void sftbit(_MIPD_ big x,int n,big z)
{ /* shift x by n bits */
int m;
mr_small sm;
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM) return;
copy(x,z);
if (n==0) return;
MR_IN(47)
m=mr_abs(n);
sm=mr_shiftbits((mr_small)1,m%mr_mip->lg2b);
if (n>0)
{ /* shift left */
#ifndef MR_ALWAYS_BINARY
if (mr_mip->base==mr_mip->base2)
{
#endif
mr_shift(_MIPP_ z,n/mr_mip->lg2b,z);
mr_pmul(_MIPP_ z,sm,z);
#ifndef MR_ALWAYS_BINARY
}
else
{
expb2(_MIPP_ m,mr_mip->w1);
multiply(_MIPP_ z,mr_mip->w1,z);
}
#endif
}
else
{ /* shift right */
#ifndef MR_ALWAYS_BINARY
if (mr_mip->base==mr_mip->base2)
{
#endif
mr_shift(_MIPP_ z,n/mr_mip->lg2b,z);
#ifdef MR_FP_ROUNDING
mr_sdiv(_MIPP_ z,sm,mr_invert(sm),z);
#else
mr_sdiv(_MIPP_ z,sm,z);
#endif
#ifndef MR_ALWAYS_BINARY
}
else
{
expb2(_MIPP_ m,mr_mip->w1);
divide(_MIPP_ z,mr_mip->w1,z);
}
#endif
}
MR_OUT
}
int logb2(_MIPD_ big x)
{ /* returns number of bits in x */
int xl,lg2;
mr_small top;
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM || size(x)==0) return 0;
MR_IN(49)
#ifndef MR_ALWAYS_BINARY
if (mr_mip->base==mr_mip->base2)
{
#endif
xl=(int)(x->len&MR_OBITS);
lg2=mr_mip->lg2b*(xl-1);
top=x->w[xl-1];
while (top>=1)
{
lg2++;
top/=2;
}
#ifndef MR_ALWAYS_BINARY
}
else
{
copy(x,mr_mip->w0);
insign(PLUS,mr_mip->w0);
lg2=0;
while (mr_mip->w0->len>1)
{
#ifdef MR_FP_ROUNDING
mr_sdiv(_MIPP_ mr_mip->w0,mr_mip->base2,mr_invert(mr_mip->base2),mr_mip->w0);
#else
mr_sdiv(_MIPP_ mr_mip->w0,mr_mip->base2,mr_mip->w0);
#endif
lg2+=mr_mip->lg2b;
}
while (mr_mip->w0->w[0]>=1)
{
lg2++;
mr_mip->w0->w[0]/=2;
}
}
#endif
MR_OUT
return lg2;
}
mr_small mr_setbase(_MIPD_ mr_small nb)
{ /* set base. Pack as many digits as *
* possible into each computer word */
mr_small temp;
#ifdef MR_FP
mr_small dres;
#endif
#ifndef MR_NOFULLWIDTH
BOOL fits;
int bits;
#ifdef MR_OS_THREADS
miracl *mr_mip=get_mip();
#endif
fits=FALSE;
bits=MIRACL;
while (bits>1)
{
bits/=2;
temp=((mr_small)1<<bits);
if (temp==nb)
{
fits=TRUE;
break;
}
if (temp<nb || (bits%2)!=0) break;
}
if (fits)
{
mr_mip->apbase=nb;
mr_mip->pack=MIRACL/bits;
mr_mip->base=0;
return 0;
}
#endif
mr_mip->apbase=nb;
mr_mip->pack=1;
mr_mip->base=nb;
if (mr_mip->base==0) return 0;
temp=MR_DIV(MAXBASE,nb);
while (temp>=nb)
{
temp=MR_DIV(temp,nb);
mr_mip->base*=nb;
mr_mip->pack++;
}
