IMHO the better definition of "current time" is not a long, fixed, int or double. It is some sort of structure containing day, month, year, hour, minute, second and milli-micro-or-nanoseconds. To measure the amount of time betewwen two different times, some helper functions can do it easily.
Victor Williams Stafusa da Silva
Peter Wang <novalazy@xxxxxxxxxx> escreveu:
On 2007-12-28, Elias Pschernig wrote: > On Fri, 2007-12-28 at 14:53 +0100, Andrei Ellman wrote: > > > If we want nanoseconds instead of milliseconds, a 32-bit integer would > > > not work though for al_get_current_time, as it would overflow pretty > > > fast (after 4 seconds) - but both Linux and Windows timers would provide > > > us with that precision nowadays so seems a pity just
rounding it down. > > > > Why not just use a 64-bit integer internally for representing the time. > > While floating point numbers have a greater dynamic range, they are > > prone to undeflow when the exponent becomes too large. A 64 bit integer > > is equally as long as a 64 bit double. > > > > Internally, all calculations involving the timer will be done using 64 > > bit integers. The user-level functions that access and manipulate the > > timer will use doubles. The double will be converted to a 64-bit integer > > before it is used in timer-calculation. Likewise, functions for > > retrieving the timer value will convert the result to doubles. As well > > as doubles, the timer can be set/accessed using Allegro's 'fixed' type > > if anyone wants to set the timer using fixed's. If speed of timer > > access/manipulation really is reqired,
another set of functions can be > > written that uses the native timer-format (64-bit integer) to avoid the > > overhead of conversion, but the docs will recommend using a 'double' > > number of seconds for ease of use. > > Makes sense. I still think it might be overkill (as I said, for 90 days > of continuous time, the precision would stay below nanoseconds with > seconds expressed as double) - but if we would have more time related > functions like something to get the unix time and not just the time > since Allegro was initialized, this solution would combine the > advantages of both.
In that case there's no point using 'time since Allegro was initialised' so might as well use 'time since arbitrary start', i.e. whatever the OS gives.
Peter
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