path: root/src/base/addr_range.hh

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 * property including but not limited to intellectual property relating
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 * Copyright (c) 2002-2005 The Regents of The University of Michigan
 * All rights reserved.
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 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
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 * neither the name of the copyright holders nor the names of its
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 * this software without specific prior written permission.
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 * 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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 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * Authors: Nathan Binkert
 *          Steve Reinhardt
 *          Andreas Hansson
 */

#ifndef __BASE_ADDR_RANGE_HH__
#define __BASE_ADDR_RANGE_HH__

#include <list>
#include <vector>

#include "base/bitfield.hh"
#include "base/cprintf.hh"
#include "base/misc.hh"
#include "base/types.hh"

/**
 * The AddrRange class encapsulates an address range, and supports a
 * number of tests to check if two ranges intersect, if a range
 * contains a specific address etc. Besides a basic range, the
 * AddrRange also support interleaved ranges, to stripe across cache
 * banks, or memory controllers. The interleaving is implemented by
 * allowing a number of bits of the address, at an arbitrary bit
 * position, to be used as interleaving bits with an associated
 * matching value. In addition, to prevent uniformly strided address
 * patterns from a very biased interleaving, we also allow basic
 * XOR-based hashing by specifying an additional set of bits to XOR
 * with before matching.
 *
 * The AddrRange is also able to coalesce a number of interleaved
 * ranges to a contiguous range.
 */
class AddrRange
{

  private:

    /// Private fields for the start and end of the range
    /// Both _start and _end are part of the range.
    Addr _start;
    Addr _end;

    /// The high bit of the slice that is used for interleaving
    uint8_t intlvHighBit;

    /// The high bit of the slice used to XOR hash the value we match
    /// against, set to 0 to disable.
    uint8_t xorHighBit;

    /// The number of bits used for interleaving, set to 0 to disable
    uint8_t intlvBits;

    /// The value to compare the slice addr[high:(high - bits + 1)]
    /// with.
    uint8_t intlvMatch;

  public:

    AddrRange()
        : _start(1), _end(0), intlvHighBit(0), xorHighBit(0), intlvBits(0),
          intlvMatch(0)
    {}

    AddrRange(Addr _start, Addr _end, uint8_t _intlv_high_bit,
              uint8_t _xor_high_bit, uint8_t _intlv_bits,
              uint8_t _intlv_match)
        : _start(_start), _end(_end), intlvHighBit(_intlv_high_bit),
          xorHighBit(_xor_high_bit), intlvBits(_intlv_bits),
          intlvMatch(_intlv_match)
    {
        // sanity checks
        fatal_if(intlvBits && intlvMatch >= ULL(1) << intlvBits,
                 "Match value %d does not fit in %d interleaving bits\n",
                 intlvMatch, intlvBits);

        // ignore the XOR bits if not interleaving
        if (intlvBits && xorHighBit) {
            if (xorHighBit == intlvHighBit) {
                fatal("XOR and interleave high bit must be different\n");
            }  else if (xorHighBit > intlvHighBit) {
                if ((xorHighBit - intlvHighBit) < intlvBits)
                    fatal("XOR and interleave high bit must be at least "
                          "%d bits apart\n", intlvBits);
            } else {
                if ((intlvHighBit - xorHighBit) < intlvBits) {
                    fatal("Interleave and XOR high bit must be at least "
                          "%d bits apart\n", intlvBits);
                }
            }
        }
    }

    AddrRange(Addr _start, Addr _end)
        : _start(_start), _end(_end), intlvHighBit(0), xorHighBit(0),
          intlvBits(0), intlvMatch(0)
    {}

