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40
41 /*
42 // Purpose:
43 // Intel(R) Integrated Performance Primitives. Cryptography Primitives.
44 // Internal Unsigned BNU misc functionality
45 //
46 // Contents:
47 // cpNLZ_BNU()
48 //
49 */
50
51 #include "owncp.h"
52 #include "pcpbnumisc.h"
53
54
55 /*F*
56 // Name: cpNLZ_BNU
57 //
58 // Purpose: Returns number of leading zeros of the BNU.
59 //
60 // Returns:
61 // number of leading zeros of the BNU
62 //
63 // Parameters:
64 // x BigNum x
65 //
66 *F*/
67
cpNLZ_BNU(BNU_CHUNK_T x)68 cpSize cpNLZ_BNU(BNU_CHUNK_T x)
69 {
70 cpSize nlz = BNU_CHUNK_BITS;
71 if(x) {
72 nlz = 0;
73 #if (BNU_CHUNK_BITS == BNU_CHUNK_64BIT)
74 if( 0==(x & 0xFFFFFFFF00000000) ) { nlz +=32; x<<=32; }
75 if( 0==(x & 0xFFFF000000000000) ) { nlz +=16; x<<=16; }
76 if( 0==(x & 0xFF00000000000000) ) { nlz += 8; x<<= 8; }
77 if( 0==(x & 0xF000000000000000) ) { nlz += 4; x<<= 4; }
78 if( 0==(x & 0xC000000000000000) ) { nlz += 2; x<<= 2; }
79 if( 0==(x & 0x8000000000000000) ) { nlz++; }
80 #else
81 if( 0==(x & 0xFFFF0000) ) { nlz +=16; x<<=16; }
82 if( 0==(x & 0xFF000000) ) { nlz += 8; x<<= 8; }
83 if( 0==(x & 0xF0000000) ) { nlz += 4; x<<= 4; }
84 if( 0==(x & 0xC0000000) ) { nlz += 2; x<<= 2; }
85 if( 0==(x & 0x80000000) ) { nlz++; }
86 #endif
87 }
88 return nlz;
89 }
90