#ifdef MR_FP_ROUNDING
mr_mip->inverse_base=mr_invert(mr_mip->base);
return mr_mip->inverse_base;
#else
return 0;
#endif
}
int egcd(_MIPD_ big x,big y,big z)
{ /* greatest common divisor z=gcd(x,y) by Euclids *
* method using Lehmers algorithm for big numbers */
int q,r,a,b,c,d,n;
mr_small sr,m,sm;
mr_small u,v,lq,lr;
#ifdef MR_FP
mr_small dres;
#endif
big t;
#ifndef MR_GENERIC_MT
miracl *mr_mip=get_mip();
#endif
if (mr_mip->ERNUM) return 0;
MR_IN(12)
copy(x,mr_mip->w1);
copy(y,mr_mip->w2);
insign(PLUS,mr_mip->w1);
insign(PLUS,mr_mip->w2);
a=b=c=d=0;
while (size(mr_mip->w2)!=0)
{
if (b==0)
{ /* update w1 and w2 */
divide(_MIPP_ mr_mip->w1,mr_mip->w2,mr_mip->w2);
t=mr_mip->w1,mr_mip->w1=mr_mip->w2,mr_mip->w2=t; /* swap(w1,w2) */
}
else
{
premult(_MIPP_ mr_mip->w1,c,z);
premult(_MIPP_ mr_mip->w1,a,mr_mip->w1);
premult(_MIPP_ mr_mip->w2,b,mr_mip->w0);
premult(_MIPP_ mr_mip->w2,d,mr_mip->w2);
add(_MIPP_ mr_mip->w1,mr_mip->w0,mr_mip->w1);
add(_MIPP_ mr_mip->w2,z,mr_mip->w2);
}
if (mr_mip->ERNUM || size(mr_mip->w2)==0) break;
n=(int)mr_mip->w1->len;
if (mr_mip->w2->len==1)
{ /* special case if mr_mip->w2 is now small */
sm=mr_mip->w2->w[0];
#ifdef MR_FP_ROUNDING
sr=mr_sdiv(_MIPP_ mr_mip->w1,sm,mr_invert(sm),mr_mip->w1);
#else
sr=mr_sdiv(_MIPP_ mr_mip->w1,sm,mr_mip->w1);
#endif
if (sr==0)
{
copy(mr_mip->w2,mr_mip->w1);
break;
}
zero(mr_mip->w1);
mr_mip->w1->len=1;
mr_mip->w1->w[0]=sr;
while ((sr=MR_REMAIN(mr_mip->w2->w[0],mr_mip->w1->w[0]))!=0)
mr_mip->w2->w[0]=mr_mip->w1->w[0],mr_mip->w1->w[0]=sr;
break;
}
a=1;
b=0;
c=0;
d=1;
m=mr_mip->w1->w[n-1]+1;
if (mr_mip->base==0)
{
#ifndef MR_NOFULLWIDTH
if (m==0)
{
u=mr_mip->w1->w[n-1];
v=mr_mip->w2->w[n-1];
}
else
{
u=muldvm(mr_mip->w1->w[n-1],mr_mip->w1->w[n-2],m,&sr);
v=muldvm(mr_mip->w2->w[n-1],mr_mip->w2->w[n-2],m,&sr);
}
#endif
}
else
{
u=muldiv(mr_mip->w1->w[n-1],mr_mip->base,mr_mip->w1->w[n-2],m,&sr);
v=muldiv(mr_mip->w2->w[n-1],mr_mip->base,mr_mip->w2->w[n-2],m,&sr);
}
forever
{ /* work only with most significant piece */
if (((v+c)==0) || ((v+d)==0)) break;
lq=MR_DIV((u+a),(v+c));
if (lq!=MR_DIV((u+b),(v+d))) break;
if (lq>=(mr_small)(MR_TOOBIG/mr_abs(d))) break;
q=(int)lq;
r=a-q*c;
a=c;
c=r;
r=b-q*d;
b=d;
d=r;
lr=u-lq*v;
u=v;
v=lr;
}
}
copy(mr_mip->w1,z);
MR_OUT
return (size(mr_mip->w1));
}
