modlib/math.lua
2021-08-16 20:07:23 +02:00

97 lines
2.5 KiB
Lua

-- Localize globals
local math, math_floor, minetest, modlib_table_reverse, os, string_char, table, table_insert, table_concat
= math, math.floor, minetest, modlib.table.reverse, os, string.char, table, table.insert, table.concat
local inf = math.huge
-- Set environment
local _ENV = {}
setfenv(1, _ENV)
-- Make random random
math.randomseed(minetest and minetest.get_us_time() or os.time() + os.clock())
for _ = 1, 100 do math.random() end
negative_nan = 0/0
positive_nan = negative_nan ^ 1
function round(number, steps)
steps = steps or 1
return math_floor(number * steps + 0.5) / steps
end
local c0 = ("0"):byte()
local cA = ("A"):byte()
function default_digit_function(digit)
if digit <= 9 then return string_char(c0 + digit) end
return string_char(cA + digit - 10)
end
default_precision = 10
-- See https://github.com/appgurueu/Luon/blob/master/index.js#L724
function tostring(number, base, digit_function, precision)
if number ~= number then
return "nan"
end
if number == inf then
return "inf"
end
if number == -inf then
return "-inf"
end
digit_function = digit_function or default_digit_function
precision = precision or default_precision
local out = {}
if number < 0 then
table_insert(out, "-")
number = -number
end
-- Rounding
number = number + base ^ -precision / 2
local digit
while number >= base do
digit = math_floor(number % base)
table_insert(out, digit_function(digit))
number = (number - digit) / base
end
digit = math_floor(number)
table_insert(out, digit_function(digit))
modlib_table_reverse(out)
number = number % 1
if number ~= 0 and number >= base ^ -precision then
table_insert(out, ".")
while precision >= 0 and number >= base ^ -precision do
number = number * base
digit = math_floor(number % base)
table_insert(out, digit_function(digit))
number = number - digit
precision = precision - 1
end
end
return table_concat(out)
end
-- See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/fround#polyfill
function fround(number)
if number == 0 or number ~= number then
return number
end
local sign = 1
if number < 0 then
sign = -1
number = -number
end
local exp = math_floor(math.log(number, 2))
local powexp = 2 ^ math.max(-126, math.min(exp, 127))
local leading = exp < -127 and 0 or 1
local mantissa = math_floor((leading - number / powexp) * 0x800000 + 0.5)
if mantissa <= -0x800000 then
return sign * inf
end
return sign * powexp * (leading - mantissa / 0x800000)
end
-- Export environment
return _ENV