Add binary module to reduce code duplication

b3d.lua

@@ -45,34 +45,9 @@ function read(stream)
         end
     end
 
+    local read_single = modlib.binary.read_single
     local function float()
-        -- TODO properly truncate to single floating point
+        return read_single(byte)
-        local byte_4, byte_3, byte_2, byte_1 = byte(), byte(), byte(), byte()
-        local sign = 1
-        if byte_1 >= 0x80 then
-            sign = -1
-            byte_1 = byte_1 - 0x80
-        end
-        local exponent = byte_1 * 2
-        if byte_2 >= 0x80 then
-            exponent = exponent + 1
-            byte_2 = byte_2 - 0x80
-        end
-        local mantissa = ((((byte_4 / 0x100) + byte_3) / 0x100) + byte_2) / 0x80
-        if exponent == 0xFF then
-            if mantissa == 0 then
-                return sign * math.huge
-            end
-            -- Differentiating quiet and signalling nan is not possible in Lua, hence we don't have to do it
-            -- HACK ((0/0)^1) yields nan, 0/0 yields -nan
-            return sign == 1 and ((0/0)^1) or 0/0
-        end
-        assert(mantissa < 1)
-        if exponent == 0 then
-            -- subnormal value
-            return sign * 2^-126 * mantissa
-        end
-        return sign * 2 ^ (exponent - 127) * (1 + mantissa)
     end
 
     local function float_array(length)

binary.lua

@@ -0,0 +1,115 @@
+-- All little endian
+
+--+ Reads doubles (f64) or floats (f32)
+--: double reads an f64 if true, f32 otherwise
+function read_float(read_byte, double)
+    -- First read the mantissa
+    local mantissa = 0
+    for _ = 1, double and 6 or 2 do
+        mantissa = (mantissa + read_byte()) / 0x100
+    end
+    -- Second and first byte in big endian: last bit of exponent + 7 bits of mantissa, sign bit + 7 bits of exponent
+    local byte_2, byte_1 = read_byte(), read_byte()
+    local sign = 1
+    if byte_1 >= 0x80 then
+        sign = -1
+        byte_1 = byte_1 - 0x80
+    end
+    local exponent = byte_1 * 2
+    if byte_2 >= 0x80 then
+        exponent = exponent + 1
+        byte_2 = byte_2 - 0x80
+    end
+    mantissa = (mantissa + byte_2) / 0x80
+    if exponent == 0xFF then
+        if mantissa == 0 then
+            return sign * math.huge
+        end
+        -- Differentiating quiet and signalling nan is not possible in Lua, hence we don't have to do it
+        -- HACK ((0/0)^1) yields nan, 0/0 yields -nan
+        return sign == 1 and ((0/0)^1) or 0/0
+    end
+    assert(mantissa < 1)
+    if exponent == 0 then
+        -- subnormal value
+        return sign * 2^-126 * mantissa
+    end
+    return sign * 2 ^ (exponent - 127) * (1 + mantissa)
+end
+
+--+ Reads a single floating point number (f32)
+function read_single(read_byte)
+    return read_float(read_byte)
+end
+
+--+ Reads a double (f64)
+function read_double(read_byte)
+    return read_float(read_byte, true)
+end
+
+function read_uint(read_byte, bytes)
+    local factor = 1
+    local uint = 0
+    for _ = 1, bytes do
+        uint = uint + read_byte() * factor
+        factor = factor * 0x100
+    end
+    return uint
+end
+
+function write_uint(write_byte, uint, bytes)
+    for _ = 1, bytes do
+        write_byte(uint % 0x100)
+        uint = math.floor(uint / 0x100)
+    end
+    assert(uint == 0)
+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)
+    local sign = 0
+    if number < 0 then
+        number = -number
+        sign = 0x80
+    end
+    local mantissa, exponent = math.frexp(number)
+    exponent = exponent + 127
+    if exponent > 1 then
+        -- TODO ensure this deals properly with subnormal numbers
+        mantissa = mantissa * 2 - 1
+        exponent = exponent - 1
+    end
+    local sign_byte = sign + math.floor(exponent / 2)
+    mantissa = mantissa * 0x80
+    local exponent_byte = (exponent % 2) * 0x80 + math.floor(mantissa)
+    mantissa = mantissa % 1
+    local mantissa_bytes = {}
+    -- TODO ensure this check is proper
+    if double == nil then
+        double = mantissa % 2^-23 > 0
+    end
+    if on_write then
+        on_write(double)
+    end
+    local len = double and 6 or 2
+    for index = len, 1, -1 do
+        mantissa = mantissa * 0x100
+        mantissa_bytes[index] = math.floor(mantissa)
+        mantissa = mantissa % 1
+    end
+    assert(mantissa == 0)
+    for index = 1, len do
+        write_byte(mantissa_bytes[index])
+    end
+    write_byte(exponent_byte)
+    write_byte(sign_byte)
+end
+
+function write_single(write_byte, number)
+    return write_float(write_byte, number, nil, false)
+end
+
+function write_double(write_byte, number)
+    return write_float(write_byte, number, nil, true)
+end

