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/*
//     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
//     GF(p^d) methods
//
*/
#include "owncp.h"

#include "pcpgfpxstuff.h"
#include "pcpgfpxmethod_com.h"

//tbcd: temporary excluded: #include <assert.h>

BNU_CHUNK_T* cpGFpxSqr_com(BNU_CHUNK_T* pR, const BNU_CHUNK_T* pA, gsEngine* pGFEx)
{
   int extDegree = GFP_EXTDEGREE(pGFEx);

   BNU_CHUNK_T* pGFpolynomial = GFP_MODULUS(pGFEx);
   int degR = extDegree-1;
   int elemLen= GFP_FELEN(pGFEx);

   int degA = degR;
   BNU_CHUNK_T* pTmpProduct = cpGFpGetPool(2, pGFEx);
   BNU_CHUNK_T* pTmpResult = pTmpProduct + GFP_PELEN(pGFEx);

   gsEngine* pGroundGFE = GFP_PARENT(pGFEx);
   BNU_CHUNK_T* r = cpGFpGetPool(1, pGroundGFE);
   int groundElemLen = GFP_FELEN(pGroundGFE);

   const BNU_CHUNK_T* pTmpA = GFPX_IDX_ELEMENT(pA, degA, groundElemLen);

    //tbcd: temporary excluded: assert(NULL!=pTmpProduct && NULL!=r);

   /* clear temporary */
   cpGFpElementPadd(pTmpProduct, elemLen, 0);

   /* R = A * A[degA-1] */
   cpGFpxMul_GFE(pTmpResult, pA, pTmpA, pGFEx);

   for(degA-=1; degA>=0; degA--) {
      /* save R[degR-1] */
      cpGFpElementCopy(r, GFPX_IDX_ELEMENT(pTmpResult, degR, groundElemLen), groundElemLen);

      { /* R = R * x */
         int j;
         for (j=degR; j>=1; j--)
            cpGFpElementCopy(GFPX_IDX_ELEMENT(pTmpResult, j, groundElemLen), GFPX_IDX_ELEMENT(pTmpResult, j-1, groundElemLen), groundElemLen);
         cpGFpElementPadd(pTmpResult, groundElemLen, 0);
      }

      cpGFpxMul_GFE(pTmpProduct, pGFpolynomial, r, pGFEx);
      GFP_METHOD(pGFEx)->sub(pTmpResult, pTmpResult, pTmpProduct, pGFEx);

      /* A[degA-i] */
      pTmpA -= groundElemLen;
      cpGFpxMul_GFE(pTmpProduct, pA, pTmpA, pGFEx);
      GFP_METHOD(pGFEx)->add(pTmpResult, pTmpResult, pTmpProduct, pGFEx);
   }

   /* copy result */
   cpGFpElementCopy(pR, pTmpResult, elemLen);

   /* release pools */
   cpGFpReleasePool(1, pGroundGFE);
   cpGFpReleasePool(2, pGFEx);

   return pR;
}