Add & use binary.(read|write)_int

b3d.lua

@@ -1,6 +1,8 @@
 -- Localize globals
 local assert, error, math, modlib, next, pairs, setmetatable, table = assert, error, math, modlib, next, pairs, setmetatable, table
 
+local read_int, read_single = modlib.binary.read_int, modlib.binary.read_single
+
 -- Set environment
 local _ENV = {}
 setfenv(1, _ENV)
@@ -21,11 +23,7 @@ function read(stream)
 	end
 
 	local function int()
-		local value = byte() + byte() * 0x100 + byte() * 0x10000 + byte() * 0x1000000
-		if value >= 2^31 then
-			return value - 2^32
-		end
-		return value
+		return read_int(byte, 4)
 	end
 
 	local function id()
@@ -52,7 +50,6 @@ function read(stream)
 		end
 	end
 
-	local read_single = modlib.binary.read_single
 	local function float()
 		return read_single(byte)
 	end

binary.lua

@@ -66,6 +66,15 @@ function read_uint(read_byte, bytes)
 	return uint
 end
 
+function read_int(read_byte, bytes)
+	local uint = read_uint(read_byte, bytes)
+	local max = 0x100 ^ bytes
+	if uint >= max / 2 then
+		return uint - max
+	end
+	return uint
+end
+
 function write_uint(write_byte, uint, bytes)
 	for _ = 1, bytes do
 		write_byte(uint % 0x100)
@@ -74,6 +83,17 @@ function write_uint(write_byte, uint, bytes)
 	assert(uint == 0)
 end
 
+function write_int(write_byte, int, bytes)
+	local max = 0x100 ^ bytes / 2
+	if int < 0 then
+		-- No bound checking is needed: If the int is too small, the uint will be too big
+		int = max - int
+	else
+		assert(int < max)
+	end
+	return write_uint(write_byte, int, bytes)
+end
+
 --: on_write function(double)
 --: double set to true to force f64, false for f32, nil for auto
 function write_float(write_byte, number, on_write, double)