path: root/lib/freebl/mpi/montmulf.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* $Id$ */

#ifdef SOLARIS
#define RF_INLINE_MACROS 1
#endif

static const double TwoTo16=65536.0;
static const double TwoToMinus16=1.0/65536.0;
static const double Zero=0.0;
static const double TwoTo32=65536.0*65536.0;
static const double TwoToMinus32=1.0/(65536.0*65536.0);

#ifdef RF_INLINE_MACROS

double upper32(double);
double lower32(double, double);
double mod(double, double, double);

void i16_to_d16_and_d32x4(const double * /*1/(2^16)*/, 
			  const double * /* 2^16*/,
			  const double * /* 0 */,
			  double *       /*result16*/, 
			  double *       /* result32 */,
			  float *  /*source - should be unsigned int*
		          	       converted to float* */);

#else
#ifdef MP_USE_FLOOR
#include <math.h>
#else
#define floor(d) ((double)((unsigned long long)(d)))
#endif

static double upper32(double x)
{
  return floor(x*TwoToMinus32);
}

static double lower32(double x, double y)
{
  return x-TwoTo32*floor(x*TwoToMinus32);
}

static double mod(double x, double oneoverm, double m)
{
  return x-m*floor(x*oneoverm);
}

#endif


static void cleanup(double *dt, int from, int tlen)
{
 int i;
 double tmp,tmp1,x,x1;

 tmp=tmp1=Zero;
 /* original code **
 for(i=2*from;i<2*tlen-2;i++)
   {
     x=dt[i];
     dt[i]=lower32(x,Zero)+tmp1;
     tmp1=tmp;
     tmp=upper32(x);
   }
 dt[tlen-2]+=tmp1;
 dt[tlen-1]+=tmp;
 **end original code ***/
 /* new code ***/
 for(i=2*from;i<2*tlen;i+=2)
   {
     x=dt[i];
     x1=dt[i+1];
     dt[i]=lower32(x,Zero)+tmp;
     dt[i+1]=lower32(x1,Zero)+tmp1;
     tmp=upper32(x);
     tmp1=upper32(x1);
   }
  /** end new code **/
}


void conv_d16_to_i32(unsigned int *i32, double *d16, long long *tmp, int ilen)
{
int i;
long long t, t1, a, b, c, d;

 t1=0;
 a=(long long)d16[0];
 b=(long long)d16[1];
 for(i=0; i<ilen-1; i++)
   {
     c=(long long)d16[2*i+2];
     t1+=(unsigned int)a;
     t=(a>>32);
     d=(long long)d16[2*i+3];
     t1+=(b&0xffff)<<16;
     t+=(b>>16)+(t1>>32);
     i32[i]=(unsigned int)t1;
     t1=t;
     a=c;
     b=d;
   }
 t1+=(unsigned int)a;
 t=(a>>32);
 t1+=(b&0xffff)<<16;
 i32[i]=(unsigned int)t1;
}

void conv_i32_to_d32(double *d32, unsigned int *i32, int len)
{
int i;

#pragma pipeloop(0)
 for(i=0;i<len;i++) d32[i]=(double)(i32[i]);
}


void conv_i32_to_d16(double *d16, unsigned int *i32, int len)
{
int i;
unsigned int a;

#pragma pipeloop(0)
 for(i=0;i<len;i++)
   {
     a=i32[i];
     d16[2*i]=(double)(a&0xffff);
     d16[2*i+1]=(double)(a>>16);
   }
}


void conv_i32_to_d32_and_d16(double *d32, double *d16, 
			     unsigned int *i32, int len)
{
int i = 0;
unsigned int a;

#pragma pipeloop(0)
#ifdef RF_INLINE_MACROS
 for(;i<len-3;i+=4)
   {
     i16_to_d16_and_d32x4(&TwoToMinus16, &TwoTo16, &Zero,
			  &(d16[2*i]), &(d32[i]), (float *)(&(i32[i])));
   }
#endif
 for(;i<len;i++)
   {
     a=i32[i];
     d32[i]=(double)(i32[i]);
     d16[2*i]=(double)(a&0xffff);
     d16[2*i+1]=(double)(a>>16);
   }
}


void adjust_montf_result(unsigned int *i32, unsigned int *nint, int len)
{
long long acc;
int i;

 if(i32[len]>0) i=-1;
 else
   {
     for(i=len-1; i>=0; i--)
       {
	 if(i32[i]!=nint[i]) break;
       }
   }
 if((i<0)||(i32[i]>nint[i]))
   {
     acc=0;
     for(i=0;i<len;i++)
       {
	 acc=acc+(unsigned long long)(i32[i])-(unsigned long long)(nint[i]);
	 i32[i]=(unsigned int)acc;
	 acc=acc>>32;
       }
   }
}




