From 3ce46496f19127038b1bb6bc07b5bb38a21edb0b Mon Sep 17 00:00:00 2001
From: Onran <100285264+Onran0@users.noreply.github.com>
Date: Tue, 27 Feb 2024 02:59:43 +0900
Subject: [PATCH] conversion to/from bytes and data buffer modules

---
 res/modules/bit_converter.lua | 270 ++++++++++++++++++++++++++++++++++
 res/modules/data_buffer.lua   | 148 +++++++++++++++++++
 2 files changed, 418 insertions(+)
 create mode 100644 res/modules/bit_converter.lua
 create mode 100644 res/modules/data_buffer.lua

diff --git a/res/modules/bit_converter.lua b/res/modules/bit_converter.lua
new file mode 100644
index 00000000..e6a49972
--- /dev/null
+++ b/res/modules/bit_converter.lua
@@ -0,0 +1,270 @@
+local bit_converter = { }
+
+local MAX_UINT16 = 65535
+local MIN_UINT16 = 0
+local MAX_UINT32 = 4294967295
+local MIN_UINT32 = 0
+local MAX_UINT64 = 18446744073709551615
+local MIN_UINT64 = 0
+
+local MAX_INT16 = 32767
+local MIN_INT16 = -32768
+local MAX_INT32 = 2147483647
+local MIN_INT32 = -2147483648
+local MAX_INT64 = 9223372036854775807
+local MIN_INT64 = -9223372036854775808
+
+local function intToByte(num)
+	return bit.band(num, 0xFF)
+end
+
+local function reverse(tab)
+    for i = 1, math.floor(#tab, 2), 1 do
+        tab[i], tab[#tab-i+1] = tab[#tab-i+1], tab[i]
+    end
+    return tab
+end
+
+function bit_converter.string_to_bytes(str)
+	local bytes = { }
+
+	local len = string.len(str)
+
+	local lenBytes = bit_converter.int32_to_bytes(len)
+
+	for i = 1, #lenBytes do
+		bytes[i] = lenBytes[i]
+	end
+
+	for i = 1, len do
+		bytes[#bytes + 1] = string.byte(string.sub(str, i, i))
+	end
+
+	return bytes
+end
+
+function bit_converter.bool_to_byte(bool)
+	return bool and 1 or 0
+end
+
+-- Credits to Iryont <https://github.com/iryont/lua-struct>
+
+local function floatOrDoubleToBytes(val, opt)
+      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, math.floor(val) % (2 ^ 8))
+          val = math.floor(val / (2 ^ 8))
+        end
+      else
+        table.insert(bytes, math.floor(mantissa) % (2 ^ 8))
+        val = math.floor(mantissa / (2 ^ 8))
+        table.insert(bytes, math.floor(val) % (2 ^ 8))
+        val = math.floor(val / (2 ^ 8))
+      end
+
+      table.insert(bytes, 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, math.floor(sign * 128 + val) % (2 ^ 8))
+      val = math.floor((sign * 128 + val) / (2 ^ 8))
+
+      if not endianness then
+        reverse(bytes)
+      end
+      return bytes
+end
+
+local function bytesToFloatOrDouble(bytes, opt)
+      local n = (opt == 'd') and 8 or 4
+
+      if not endianness then
+        reverse(bytes)
+      end
+
+      local sign = 1
+      local mantissa = bytes[n - 1] % ((opt == 'd') and 16 or 128)
+      for i = n - 2, 1, -1 do
+        mantissa = mantissa * (2 ^ 8) + bytes[i]
+      end
+
+      if bytes[n] > 127 then
+        sign = -1
+      end
+
+      local exponent = (bytes[n] % 128) * ((opt == 'd') and 16 or 2) + math.floor(bytes[n - 1] / ((opt == 'd') and 16 or 128))
+      if exponent == 0 then
+        return 0.0
+      else
+        mantissa = (math.ldexp(mantissa, (opt == 'd') and -52 or -23) + 1) * sign
+        return math.ldexp(mantissa, exponent - ((opt == 'd') and 1023 or 127))
+      end
+end
+
+--
