The Tor Browser: security/nss/lib/freebl/mpi/montmulf.c@b8a032363ba2 (annotated)

security/nss/lib/freebl/mpi/montmulf.c@b8a032363ba2 (annotated)

security/nss/lib/freebl/mpi/montmulf.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* 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/. */
 #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);
 }

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