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eba9c15746
The patch adjust the code of the base, base-<kernel>, and os repository.
To adapt existing components to fix violations of the best practices
suggested by "Effective C++" as reported by the -Weffc++ compiler
argument. The changes follow the patterns outlined below:
* A class with virtual functions can no longer publicly inherit base
classed without a vtable. The inherited object may either be moved
to a member variable, or inherited privately. The latter would be
used for classes that inherit 'List::Element' or 'Avl_node'. In order
to enable the 'List' and 'Avl_tree' to access the meta data, the
'List' must become a friend.
* Instead of adding a virtual destructor to abstract base classes,
we inherit the new 'Interface' class, which contains a virtual
destructor. This way, single-line abstract base classes can stay
as compact as they are now. The 'Interface' utility resides in
base/include/util/interface.h.
* With the new warnings enabled, all member variables must be explicitly
initialized. Basic types may be initialized with '='. All other types
are initialized with braces '{ ... }' or as class initializers. If
basic types and non-basic types appear in a row, it is nice to only
use the brace syntax (also for basic types) and align the braces.
* If a class contains pointers as members, it must now also provide a
copy constructor and assignment operator. In the most cases, one
would make them private, effectively disallowing the objects to be
copied. Unfortunately, this warning cannot be fixed be inheriting
our existing 'Noncopyable' class (the compiler fails to detect that
the inheriting class cannot be copied and still gives the error).
For now, we have to manually add declarations for both the copy
constructor and assignment operator as private class members. Those
declarations should be prepended with a comment like this:
/*
* Noncopyable
*/
Thread(Thread const &);
Thread &operator = (Thread const &);
In the future, we should revisit these places and try to replace
the pointers with references. In the presence of at least one
reference member, the compiler would no longer implicitly generate
a copy constructor. So we could remove the manual declaration.
Issue #465
117 lines
2.5 KiB
C++
117 lines
2.5 KiB
C++
/*
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* \brief Flexpage iterator
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* \author Alexander Boettcher
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* \date 2013-01-07
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*/
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/*
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* Copyright (C) 2013-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__UTIL__FLEX_ITERATOR_H_
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#define _INCLUDE__UTIL__FLEX_ITERATOR_H_
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#include <base/stdint.h>
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#include <util/misc_math.h>
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namespace Genode {
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struct Flexpage;
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class Flexpage_iterator;
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}
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struct Genode::Flexpage
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{
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addr_t addr = ~0UL;
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addr_t hotspot = 0;
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size_t log2_order = 0;
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Flexpage() { }
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Flexpage(addr_t a, addr_t h, size_t o)
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: addr(a), hotspot(h), log2_order(o) { }
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bool valid() { return addr != ~0UL; }
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};
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class Genode::Flexpage_iterator
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{
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private:
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addr_t _src_start = 0, _src_size = 0;
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addr_t _dst_start = 0, _dst_size = 0;
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addr_t _hotspot = 0, _offset = 0;
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/**
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* Find least significant set bit in value
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*/
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inline addr_t
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lsb_bit(addr_t const scan)
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{
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if (scan == 0)
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return ~0UL;
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return __builtin_ctzl(scan);
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}
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public:
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Flexpage_iterator() { }
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Flexpage_iterator(addr_t src_start, size_t src_size,
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addr_t dst_start, size_t dst_size,
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addr_t hotspot)
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:
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_src_start(src_start), _src_size(src_size),
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_dst_start(dst_start), _dst_size(dst_size),
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_hotspot(hotspot), _offset(0)
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{ }
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Flexpage page()
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{
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size_t const size = min (_src_size, _dst_size);
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addr_t const from_end = _src_start + size;
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addr_t const to_end = _dst_start + size;
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if (_offset >= size)
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return Flexpage();
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addr_t const from_curr = _src_start + _offset;
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addr_t const to_curr = _dst_start + _offset;
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/*
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* The common alignment corresponds to the number of least
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* significant zero bits in both addresses.
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*/
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addr_t const common_bits = from_curr | to_curr;
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/* find least set bit in common bits */
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size_t order = lsb_bit(common_bits);
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size_t max = (order == ~0UL) ? ~0UL : (1UL << order);
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/* look if it still fits into both 'src' and 'dst' ranges */
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if ((from_end - from_curr) < max) {
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order = log2(from_end - from_curr);
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order = (order == ~0UL) ? 12 : order;
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max = 1UL << order;
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}
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if ((to_end - to_curr) < max) {
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order = log2(to_end - to_curr);
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order = (order == ~0UL) ? 12 : order;
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}
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/* advance offset by current flexpage size */
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_offset += (1UL << order);
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return Flexpage(from_curr, _hotspot + _offset - (1UL << order), order);
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}
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};
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#endif /* _INCLUDE__UTIL__FLEX_ITERATOR_H_ */
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