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40 
41 /*
42 //  Purpose:
43 //     Intel(R) Integrated Performance Primitives. Cryptography Primitives.
44 //     Internal Unsigned arithmetic
45 //
46 //  Contents:
47 //     cpDec_BNU()
48 //
49 */
50 
51 #include "owncp.h"
52 #include "pcpbnuarith.h"
53 #include "pcpbnumisc.h"
54 
55 /*F*
56 //    Name: cpDec_BNU
57 //
58 // Purpose: decrement BigNum.
59 //
60 // Returns:
61 //    borrow of result of dec BigNum.
62 //
63 // Parameters:
64 //    pA    source BigNum A
65 //    pR    resultant BigNum
66 //    ns    size of BigNum
67 //    val   carry
68 *F*/
69 
70 #if !((_IPP32E==_IPP32E_M7) || \
71       (_IPP32E==_IPP32E_U8) || \
72       (_IPP32E==_IPP32E_Y8) || \
73       (_IPP32E>=_IPP32E_E9) || \
74       (_IPP32E==_IPP32E_N8))
cpDec_BNU(BNU_CHUNK_T * pR,const BNU_CHUNK_T * pA,cpSize ns,BNU_CHUNK_T val)75 BNU_CHUNK_T cpDec_BNU(BNU_CHUNK_T* pR, const BNU_CHUNK_T* pA, cpSize ns, BNU_CHUNK_T val)
76 {
77    cpSize i;
78    for(i=0; i<ns && val; i++) {
79       BNU_CHUNK_T borrow;
80       SUB_AB(borrow, pR[i], pA[i], val);
81       val = borrow;
82    }
83    if(pR!=pA)
84       for(; i<ns; i++)
85          pR[i] = pA[i];
86    return val;
87 }
88 #endif
89