+
+function bit_converter.single_to_bytes(float)
+	return floatOrDoubleToBytes(float, 'f')
+end
+
+function bit_converter.double_to_bytes(double)
+	return floatOrDoubleToBytes(double, 'd')
+end
+
+function bit_converter.int64_to_bytes(int)
+	if int > MAX_INT64 or int < MIN_INT64 then
+		error("invalid int64")
+	end
+
+	return {
+		intToByte(bit.rshift(int, 56)),
+		intToByte(bit.rshift(int, 48)),
+		intToByte(bit.rshift(int, 40)),
+		intToByte(bit.rshift(int, 32)),
+		intToByte(bit.rshift(int, 24)),
+		intToByte(bit.rshift(int, 16)),
+		intToByte(bit.rshift(int, 8)),
+		intToByte(int)
+	}
+end
+
+function bit_converter.uint32_to_bytes(int)
+	if int > MAX_UINT32 or int < MIN_UINT32 then
+		error("invalid uint32")
+	end
+
+	return {
+		intToByte(bit.rshift(int, 24)),
+		intToByte(bit.rshift(int, 16)),
+		intToByte(bit.rshift(int, 8)),
+		intToByte(int)
+	}
+end
+
+function bit_converter.uint16_to_bytes(int)
+	if int > MAX_UINT16 or int < MIN_UINT16 then
+		error("invalid uint16")
+	end
+
+	return {
+		intToByte(bit.rshift(int, 8)),
+		intToByte(int)
+	}
+end
+
+function bit_converter.int32_to_bytes(int)
+	if int > MAX_INT32 or int < MIN_INT32 then
+		error("invalid int32")
+	end
+
+	return bit_converter.uint32_to_bytes(int + MAX_INT32)
+end
+
+function bit_converter.int16_to_bytes(int)
+	if int > MAX_INT16 or int < MIN_INT16 then
+		error("invalid int16")
+	end
+
+	return bit_converter.uint16_to_bytes(int + MAX_INT16)
+end
+
+function bit_converter.bytes_to_single(bytes)
+	return bytesToFloatOrDouble(bytes, 'f')
+end
+
+function bit_converter.bytes_to_double(bytes)
+	return bytesToFloatOrDouble(bytes, 'd')
+end
+
+function bit_converter.bytes_to_string(bytes)
+	local len = bit_converter.bytes_to_int32({ bytes[1], bytes[2], bytes[3], bytes[4]})
+
+	local str = ""
+
+	for i = 1, len do
+		str = str..string.char(bytes[i])
+	end
+
+	return str
+end
+
+function bit_converter.byte_to_bool(byte)
+	return byte ~= 0
+end
+
+function bit_converter.bytes_to_float(bytes)
+	if #bytes < 8 then
+		error("eof")
+	end
+	error("unsupported operation")
+end
+
+function bit_converter.bytes_to_int64(bytes)
+	if #bytes < 8 then
+		error("eof")
+	end
+     return
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.lshift(bytes[1], 56),
+     bit.lshift(bytes[2], 48)),
+     bit.lshift(bytes[3], 40)),
+     bit.lshift(bytes[4], 32)),
+     bit.lshift(bytes[5], 24)),
+     bit.lshift(bit.band(bytes[6], 0xFF), 16)),
+     bit.lshift(bit.band(bytes[7], 0xFF), 8)),bit.band(bytes[8], 0xFF))
+end
+
+function bit_converter.bytes_to_uint32(bytes)
+	if #bytes < 4 then
+		error("eof")
+	end
+     return
+     bit.bor(
+     bit.bor(
+     bit.bor(
+     bit.lshift(bytes[1], 24),
+     bit.lshift(bytes[2], 16)),
+     bit.lshift(bytes[3], 8)),bytes[4])
+end
+
+function bit_converter.bytes_to_uint16(bytes)
+	if #bytes < 2 then
+		error("eof")
+	end
+     return
+     bit.bor(
+     bit.lshift(bytes[1], 8),
+     bytes[2], 0)
+end
+
+function bit_converter.bytes_to_int32(bytes)
+	return bit_converter.bytes_to_uint32(bytes) - MAX_INT32
+end
+
+function bit_converter.bytes_to_int16(bytes)
+	return bit_converter.bytes_to_uint16(bytes) - MAX_INT16
+end
+
+return bit_converter
\ No newline at end of file
