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/* 
//  Purpose:
//     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
//     Internal BNU32 arithmetic.
// 
//  Contents:
//     cpDec_BNU32()
// 
*/

#include "owncp.h"
#include "pcpbnumisc.h"
#include "pcpbnu32misc.h"
#include "pcpbnu32arith.h"

/*F*
//    Name: cpDec_BNU32
//
// Purpose: BNU32 decrement.
//
// Returns:
//    borrow
//
// Parameters:
//    pA    source
//    pR    result
//    ns    size
//    v     borrow
//
*F*/

Ipp32u cpDec_BNU32(Ipp32u* pR, const Ipp32u* pA, cpSize ns, Ipp32u v)
{
   Ipp32u borrow = v;
   int n;
   for(n=0; n<ns; n++) {
      Ipp64u t = (Ipp64u)(pA[n]) - (Ipp64u)borrow;
      pR[n] = LODWORD(t);
      borrow = HIDWORD(t)>>(32-1);
   }
   return borrow;
}