bluon.lua

@@ -160,48 +160,21 @@ function write(self, object, stream)
     local function byte(byte)
         stream:write(string.char(byte))
     end
+    local write_uint = modlib.binary.write_uint
     local function uint(type, uint)
-        for _ = 1, uint_widths[type] do
+        write_uint(byte, uint, uint_widths[type])
-            byte(uint % 0x100)
-            uint = math.floor(uint / 0x100)
-        end
     end
     local function uint_with_type(base, _uint)
         local type_offset = uint_type(_uint)
         byte(base + type_offset)
         uint(type_offset, _uint)
     end
-    local function float(number)
+    local write_float = modlib.binary.write_float
-        local sign = 0
+    local function float_on_write(double)
-        if number < 0 then
-            number = -number
-            sign = 0x80
-        end
-        local mantissa, exponent = math.frexp(number)
-        exponent = exponent + 127
-        if exponent > 1 then
-            -- TODO ensure this deals properly with subnormal numbers
-            mantissa = mantissa * 2 - 1
-            exponent = exponent - 1
-        end
-        local sign_byte = sign + math.floor(exponent / 2)
-        mantissa = mantissa * 0x80
-        local exponent_byte = (exponent % 2) * 0x80 + math.floor(mantissa)
-        mantissa = mantissa % 1
-        local mantissa_bytes = {}
-        -- TODO ensure this check is proper
-        local double = mantissa % 2^-23 > 0
         byte(double and type_ranges.number or type_ranges.number_f32)
-        local len = double and 6 or 2
-        for index = len, 1, -1 do
-            mantissa = mantissa * 0x100
-            mantissa_bytes[index] = string.char(math.floor(mantissa))
-            mantissa = mantissa % 1
     end
-        assert(mantissa == 0)
+    local function float(number)
-        stream:write(table.concat(mantissa_bytes))
+        write_float(byte, number, float_on_write)
-        byte(exponent_byte)
-        byte(sign_byte)
     end
     local aux_write = self.aux_write
     local function _write(object)
@@ -285,49 +258,13 @@ function read(self, stream)
     local function byte()
         return stream_read(1):byte()
     end
-    local function uint(bytes)
+    local read_uint = modlib.binary.read_uint
-        local factor = 1
+    local function uint(type)
-        local int = 0
+        return read_uint(byte, uint_widths[type])
-        for _ = 1, uint_widths[bytes] do
-            int = int + byte() * factor
-            factor = factor * 0x100
     end
-        return int
+    local read_float = modlib.binary.read_float
-    end
-    -- TODO get rid of code duplication (see b3d.lua)
     local function float(double)
-        -- First read the mantissa
+        return read_float(byte, double)
-        local mantissa = 0
-        for _ = 1, double and 6 or 2 do
-            mantissa = (mantissa + byte()) / 0x100
-        end
-        -- Second and first byte in big endian: last bit of exponent + 7 bits of mantissa, sign bit + 7 bits of exponent
-        local byte_2, byte_1 = byte(), byte()
-        local sign = 1
-        if byte_1 >= 0x80 then
-            sign = -1
-            byte_1 = byte_1 - 0x80
-        end
-        local exponent = byte_1 * 2
-        if byte_2 >= 0x80 then
-            exponent = exponent + 1
-            byte_2 = byte_2 - 0x80
-        end
-        mantissa = (mantissa + byte_2) / 0x80
-        if exponent == 0xFF then
-            if mantissa == 0 then
-                return sign * math.huge
-            end
-            -- Differentiating quiet and signalling nan is not possible in Lua, hence we don't have to do it
-            -- HACK ((0/0)^1) yields nan, 0/0 yields -nan
-            return sign == 1 and ((0/0)^1) or 0/0
-        end
-        assert(mantissa < 1)
-        if exponent == 0 then
-            -- subnormal value
-            return sign * 2^-126 * mantissa
-        end
-        return sign * 2 ^ (exponent - 127) * (1 + mantissa)
     end
     local aux_read = self.aux_read
     local function _read(type)

init.lua

@@ -90,6 +90,7 @@ for _, component in ipairs{
     "kdtree",
     "heap",
     "ranked_set",
+    "binary",
     "b3d",
     "bluon"
 } do