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cf_util.cc File Reference

miscellaneous functions, not necessarily related to canonical forms. More...

#include "globaldefs.h"
#include "config.h"
#include "cf_util.h"
#include <stdio.h>
#include <stdlib.h>

Go to the source code of this file.

Functions

int ipower (int b, int m)
 int ipower ( int b, int m ) More...
 
int ilog2 (int v)
 
int igcd (int a, int b)
 
void factoryError_intern (const char *s)
 

Variables

VAR void(* factoryError )(const char *s) = factoryError_intern
 

Detailed Description

miscellaneous functions, not necessarily related to canonical forms.

Used by: fac_cantzass.cc, gfops.cc

Definition in file cf_util.cc.

Function Documentation

◆ factoryError_intern()

void factoryError_intern ( const char *  s)

Definition at line 75 of file cf_util.cc.

76 {
77  fputs(s,stderr);
78  abort();
79 }
const CanonicalForm int s
Definition: facAbsFact.cc:51

◆ igcd()

int igcd ( int  a,
int  b 
)

Definition at line 56 of file cf_util.cc.

57 {
58  if ( a < 0 ) a = -a;
59  if ( b < 0 ) b = -b;
60 
61  int c;
62 
63  while ( b != 0 )
64  {
65  c = a % b;
66  a = b;
67  b = c;
68  }
69  return a;
70 }
CanonicalForm b
Definition: cfModGcd.cc:4105

◆ ilog2()

int ilog2 ( int  v)

Definition at line 42 of file cf_util.cc.

43 {
44  const unsigned int b[] = {0x2, 0xC, 0xF0, 0xFF00, 0xFFFF0000};
45  const unsigned int S[] = {1, 2, 4, 8, 16};
46 
47  unsigned int r = 0; // result of log2(v) will go here
48  if (v & b[4]) { v >>= S[4]; r |= S[4]; }
49  if (v & b[3]) { v >>= S[3]; r |= S[3]; }
50  if (v & b[2]) { v >>= S[2]; r |= S[2]; }
51  if (v & b[1]) { v >>= S[1]; r |= S[1]; }
52  if (v & b[0]) { v >>= S[0]; r |= S[0]; }
53  return (int)r;
54 }
const Variable & v
< [in] a sqrfree bivariate poly
Definition: facBivar.h:39

◆ ipower()

int ipower ( int  b,
int  m 
)

int ipower ( int b, int m )

ipower() - calculate b^m in standard integer arithmetic.

Note: Beware of overflows.

Definition at line 27 of file cf_util.cc.

28 {
29  int prod = 1;
30 
31  while ( m != 0 )
32  {
33  if ( m % 2 != 0 )
34  prod *= b;
35  m /= 2;
36  if ( m != 0 )
37  b *= b;
38  }
39  return prod;
40 }
int m
Definition: cfEzgcd.cc:128
fq_nmod_poly_t prod
Definition: facHensel.cc:100

Variable Documentation

◆ factoryError

VAR void(* factoryError) (const char *s) ( const char *  s) = factoryError_intern

Definition at line 80 of file cf_util.cc.