zzx.c

密码大家Shoup写的数论算法c语言实现

#include <NTL/ZZX.h>

#include <NTL/new.h>

NTL_START_IMPL



const ZZX& ZZX::zero()
{
   static ZZX z;
   return z;
}



void conv(ZZ_pX& x, const ZZX& a)
{
   conv(x.rep, a.rep);
   x.normalize();
}

void conv(ZZX& x, const ZZ_pX& a)
{
   conv(x.rep, a.rep);
   x.normalize();
}


istream& operator>>(istream& s, ZZX& x)
{
   s >> x.rep;
   x.normalize();
   return s;
}

ostream& operator<<(ostream& s, const ZZX& a)
{
   return s << a.rep;
}


void ZZX::normalize()
{
   long n;
   const ZZ* p;

   n = rep.length();
   if (n == 0) return;
   p = rep.elts() + (n-1);
   while (n > 0 && IsZero(*p)) {
      p--; 
      n--;
   }
   rep.SetLength(n);
}


long IsZero(const ZZX& a)
{
   return a.rep.length() == 0;
}


long IsOne(const ZZX& a)
{
    return a.rep.length() == 1 && IsOne(a.rep[0]);
}

long operator==(const ZZX& a, const ZZX& b)
{
   long i, n;
   const ZZ *ap, *bp;

   n = a.rep.length();
   if (n != b.rep.length()) return 0;

   ap = a.rep.elts();
   bp = b.rep.elts();

   for (i = 0; i < n; i++)
      if (ap[i] != bp[i]) return 0;

   return 1;
}


long operator==(const ZZX& a, long b)
{
   if (b == 0)
      return IsZero(a);

   if (deg(a) != 0)
      return 0;

   return a.rep[0] == b;
}

long operator==(const ZZX& a, const ZZ& b)
{
   if (IsZero(b))
      return IsZero(a);

   if (deg(a) != 0)
      return 0;

   return a.rep[0] == b;
}


void GetCoeff(ZZ& x, const ZZX& a, long i)
{
   if (i < 0 || i > deg(a))
      clear(x);
   else
      x = a.rep[i];
}

void SetCoeff(ZZX& x, long i, const ZZ& a)
{
   long j, m;

   if (i < 0) 
      Error("SetCoeff: negative index");

   if (i >= (1L << (NTL_BITS_PER_LONG-4)))
      Error("overflow in SetCoeff");

   m = deg(x);

   if (i > m) {
      long pos = x.rep.position(a);
      x.rep.SetLength(i+1);

      if (pos != -1)
         x.rep[i] = x.rep.RawGet(pos);
      else
         x.rep[i] = a;

      for (j = m+1; j < i; j++)
         clear(x.rep[j]);
   }
   else
      x.rep[i] = a;

   x.normalize();
}

void SetCoeff(ZZX& x, long i)
{
   long j, m;

   if (i < 0) 
      Error("coefficient index out of range");

   if (i >= (1L << (NTL_BITS_PER_LONG-4)))
      Error("overflow in SetCoeff");

   m = deg(x);

   if (i > m) {
      x.rep.SetLength(i+1);
      for (j = m+1; j < i; j++)
         clear(x.rep[j]);
   }
   set(x.rep[i]);
   x.normalize();
}


void SetX(ZZX& x)
{
   clear(x);
   SetCoeff(x, 1);
}


long IsX(const ZZX& a)
{
   return deg(a) == 1 && IsOne(LeadCoeff(a)) && IsZero(ConstTerm(a));
}
      
      

const ZZ& coeff(const ZZX& a, long i)
{
   if (i < 0 || i > deg(a))
      return ZZ::zero();
   else
      return a.rep[i];
}


const ZZ& LeadCoeff(const ZZX& a)
{
   if (IsZero(a))
      return ZZ::zero();
   else
      return a.rep[deg(a)];
}

const ZZ& ConstTerm(const ZZX& a)
{
   if (IsZero(a))
      return ZZ::zero();
   else
      return a.rep[0];
}



void conv(ZZX& x, const ZZ& a)
{
   if (IsZero(a))
      x.rep.SetLength(0);
   else {
      x.rep.SetLength(1);
      x.rep[0] = a;
   }
}

void conv(ZZX& x, long a)
{
   if (a == 0) 
      x.rep.SetLength(0);
   else {
      x.rep.SetLength(1);
      conv(x.rep[0], a);
   }
}


void conv(ZZX& x, const vec_ZZ& a)
{
   x.rep = a;
   x.normalize();
}


void add(ZZX& x, const ZZX& a, const ZZX& b)
{
   long da = deg(a);
   long db = deg(b);
   long minab = min(da, db);
   long maxab = max(da, db);
   x.rep.SetLength(maxab+1);

   long i;
   const ZZ *ap, *bp; 
   ZZ* xp;

   for (i = minab+1, ap = a.rep.elts(), bp = b.rep.elts(), xp = x.rep.elts();
        i; i--, ap++, bp++, xp++)
      add(*xp, (*ap), (*bp));

   if (da > minab && &x != &a)
      for (i = da-minab; i; i--, xp++, ap++)
         *xp = *ap;
   else if (db > minab && &x != &b)
      for (i = db-minab; i; i--, xp++, bp++)
         *xp = *bp;
   else
      x.normalize();
}

void add(ZZX& x, const ZZX& a, const ZZ& b)
{
   long n = a.rep.length();
   if (n == 0) {
      conv(x, b);
   }
   else if (&x == &a) {
      add(x.rep[0], a.rep[0], b);
      x.normalize();
   }
   else if (x.rep.MaxLength() == 0) {
      x = a;
      add(x.rep[0], a.rep[0], b);
      x.normalize();
   }
   else {
      // ugly...b could alias a coeff of x

