507200889e-308, "\255\255\255\255\255\255\015\128")
test(-2.2250738585072013831e-308, "\000\000\000\000\000\000\016\128")
test(-1.7976931348623157081e+308, "\255\255\255\255\255\255\239\255")
test(-inf, "\000\000\000\000\000\000\240\255")
test(nz, "\000\000\000\000\000\000\000\128")
