First commit

app/SabrehavenServer/SabrehavenOTClient/modules/corelib/struct.lua

@@ -0,0 +1,173 @@
+Struct = {}
+
+function Struct.pack(format, ...)
+  local stream = {}
+  local vars = {...}
+  local endianness = true
+
+  for i = 1, format:len() do
+    local opt = format:sub(i, i)
+
+    if opt == '>' then
+      endianness = false
+    elseif opt:find('[bBhHiIlL]') then
+      local n = opt:find('[hH]') and 2 or opt:find('[iI]') and 4 or opt:find('[lL]') and 8 or 1
+      local val = tonumber(table.remove(vars, 1))
+
+      if val < 0 then
+        val = val + 2 ^ (n * 8 - 1)
+      end
+
+      local bytes = {}
+      for j = 1, n do
+        table.insert(bytes, string.char(val % (2 ^ 8)))
+        val = math.floor(val / (2 ^ 8))
+      end
+
+      if not endianness then
+        table.insert(stream, string.reverse(table.concat(bytes)))
+      else
+        table.insert(stream, table.concat(bytes))
+      end
+    elseif opt:find('[fd]') then
+      local val = tonumber(table.remove(vars, 1))
+      local sign = 0
+
+      if val < 0 then
+        sign = 1 
+        val = -val 
+      end
+
+      local mantissa, exponent = math.frexp(val)
+      if val == 0 then
+        mantissa = 0
+        exponent = 0
+      else
+        mantissa = (mantissa * 2 - 1) * math.ldexp(0.5, (opt == 'd') and 53 or 24)
+        exponent = exponent + ((opt == 'd') and 1022 or 126)
+      end
+
+      local bytes = {}
+      if opt == 'd' then
+        val = mantissa
+        for i = 1, 6 do
+          table.insert(bytes, string.char(math.floor(val) % (2 ^ 8)))
+          val = math.floor(val / (2 ^ 8))
+        end
+      else
+        table.insert(bytes, string.char(math.floor(mantissa) % (2 ^ 8)))
+        val = math.floor(mantissa / (2 ^ 8))
+        table.insert(bytes, string.char(math.floor(val) % (2 ^ 8)))
+        val = math.floor(val / (2 ^ 8))
+      end
+
+      table.insert(bytes, string.char(math.floor(exponent * ((opt == 'd') and 16 or 128) + val) % (2 ^ 8)))
+      val = math.floor((exponent * ((opt == 'd') and 16 or 128) + val) / (2 ^ 8))
+      table.insert(bytes, string.char(math.floor(sign * 128 + val) % (2 ^ 8)))
+      val = math.floor((sign * 128 + val) / (2 ^ 8))
+
+      if not endianness then
+        table.insert(stream, string.reverse(table.concat(bytes)))
+      else
+        table.insert(stream, table.concat(bytes))
+      end
+    elseif opt == 's' then
+      table.insert(stream, tostring(table.remove(vars, 1)))
+      table.insert(stream, string.char(0))
+    elseif opt == 'c' then
+      local n = format:sub(i + 1):match('%d+')
+      local length = tonumber(n)
+
+      if length > 0 then
+        local str = tostring(table.remove(vars, 1))
+        if length - str:len() > 0 then
+          str = str .. string.rep(' ', length - str:len())
+        end
+        table.insert(stream, str:sub(1, length))
+      end
+      i = i + n:len()
+    end
+  end
+
+  return table.concat(stream)
+end
+
+function Struct.unpack(format, stream)
+  local vars = {}
+  local iterator = 1
+  local endianness = true
+
+  for i = 1, format:len() do
+    local opt = format:sub(i, i)
+
+    if opt == '>' then
+      endianness = false
+    elseif opt:find('[bBhHiIlL]') then
+      local n = opt:find('[hH]') and 2 or opt:find('[iI]') and 4 or opt:find('[lL]') and 8 or 1
+      local signed = opt:lower() == opt
+
+      local val = 0
+      for j = 1, n do
+        local byte = string.byte(stream:sub(iterator, iterator))
+        if endianness then
+          val = val + byte * (2 ^ ((j - 1) * 8))
+        else
+          val = val + byte * (2 ^ ((n - j) * 8))
+        end
+        iterator = iterator + 1
+      end
+
+      if signed then
+        val = val - 2 ^ (n * 8 - 1)
+      end
+
+      table.insert(vars, val)
+    elseif opt:find('[fd]') then
+      local n = (opt == 'd') and 8 or 4
+      local x = stream:sub(iterator, iterator + n - 1)
+      iterator = iterator + n
+
+      if not endianness then
+        x = string.reverse(x)
+      end
+
+      local sign = 1
+      local mantissa = string.byte(x, (opt == 'd') and 7 or 3) % ((opt == 'd') and 16 or 128)
+      for i = n - 2, 1, -1 do
+        mantissa = mantissa * (2 ^ 8) + string.byte(x, i)
+      end
+
+      if string.byte(x, n) > 127 then
+        sign = -1
+      end
+
+      local exponent = (string.byte(x, n) % 128) * ((opt == 'd') and 16 or 2) + math.floor(string.byte(x, n - 1) / ((opt == 'd') and 16 or 128))
+      if exponent == 0 then
+        table.insert(vars, 0.0)
+      else
+        mantissa = (math.ldexp(mantissa, (opt == 'd') and -52 or -23) + 1) * sign
+        table.insert(vars, math.ldexp(mantissa, exponent - ((opt == 'd') and 1023 or 127)))
+      end
+    elseif opt == 's' then
+      local bytes = {}
+      for j = iterator, stream:len() do
+        if stream:sub(j, j) == string.char(0) then
+          break
+        end
+
+        table.insert(bytes, stream:sub(j, j))
+      end
+
+      local str = table.concat(bytes)
+      iterator = iterator + str:len() + 1
+      table.insert(vars, str)
+    elseif opt == 'c' then
+      local n = format:sub(i + 1):match('%d+')
+      table.insert(vars, stream:sub(iterator, iterator + tonumber(n)))
+      iterator = iterator + tonumber(n)
+      i = i + n:len()
+    end
+  end
+
+  return unpack(vars)
+end