142ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// Copyright 2014 the V8 project authors. All rights reserved. 242ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// Use of this source code is governed by a BSD-style license that can be 342ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// found in the LICENSE file. 442ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 542ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org#ifndef V8_BASE_DIVISION_BY_CONSTANT_H_ 642ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org#define V8_BASE_DIVISION_BY_CONSTANT_H_ 742ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 842ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgnamespace v8 { 942ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgnamespace base { 1042ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 1142ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// ---------------------------------------------------------------------------- 1242ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 1342ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// The magic numbers for division via multiplication, see Warren's "Hacker's 1442ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// Delight", chapter 10. The template parameter must be one of the unsigned 1542ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// integral types. 1642ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgtemplate <class T> 1742ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgstruct MagicNumbersForDivision { 1842ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org MagicNumbersForDivision(T m, unsigned s, bool a) 1942ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org : multiplier(m), shift(s), add(a) {} 2042ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org bool operator==(const MagicNumbersForDivision& rhs) const; 2142ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 2242ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org T multiplier; 2342ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org unsigned shift; 2442ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org bool add; 2542ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org}; 2642ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 2742ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 2842ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// Calculate the multiplier and shift for signed division via multiplication. 2942ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// The divisor must not be -1, 0 or 1 when interpreted as a signed value. 3042ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgtemplate <class T> 3142ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgMagicNumbersForDivision<T> SignedDivisionByConstant(T d); 3242ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 3342ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 3442ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// Calculate the multiplier and shift for unsigned division via multiplication, 3542ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// see Warren's "Hacker's Delight", chapter 10. The divisor must not be 0 and 3642ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// leading_zeros can be used to speed up the calculation if the given number of 3742ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org// upper bits of the dividend value are known to be zero. 3842ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgtemplate <class T> 3942ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.orgMagicNumbersForDivision<T> UnsignedDivisionByConstant( 4042ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org T d, unsigned leading_zeros = 0); 4142ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 4242ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org} // namespace base 4342ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org} // namespace v8 4442ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org 4542ed2fc449e83fab2ccbf1b769a5e83715c9d783machenbach@chromium.org#endif // V8_BASE_DIVISION_BY_CONSTANT_H_ 46