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// Origin: abbott@dima.unige.it

// PR c/5120

extern void * malloc (__SIZE_TYPE__);

extern void * calloc (__SIZE_TYPE__, __SIZE_TYPE__);

typedef unsigned int FFelem;

FFelem FFmul(const FFelem x, const FFelem y)

{

  return x;

}

struct DUPFFstruct

{

  int maxdeg;

  int deg;

  FFelem *coeffs;

};

typedef struct DUPFFstruct *DUPFF;

int DUPFFdeg(const DUPFF f)

{

  return f->deg;

}

DUPFF DUPFFnew(const int maxdeg)

{

  DUPFF ans = (DUPFF)malloc(sizeof(struct DUPFFstruct));

  ans->coeffs = 0;

  if (maxdeg >= 0) ans->coeffs = (FFelem*)calloc(maxdeg+1,sizeof(FFelem));

  ans->maxdeg = maxdeg;

  ans->deg = -1;

  return ans;

}

void DUPFFfree(DUPFF x)

{

}

void DUPFFswap(DUPFF x, DUPFF y)

{

}

DUPFF DUPFFcopy(const DUPFF x)

{

  return x;

}

void DUPFFshift_add(DUPFF f, const DUPFF g, int deg, const FFelem coeff)

{

}

DUPFF DUPFFexgcd(DUPFF *fcofac, DUPFF *gcofac, const DUPFF f, const DUPFF g)

{

  DUPFF u, v, uf, ug, vf, vg;

  FFelem q, lcu, lcvrecip, p;

  int df, dg, du, dv;

  printf("DUPFFexgcd called on degrees %d and %d\n", DUPFFdeg(f), DUPFFdeg(g));

  if (DUPFFdeg(f) < DUPFFdeg(g)) return DUPFFexgcd(gcofac, fcofac, g, f);  /*** BUG IN THIS LINE ***/

  if (DUPFFdeg(f) != 2 || DUPFFdeg(g) != 1) abort();

  if (f->coeffs[0] == 0) return f;

  /****** NEVER REACH HERE IN THE EXAMPLE ******/

  p = 2;

  df = DUPFFdeg(f);  if (df < 0) df = 0; /* both inputs are zero */

  dg = DUPFFdeg(g);  if (dg < 0) dg = 0; /* one input is zero */

  u = DUPFFcopy(f);

  v = DUPFFcopy(g);

  uf = DUPFFnew(dg); uf->coeffs[0] = 1; uf->deg = 0;

  ug = DUPFFnew(df);

  vf = DUPFFnew(dg);

  vg = DUPFFnew(df); vg->coeffs[0] = 1; vg->deg = 0;

  while (DUPFFdeg(v) > 0)

  {

    dv = DUPFFdeg(v);

    lcvrecip = FFmul(1, v->coeffs[dv]);

    while (DUPFFdeg(u) >= dv)

    {

      du = DUPFFdeg(u);

      lcu = u->coeffs[du];

      q = FFmul(lcu, lcvrecip);

      DUPFFshift_add(u, v, du-dv, p-q);

      DUPFFshift_add(uf, vf, du-dv, p-q);

      DUPFFshift_add(ug, vg, du-dv, p-q);

    }

    DUPFFswap(u, v);

    DUPFFswap(uf, vf);

    DUPFFswap(ug, vg);

  }

  if (DUPFFdeg(v) == 0)

  {

    DUPFFswap(u, v);

    DUPFFswap(uf, vf);

    DUPFFswap(ug, vg);

  }

  DUPFFfree(vf);

  DUPFFfree(vg);

  DUPFFfree(v);

  *fcofac = uf;

  *gcofac = ug;

  return u;

}

int main()

{

  DUPFF f, g, cf, cg, h;

  f = DUPFFnew(1); f->coeffs[1] = 1; f->deg = 1;

  g = DUPFFnew(2); g->coeffs[2] = 1; g->deg = 2;

  printf("calling DUPFFexgcd on degrees %d and %d\n", DUPFFdeg(f), DUPFFdeg(g)) ;

  h = DUPFFexgcd(&cf, &cg, f, g);

  return 0;

}