    /**
     * Create an address range by merging a collection of interleaved
     * ranges.
     *
     * @param ranges Interleaved ranges to be merged
     */
    AddrRange(const std::vector<AddrRange>& ranges)
        : _start(1), _end(0), intlvHighBit(0), xorHighBit(0), intlvBits(0),
          intlvMatch(0)
    {
        if (!ranges.empty()) {
            // get the values from the first one and check the others
            _start = ranges.front()._start;
            _end = ranges.front()._end;
            intlvHighBit = ranges.front().intlvHighBit;
            xorHighBit = ranges.front().xorHighBit;
            intlvBits = ranges.front().intlvBits;

            if (ranges.size() != (ULL(1) << intlvBits))
                fatal("Got %d ranges spanning %d interleaving bits\n",
                      ranges.size(), intlvBits);

            uint8_t match = 0;
            for (const auto& r : ranges) {
                if (!mergesWith(r))
                    fatal("Can only merge ranges with the same start, end "
                          "and interleaving bits\n");

                if (r.intlvMatch != match)
                    fatal("Expected interleave match %d but got %d when "
                          "merging\n", match, r.intlvMatch);
                ++match;
            }

            // our range is complete and we can turn this into a
            // non-interleaved range
            intlvHighBit = 0;
            xorHighBit = 0;
            intlvBits = 0;
        }
    }

    /**
     * Determine if the range is interleaved or not.
     *
     * @return true if interleaved
     */
    bool interleaved() const { return intlvBits != 0; }

    /**
     * Determine if the range interleaving is hashed or not.
     */
    bool hashed() const { return interleaved() && xorHighBit != 0; }

    /**
     * Determing the interleaving granularity of the range.
     *
     * @return The size of the regions created by the interleaving bits
     */
    uint64_t granularity() const
    {
        return ULL(1) << (intlvHighBit - intlvBits + 1);
    }

    /**
     * Determine the number of interleaved address stripes this range
     * is part of.
     *
     * @return The number of stripes spanned by the interleaving bits
     */
    uint32_t stripes() const { return ULL(1) << intlvBits; }

    /**
     * Get the size of the address range. For a case where
     * interleaving is used we make the simplifying assumption that
     * the size is a divisible by the size of the interleaving slice.
     */
    Addr size() const
    {
        return (_end - _start + 1) >> intlvBits;
    }

    /**
     * Determine if the range is valid.
     */
    bool valid() const { return _start <= _end; }

    /**
     * Get the start address of the range.
     */
    Addr start() const { return _start; }

    /**
     * Get the end address of the range.
     */
    Addr end() const { return _end; }

    /**
     * Get a string representation of the range. This could
     * alternatively be implemented as a operator<<, but at the moment
     * that seems like overkill.
     */
    std::string to_string() const
    {
        if (interleaved()) {
            if (hashed()) {
                return csprintf("[%#llx : %#llx], [%d : %d] XOR [%d : %d] = %d",
                                _start, _end,
                                intlvHighBit, intlvHighBit - intlvBits + 1,
                                xorHighBit, xorHighBit - intlvBits + 1,
                                intlvMatch);
            } else {
                return csprintf("[%#llx : %#llx], [%d : %d] = %d",
                                _start, _end,
                                intlvHighBit, intlvHighBit - intlvBits + 1,
                                intlvMatch);
            }
        } else {
            return csprintf("[%#llx : %#llx]", _start, _end);
        }
    }

    /**
     * Determine if another range merges with the current one, i.e. if
     * they are part of the same contigous range and have the same
     * interleaving bits.
     *
     * @param r Range to evaluate merging with
     * @return true if the two ranges would merge
     */
    bool mergesWith(const AddrRange& r) const
    {
        return r._start == _start && r._end == _end &&
            r.intlvHighBit == intlvHighBit &&
            r.xorHighBit == xorHighBit &&
            r.intlvBits == intlvBits;
    }

    /**
     * Determine if another range intersects this one, i.e. if there
     * is an address that is both in this range and the other
     * range. No check is made to ensure either range is valid.
     *
     * @param r Range to intersect with
     * @return true if the intersection of the two ranges is not empty
     */
    bool intersects(const AddrRange& r) const
    {
        if (_start > r._end || _end < r._start)
            // start with the simple case of no overlap at all,
            // applicable even if we have interleaved ranges
            return false;
        else if (!interleaved() && !r.interleaved())
            // if neither range is interleaved, we are done
            return true;

        // now it gets complicated, focus on the cases we care about
        if (r.size() == 1)
            // keep it simple and check if the address is within
            // this range
            return contains(r.start());
        else if (mergesWith(r))
            // restrict the check to ranges that belong to the
            // same chunk
            return intlvMatch == r.intlvMatch;
        else
            panic("Cannot test intersection of %s and %s\n",
                  to_string(), r.to_string());
    }

