13cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// Copyright 2011 the V8 project authors. All rights reserved. 23cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// Redistribution and use in source and binary forms, with or without 33cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// modification, are permitted provided that the following conditions are 43cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// met: 53cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// 63cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// * Redistributions of source code must retain the above copyright 73cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// notice, this list of conditions and the following disclaimer. 83cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// * Redistributions in binary form must reproduce the above 93cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// copyright notice, this list of conditions and the following 103cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// disclaimer in the documentation and/or other materials provided 113cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// with the distribution. 123cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// * Neither the name of Google Inc. nor the names of its 133cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// contributors may be used to endorse or promote products derived 143cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// from this software without specific prior written permission. 153cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// 163cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 173cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 183cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 193cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 203cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 213cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 223cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 233cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 243cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 253cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 263cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 273cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 283cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#ifndef V8_MISC_INTRINSICS_H_ 293cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#define V8_MISC_INTRINSICS_H_ 303cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 313cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#include "../include/v8.h" 323cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#include "globals.h" 333cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 343cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orgnamespace v8 { 353cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orgnamespace internal { 363cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 373cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// Returns the index of the leading 1 bit, counting the least significant bit at 383cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// index 0. (1 << IntegerLog2(x)) is a mask for the most significant bit of x. 393cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// Result is undefined if input is zero. 403cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orgint IntegerLog2(uint32_t value); 413cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 423cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#if defined(__GNUC__) 433cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 443cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orginline int IntegerLog2(uint32_t value) { 453cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org return 31 - __builtin_clz(value); 463cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org} 473cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 483cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#elif defined(_MSC_VER) 493cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 503cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#pragma intrinsic(_BitScanReverse) 513cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 523cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orginline int IntegerLog2(uint32_t value) { 533cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org unsigned long result; // NOLINT: MSVC intrinsic demands this type. 543cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org _BitScanReverse(&result, value); 553cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org return result; 563cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org} 573cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 583cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#else 593cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 603cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// Default version using regular operations. Code taken from: 613cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog 623cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.orginline int IntegerLog2(uint32_t value) { 633cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org int result, shift; 643cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 653cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org shift = (value > 0xFFFF) << 4; 663cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org value >>= shift; 673cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org result = shift; 683cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 693cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org shift = (value > 0xFF) << 3; 703cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org value >>= shift; 713cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org result |= shift; 723cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 733cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org shift = (value > 0xF) << 2; 743cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org value >>= shift; 753cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org result |= shift; 763cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 773cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org shift = (value > 0x3) << 1; 783cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org value >>= shift; 793cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org result |= shift; 803cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 813cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org result |= (value >> 1); 823cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 833cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org return result; 843cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org} 853cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#endif 863cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 873cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org} } // namespace v8::internal 883cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org 893cf47318da216c319ecf1f7a59de23455f117197vegorov@chromium.org#endif // V8_MISC_INTRINSICS_H_ 90