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/* 
// 
//  Purpose:
//     Cryptography Primitive.
//     Fixed window exponentiation scramble/unscramble
// 
//  Contents:
//     gsScramblePut()
//     gsScrambleGet()
//     gsScrambleGet_sscm()
// 
*/
#include "owncp.h"
#include "gsscramble.h"
#include "pcpmask_ct.h"

int gsGetScrambleBufferSize(int modulusLen, int w)
{
   /* size of resource to store 2^w values of modulusLen*sizeof(BNU_CHUNK_T) each */
   int size = (1<<w) * modulusLen * sizeof(BNU_CHUNK_T);
   /* padd it up to CACHE_LINE_SIZE */
   size += (CACHE_LINE_SIZE - (size % CACHE_LINE_SIZE)) %CACHE_LINE_SIZE;
   return size/sizeof(BNU_CHUNK_T);
}

void gsScramblePut(BNU_CHUNK_T* tbl, int idx, const BNU_CHUNK_T* val, int vLen, int w)
{
   int width = 1 << w;
   int i, j;
   for(i=0, j=idx; i<vLen; i++, j+= width) {
      tbl[j] = val[i];
   }
}

void gsScrambleGet(BNU_CHUNK_T* val, int vLen, const BNU_CHUNK_T* tbl, int idx, int w)
{
   int width = 1 << w;
   int i, j;
   for(i=0, j=idx; i<vLen; i++, j+= width) {
      val[i] = tbl[j];
   }
}

void gsScrambleGet_sscm(BNU_CHUNK_T* val, int vLen, const BNU_CHUNK_T* tbl, int idx, int w)
{
   BNU_CHUNK_T mask[1<<MAX_W];

   int width = 1 << w;

   int n, i;
   switch (w) {
   case 6:
      for(n=0; n<(1<<6); n++)
         mask[n] = cpIsEqu_ct(n, idx);
      break;
   case 5:
      for(n=0; n<(1<<5); n++)
         mask[n] = cpIsEqu_ct(n, idx);
      break;
   case 4:
      for(n=0; n<(1<<4); n++)
         mask[n] = cpIsEqu_ct(n, idx);
      break;
   case 3:
      for(n=0; n<(1<<3); n++)
         mask[n] = cpIsEqu_ct(n, idx);
      break;
   case 2:
      for(n=0; n<(1<<2); n++)
         mask[n] = cpIsEqu_ct(n, idx);
      break;
   default:
      mask[0] = cpIsEqu_ct(0, idx);
      mask[1] = cpIsEqu_ct(1, idx);
      break;
   }

   for(i=0; i<vLen; i++, tbl += width) {
      BNU_CHUNK_T acc = 0;

      switch (w) {
      case 6:
         for(n=0; n<(1<<6); n++)
            acc |= tbl[n] & mask[n];
         break;
      case 5:
         for(n=0; n<(1<<5); n++)
            acc |= tbl[n] & mask[n];
         break;
      case 4:
         for(n=0; n<(1<<4); n++)
            acc |= tbl[n] & mask[n];
         break;
      case 3:
         for(n=0; n<(1<<3); n++)
            acc |= tbl[n] & mask[n];
         break;
      case 2:
         for(n=0; n<(1<<2); n++)
            acc |= tbl[n] & mask[n];
         break;
      default:
         acc |= tbl[0] & mask[0];
         acc |= tbl[1] & mask[1];
         break;
      }

      val[i] = acc;
   }
}