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(*
Title: Standard Basis Library: Time Signature and structure.
Author: David Matthews
Copyright David Matthews 2000, 2005
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*)
(* G&R 2004 status: updated. *)
signature TIME =
sig
eqtype time
exception Time
val zeroTime : time
val fromReal : LargeReal.real -> time
val toReal : time -> LargeReal.real
val toSeconds : time -> LargeInt.int
val toMilliseconds : time -> LargeInt.int
val toMicroseconds : time -> LargeInt.int
val toNanoseconds : time -> LargeInt.int
val fromSeconds : LargeInt.int -> time
val fromMilliseconds : LargeInt.int -> time
val fromMicroseconds : LargeInt.int -> time
val fromNanoseconds : LargeInt.int -> time
val + : time * time -> time
val - : time * time -> time
val compare : time * time -> General.order
val < : time * time -> bool
val <= : time * time -> bool
val > : time * time -> bool
val >= : time * time -> bool
val now : unit -> time
val fmt : int -> time -> string
val toString : time -> string
val fromString : string -> time option
val scan : (char, 'a) StringCvt.reader -> (time, 'a) StringCvt.reader
end;
structure Time :> TIME =
struct
(* Unix and Windows both use 64 bit quantities for times. Windows
uses a 64-bit number of 100ns ticks, Unix uses one word of seconds
and another of microseconds. To handle both easily we use a single
arbitrary precision number for times with the actual resolution
returned as an RTS call. The intention is retain as much precision
as possible. *)
type time = int (* Becomes abstract *)
exception Time
open RuntimeCalls
val doTiming: int*int->int = RunCall.run_call2 POLY_SYS_timing_dispatch
fun callTiming (code: int) args = doTiming (code,args);
(* Get the number of ticks per microsecond and compute the corresponding
values for milliseconds and seconds. *)
val ticksPerMicrosecond = callTiming 0 0
val ticksPerMillisecond = ticksPerMicrosecond * 1000
val ticksPerSecond = ticksPerMillisecond * 1000
(* Check for very large time values. These cause problems if
converted to dates. *)
local
val Years100000 = ticksPerSecond*60*60*24*365*100000
in
fun checkTimeValue t =
if t < ~ Years100000 orelse t > Years100000
then raise Time else t
end;
(* The real representation is as a number of seconds. *)
local
val realTicks = Real.fromInt ticksPerSecond
in
fun fromReal (x: real): time =
checkTimeValue(Real.round (x * realTicks))
and toReal (t: time): real = Real.fromInt t / realTicks
end
val zeroTime = fromReal 0.0
(* Convert to seconds, etc.*)
fun toSeconds x = x div ticksPerSecond
and toMilliseconds x = x div ticksPerMillisecond
and toMicroseconds x = x div ticksPerMicrosecond
and toNanoseconds x = x * 1000 div ticksPerMicrosecond
(* Convert from the integer representations. *)
fun fromSeconds i = checkTimeValue(i * ticksPerSecond)
and fromMilliseconds i = checkTimeValue(i * ticksPerMillisecond)
and fromMicroseconds i = checkTimeValue(i * ticksPerMicrosecond)
and fromNanoseconds i = checkTimeValue(i * ticksPerMicrosecond div 1000)
(* Format as a fixed precision number. if n < 0 treat as n = 0. *)
fun fmt n r = Real.fmt (StringCvt.FIX(SOME(Int.max(n, 0)))) (toReal r)
val toString = fmt 3
(* The scanned string is a subset of the format of a real number.
It does not have an exponent. At present we convert it as a real
number but it would probably be better to treat it as an integer. *)
fun scan getc src =
let
(* Return a list of digits. *)
fun getdigits inp src =
case getc src of
NONE => (List.rev inp, src)
| SOME(ch, src') =>
if ch >= #"0" andalso ch <= #"9"
then getdigits ((Char.ord ch - Char.ord #"0") :: inp) src'
else (List.rev inp, src)
fun read_number sign src =
case getc src of
NONE => NONE
| SOME(ch, src') =>
if not (ch >= #"0" andalso ch <= #"9" orelse ch = #".")
then NONE (* Bad "*)
else (* Digits or decimal. *)
let
(* Get the digits before the decimal point (if any) *)
val (intPart, src'') = getdigits [] src
(* Get the digits after the decimal point (if any).
If there is a decimal point we swallow the decimal only
if there is at least one digit after it. *)
val (decPart, srcAfterMant) =
case getc src'' of
SOME (#".", src''') =>
( (* Check that the next character is a digit. *)
case getc src''' of
NONE => ([], src'')
| SOME(ch, _) =>
if ch >= #"0" andalso ch <= #"9"
then getdigits [] src'''
else ([], src'')
)
| _ => ([], src'')
in
case (intPart, decPart) of
([], []) => NONE (* Must have a digit either before or after the dp. *)
| _ =>
let
(* Get exactly 9 digits after the decimal point. *)
val decs = intPart @ (List.take(decPart @ [ 0, 0, 0, 0, 0, 0, 0, 0, 0 ], 9));
(* It's now in nanoseconds. *)
val toInt = List.foldl (fn (i, j) => i + j*10) 0 decs
in
SOME(fromNanoseconds(if sign then ~toInt else toInt), srcAfterMant)
end
end
in
case getc src of
NONE => NONE
| SOME(ch, src') =>
if Char.isSpace ch (* Skip white space. *)
then scan getc src' (* Recurse *)
else if ch = #"+" (* Remove the + sign *)
then read_number false src'
else if ch = #"-" orelse ch = #"~"
then read_number true src'
else (* See if it's a valid digit or decimal point. *)
read_number false src
end
val fromString = StringCvt.scanString scan
(* Use the integer operations for these. *)
val op < : (time * time) -> bool = Int.<
val op <= : (time * time) -> bool = Int.<=
val op > : (time * time) -> bool = Int.>
val op >= : (time * time) -> bool = Int.>=;
val compare = Int.compare
val op + : (time * time) -> time = Int.+
val op - : (time * time) -> time = Int.-
fun now () = callTiming 1 0 handle _ => raise Time
end;
local
(* Install the pretty printer for Time.time. This has to be
done outside the structure because of the opaque matching. *)
fun pretty(p, _, _, _) _ _ x = p(Time.toString x)
in
val it = PolyML.install_pp pretty
(* Add overloads for +, -, <= etc *)
val it = RunCall.addOverload Time.+ "+";
val it = RunCall.addOverload Time.- "-";
val it = RunCall.addOverload Time.< "<";
val it = RunCall.addOverload Time.> ">";
val it = RunCall.addOverload Time.<= "<=";
val it = RunCall.addOverload Time.>= ">=";
end
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