-/* Hey EMACS, this is -*- C -*- code! */
-
-/****************************************************************
-* *
-* Copyright (c) 1984 *
-* Massachusetts Institute of Technology *
-* *
-* This material was developed by the Scheme project at the *
-* Massachusetts Institute of Technology, Department of *
-* Electrical Engineering and Computer Science. Permission to *
-* copy this software, to redistribute it, and to use it for any *
-* purpose is granted, subject to the following restrictions and *
-* understandings. *
-* *
-* 1. Any copy made of this software must include this copyright *
-* notice in full. *
-* *
-* 2. Users of this software agree to make their best efforts (a)*
-* to return to the MIT Scheme project any improvements or *
-* extensions that they make, so that these may be included in *
-* future releases; and (b) to inform MIT of noteworthy uses of *
-* this software. *
-* *
-* 3. All materials developed as a consequence of the use of *
-* this software shall duly acknowledge such use, in accordance *
-* with the usual standards of acknowledging credit in academic *
-* research. *
-* *
-* 4. MIT has made no warrantee or representation that the *
-* operation of this software will be error-free, and MIT is *
-* under no obligation to provide any services, by way of *
-* maintenance, update, or otherwise. *
-* *
-* 5. In conjunction with products arising from the use of this *
-* material, there shall be no use of the name of the *
-* Massachusetts Institute of Technology nor of any adaptation *
-* thereof in any advertising, promotional, or sales literature *
-* without prior written consent from MIT in each case. *
-* *
-****************************************************************/
-\f
-/* File: BIGNUM.C
- *
- * This file contains the procedures for handling BIGNUM Arithmetic
- *
- */
+/* -*-C-*-
+
+Copyright (c) 1986 Massachusetts Institute of Technology
+
+This material was developed by the Scheme project at the Massachusetts
+Institute of Technology, Department of Electrical Engineering and
+Computer Science. Permission to copy this software, to redistribute
+it, and to use it for any purpose is granted, subject to the following
+restrictions and understandings.
+
+1. Any copy made of this software must include this copyright notice
+in full.
+
+2. Users of this software agree to make their best efforts (a) to
+return to the MIT Scheme project any improvements or extensions that
+they make, so that these may be included in future releases; and (b)
+to inform MIT of noteworthy uses of this software.
+
+3. All materials developed as a consequence of the use of this
+software shall duly acknowledge such use, in accordance with the usual
+standards of acknowledging credit in academic research.
+
+4. MIT has made no warrantee or representation that the operation of
+this software will be error-free, and MIT is under no obligation to
+provide any services, by way of maintenance, update, or otherwise.
+
+5. In conjunction with products arising from the use of this material,
+there shall be no use of the name of the Massachusetts Institute of
+Technology nor of any adaptation thereof in any advertising,
+promotional, or sales literature without prior written consent from
+MIT in each case. */
+
+/* $Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/microcode/bignum.c,v 5.2 1986/12/17 05:58:31 cph Exp $
+
+This file contains the procedures for handling BIGNUM Arithmetic. */
#include "scheme.h"
#include <math.h>
}
\f
/* (BIG_TO_FIX BIGNUM)
- [Primitive number 0x68]
- When given a bignum, returns the equivalent fixnum if there is
- one. If BIGNUM is out of range, or isn't a bignum, returns
- BIGNUM.
-*/
-Built_In_Primitive(Prim_Big_To_Fix, 1, "BIG->FIX")
-{ Primitive_1_Arg();
- Arg_1_Type(TC_BIG_FIXNUM);
- return Big_To_Fix(Arg1);
+ [Primitive number 0x68]
+ When given a bignum, returns the equivalent fixnum if there is
+ one. If BIGNUM is out of range, or isn't a bignum, returns
+ BIGNUM. */
+
+Built_In_Primitive (Prim_Big_To_Fix, 1, "BIG->FIX")
+{
+ Primitive_1_Arg ();
+
+ Arg_1_Type (TC_BIG_FIXNUM);
+ return (Big_To_Fix (Arg1));
}
-Pointer Big_To_Fix(Arg1)
-Pointer Arg1;
-{ fast bigdigit *SCAN, *ARG1;
- fast long Answer, i;
+Pointer
+Big_To_Fix (bignum)
+ Pointer bignum;
+{
+ fast bigdigit *bptr, *scan;
+ fast long result, i;
long Length;
- if (Type_Code(Arg1) != TC_BIG_FIXNUM) return Arg1;
- ARG1 = BIGNUM(Get_Pointer(Arg1));
- Length = LEN(ARG1);
- if (Length==0) Answer = 0;
- else if (Length > FIXNUM_LENGTH_AS_BIGNUM) return Arg1;
- else if (Length < FIXNUM_LENGTH_AS_BIGNUM)
- for (SCAN=Bignum_Top(ARG1), i=0, Answer=0; i< Length; i++)
- Answer = Mul_Radix(Answer) + *SCAN--;
- else
- /* Length == FIXNUM_LENGTH_AS_BIGNUM */
- for (SCAN=Bignum_Top(ARG1), i=0, Answer=0; i< Length; i++)
- { Answer = Mul_Radix(Answer) + *SCAN--;
- /* This takes care of signed arithmetic */
