source: git/libpolys/coeffs/modulop.h @ f081b9

#ifndef MODULOP_H
#define MODULOP_H
/****************************************
*  Computer Algebra System SINGULAR     *
****************************************/
/*
* ABSTRACT: numbers modulo p (<=32749)
*/
#include "misc/auxiliary.h"


// define if a*b is with mod instead of tables
//#define HAVE_GENERIC_MULT
// define if 1/b is from  tables
//#define HAVE_INVTABLE
// define if an if should be used
//#define HAVE_GENERIC_ADD

//#undef HAVE_GENERIC_ADD
//#undef HAVE_GENERIC_MULT
//#undef HAVE_INVTABLE

//#define HAVE_GENERIC_ADD 1
//#define HAVE_GENERIC_MULT 1
//#define HAVE_INVTABLE 1

// enable large primes (32749 < p < 2^31-)
#define NV_OPS
#define NV_MAX_PRIME 32749
#define FACTORY_MAX_PRIME 536870909

struct n_Procs_s; typedef struct  n_Procs_s  *coeffs;
struct snumber; typedef struct snumber *   number;

BOOLEAN npInitChar(coeffs r, void* p);

// inline number npMultM(number a, number b, int npPrimeM)
// // return (a*b)%n
// {
//    double ab;
//    long q, res;
//
//    ab = ((double) ((int)a)) * ((double) ((int)b));
//    q  = (long) (ab/((double) npPrimeM));  // q could be off by (+/-) 1
//    res = (long) (ab - ((double) q)*((double) npPrimeM));
//    res += (res >> 31) & npPrimeM;
//    res -= npPrimeM;
//    res += (res >> 31) & npPrimeM;
//    return (number)res;
// }
#ifdef HAVE_GENERIC_MULT
static inline number npMultM(number a, number b, const coeffs r)
{
  return (number)
    ((((unsigned long) a)*((unsigned long) b)) % ((unsigned long) r->ch));
}
static inline void npInpMultM(number &a, number b, const coeffs r)
{
  a=(number)
    ((((unsigned long) a)*((unsigned long) b)) % ((unsigned long) r->ch));
}
#else
static inline number npMultM(number a, number b, const coeffs r)
{
  long x = (long)r->npLogTable[(long)a]+ r->npLogTable[(long)b];
  #ifdef HAVE_GENERIC_ADD
    if (x>=r->npPminus1M) x-=r->npPminus1M;
  #else
    x-=r->npPminus1M;
    #if SIZEOF_LONG == 8
      x += (x >> 63) & r->npPminus1M;
    #else
      x += (x >> 31) & r->npPminus1M;
    #endif
  #endif
  return (number)(long)r->npExpTable[x];
}
static inline void npInpMultM(number &a, number b, const coeffs r)
{
  long x = (long)r->npLogTable[(long)a]+ r->npLogTable[(long)b];
  #ifdef HAVE_GENERIC_ADD
    if (x>=r->npPminus1M) x-=r->npPminus1M;
  #else
    x-=r->npPminus1M;
    #if SIZEOF_LONG == 8
      x += (x >> 63) & r->npPminus1M;
    #else
      x += (x >> 31) & r->npPminus1M;
    #endif
  #endif
  a=(number)(long)r->npExpTable[x];
}
#endif

#if 0
inline number npAddAsm(number a, number b, int m)
{
  number r;
    asm ("addl %2, %1; cmpl %3, %1; jb 0f; subl %3, %1; 0:"
         : "=&r" (r)
         : "%0" (a), "g" (b), "g" (m)
         : "cc");
  return r;
}
inline number npSubAsm(number a, number b, int m)
{
  number r;
  asm ("subl %2, %1; jnc 0f; addl %3, %1; 0:"
        : "=&r" (r)
        : "%0" (a), "g" (b), "g" (m)
        : "cc");
  return r;
}
#endif
#ifdef HAVE_GENERIC_ADD
static inline number npAddM(number a, number b, const coeffs r)
{
  unsigned long R = (unsigned long)a + (unsigned long)b;
  return (number)(R >= (unsigned long)r->ch ? R - (unsigned long)r->ch : R);
}
static inline void npInpAddM(number &a, number b, const coeffs r)
{
  unsigned long R = (unsigned long)a + (unsigned long)b;
  a=(number)(R >= (unsigned long)r->ch ? R - (unsigned long)r->ch : R);
}
static inline number npSubM(number a, number b, const coeffs r)
{
  return (number)((long)a<(long)b ?
                       r->ch-(long)b+(long)a : (long)a-(long)b);
}
#else
static inline number npAddM(number a, number b, const coeffs r)
{
   unsigned long res = ((unsigned long)a + (unsigned long)b);
   res -= r->ch;
#if SIZEOF_LONG == 8
   res += ((long)res >> 63) & r->ch;
#else
   res += ((long)res >> 31) & r->ch;
#endif
   return (number)res;
}
static inline void npInpAddM(number &a, number b, const coeffs r)
{
   unsigned long res = ((unsigned long)a + (unsigned long)b);
   res -= r->ch;
#if SIZEOF_LONG == 8
   res += ((long)res >> 63) & r->ch;
#else
   res += ((long)res >> 31) & r->ch;
#endif
   a=(number)res;
}
static inline number npSubM(number a, number b, const coeffs r)
{
   long res = ((long)a - (long)b);
#if SIZEOF_LONG == 8
   res += (res >> 63) & r->ch;
#else
   res += (res >> 31) & r->ch;
#endif
   return (number)res;
}
#endif

static inline number npNegM(number a, const coeffs r)
{
  return (number)((long)(r->ch)-(long)(a));
}

static inline BOOLEAN npIsOne (number a, const coeffs)
{
  return 1 == (long)a;
}

static inline long npInvMod(long a, const coeffs R)
{
   long s;

   long  u, v, u0, u1, u2, q, r;

   assume(a>0);
   u1=1; u2=0;
   u = a; v = R->ch;

   do
   {
      q = u / v;
      //r = u % v;
      r = u - q*v;
      u = v;
      v = r;
      u0 = u2;
      u2 = u1 - q*u2;
      u1 = u0;
   } while (v != 0);

   assume(u==1);
   s = u1;
#ifdef HAVE_GENERIC_ADD
   if (s < 0)
      return s + R->ch;
   else
      return s;
#else
  #if SIZEOF_LONG == 8
  s += (s >> 63) & R->ch;
  #else
  s += (s >> 31) & R->ch;
  #endif
  return s;
#endif
}

static inline number npInversM (number c, const coeffs r)
{
  n_Test(c, r);
#ifndef HAVE_GENERIC_MULT
  #ifndef HAVE_INVTABLE
  number d = (number)(long)r->npExpTable[r->npPminus1M - r->npLogTable[(long)c]];
  #else
  long inv=(long)r->npInvTable[(long)c];
  if (inv==0)
  {
    inv = (long)r->npExpTable[r->npPminus1M - r->npLogTable[(long)c]];
    r->npInvTable[(long)c]=inv;
  }
  number d = (number)inv;
  #endif
#else
  #ifdef HAVE_INVTABLE
  long inv=(long)r->npInvTable[(long)c];
  if (inv==0)
  {
    inv=npInvMod((long)c,r);
    r->npInvTable[(long)c]=inv;
  }
  #else
  long  inv=npInvMod((long)c,r);
  #endif
  number d = (number)inv;
#endif
  n_Test(d, r);
  return d;
}


// The folloing is reused inside gnumpc.cc, gnumpfl.cc and longrat.cc
long    npInt         (number &n, const coeffs r);

#define npEqualM(A,B,r)  ((A)==(B))

#endif