"

 COPYRIGHT (c) 1994 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

Integer subclass:#LargeInteger

	instanceVariableNames:'sign digitByteArray'

	classVariableNames:''

	poolDictionaries:''

	category:'Magnitude-Numbers'

!

!LargeInteger class methodsFor:'documentation'!

copyright

"

 COPYRIGHT (c) 1994 by Claus Gittinger

	      All Rights Reserved

 This software is furnished under a license and may be used

 only in accordance with the terms of that license and with the

 inclusion of the above copyright notice.   This software may not

 be provided or otherwise made available to, or used by, any

 other person.  No title to or ownership of the software is

 hereby transferred.

"

!

documentation

"

    This class provides arbitrary precision integers. These are represented as:

      sign (-1/0/+1) and, if sign ~~ 0

      a ByteArray of digits with 8 bits per element; 

      least significant 8 bits at index 1 ...

    The implementation is definitely not tuned for high performance

    (some key-methods should be rewritten as primitives),

    but ok for now, since LargeIntegers are not used very often.

    It will be reimplemented when everything else runs fine and a need arises

    (or someone rewrites it and sends me the code :-).

    For real speed, its implementation should be mapped onto a tuned arbitrary

    precision math package (maybe even special-cased for 32 and 64 bit 

    large-ints, since those are the most common).

    LargeIntegers are usually not created explicitely, but result from 

    SmallInteger arithmetic overflowing the SmallInteger range.

    Also, results of LargeInteger operations are converted to back to 

    SmallIntegers, when possible (see normalize).

    In contrast to ST-80, there is only one class for LargeIntegers, keeping

    the sign as an instance variable (ST-80 has LargePositiveInteger and

    LargeNegativeInteger). This may change.

    [author:]

	Claus Gittinger

    [see also:]

	Number

	Float Fraction FixedPoint 

	SmallInteger

"

!

testing

"

   test largeInt multiplication & division 

   (at least, test if they have not both errors which anull each other ;-)

   |last v|

   v := last := 1.

   2 to:3000 do:[:i |

       i printCR.

       v := v * i.

       (v / i) ~= last ifTrue:[

	   self halt

       ].

       last := v.

   ]

   test addition, subtraction:

   SmallInteger maxVal                -> 1073741823

   SmallInteger maxVal + 1            -> 1073741824

   SmallInteger maxVal + 2            -> 1073741825

   (SmallInteger maxVal + 2) - 2      -> 1073741823

   SmallInteger minVal                -> -1073741824

   SmallInteger minVal - 1            -> -1073741825

   SmallInteger minVal - 2            -> -1073741826

   (SmallInteger minVal - 2) + 2      -> -1073741824

   1234567890 + 10                    -> 1234567900

   1111111111 + 1111111111            -> 2222222222

   1111111111 - 1111111111            -> 0

   1111111111 - 2222222222            -> -1111111111

   1111111111 * 2                     -> 2222222222

   1111111111 * -2                    -> -2222222222

   1111111111 * 1111111111            -> 1234567900987654321

   1234567900987654321 // 1111111111  -> 1111111111

   1234567900987654321 \\ 1111111111  -> 0

   1234567900987654322 \\ 1111111111  -> 1

   1234567900987654421 \\ 1111111111  -> 100

   test comparison:

