translation_gen.hh

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/*
 * Copyright 2021 Google, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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#ifndef __MEM_TRANSLATION_GEN_HH__
#define __MEM_TRANSLATION_GEN_HH__
 
#include <iterator>
#include <memory>
 
#include "base/logging.hh"
#include "base/types.hh"
 
namespace gem5
{
 
class TranslationGenConstIterator;
 
class TranslationGen
{
  public:
    struct Range
    {
        Addr vaddr;
        Addr size = 0;
 
        Addr paddr = 0;
        Fault fault = NoFault;
    };
 
  protected:
    virtual void translate(Range &range) const = 0;
 
    Addr _start;
    Addr _size;
 
  public:
    TranslationGen(Addr new_start, Addr new_size) :
        _start(new_start), _size(new_size)
    {}
    virtual ~TranslationGen() {}
 
    Addr start() const { return _start; }
    Addr size() const { return _size; }
 
    friend class TranslationGenConstIterator;
    using const_iterator = TranslationGenConstIterator;
 
    inline const_iterator begin() const;
    inline const_iterator end() const;
};
 
using TranslationGenPtr = std::unique_ptr<TranslationGen>;
 
class TranslationGenConstIterator
{
  private:
    TranslationGen::Range current = {0};
    const TranslationGen *gen = nullptr;
    bool end = true;
 
    friend class TranslationGen;
 
    void
    update()
    {
        current.paddr = 0;
        // Set the size to however much is left, aka the maximum.
        current.size = gen->size() - (current.vaddr - gen->start());
 
        if (current.size == 0) {
            // Transform into the end iterator.
            end = true;
            current.vaddr = 0;
            gen = nullptr;
        } else {
            gen->translate(current);
        }
    }
 
    TranslationGenConstIterator() {}
    TranslationGenConstIterator(const TranslationGen *parent, Addr start) :
        current{start}, gen(parent), end(false)
    {
        update();
    }
 
  public:
    using value_type = TranslationGen::Range;
    using reference = const value_type &;
    using pointer = const value_type *;
    using iterator_category = std::forward_iterator_tag;
 
    TranslationGenConstIterator(const TranslationGenConstIterator &other) :
        current(other.current), gen(other.gen)
    {}
 
    TranslationGenConstIterator &
    operator=(const TranslationGenConstIterator &other)
    {
        gen = other.gen;
        current = other.current;
        return *this;
    }
 
    reference operator*() { return current; }
    pointer operator->() { return &current; }
 
    TranslationGenConstIterator &
    operator++()
    {
        panic_if(end, "Can't increment end iterator.");
        assert(gen);
 
        if (current.fault == NoFault) {
            // If the last translation was successful, move forward.
            current.vaddr += current.size;
        } else {
            // If not, clear out the fault and try again, assuming the
            // caller has fixed whatever the problem was.
            current.fault = NoFault;
        }
 
        update();
 
        return *this;
    }
 
    TranslationGenConstIterator
    operator++(int)
    {
        const auto orig(*this);
        ++*this;
        return orig;
    }
 
    bool
    operator==(const TranslationGenConstIterator &other) const
    {
        return other.gen == gen && other.current.vaddr == current.vaddr;
    }
 
    bool
    operator!=(const TranslationGenConstIterator &other) const
    {
        return !(*this == other);
    }
};
 
TranslationGenConstIterator
TranslationGen::begin() const
{
    return const_iterator(this, start());
}
 
TranslationGenConstIterator
TranslationGen::end() const
{
    return const_iterator();
}
 
} // namespace gem5
 
#endif // __MEM_TRANSLATION_GEN_HH__