      ZZ *xp = x.rep.elts();
      add(xp[0], a.rep[0], b);
      x.rep.SetLength(n);
      xp = x.rep.elts();
      const ZZ *ap = a.rep.elts();
      long i;
      for (i = 1; i < n; i++)
         xp[i] = ap[i];
      x.normalize();
   }
}

void add(ZZX& x, const ZZX& a, long b)
{
   if (a.rep.length() == 0) {
      conv(x, b);
   }
   else {
      if (&x != &a) x = a;
      add(x.rep[0], x.rep[0], b);
      x.normalize();
   }
}


void sub(ZZX& x, const ZZX& a, const ZZX& b)
{
   long da = deg(a);
   long db = deg(b);
   long minab = min(da, db);
   long maxab = max(da, db);
   x.rep.SetLength(maxab+1);

   long i;
   const ZZ *ap, *bp; 
   ZZ* xp;

   for (i = minab+1, ap = a.rep.elts(), bp = b.rep.elts(), xp = x.rep.elts();
        i; i--, ap++, bp++, xp++)
      sub(*xp, (*ap), (*bp));

   if (da > minab && &x != &a)
      for (i = da-minab; i; i--, xp++, ap++)
         *xp = *ap;
   else if (db > minab)
      for (i = db-minab; i; i--, xp++, bp++)
         negate(*xp, *bp);
   else
      x.normalize();

}

void sub(ZZX& x, const ZZX& a, const ZZ& b)
{
   long n = a.rep.length();
   if (n == 0) {
      conv(x, b);
      negate(x, x);
   }
   else if (&x == &a) {
      sub(x.rep[0], a.rep[0], b);
      x.normalize();
   }
   else if (x.rep.MaxLength() == 0) {
      x = a;
      sub(x.rep[0], a.rep[0], b);
      x.normalize();
   }
   else {
      // ugly...b could alias a coeff of x

      ZZ *xp = x.rep.elts();
      sub(xp[0], a.rep[0], b);
      x.rep.SetLength(n);
      xp = x.rep.elts();
      const ZZ *ap = a.rep.elts();
      long i;
      for (i = 1; i < n; i++)
         xp[i] = ap[i];
      x.normalize();
   }
}

void sub(ZZX& x, const ZZX& a, long b)
{
   if (b == 0) {
      x = a;
      return;
   }

   if (a.rep.length() == 0) {
      x.rep.SetLength(1);
      conv(x.rep[0], b);
      negate(x.rep[0], x.rep[0]);
   }
   else {
      if (&x != &a) x = a;
      sub(x.rep[0], x.rep[0], b);
   }
   x.normalize();
}

void sub(ZZX& x, long a, const ZZX& b)
{
   negate(x, b);
   add(x, x, a);
}


void sub(ZZX& x, const ZZ& b, const ZZX& a)
{
   long n = a.rep.length();
   if (n == 0) {
      conv(x, b);
   }
   else if (x.rep.MaxLength() == 0) {
      negate(x, a);
      add(x.rep[0], a.rep[0], b);
      x.normalize();
   }
   else {
      // ugly...b could alias a coeff of x

      ZZ *xp = x.rep.elts();
      sub(xp[0], b, a.rep[0]);
      x.rep.SetLength(n);
      xp = x.rep.elts();
      const ZZ *ap = a.rep.elts();
      long i;
      for (i = 1; i < n; i++)
         negate(xp[i], ap[i]);
      x.normalize();
   }
}



void negate(ZZX& x, const ZZX& a)
{
   long n = a.rep.length();
   x.rep.SetLength(n);

   const ZZ* ap = a.rep.elts();
   ZZ* xp = x.rep.elts();
   long i;

   for (i = n; i; i--, ap++, xp++)
      negate((*xp), (*ap));

}

long MaxBits(const ZZX& f)
{
   long i, m;
   m = 0;

   for (i = 0; i <= deg(f); i++) {
      m = max(m, NumBits(f.rep[i]));
   }

   return m;
}


void PlainMul(ZZX& x, const ZZX& a, const ZZX& b)
{
   if (&a == &b) {
      PlainSqr(x, a);
      return;
   }

   long da = deg(a);
   long db = deg(b);

   if (da < 0 || db < 0) {
      clear(x);
      return;
   }

   long d = da+db;



   const ZZ *ap, *bp;
   ZZ *xp;
   
   ZZX la, lb;

   if (&x == &a) {
      la = a;
      ap = la.rep.elts();
   }
   else
      ap = a.rep.elts();