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(* Copyright (C) 1999-2005 Henry Cejtin, Matthew Fluet, Suresh
* Jagannathan, and Stephen Weeks.
* Copyright (C) 1997-2000 NEC Research Institute.
*
* MLton is released under a BSD-style license.
* See the file MLton-LICENSE for details.
*)
functor Integer (I: PRE_INTEGER_EXTRA) =
struct
open I
structure PI = Primitive.Int
val detectOverflow = Primitive.detectOverflow
val (toInt, fromInt) =
if detectOverflow andalso
precision' <> PI.precision'
then if PI.<(precision', PI.precision')
then (I.toInt,
fn i =>
if (PI.<= (I.toInt minInt', i)
andalso PI.<= (i, I.toInt maxInt'))
then I.fromInt i
else raise Overflow)
else (fn i =>
if (I.<= (I.fromInt PI.minInt', i)
andalso I.<= (i, I.fromInt PI.maxInt'))
then I.toInt i
else raise Overflow,
I.fromInt)
else (I.toInt, I.fromInt)
val precision: Int.int option = SOME precision'
val maxInt: int option = SOME maxInt'
val minInt: int option = SOME minInt'
val one: int = fromInt 1
val zero: int = fromInt 0
fun quot (x, y) =
if y = zero
then raise Div
else if detectOverflow andalso x = minInt' andalso y = ~one
then raise Overflow
else I.quot (x, y)
fun rem (x, y) =
if y = zero
then raise Div
else if x = minInt' andalso y = ~one
then zero
else I.rem (x, y)
fun x div y =
if x >= zero
then if y > zero
then I.quot (x, y)
else if y < zero
then if x = zero
then zero
else I.quot (x - one, y) -? one
else raise Div
else if y < zero
then if detectOverflow andalso x = minInt' andalso y = ~one
then raise Overflow
else I.quot (x, y)
else if y > zero
then I.quot (x + one, y) -? one
else raise Div
fun x mod y =
if x >= zero
then if y > zero
then I.rem (x, y)
else if y < zero
then if x = zero
then zero
else I.rem (x - one, y) +? (y + one)
else raise Div
else if y < zero
then if x = minInt' andalso y = ~one
then zero
else I.rem (x, y)
else if y > zero
then I.rem (x + one, y) +? (y - one)
else raise Div
val sign: int -> Int.int =
fn i => if i = zero
then (0: Int.int)
else if i < zero
then (~1: Int.int)
else (1: Int.int)
fun sameSign (x, y) = sign x = sign y
fun abs (x: int) = if x < zero then ~ x else x
val {compare, min, max} = Util.makeCompare (op <)
(* fmt constructs a string to represent the integer by building it into a
* statically allocated buffer. For the most part, this is a textbook
* algorithm: loop starting at the end of the buffer; we use rem to
* extract the next digit to put into the buffer; and we use quot to
* figure out the part of the integer that we haven't yet formatted.
* However, this function uses the negative absolute value of the input
* number, which allows it to take into account minInt without any
* special-casing. This requires the rem function to behave in a very
* specific way, or else things will go terribly wrong. This may be a
* concern when porting to platforms where the division hardware has a
* different interpretation than SML about what happens when doing
* division of negative numbers.
*)
local
(* Allocate a buffer large enough to hold any formatted integer in any radix.
* The most that will be required is for minInt in binary.
*)
val maxNumDigits = PI.+ (precision', 1)
val one = One.make (fn () => CharArray.array (maxNumDigits, #"\000"))
in
fun fmt radix (n: int): string =
One.use
(one, fn buf =>
let
val radix = fromInt (StringCvt.radixToInt radix)
fun loop (q, i: Int.int) =
let
val _ =
CharArray.update
(buf, i, StringCvt.digitToChar (toInt (~? (rem (q, radix)))))
val q = quot (q, radix)
in
if q = zero
then
let
val start =
if n < zero
then
let
val i = PI.- (i, 1)
val () = CharArray.update (buf, i, #"~")
in
i
end
else i
in
CharArraySlice.vector
(CharArraySlice.slice (buf, start, NONE))
end
else loop (q, PI.- (i, 1))
end
in
loop (if n < zero then n else ~? n, PI.- (maxNumDigits, 1))
end)
end
val toString = fmt StringCvt.DEC
fun scan radix reader s =
let
(* Works with the negative of the number so that minInt can be scanned. *)
val s = StringCvt.skipWS reader s
fun charToDigit c =
case StringCvt.charToDigit radix c of
NONE => NONE
| SOME n => SOME (fromInt n)
val radixInt = fromInt (StringCvt.radixToInt radix)
fun finishNum (s, n) =
case reader s of
NONE => SOME (n, s)
| SOME (c, s') =>
case charToDigit c of
NONE => SOME (n, s)
| SOME n' => finishNum (s', n * radixInt - n')
fun num s =
case (reader s, radix) of
(NONE, _) => NONE
| (SOME (#"0", s), StringCvt.HEX) =>
(case reader s of
NONE => SOME (zero, s)
| SOME (c, s') =>
if c = #"x" orelse c = #"X" then
case reader s' of
NONE => SOME (zero, s)
| SOME (c, s') =>
case charToDigit c of
NONE => SOME (zero, s)
| SOME n => finishNum (s', ~? n)
else
case charToDigit c of
NONE => SOME (zero, s)
| SOME n => finishNum (s', ~? n))
| (SOME (c, s), _) =>
case charToDigit c of
NONE => NONE
| SOME n => finishNum (s, ~? n)
fun negate s =
case num s of
NONE => NONE
| SOME (n, s) => SOME (~ n, s)
in
case reader s of
NONE => NONE
| SOME (c, s') =>
case c of
#"~" => num s'
| #"-" => num s'
| #"+" => negate s'
| _ => negate s
end
val fromString = StringCvt.scanString (scan StringCvt.DEC)
fun power {base, exp} =
if Primitive.safe andalso exp < zero
then raise Fail "Int.power"
else let
fun loop (exp, accum) =
if exp <= zero
then accum
else loop (exp - one, base * accum)
in loop (exp, one)
end
end
structure Int8 = Integer (Primitive.Int8)
structure Int16 = Integer (Primitive.Int16)
structure Int32 = Integer (Primitive.Int32)
structure Int = Int32
structure IntGlobal: INTEGER_GLOBAL = Int
open IntGlobal
structure Int64 =
struct
local
structure P = Primitive.Int64
structure I = Integer (P)
in
open I
val toWord = P.toWord
end
end
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