+++ /dev/null
-//$$CDS-header$$
-
-#ifndef __CDS_DETAILS_NUMERIC_TRAITS_H
-#define __CDS_DETAILS_NUMERIC_TRAITS_H
-
-/*
- Filename: numtraits.h
- Created 2007.04.22 by Maxim.Khiszinsky
-
- Description:
- Various numeric constants and algorithms
- Many algorithms are static (compile-time)
- Result of static algorithm is the constant (enum) called "result".
-
- Editions:
- 2007.04.22 Maxim.Khiszinsky Created
- 2007.07.20 Maxim.Khiszinsky Added functions: exponent2, exp2Ceil
-*/
-
-namespace cds {
- /// Some helper compile-time tricks
- namespace beans {
-
- // @cond details
- namespace details {
- template <int N, int MOD> struct Exponent2Helper;
- template <int N> struct Exponent2Helper< N, 0 > {
- enum { result = Exponent2Helper< N / 2, N % 2 >::result + 1 };
- };
- template <> struct Exponent2Helper< 1, 0 > {
- enum { result = 0 };
- };
- }
- // @endcond
-
- /*! Compile-time computing of log2(N)
-
- If N = 2**k for some natural k then Exponent2<N>::result = k
- If N != 2**k for any natural k then compile-time error has been encountered
- */
- template <int N> struct Exponent2 {
- enum {
- native = N,
- base = 2,
- result = details::Exponent2Helper< N / 2, N % 2 >::result + 1
- };
- };
- //@cond details
- template <> struct Exponent2<1> {
- enum {
- native = 1,
- base = 2,
- result = 0
- };
- };
- //@endcond
-
- /// Returns @a N: 2**N is nearest to @p nNumber, 2**N < nNumber
- static inline size_t exp2Ceil( size_t nNumber )
- {
- static_assert( sizeof(size_t) == (CDS_BUILD_BITS / 8), "Internal assumption error" );
-
- size_t nExp = 0;
- size_t nBit = CDS_BUILD_BITS - 1;
-#if CDS_BUILD_BITS == 32
- size_t nMask = 0x80000000;
-#else
- size_t nMask = 0x8000000000000000;
-#endif
- while ( nMask != 0 ) {
- if ( nNumber & nMask ) {
- nExp = nBit;
- break;
- }
- nMask = nMask >> 1;
- --nBit;
- }
- if ( ( nNumber % ( ((size_t) 1) << nExp )) > ( ((size_t) 1) << (nExp - 1)) )
- ++nExp;
- return nExp;
- }
-
- /* ExponentN< int BASE, int N >
- Exponent
- If N = BASE**k then the algorithm returns k
- Else compile-time error is encountered
- */
- //@cond details
- namespace details {
- template <int N, int BASE, int MOD> struct ExponentNHelper;
- template <int N, int BASE> struct ExponentNHelper< N, BASE, 0 > {
- enum { result = ExponentNHelper< N / BASE, BASE, N % BASE >::result + 1 };
- };
- template <int BASE> struct ExponentNHelper< 1, BASE, 0 > {
- enum { result = 0 };
- };
- }
- //@endcond
-
- /// Compile-time computing log(@p N) based @p BASE. Result in @a Exponent<BASE, N>::result
- template <int BASE, int N> struct ExponentN {
- enum {
- native = N,
- base = BASE,
- result = details::ExponentNHelper< N / BASE, BASE, N % BASE >::result + 1
- };
- };
- //@cond
- template <int BASE> struct ExponentN< BASE, 1 > {
- enum {
- native = 1,
- base = BASE,
- result = 0
- };
- };
- template <int BASE> struct ExponentN< BASE, 0 >;
- //@endcond
-
- //@cond none
- template <int N> struct Power2 {
- enum {
- exponent = N,
- result = 1 << N
- };
- };
- template <> struct Power2<0> {
- enum {
- exponent = 0,
- result = 1
- };
- };
- //@endcond
-
- //@cond none
- template <int BASE, int N > struct PowerN {
- enum {
- exponent = N,
- base = BASE,
- result = PowerN< BASE, N - 1 >::result * BASE
- };
- };
- template <int BASE> struct PowerN<BASE, 0> {
- enum {
- exponent = 0,
- base = BASE,
- result = 1
- };
- };
- //@endcond
-
- //@cond none
- namespace details {
- template <int N, int ALIGN, int MOD> struct NearestCeilHelper {
- enum { result = N + ALIGN - MOD };
- };
- template <int N, int ALIGN> struct NearestCeilHelper< N, ALIGN, 0> {
- enum { result = N };
- };
- }
- template <int N, int ALIGN> struct NearestCeil {
- enum {
- native = N,
- align = ALIGN,
- result = details::NearestCeilHelper< N, ALIGN, N % ALIGN >::result
- };
- };
- //@endcond
-
- //@cond none
- template <typename T, int ALIGN> struct AlignedSize {
- typedef T NativeType;
- enum {
- nativeSize = sizeof(T),
- result = NearestCeil< sizeof(T), ALIGN >::result,
- alignBytes = result - nativeSize,
- alignedSize = result
- };
- };
- //@endcond
-
- //@cond none
- namespace details {
- template < int N1, int N2, bool LESS > struct Max;
- template < int N1, int N2 >
- struct Max< N1, N2, true > {
- enum { result = N2 };
- };
-
- template < int N1, int N2 >
- struct Max< N1, N2, false > {
- enum { result = N1 };
- };
-
- template < int N1, int N2, bool LESS > struct Min;
- template < int N1, int N2 >
- struct Min< N1, N2, true > {
- enum { result = N1 };
- };
-
- template < int N1, int N2 >
- struct Min< N1, N2, false > {
- enum { result = N2 };
- };
- }
- //@endcond
-
- /// Returns max(N1, N2) as Max<N1,N2>::result
- template <int N1, int N2>
- struct Max {
- enum { result = details::Max< N1, N2, N1 < N2 >::result };
- };
-
- /// Returns min(N1, N2) as Min<N1,N2>::result
- template <int N1, int N2>
- struct Min {
- enum { result = details::Min< N1, N2, N1 < N2 >::result };
- };
-
- } // namespace beans
-} // namespace cds
-
-#endif // __CDS_DETAILS_NUMERIC_TRAITS_H
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