/* $OpenXM: OpenXM_contrib2/asir2000/engine/gf2n.c,v 1.1 1999/12/03 07:39:08 noro Exp $ */
#include "ca.h"
#include "base.h"

extern int lm_lazy;

GEN_UP2 current_mod_gf2n;

void setmod_gf2n(p)
P p;
{
	if ( !current_mod_gf2n ) {
		current_mod_gf2n = (GEN_UP2)MALLOC(sizeof(struct oGEN_UP2));
		current_mod_gf2n->id = UP2_SPARSE; /* use sparse rep. by default */
	}
	ptoup2(p,&current_mod_gf2n->dense);
	ptoup2_sparse(p,&current_mod_gf2n->sparse);
}

void getmod_gf2n(p)
UP2 *p;
{
	if ( current_mod_gf2n )
		*p = current_mod_gf2n->dense;
	else
		*p = 0;
}

void simpgf2n(n,r)
GF2N n;
GF2N *r;
{
	UP2 rem;

	if ( !n )
		*r = 0;
	else if ( NID(n) != N_GF2N )
		*r = n;
	else {
		gen_simpup2(n->body,current_mod_gf2n,&rem);
		MKGF2N(rem,*r);
	}
}

void ptogf2n(q,l)
Obj q;
GF2N *l;
{
	UP2 q1;

	if ( !q || (OID(q)==O_N && NID(q)==N_GF2N) ) {
		*l = (GF2N)q;
	} else if ( (OID(q)==O_N && NID(q)==N_Q) || OID(q)==O_P ) {
		ptoup2((P)q,&q1);
		MKGF2N(q1,*l);
	} else
		error("ptogf2n : invalid argument");
}

void gf2ntop(q,l)
GF2N q;
P *l;
{
	if ( !q )
		*l = 0;
	else
		up2top(q->body,l);
}

void gf2ntovect(q,l)
GF2N q;
VECT *l;
{
	if ( !q )
		*l = 0;
	else
		up2tovect(q->body,l);
}

#define NZGF2N(a) ((a)&&(OID(a)==O_N)&&(NID(a)==N_GF2N))

void addgf2n(a,b,c)
GF2N a,b;
GF2N *c;
{
	UP2 t,t1;
	GF2N z;

	ptogf2n((Obj)a,&z); a = z; ptogf2n((Obj)b,&z); b = z;
	if ( !a )
		*c = b;
	else if ( !b )
		*c = a;
	else {
		addup2(a->body,b->body,&t);
		gen_simpup2(t,current_mod_gf2n,&t1);
		MKGF2N(t1,*c);
	}
}

void subgf2n(a,b,c)
GF2N a,b;
GF2N *c;
{
	addgf2n(a,b,c);
}

void mulgf2n(a,b,c)
GF2N a,b;
GF2N *c;
{
	UP2 t;
	GF2N z;

	ptogf2n((Obj)a,&z); a = z; ptogf2n((Obj)b,&z); b = z;
	if ( !a || !b )
		*c = 0;
	else {
		mulup2(a->body,b->body,&t);
#if 0
		gen_simpup2(t,current_mod_gf2n,&t1);
		MKGF2N(t1,*c);	
#else
		gen_simpup2_destructive(t,current_mod_gf2n);
		if ( !t || !t->w )
			*c = 0;
		else
			MKGF2N(t,*c);	
#endif
	}
}

void squaregf2n(a,c)
GF2N a;
GF2N *c;
{
	UP2 t;
	GF2N z;

	ptogf2n((Obj)a,&z); a = z;
	if ( !a )
		*c = 0;
	else {
		squareup2(a->body,&t);
#if 0
		gen_simpup2(t,current_mod_gf2n,&t1);
		MKGF2N(t1,*c);	
#else
		gen_simpup2_destructive(t,current_mod_gf2n);
		if ( !t || !t->w )
			*c = 0;
		else
			MKGF2N(t,*c);	
#endif
	}
}

void divgf2n(a,b,c)
GF2N a,b;
GF2N *c;
{
	UP2 t,i,s;
	GF2N z;

	ptogf2n((Obj)a,&z); a = z; ptogf2n((Obj)b,&z); b = z;
	if ( !b )
		error("divgf2n: division by 0");
	else if ( !a )
		*c = 0;
	else {
		gen_invup2(b->body,current_mod_gf2n,&i);
		mulup2(a->body,i,&t);
		gen_simpup2(t,current_mod_gf2n,&s);
		MKGF2N(s,*c);
	}
}

void invgf2n(b,c)
GF2N b;
GF2N *c;
{
	UP2 i;
	GF2N z;

	ptogf2n((Obj)b,&z); b = z;
	if ( !b )
		error("divgf2n: division by 0");
	else {
		gen_invup2(b->body,current_mod_gf2n,&i);
		MKGF2N(i,*c);
	}
}

void chsgngf2n(a,c)
GF2N a,*c;
{
	*c = a;
}

void pwrgf2n(a,b,c)
GF2N a;
Q b;
GF2N *c;
{
	UP2 t;
	GF2N r;

	if ( !b ) {
		MKGF2N(ONEUP2,*c);
	} else if ( !a )
		*c = 0;
	else {
		gen_pwrmodup2(a->body,b,current_mod_gf2n,&t);
		MKGF2N(t,r);
		if ( SGN(b) < 0 )
			invgf2n(r,c);
		else
			*c = r;
	}
}

int cmpgf2n(a,b)
GF2N a,b;
{
	GF2N z;

	ptogf2n((Obj)a,&z); a = z; ptogf2n((Obj)b,&z); b = z;
	if ( !a )
		if ( !b )
			return 0;
		else
			return -1;
	else if ( !b )
			return 1;
	else
		return compup2(a->body,b->body);
}

void randomgf2n(r)
GF2N *r;
{
	int i,w,d;
	unsigned int *tb;
	UP2 t;

	if ( !current_mod_gf2n )
		error("randomgf2n : current_mod_gf2n is not set");
	w = current_mod_gf2n->dense->w;
	d = degup2(current_mod_gf2n->dense);
	NEWUP2(t,w);
	for ( i = 0, tb = t->b; i < w; i++ )
		tb[i] = mt_genrand();
	tb[w-1] &= (1<<(d%BSH))-1;
	for ( i = w-1; i >= 0 && !tb[i]; i-- );
	if ( i < 0 )
		*r = 0;
	else {
		t->w = i+1; MKGF2N(t,*r);
	}
}