diff --git a/res/modules/data_buffer.lua b/res/modules/data_buffer.lua
new file mode 100644
index 00000000..93576a12
--- /dev/null
+++ b/res/modules/data_buffer.lua
@@ -0,0 +1,148 @@
+local bit_converter = require "core:bit_converter"
+
+-- Data buffer
+
+local data_buffer = { }
+
+function data_buffer.__call(bytes)
+	return setmetatable({ pos = 1, bytes = bytes or { } }, { __index = data_buffer })
+end
+
+-- Push functions
+
+function data_buffer:put_byte(byte)
+	if byte < 0 or byte > 255 then
+		error("invalid byte")
+	end
+
+	self.bytes[self.pos] = byte
+
+	self.pos = self.pos + 1
+end
+
+function data_buffer:put_bytes(bytes)
+	for i = 1, #bytes do
+		self:put_byte(bytes[i])
+	end
+end
+
+function data_buffer:put_single(single)
+	self:put_bytes(bit_converter.single_to_bytes(single))
+end
+
+function data_buffer:put_double(double)
+	self:put_bytes(bit_converter.double_to_bytes(double))
+end
+
+function data_buffer:put_string(str)
+	self:put_bytes(bit_converter.string_to_bytes(str))
+end
+
+function data_buffer:put_bool(bool)
+	self:put_byte(bit_converter.bool_to_byte(bool))
+end
+
+function data_buffer:put_uint16(uint16)
+	self:put_bytes(bit_converter.uint16_to_bytes(uint16))
+end
+
+function data_buffer:put_uint32(uint32)
+	self:put_bytes(bit_converter.uint32_to_bytes(uint32))
+end
+
+function data_buffer:put_int16(int16)
+	self:put_bytes(bit_converter.int16_to_bytes(int16))
+end
+
+function data_buffer:put_int32(int32)
+	self:put_bytes(bit_converter.int32_to_bytes(int32))
+end
+
+function data_buffer:put_int64(int64)
+	self:put_bytes(bit_converter.int64_to_bytes(int64))
+end
+
+-- Get functions
+
+function data_buffer:get_byte()
+	local byte = self.bytes[self.pos]
+	self.pos = self.pos + 1
+	return byte
+end
+
+function data_buffer:get_single()
+	return bit_converter.bytes_to_single(self:get_bytes(4))
+end
+
+function data_buffer:get_double()
+	return bit_converter.bytes_to_double(self:get_bytes(8))
+end
+
+function data_buffer:get_string()
+	local len = self:get_bytes(4)
+	local str = self:get_bytes(bit_converter.bytes_to_int32(len))
+	local bytes = { }
+
+	for i = 1, #len do
+		bytes[i] = len[i]
+	end
+
+	for i = 1, #str do
+		bytes[#bytes + 1] = str[i]
+	end
+
+	return bit_converter.bytes_to_string(bytes)
+end
+
+function data_buffer:get_bool()
+	return bit_converter.byte_to_bool(self:get_byte())
+end
+
+function data_buffer:get_int16()
+	return bit_converter.bytes_to_int16(self:get_bytes(2))
+end
+
+function data_buffer:get_int32()
+	return bit_converter.bytes_to_int32(self:get_bytes(4))
+end
+
+function data_buffer:get_int64()
+	return bit_converter.bytes_to_int64(self:get_bytes(8))
+end
+
+function data_buffer:size()
+	return #self.bytes
+end
+
+function data_buffer:get_bytes(len)
+	if len == nil then
+		return self.bytes
+	else
+		local bytes = { }
+
+		for i = 1, n do
+			bytes[i] = self:get_byte()
+		end
+
+		return bytes
+	end
+end
+
+function data_buffer:set_position(pos)
+	self.pos = pos
+end
+
+function data_buffer:set_bytes(bytes)
+	for i = 1, #bytes do
+		local byte = bytes[i]
+		if byte < 0 or byte > 255 then
+			error("invalid byte")
+		end
+	end
+
+	self.bytes = bytes
+end
+
+setmetatable(data_buffer, data_buffer)
+
+return data_buffer
\ No newline at end of file