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/* 
// 
//  Purpose:
//     Cryptography Primitive.
//     PRNG Functions
// 
//  Contents:
//        ippsPRNGSetSeed()
//
*/

#include "owndefs.h"
#include "owncp.h"
#include "pcpbn.h"
#include "pcpprng.h"

/*F*
// Name: ippsPRNGSetSeed
//
// Purpose: Sets the initial state with the SEED value
//
// Returns:                   Reason:
//    ippStsNullPtrErr           NULL == pCtx
//                               NULL == pSeed
//
//    ippStsContextMatchErr      illegal pCtx->idCtx
//                               illegal pSeed->idCtx
//
//    ippStsNoErr                no error
//
// Parameters:
//    pSeed    pointer to the SEED
//    pCtx     pointer to the context
*F*/
IPPFUN(IppStatus, ippsPRNGSetSeed, (const IppsBigNumState* pSeed, IppsPRNGState* pCtx))
{
   /* test PRNG context */
   IPP_BAD_PTR1_RET(pCtx);
   pCtx = (IppsPRNGState*)( IPP_ALIGNED_PTR(pCtx, PRNG_ALIGNMENT) );
   IPP_BADARG_RET(!RAND_VALID_ID(pCtx), ippStsContextMatchErr);

   /* test seed */
   IPP_BAD_PTR1_RET(pSeed);
   pSeed = (IppsBigNumState*)( IPP_ALIGNED_PTR(pSeed, BN_ALIGNMENT) );
   IPP_BADARG_RET(!BN_VALID_ID(pSeed), ippStsContextMatchErr);

   {
      cpSize argSize = BITS_BNU_CHUNK( RAND_SEEDBITS(pCtx) );
      BNU_CHUNK_T mask = MASK_BNU_CHUNK(RAND_SEEDBITS(pCtx));
      cpSize size = IPP_MIN(BN_SIZE(pSeed), argSize);

      ZEXPAND_COPY_BNU(RAND_XKEY(pCtx), (cpSize)(sizeof(RAND_XKEY(pCtx))/sizeof(BNU_CHUNK_T)), BN_NUMBER(pSeed), size);
      RAND_XKEY(pCtx)[argSize-1] &= mask;

      return ippStsNoErr;
   }
}