311 lines
6.1 KiB
C++
311 lines
6.1 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#pragma once
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#include "td/utils/common.h"
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#if TD_MSVC
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#include <intrin.h>
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#endif
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#ifdef bswap32
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#undef bswap32
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#endif
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#ifdef bswap64
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#undef bswap64
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#endif
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namespace td {
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int32 count_leading_zeroes32(uint32 x);
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int32 count_leading_zeroes64(uint64 x);
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int32 count_trailing_zeroes32(uint32 x);
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int32 count_trailing_zeroes64(uint64 x);
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uint32 bswap32(uint32 x);
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uint64 bswap64(uint64 x);
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int32 count_bits32(uint32 x);
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int32 count_bits64(uint64 x);
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inline uint32 bits_negate32(uint32 x) {
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return ~x + 1;
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}
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inline uint64 bits_negate64(uint64 x) {
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return ~x + 1;
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}
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inline uint32 lower_bit32(uint32 x) {
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return x & bits_negate32(x);
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}
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inline uint64 lower_bit64(uint64 x) {
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return x & bits_negate64(x);
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}
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inline uint64 host_to_big_endian64(uint64 x) {
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// NB: works only for little-endian systems
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return bswap64(x);
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}
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inline uint64 big_endian_to_host64(uint64 x) {
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// NB: works only for little-endian systems
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return bswap64(x);
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}
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//TODO: optimize
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inline int32 count_leading_zeroes_non_zero32(uint32 x) {
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DCHECK(x != 0);
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return count_leading_zeroes32(x);
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}
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inline int32 count_leading_zeroes_non_zero64(uint64 x) {
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DCHECK(x != 0);
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return count_leading_zeroes64(x);
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}
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inline int32 count_trailing_zeroes_non_zero32(uint32 x) {
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DCHECK(x != 0);
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return count_trailing_zeroes32(x);
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}
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inline int32 count_trailing_zeroes_non_zero64(uint64 x) {
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DCHECK(x != 0);
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return count_trailing_zeroes64(x);
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}
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//
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// Platform specific implementation
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//
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#if TD_MSVC
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inline int32 count_leading_zeroes32(uint32 x) {
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unsigned long res = 0;
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if (_BitScanReverse(&res, x)) {
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return 31 - res;
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}
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return 32;
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}
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inline int32 count_leading_zeroes64(uint64 x) {
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#if defined(_M_X64)
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unsigned long res = 0;
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if (_BitScanReverse64(&res, x)) {
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return 63 - res;
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}
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return 64;
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#else
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if ((x >> 32) == 0) {
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return count_leading_zeroes32(static_cast<uint32>(x)) + 32;
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} else {
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return count_leading_zeroes32(static_cast<uint32>(x >> 32));
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}
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#endif
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}
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inline int32 count_trailing_zeroes32(uint32 x) {
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unsigned long res = 0;
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if (_BitScanForward(&res, x)) {
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return res;
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}
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return 32;
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}
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inline int32 count_trailing_zeroes64(uint64 x) {
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#if defined(_M_X64)
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unsigned long res = 0;
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if (_BitScanForward64(&res, x)) {
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return res;
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}
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return 64;
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#else
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if (static_cast<uint32>(x) == 0) {
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return count_trailing_zeroes32(static_cast<uint32>(x >> 32)) + 32;
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} else {
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return count_trailing_zeroes32(static_cast<uint32>(x));
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}
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#endif
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}
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inline uint32 bswap32(uint32 x) {
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return _byteswap_ulong(x);
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}
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inline uint64 bswap64(uint64 x) {
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return _byteswap_uint64(x);
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}
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inline int32 count_bits32(uint32 x) {
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// Do not use __popcnt because it will fail on some platforms.
