blob: 21881538e202c7f243c0d9485394f7aaebdfe17a [file] [log] [blame]
Guido van Rossuma3309961993-07-28 09:05:47 +00001#ifndef Py_LONGINTREPR_H
2#define Py_LONGINTREPR_H
3#ifdef __cplusplus
4extern "C" {
5#endif
6
Guido van Rossumedcc38a1991-05-05 20:09:44 +00007/***********************************************************
Guido van Rossum9bfef441993-03-29 10:43:31 +00008Copyright 1991, 1992, 1993 by Stichting Mathematisch Centrum,
9Amsterdam, The Netherlands.
Guido van Rossumedcc38a1991-05-05 20:09:44 +000010
11 All Rights Reserved
12
13Permission to use, copy, modify, and distribute this software and its
14documentation for any purpose and without fee is hereby granted,
15provided that the above copyright notice appear in all copies and that
16both that copyright notice and this permission notice appear in
17supporting documentation, and that the names of Stichting Mathematisch
18Centrum or CWI not be used in advertising or publicity pertaining to
19distribution of the software without specific, written prior permission.
20
21STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
22THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
23FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
24FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
25WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
26ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
27OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
28
29******************************************************************/
30
Guido van Rossum3d095431992-01-19 16:30:12 +000031/* This is published for the benefit of "friend" marshal.c only. */
32
Guido van Rossumedcc38a1991-05-05 20:09:44 +000033/* Parameters of the long integer representation.
34 These shouldn't have to be changed as C should guarantee that a short
35 contains at least 16 bits, but it's made changeable any way.
36 Note: 'digit' should be able to hold 2*MASK+1, and 'twodigits'
37 should be able to hold the intermediate results in 'mul'
38 (at most MASK << SHIFT).
39 Also, x_sub assumes that 'digit' is an unsigned type, and overflow
40 is handled by taking the result mod 2**N for some N > SHIFT.
41 And, at some places it is assumed that MASK fits in an int, as well. */
42
43typedef unsigned short digit;
Guido van Rossumbadb1161991-05-14 12:06:16 +000044typedef unsigned int wdigit; /* digit widened to parameter size */
Guido van Rossumedcc38a1991-05-05 20:09:44 +000045typedef unsigned long twodigits;
Guido van Rossumbadb1161991-05-14 12:06:16 +000046typedef long stwodigits; /* signed variant of twodigits */
Guido van Rossumedcc38a1991-05-05 20:09:44 +000047
48#define SHIFT 15
49#define BASE ((digit)1 << SHIFT)
50#define MASK ((int)(BASE - 1))
51
52/* Long integer representation.
53 The absolute value of a number is equal to
54 SUM(for i=0 through abs(ob_size)-1) ob_digit[i] * 2**(SHIFT*i)
55 Negative numbers are represented with ob_size < 0;
56 zero is represented by ob_size == 0.
57 In a normalized number, ob_digit[abs(ob_size)-1] (the most significant
58 digit) is never zero. Also, in all cases, for all valid i,
59 0 <= ob_digit[i] <= MASK.
60 The allocation fuction takes care of allocating extra memory
61 so that ob_digit[0] ... ob_digit[abs(ob_size)-1] are actually available. */
62
Guido van Rossum3d095431992-01-19 16:30:12 +000063struct _longobject {
Guido van Rossumedcc38a1991-05-05 20:09:44 +000064 OB_HEAD
65 int ob_size; /* XXX Hack! newvarobj() stores it as unsigned! */
66 digit ob_digit[1];
Guido van Rossum3d095431992-01-19 16:30:12 +000067};
Guido van Rossumedcc38a1991-05-05 20:09:44 +000068
Guido van Rossumedcc38a1991-05-05 20:09:44 +000069longobject *alloclongobject PROTO((int));
Guido van Rossuma3309961993-07-28 09:05:47 +000070
71#ifdef __cplusplus
72}
73#endif
74#endif /* !Py_LONGINTREPR_H */