- if ((Answer < 0) || (!(Fixnum_Fits(Answer)))) return Arg1;
- }
- if NEG_BIGNUM(ARG1) Answer = - Answer;
- return Make_Non_Pointer(TC_FIXNUM, Answer);
+
+ if ((Type_Code (bignum_object)) != TC_BIG_FIXNUM)
+ return (bignum_object);
+ bptr = BIGNUM (Get_Pointer (bignum_object));
+ Length = LEN (bptr);
+ if (Length = 0)
+ return (FIXNUM_0);
+ if (Length > FIXNUM_LENGTH_AS_BIGNUM)
+ return (bignum_object);
+
+ scan = Bignum_Top (bptr);
+ result = *scan--;
+#if ((FIXNUM_LENGTH_AS_BIGNUM * SHIFT) > ULONG_SIZE)
+ /* Mask the MS digit to prevent overflow during left shift. */
+ if (Length = FIXNUM_LENGTH_AS_BIGNUM)
+ result &=
+ ((1 << ((FIXNUM_LENGTH + 1) - ((FIXNUM_LENGTH + 1) % SHIFT))) - 1);
+#endif
+ for (i = (Length - 1); (i > 0); i -= 1)
+ result = (Mul_Radix (result) + *scan--);
+ if (result < 0)
+ return (bignum_object);
+ if (NEG_BIGNUM (bptr))
+ result = (- result);
+ return
+ (Fixnum_Fits (result)
+ ? Make_Signed_Fixnum (result)
+ : bignum_object);
}
\f
Boolean Fits_Into_Flonum(Bignum)
-/* Hey EMACS, this is -*- C -*- code! */
-
-/****************************************************************
-* *
-* Copyright (c) 1984 *
-* Massachusetts Institute of Technology *
-* *
-* This material was developed by the Scheme project at the *
-* Massachusetts Institute of Technology, Department of *
-* Electrical Engineering and Computer Science. Permission to *
-* copy this software, to redistribute it, and to use it for any *
-* purpose is granted, subject to the following restrictions and *
-* understandings. *
-* *
-* 1. Any copy made of this software must include this copyright *
-* notice in full. *
-* *
-* 2. Users of this software agree to make their best efforts (a)*
-* to return to the MIT Scheme project any improvements or *
-* extensions that they make, so that these may be included in *
-* future releases; and (b) to inform MIT of noteworthy uses of *
-* this software. *
-* *
-* 3. All materials developed as a consequence of the use of *
-* this software shall duly acknowledge such use, in accordance *
-* with the usual standards of acknowledging credit in academic *
-* research. *
-* *
-* 4. MIT has made no warrantee or representation that the *
-* operation of this software will be error-free, and MIT is *
-* under no obligation to provide any services, by way of *
-* maintenance, update, or otherwise. *
-* *
-* 5. In conjunction with products arising from the use of this *
-* material, there shall be no use of the name of the *
-* Massachusetts Institute of Technology nor of any adaptation *
-* thereof in any advertising, promotional, or sales literature *
-* without prior written consent from MIT in each case. *
-* *
-****************************************************************/
-\f
-/* Head file for bignums. This is shared by bignum.c and generic.c. */
+/* -*-C-*-
+
+Copyright (c) 1986 Massachusetts Institute of Technology
+
+This material was developed by the Scheme project at the Massachusetts
+Institute of Technology, Department of Electrical Engineering and
+Computer Science. Permission to copy this software, to redistribute
+it, and to use it for any purpose is granted, subject to the following
+restrictions and understandings.
+
+1. Any copy made of this software must include this copyright notice
+in full.
+
+2. Users of this software agree to make their best efforts (a) to
+return to the MIT Scheme project any improvements or extensions that
+they make, so that these may be included in future releases; and (b)
+to inform MIT of noteworthy uses of this software.
+3. All materials developed as a consequence of the use of this
+software shall duly acknowledge such use, in accordance with the usual
+standards of acknowledging credit in academic research.
+
+4. MIT has made no warrantee or representation that the operation of
+this software will be error-free, and MIT is under no obligation to
+provide any services, by way of maintenance, update, or otherwise.
+
+5. In conjunction with products arising from the use of this material,
+there shall be no use of the name of the Massachusetts Institute of
+Technology nor of any adaptation thereof in any advertising,
+promotional, or sales literature without prior written consent from
+MIT in each case. */
+
+/* $Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/microcode/bignum.h,v 5.2 1986/12/17 06:00:03 cph Exp $
+
+Head file for bignums. This is shared by bignum.c and generic.c. */
+\f
#ifdef ENABLE_DEBUGGING_TOOLS
#define Debug_Test(Res) \
{ Pointer R = Make_Pointer(TC_BIG_FIXNUM, Res); \
/* Length of the BIGNUM that contains the largest FIXNUM */
-#define FIXNUM_LENGTH_AS_BIGNUM ((FIXNUM_LENGTH+(SHIFT-1))/SHIFT)
+#define FIXNUM_LENGTH_AS_BIGNUM (((FIXNUM_LENGTH+1)+(SHIFT-1))/SHIFT)
#define C_INTEGER_LENGTH_AS_BIGNUM ((POINTER_LENGTH+(SHIFT-1))/SHIFT)
\f
/* Cases returned by the comparison function big_compare() */
projects / mit-scheme.git / commitdiff