    /**
     * Determine if this range is a subset of another range, i.e. if
     * every address in this range is also in the other range. No
     * check is made to ensure either range is valid.
     *
     * @param r Range to compare with
     * @return true if the this range is a subset of the other one
     */
    bool isSubset(const AddrRange& r) const
    {
        if (interleaved())
            panic("Cannot test subset of interleaved range %s\n", to_string());
        return _start >= r._start && _end <= r._end;
    }

    /**
     * Determine if the range contains an address.
     *
     * @param a Address to compare with
     * @return true if the address is in the range
     */
    bool contains(const Addr& a) const
    {
        // check if the address is in the range and if there is either
        // no interleaving, or with interleaving also if the selected
        // bits from the address match the interleaving value
        bool in_range = a >= _start && a <= _end;
        if (!interleaved()) {
            return in_range;
        } else if (in_range) {
            if (!hashed()) {
                return bits(a, intlvHighBit, intlvHighBit - intlvBits + 1) ==
                    intlvMatch;
            } else {
                return (bits(a, intlvHighBit, intlvHighBit - intlvBits + 1) ^
                        bits(a, xorHighBit, xorHighBit - intlvBits + 1)) ==
                    intlvMatch;
            }
        }
        return false;
    }

    /**
     * Remove the interleaving bits from an input address.
     *
     * This function returns a new address that doesn't have the bits
     * that are use to determine which of the interleaved ranges it
     * belongs to.
     *
     * e.g., if the input address is:
     * -------------------------------
     * | prefix | intlvBits | suffix |
     * -------------------------------
     * this function will return:
     * -------------------------------
     * |         0 | prefix | suffix |
     * -------------------------------
     *
     * @param the input address
     * @return the address without the interleaved bits
     */
    inline Addr removeIntlvBits(const Addr &a) const
    {
        const auto intlv_low_bit = intlvHighBit - intlvBits + 1;
        return insertBits(a >> intlvBits, intlv_low_bit - 1, 0, a);
    }

    /**
     * Determine the offset of an address within the range.
     *
     * This function returns the offset of the given address from the
     * starting address discarding any bits that are used for
     * interleaving. This way we can convert the input address to a
     * new unique address in a continuous range that starts from 0.
     *
     * @param the input address
     * @return the flat offset in the address range
     */
    Addr getOffset(const Addr& a) const
    {
        bool in_range = a >= _start && a <= _end;
        if (!in_range) {
            return MaxAddr;
        }
        if (interleaved()) {
            return removeIntlvBits(a) - removeIntlvBits(_start);
        } else {
            return a - _start;
        }
    }

    /**
     * Less-than operator used to turn an STL map into a binary search
     * tree of non-overlapping address ranges.
     *
     * @param r Range to compare with
     * @return true if the start address is less than that of the other range
     */
    bool operator<(const AddrRange& r) const
    {
        if (_start != r._start)
            return _start < r._start;
        else
            // for now assume that the end is also the same, and that
            // we are looking at the same interleaving bits
            return intlvMatch < r.intlvMatch;
    }

    bool operator==(const AddrRange& r) const
    {
        if (_start    != r._start)    return false;
        if (_end      != r._end)      return false;
        if (intlvBits != r.intlvBits) return false;
        if (intlvBits != 0) {
            if (intlvHighBit != r.intlvHighBit) return false;
            if (intlvMatch   != r.intlvMatch)   return false;
        }
        return true;
    }

    bool operator!=(const AddrRange& r) const
    {
        return !(*this == r);
    }
};

/**
 * Convenience typedef for a collection of address ranges
 */
typedef std::list<AddrRange> AddrRangeList;

inline AddrRange
RangeEx(Addr start, Addr end)
{ return AddrRange(start, end - 1); }

inline AddrRange
RangeIn(Addr start, Addr end)
{ return AddrRange(start, end); }

inline AddrRange
RangeSize(Addr start, Addr size)
{ return AddrRange(start, start + size - 1); }

#endif // __BASE_ADDR_RANGE_HH__