   -1234567890 >  -1234567890         false

   -1234567890 >= -1234567890         true

   -1234567890 <  -1234567890         false

   -1234567890 <= -1234567890         true

   -1234567890 =  -1234567890         true

   -1234567890 ~= -1234567890         false

   -1234567890 >  -1234567891         true

   -1234567890 >= -1234567891         true

   -1234567890 <  -1234567891         false

   -1234567890 <= -1234567891         false

   -1234567890 =  -1234567891         false

   -1234567890 ~= -1234567891         true

   -1234567891 >  -1234567890         false

   -1234567891 >= -1234567890         false

   -1234567891 <  -1234567890         true

   -1234567891 <= -1234567890         true

   -1234567891 =  -1234567890         false

   -1234567891 ~= -1234567890         true

    1234567890 >  -1234567890         true

    1234567890 >= -1234567890         true

    1234567890 <  -1234567890         false

    1234567890 <= -1234567890         false

    1234567890 =  -1234567890         false

    1234567890 ~= -1234567890         true

   -1234567890 >  1234567890          false

   -1234567890 >= 1234567890          false

   -1234567890 <  1234567890          true

   -1234567890 <= 1234567890          true

   -1234567890 =  1234567890          false

   -1234567890 ~= 1234567890          true

    1234567890 >  1234567890          false

    1234567890 >= 1234567890          true

    1234567890 <  1234567890          false

    1234567890 <= 1234567890          true

    1234567890 =  1234567890          true

    1234567890 ~= 1234567890          false

   -1234567890 >  -10                 false

   -1234567890 >= -10                 false

   -1234567890 <  -10                 true

   -1234567890 <= -10                 true

   -1234567890 =  -10                 false

   -1234567890 ~= -10                 true

   -1234567890 >  10                  false

   -1234567890 >= 10                  false

   -1234567890 <  10                  true

   -1234567890 <= 10                  true

   -1234567890 =  10                  false

   -1234567890 ~= 10                  true

   -10 >  -1234567890                 true

   -10 >= -1234567890                 true

   -10 <  -1234567890                 false

   -10 <= -1234567890                 false

   -10 =  -1234567890                 false

   -10 ~= -1234567890                 true

    10 >  -1234567890                 true

    10 >= -1234567890                 true

    10 <  -1234567890                 false

    10 <= -1234567890                 false

    10 =  -1234567890                 false

    10 ~= -1234567890                 true

    1234567890 >  -10                 true  

    1234567890 >= -10                 true  

    1234567890 <  -10                 false  

    1234567890 <= -10                 false  

    1234567890 =  -10                 false  

    1234567890 ~= -10                 true  

    1234567890 >  10                  true

    1234567890 >= 10                  true

    1234567890 <  10                  false

    1234567890 <= 10                  false

    1234567890 =  10                  false

    1234567890 ~= 10                  true

   -10 >   1234567890                 false

   -10 >=  1234567890                 false

   -10 <   1234567890                 true

   -10 <=  1234567890                 true

   -10 =   1234567890                 false

   -10 ~=  1234567890                 true

    10 >   1234567890                 false

    10 >=  1234567890                 false

    10 <   1234567890                 true

    10 <=  1234567890                 true

    10 =   1234567890                 false

    10 ~=  1234567890                 true

"

! !

!LargeInteger class methodsFor:'instance creation'!

new

    "catch creation message"

    self error:'LargeIntegers cannot be created with new'

!

new:numberOfDigits

    "catch creation message"

    self error:'LargeIntegers cannot be created with new'

!

value:aSmallInteger

    "create and return a new LargeInteger with value taken from

     the argument, aSmallInteger.

     Notice: 

        this should be only used internally, since such small

        largeIntegers do not normally occur in the system.

        (They are used by myself)

     May change/be removed without notice."

    ^ self basicNew value:aSmallInteger

    "LargeInteger value:3689"

    "Modified: / 8.5.1998 / 21:40:41 / cg"

! !

!LargeInteger class methodsFor:'queries'!

isBuiltInClass

    "return true if this class is known by the run-time-system.

     Here, true is returned."

    ^ true

    "Modified: 23.4.1996 / 15:59:21 / cg"

! !

!LargeInteger methodsFor:'arithmetic'!

* aNumber

    "return the product of the receiver and the argument, aNumber"

    |otherSign numberClass|

    (sign == 0) ifTrue:[^ 0].  "cannot happen if correctly normalized"

    "

     this is the common case, multiplying with SmallInteger.

     Use a special method for this case ...

    "

    ((numberClass := aNumber class) == SmallInteger) ifTrue:[

	^ self productFromInteger:aNumber

    ].

    "

     if the argument is not a largeInteger, coerce

    "

    (numberClass == self class) ifFalse:[

	^ self retry:#* coercing:aNumber

    ].

    otherSign := aNumber sign.

    (sign == otherSign) ifTrue:[^ self absMul:aNumber].

    (otherSign == 0) ifTrue:[^ 0].

    ^ (self absMul:aNumber) sign:-1

!

+ aNumber

    "return the sum of the receiver and the argument, aNumber"

    |otherSign numberClass|

    (sign == 0) ifTrue:[^ aNumber].  "cannot happen if correctly normalized"

    "

     this is the common case, adding a SmallInteger.

     Use a special method for this case ...

    "

    ((numberClass := aNumber class) == SmallInteger) ifTrue:[

	^ self sumFromInteger:aNumber

    ].

    "

     if the argument is not a largeInteger, coerce

    "

    (numberClass == self class) ifFalse:[

	^ self retry:#+ coercing:aNumber

    ].

    otherSign := aNumber sign.

    (sign > 0) ifTrue:[

	"I am positive"

	(otherSign > 0) ifTrue:[^ self absPlus:aNumber].

	(otherSign < 0) ifTrue:[^ self absMinus:aNumber].

	^ self

    ].

    "I am negative"

    (otherSign > 0) ifTrue:[^ aNumber absMinus:self].

    (otherSign < 0) ifTrue:[^ (self absPlus:aNumber) sign:-1].

    ^ self

    "

     SmallInteger maxVal 

     SmallInteger maxVal + 1  

     SmallInteger maxVal + 2 

     SmallInteger minVal    

     SmallInteger minVal - 1

    "

    "Modified: / 9.1.1998 / 13:26:28 / cg"

!

- aNumber

    "return the difference of the receiver and the argument, aNumber"

    |otherSign numberClass|

    (sign == 0) ifTrue:[^ aNumber negated].     "cannot happen if correctly normalized"

    "

     this is the common case, subtracting a SmallInteger.