/*
** the lengths of the input arrays should be at least the following:
** result[nlen+1], dm1[nlen], dm2[2*nlen+1], dt[4*nlen+2], dn[nlen], nint[nlen]
** all of them should be different from one another
**
*/
void mont_mulf_noconv(unsigned int *result,
		     double *dm1, double *dm2, double *dt,
		     double *dn, unsigned int *nint,
		     int nlen, double dn0)
{
 int i, j, jj;
 int tmp;
 double digit, m2j, nextm2j, a, b;
 double *dptmp, *pdm1, *pdm2, *pdn, *pdtj, pdn_0, pdm1_0;

 pdm1=&(dm1[0]);
 pdm2=&(dm2[0]);
 pdn=&(dn[0]);
 pdm2[2*nlen]=Zero;

 if (nlen!=16)
   {
     for(i=0;i<4*nlen+2;i++) dt[i]=Zero;

     a=dt[0]=pdm1[0]*pdm2[0];
     digit=mod(lower32(a,Zero)*dn0,TwoToMinus16,TwoTo16);

     pdtj=&(dt[0]);
     for(j=jj=0;j<2*nlen;j++,jj++,pdtj++)
       {
	 m2j=pdm2[j];
	 a=pdtj[0]+pdn[0]*digit;
	 b=pdtj[1]+pdm1[0]*pdm2[j+1]+a*TwoToMinus16;
	 pdtj[1]=b;

#pragma pipeloop(0)
	 for(i=1;i<nlen;i++)
	   {
	     pdtj[2*i]+=pdm1[i]*m2j+pdn[i]*digit;
	   }
 	 if((jj==30)) {cleanup(dt,j/2+1,2*nlen+1); jj=0;}
	 
	 digit=mod(lower32(b,Zero)*dn0,TwoToMinus16,TwoTo16);
       }
   }
 else
   {
     a=dt[0]=pdm1[0]*pdm2[0];

     dt[65]=     dt[64]=     dt[63]=     dt[62]=     dt[61]=     dt[60]=
     dt[59]=     dt[58]=     dt[57]=     dt[56]=     dt[55]=     dt[54]=
     dt[53]=     dt[52]=     dt[51]=     dt[50]=     dt[49]=     dt[48]=
     dt[47]=     dt[46]=     dt[45]=     dt[44]=     dt[43]=     dt[42]=
     dt[41]=     dt[40]=     dt[39]=     dt[38]=     dt[37]=     dt[36]=
     dt[35]=     dt[34]=     dt[33]=     dt[32]=     dt[31]=     dt[30]=
     dt[29]=     dt[28]=     dt[27]=     dt[26]=     dt[25]=     dt[24]=
     dt[23]=     dt[22]=     dt[21]=     dt[20]=     dt[19]=     dt[18]=
     dt[17]=     dt[16]=     dt[15]=     dt[14]=     dt[13]=     dt[12]=
     dt[11]=     dt[10]=     dt[ 9]=     dt[ 8]=     dt[ 7]=     dt[ 6]=
     dt[ 5]=     dt[ 4]=     dt[ 3]=     dt[ 2]=     dt[ 1]=Zero;

     pdn_0=pdn[0];
     pdm1_0=pdm1[0];

     digit=mod(lower32(a,Zero)*dn0,TwoToMinus16,TwoTo16);
     pdtj=&(dt[0]);

     for(j=0;j<32;j++,pdtj++)
       {

	 m2j=pdm2[j];
	 a=pdtj[0]+pdn_0*digit;
	 b=pdtj[1]+pdm1_0*pdm2[j+1]+a*TwoToMinus16;
	 pdtj[1]=b;

	 /**** this loop will be fully unrolled:
	 for(i=1;i<16;i++)
	   {
	     pdtj[2*i]+=pdm1[i]*m2j+pdn[i]*digit;
	   }
	 *************************************/
	     pdtj[2]+=pdm1[1]*m2j+pdn[1]*digit;
	     pdtj[4]+=pdm1[2]*m2j+pdn[2]*digit;
	     pdtj[6]+=pdm1[3]*m2j+pdn[3]*digit;
	     pdtj[8]+=pdm1[4]*m2j+pdn[4]*digit;
	     pdtj[10]+=pdm1[5]*m2j+pdn[5]*digit;
	     pdtj[12]+=pdm1[6]*m2j+pdn[6]*digit;
	     pdtj[14]+=pdm1[7]*m2j+pdn[7]*digit;
	     pdtj[16]+=pdm1[8]*m2j+pdn[8]*digit;
	     pdtj[18]+=pdm1[9]*m2j+pdn[9]*digit;
	     pdtj[20]+=pdm1[10]*m2j+pdn[10]*digit;
	     pdtj[22]+=pdm1[11]*m2j+pdn[11]*digit;
	     pdtj[24]+=pdm1[12]*m2j+pdn[12]*digit;
	     pdtj[26]+=pdm1[13]*m2j+pdn[13]*digit;
	     pdtj[28]+=pdm1[14]*m2j+pdn[14]*digit;
	     pdtj[30]+=pdm1[15]*m2j+pdn[15]*digit;
	 /* no need for cleenup, cannot overflow */
	 digit=mod(lower32(b,Zero)*dn0,TwoToMinus16,TwoTo16);
       }
   }

 conv_d16_to_i32(result,dt+2*nlen,(long long *)dt,nlen+1);

 adjust_montf_result(result,nint,nlen); 
 
}