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https://github.com/koreader/koreader
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abba7ba873
In principle, any negative subtraction result should be caused by a logical error.
159 lines
3.5 KiB
Lua
159 lines
3.5 KiB
Lua
--[[--
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A simple module to module to compare and do arithmetic with time values.
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@usage
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local TimeVal = require("ui/timeval")
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local tv_start = TimeVal:now()
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-- Do some stuff.
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-- You can add and subtract `TimeVal` objects.
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local tv_duration = TimeVal:now() - tv_start
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-- If you need more precision (like 2.5 s),
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-- you can add the milliseconds to the seconds.
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local tv_duration_seconds_float = tv_duration.sec + tv_duration.usec/1000000
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]]
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local dbg = require("dbg")
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local util = require("ffi/util")
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--[[--
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TimeVal object.
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@table TimeVal
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@int sec floored number of seconds
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@int usec remaining number of milliseconds
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]]
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local TimeVal = {
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sec = 0,
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usec = 0,
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}
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--[[--
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Creates a new TimeVal object.
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@usage
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local timev = TimeVal:new{
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sec = 10,
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usec = 10000,
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}
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@treturn TimeVal
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]]
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function TimeVal:new(from_o)
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local o = from_o or {}
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if o.sec == nil then
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o.sec = 0
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end
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if o.usec == nil then
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o.usec = 0
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elseif o.usec > 1000000 then
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o.sec = o.sec + math.floor(o.usec/1000000)
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o.usec = o.usec % 1000000
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end
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setmetatable(o, self)
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self.__index = self
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return o
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end
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function TimeVal:__lt(time_b)
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if self.sec < time_b.sec then
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return true
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elseif self.sec > time_b.sec then
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return false
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else
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-- self.sec == time_b.sec
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if self.usec < time_b.usec then
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return true
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else
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return false
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end
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end
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end
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function TimeVal:__le(time_b)
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if self.sec < time_b.sec then
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return true
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elseif self.sec > time_b.sec then
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return false
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else
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-- self.sec == time_b.sec
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if self.usec > time_b.usec then
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return false
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else
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return true
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end
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end
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end
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function TimeVal:__eq(time_b)
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if self.sec == time_b.sec and self.usec == time_b.usec then
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return true
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else
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return false
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end
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end
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function TimeVal:__sub(time_b)
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local diff = TimeVal:new{}
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diff.sec = self.sec - time_b.sec
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diff.usec = self.usec - time_b.usec
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if diff.sec < 0 and diff.usec > 0 then
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diff.sec = diff.sec + 1
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diff.usec = diff.usec - 1000000
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elseif diff.sec > 0 and diff.usec < 0 then
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diff.sec = diff.sec - 1
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diff.usec = diff.usec + 1000000
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end
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return diff
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end
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dbg:guard(TimeVal, '__sub',
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function(self, time_b)
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assert(self.sec > time_b.sec or (self.sec == time_b.sec and self.usec >= time_b.usec),
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"Subtract the first timeval from the latest, not vice versa.")
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end)
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function TimeVal:__add(time_b)
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local sum = TimeVal:new{}
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sum.sec = self.sec + time_b.sec
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sum.usec = self.usec + time_b.usec
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if sum.usec > 1000000 then
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sum.usec = sum.usec - 1000000
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sum.sec = sum.sec + 1
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end
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if sum.sec < 0 and sum.usec > 0 then
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sum.sec = sum.sec + 1
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sum.usec = sum.usec - 1000000
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elseif sum.sec > 0 and sum.usec < 0 then
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sum.sec = sum.sec - 1
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sum.usec = sum.usec + 1000000
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end
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return sum
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end
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--[[--
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Creates a new TimeVal object based on the current time.
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@usage
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local TimeVal = require("ui/timeval")
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local tv_start = TimeVal:now()
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-- Do some stuff.
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-- You can add and substract `TimeVal` objects.
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local tv_duration = TimeVal:now() - tv_start
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@treturn TimeVal
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]]
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function TimeVal:now()
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local sec, usec = util.gettime()
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return TimeVal:new{sec = sec, usec = usec}
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end
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return TimeVal
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