     Use a special method for this case ...

    "

    ((numberClass := aNumber class) == SmallInteger) ifTrue:[

	sign > 0 ifTrue:[

	    aNumber > 0 ifTrue:[

		^ self absFastMinus:aNumber

	    ].

	    ^ self absFastPlus:aNumber

	].

	aNumber > 0 ifTrue:[

	    ^ (self absFastPlus:aNumber) sign:-1

	].

	^ (self absFastMinus:aNumber) sign:-1

    ].

    "

     if the argument is not a largeInteger, coerce

    "

    (numberClass == self class) ifFalse:[

	^ self retry:#- coercing:aNumber

    ].

    otherSign := aNumber sign.

    (sign > 0) ifTrue:[

	"I am positive"

	(otherSign > 0) ifTrue:[^ self absMinus:aNumber].

	(otherSign < 0) ifTrue:[^ self absPlus:aNumber].

	^ self

    ].

    "I am negative"

    (otherSign > 0) ifTrue:[^ (self absPlus:aNumber) negated].

    (otherSign < 0) ifTrue:[^ (self absMinus:aNumber) negated].

    ^ self

    "

     12345678901234567890 - 0     

     12345678901234567890 - 1      

     12345678901234567890 - -1    

     -12345678901234567890 - 1     

     -12345678901234567890 - -1    

     12345678901234567890 - 12345678901234567880     

     12345678901234567890 - 12345000000000000000     

     12345678901234567890 - -87654321098765432110    

     -12345678901234567890 - 87654321098765432110    

     -12345678901234567890 - -12345678901234567880   

     -12345678901234567890 - -12345678901234567980   

    "

    "Modified: 20.10.1996 / 18:42:16 / cg"

!

/ aNumber

    "return the quotient of the receiver and the argument, aNumber"

    aNumber isInteger ifTrue:[

	^ Fraction numerator:self

		  denominator:aNumber

    ].

    "this is a q&d hack - we loose lots of precision here ..."

    ^ (self asFloat / aNumber asFloat)

    "Modified: 28.7.1997 / 19:07:55 / cg"

!

// aNumber

    "return the quotient of the receiver and the argument, aNumber.

     The result is truncated toward negative infinity and negative,

     if the operands signs differ."

    |cls divMod quo abs "{ Class: SmallInteger }" n|

    cls := aNumber class.

    "

     this is the common case, dividing by a SmallInteger.

     Use a special method for this case ...

    "

    (cls == SmallInteger) ifTrue:[

        abs := aNumber.

        abs := abs abs.

        (abs between:1 and:16r00ffffff) ifTrue:[

            divMod := self absFastDivMod:abs.

        ] ifFalse:[

            n := abs asLargeInteger.

        ].

    ] ifFalse:[

        "

         if the argument is not a largeInteger, coerce

        "

        (cls == self class) ifFalse:[

            ^ self retry:#// coercing:aNumber

        ].

        n := aNumber

    ].

    divMod isNil ifTrue:[

        divMod := self absDivMod:n.

    ].

    quo := divMod at:1.

    (sign == aNumber sign) ifFalse:[

        "/ adjust for truncation if negative and there is a remainder ...

        quo := quo sign:-1.

        (divMod at:2) == 0 ifFalse:[

            ^ quo - 1

        ].

    ].

    ^ quo

    "

     (9000000000 // 4000000000)   =   (900 // 400)   ifFalse:[self halt].

     (-9000000000 // 4000000000)  =   (-900 // 400)  ifFalse:[self halt].

     (9000000000 // -4000000000)  =   (900 // -400)  ifFalse:[self halt].

     (-9000000000 // -4000000000) =   (-900 // -400) ifFalse:[self halt].

     16rfffffffff // 16r01ffffff  =   2048 ifFalse:[self halt].

     16rfffffffff // 16r00ffffff  =   4096 ifFalse:[self halt].

     16rfffffffff // 16r001fffff  =  32768 ifFalse:[self halt].

     900 quo: 400   

     -900 quo: 400                   

     900 quo: -400                   

     -900 quo: -400 

     9000000000 quo: 4000000000   

     -9000000000 quo: 4000000000  

     9000000000 quo: -4000000000  

     -9000000000 quo: -4000000000 

    "

    "Modified: / 5.11.1996 / 16:39:36 / cg"

    "Modified: / 27.4.1999 / 19:50:26 / stefan"

!

\\ aNumber

    "Answer the integer remainder m defined by division with truncation toward

     negative infinity. The remainder has the same sign as aNumber.

     m < |aNumber| AND there is an integer k with (k * aNumber + m) = self

     Compare with #rem:"

    |abs rem negativeDivisor|

    aNumber negative ifTrue:[

        negativeDivisor := true.

        abs := aNumber negated.