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Localize global fields

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Lars Mueller 2021-07-07 12:52:37 +02:00
parent 4026f6dd0d
commit 35081f3e4b
1 changed files with 8 additions and 7 deletions
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15
binary.lua
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@ -1,5 +1,6 @@
-- Localize globals -- Localize globals
local assert, math = assert, math local assert, math_huge, math_frexp, math_floor
= assert, math.huge, math.frexp, math.floor
-- Set environment -- Set environment
local _ENV = {} local _ENV = {}
@ -30,7 +31,7 @@ function read_float(read_byte, double)
mantissa = (mantissa + byte_2) / 0x80 mantissa = (mantissa + byte_2) / 0x80
if exponent == 0xFF then if exponent == 0xFF then
if mantissa == 0 then if mantissa == 0 then
return sign * math.huge return sign * math_huge
end end
-- Differentiating quiet and signalling nan is not possible in Lua, hence we don't have to do it -- 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 -- HACK ((0/0)^1) yields nan, 0/0 yields -nan
@ -67,7 +68,7 @@ end
function write_uint(write_byte, uint, bytes) function write_uint(write_byte, uint, bytes)
for _ = 1, bytes do for _ = 1, bytes do
write_byte(uint % 0x100) write_byte(uint % 0x100)
uint = math.floor(uint / 0x100) uint = math_floor(uint / 0x100)
end end
assert(uint == 0) assert(uint == 0)
end end
@ -80,16 +81,16 @@ function write_float(write_byte, number, on_write, double)
number = -number number = -number
sign = 0x80 sign = 0x80
end end
local mantissa, exponent = math.frexp(number) local mantissa, exponent = math_frexp(number)
exponent = exponent + 127 exponent = exponent + 127
if exponent > 1 then if exponent > 1 then
-- TODO ensure this deals properly with subnormal numbers -- TODO ensure this deals properly with subnormal numbers
mantissa = mantissa * 2 - 1 mantissa = mantissa * 2 - 1
exponent = exponent - 1 exponent = exponent - 1
end end
local sign_byte = sign + math.floor(exponent / 2) local sign_byte = sign + math_floor(exponent / 2)
mantissa = mantissa * 0x80 mantissa = mantissa * 0x80
local exponent_byte = (exponent % 2) * 0x80 + math.floor(mantissa) local exponent_byte = (exponent % 2) * 0x80 + math_floor(mantissa)
mantissa = mantissa % 1 mantissa = mantissa % 1
local mantissa_bytes = {} local mantissa_bytes = {}
-- TODO ensure this check is proper -- TODO ensure this check is proper
@ -102,7 +103,7 @@ function write_float(write_byte, number, on_write, double)
local len = double and 6 or 2 local len = double and 6 or 2
for index = len, 1, -1 do for index = len, 1, -1 do
mantissa = mantissa * 0x100 mantissa = mantissa * 0x100
mantissa_bytes[index] = math.floor(mantissa) mantissa_bytes[index] = math_floor(mantissa)
mantissa = mantissa % 1 mantissa = mantissa % 1
end end
assert(mantissa == 0) assert(mantissa == 0)