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x -= (x >> 1) & 0x55555555;
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x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
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x = (x + (x >> 4)) & 0x0F0F0F0F;
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x += x >> 8;
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return (x + (x >> 16)) & 0x3F;
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}
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inline int32 count_bits64(uint64 x) {
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#if defined(_M_X64)
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return static_cast<int32>(__popcnt64(x));
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#else
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return count_bits32(static_cast<uint32>(x >> 32)) + count_bits32(static_cast<uint32>(x));
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#endif
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}
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#elif TD_INTEL
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inline int32 count_leading_zeroes32(uint32 x) {
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unsigned __int32 res = 0;
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if (_BitScanReverse(&res, x)) {
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return 31 - res;
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}
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return 32;
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}
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inline int32 count_leading_zeroes64(uint64 x) {
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#if defined(_M_X64) || defined(__x86_64__)
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unsigned __int32 res = 0;
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if (_BitScanReverse64(&res, x)) {
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return 63 - res;
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}
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return 64;
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#else
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if ((x >> 32) == 0) {
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return count_leading_zeroes32(static_cast<uint32>(x)) + 32;
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} else {
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return count_leading_zeroes32(static_cast<uint32>(x >> 32));
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}
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#endif
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}
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inline int32 count_trailing_zeroes32(uint32 x) {
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unsigned __int32 res = 0;
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if (_BitScanForward(&res, x)) {
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return res;
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}
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return 32;
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}
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inline int32 count_trailing_zeroes64(uint64 x) {
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#if defined(_M_X64) || defined(__x86_64__)
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unsigned __int32 res = 0;
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if (_BitScanForward64(&res, x)) {
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return res;
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}
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return 64;
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#else
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if (static_cast<uint32>(x) == 0) {
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return count_trailing_zeroes32(static_cast<uint32>(x >> 32)) + 32;
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} else {
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return count_trailing_zeroes32(static_cast<uint32>(x));
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}
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#endif
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}
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inline uint32 bswap32(uint32 x) {
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return _bswap(static_cast<int>(x));
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}
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inline uint64 bswap64(uint64 x) {
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return _bswap64(static_cast<__int64>(x));
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}
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inline int32 count_bits32(uint32 x) {
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x -= (x >> 1) & 0x55555555;
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x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
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x = (x + (x >> 4)) & 0x0F0F0F0F;
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x += x >> 8;
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return (x + (x >> 16)) & 0x3F;
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}
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inline int32 count_bits64(uint64 x) {
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return count_bits32(static_cast<uint32>(x >> 32)) + count_bits32(static_cast<uint32>(x));
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}
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#else
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inline int32 count_leading_zeroes32(uint32 x) {
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if (x == 0) {
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return 32;
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}
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return __builtin_clz(x);
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}
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inline int32 count_leading_zeroes64(uint64 x) {
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if (x == 0) {
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return 64;
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}
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return __builtin_clzll(x);
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}
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inline int32 count_trailing_zeroes32(uint32 x) {
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if (x == 0) {
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return 32;
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}
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return __builtin_ctz(x);
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}
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inline int32 count_trailing_zeroes64(uint64 x) {
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if (x == 0) {
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return 64;
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}
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return __builtin_ctzll(x);
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}
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inline uint32 bswap32(uint32 x) {
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return __builtin_bswap32(x);
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}
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inline uint64 bswap64(uint64 x) {
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return __builtin_bswap64(x);
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}
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inline int32 count_bits32(uint32 x) {
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return __builtin_popcount(x);
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}
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inline int32 count_bits64(uint64 x) {
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return __builtin_popcountll(x);
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}
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#endif
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struct BitsRange {
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explicit BitsRange(uint64 bits = 0) : bits{bits}, pos{-1} {
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}
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BitsRange begin() const {
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return *this;
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}
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BitsRange end() const {
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return BitsRange{};
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}
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int32 operator*() const {
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if (pos == -1) {
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pos = count_trailing_zeroes64(bits);
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}
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return pos;
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}
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bool operator!=(const BitsRange &other) const {
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return bits != other.bits;
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}
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BitsRange &operator++() {
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auto i = **this;
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if (i != 64) {
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bits ^= 1ull << i;
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}
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pos = -1;
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return *this;
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}
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private:
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uint64 bits{0};
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mutable int32 pos{-1};
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};
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} // namespace td
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