b5e34e22aa
R=reed@google.com Author: bungeman@google.com Review URL: https://chromiumcodereview.appspot.com/14873006 git-svn-id: http://skia.googlecode.com/svn/trunk@9037 2bbb7eff-a529-9590-31e7-b0007b416f81
55 lines
1.4 KiB
C++
55 lines
1.4 KiB
C++
/*
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* Copyright 2011 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkConstexprMath_DEFINED
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#define SkConstexprMath_DEFINED
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#include "SkTypes.h"
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#include <limits.h>
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template <uintmax_t N, uintmax_t B>
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struct SK_LOG {
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//! Compile-time constant ceiling(logB(N)).
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static const uintmax_t value = 1 + SK_LOG<N/B, B>::value;
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};
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template <uintmax_t B>
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struct SK_LOG<1, B> {
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static const uintmax_t value = 0;
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};
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template <uintmax_t B>
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struct SK_LOG<0, B> {
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static const uintmax_t value = 0;
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};
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template<uintmax_t N>
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struct SK_2N1 {
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//! Compile-time constant (2^N)-1.
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static const uintmax_t value = (SK_2N1<N-1>::value << 1) + 1;
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};
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template<>
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struct SK_2N1<1> {
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static const uintmax_t value = 1;
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};
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/** Compile-time constant number of base n digits in type t
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if the bits of type t are considered as unsigned base two.
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*/
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#define SK_BASE_N_DIGITS_IN(n, t) (\
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SK_LOG<SK_2N1<(sizeof(t) * CHAR_BIT)>::value, n>::value\
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)
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/** Compile-time constant number of base 10 digits in type t
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if the bits of type t are considered as unsigned base two.
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*/
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#define SK_DIGITS_IN(t) SK_BASE_N_DIGITS_IN(10, (t))
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// Compile-time constant maximum value of two unsigned values.
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template <uintmax_t a, uintmax_t b> struct SkTUMax {
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static const uintmax_t value = (b < a) ? a : b;
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};
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#endif
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