Add binary module to reduce code duplication

This commit is contained in:
Lars Mueller 2021-03-13 16:55:21 +01:00
parent 7a92f3b492
commit 2005754a46
4 changed files with 130 additions and 102 deletions

29
b3d.lua

@ -45,34 +45,9 @@ function read(stream)
end end
end end
local read_single = modlib.binary.read_single
local function float() 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 end
local function float_array(length) local function float_array(length)

115
binary.lua Normal file

@ -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

@ -160,48 +160,21 @@ function write(self, object, stream)
local function byte(byte) local function byte(byte)
stream:write(string.char(byte)) stream:write(string.char(byte))
end end
local write_uint = modlib.binary.write_uint
local function uint(type, 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 end
local function uint_with_type(base, _uint) local function uint_with_type(base, _uint)
local type_offset = uint_type(_uint) local type_offset = uint_type(_uint)
byte(base + type_offset) byte(base + type_offset)
uint(type_offset, _uint) uint(type_offset, _uint)
end 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) byte(double and type_ranges.number or type_ranges.number_f32)
local len = double and 6 or 2 end
for index = len, 1, -1 do local function float(number)
mantissa = mantissa * 0x100 write_float(byte, number, float_on_write)
mantissa_bytes[index] = string.char(math.floor(mantissa))
mantissa = mantissa % 1
end
assert(mantissa == 0)
stream:write(table.concat(mantissa_bytes))
byte(exponent_byte)
byte(sign_byte)
end end
local aux_write = self.aux_write local aux_write = self.aux_write
local function _write(object) local function _write(object)
@ -285,49 +258,13 @@ function read(self, stream)
local function byte() local function byte()
return stream_read(1):byte() return stream_read(1):byte()
end 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
end end
-- TODO get rid of code duplication (see b3d.lua) local read_float = modlib.binary.read_float
local function float(double) 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 end
local aux_read = self.aux_read local aux_read = self.aux_read
local function _read(type) local function _read(type)

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