361 lines
12 KiB
C++
361 lines
12 KiB
C++
/*
|
|
* Copyright (c) 2003-2005 The Regents of The University of Michigan
|
|
* All rights reserved.
|
|
*
|
|
* 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
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
|
|
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
|
|
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* Authors: Steve Reinhardt
|
|
* Nathan Binkert
|
|
*/
|
|
|
|
#ifndef __BASE_BITFIELD_HH__
|
|
#define __BASE_BITFIELD_HH__
|
|
|
|
#include <inttypes.h>
|
|
|
|
/**
|
|
* Generate a 64-bit mask of 'nbits' 1s, right justified.
|
|
*/
|
|
inline uint64_t
|
|
mask(int nbits)
|
|
{
|
|
return (nbits == 64) ? (uint64_t)-1LL : (1ULL << nbits) - 1;
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
* Extract the bitfield from position 'first' to 'last' (inclusive)
|
|
* from 'val' and right justify it. MSB is numbered 63, LSB is 0.
|
|
*/
|
|
template <class T>
|
|
inline
|
|
T
|
|
bits(T val, int first, int last)
|
|
{
|
|
int nbits = first - last + 1;
|
|
return (val >> last) & mask(nbits);
|
|
}
|
|
|
|
/**
|
|
* Mask off the given bits in place like bits() but without shifting.
|
|
* msb = 63, lsb = 0
|
|
*/
|
|
template <class T>
|
|
inline
|
|
T
|
|
mbits(T val, int first, int last)
|
|
{
|
|
return val & (mask(first+1) & ~mask(last));
|
|
}
|
|
|
|
inline uint64_t
|
|
mask(int first, int last)
|
|
{
|
|
return mbits((uint64_t)-1LL, first, last);
|
|
}
|
|
|
|
/**
|
|
* Sign-extend an N-bit value to 64 bits.
|
|
*/
|
|
template <int N>
|
|
inline
|
|
int64_t
|
|
sext(uint64_t val)
|
|
{
|
|
int sign_bit = bits(val, N-1, N-1);
|
|
return sign_bit ? (val | ~mask(N)) : val;
|
|
}
|
|
|
|
/**
|
|
* Return val with bits first to last set to bit_val
|
|
*/
|
|
template <class T, class B>
|
|
inline
|
|
T
|
|
insertBits(T val, int first, int last, B bit_val)
|
|
{
|
|
T bmask = mask(first - last + 1) << last;
|
|
return ((bit_val << last) & bmask) | (val & ~bmask);
|
|
}
|
|
|
|
/**
|
|
* A convenience function to replace bits first to last of val with bit_val
|
|
* in place.
|
|
*/
|
|
template <class T, class B>
|
|
inline
|
|
void
|
|
replaceBits(T& val, int first, int last, B bit_val)
|
|
{
|
|
val = insertBits(val, first, last, bit_val);
|
|
}
|
|
|
|
/**
|
|
* Returns the bit position of the MSB that is set in the input
|
|
*/
|
|
inline
|
|
int
|
|
findMsbSet(uint64_t val) {
|
|
int msb = 0;
|
|
if (!val)
|
|
return 0;
|
|
if (bits(val, 63,32)) { msb += 32; val >>= 32; }
|
|
if (bits(val, 31,16)) { msb += 16; val >>= 16; }
|
|
if (bits(val, 15,8)) { msb += 8; val >>= 8; }
|
|
if (bits(val, 7,4)) { msb += 4; val >>= 4; }
|
|
if (bits(val, 3,2)) { msb += 2; val >>= 2; }
|
|
if (bits(val, 1,1)) { msb += 1; }
|
|
return msb;
|
|
}
|
|
|
|
// The following implements the BitUnion system of defining bitfields
|
|
//on top of an underlying class. This is done through the extensive use of
|
|
//both named and unnamed unions which all contain the same actual storage.
|
|
//Since they're unioned with each other, all of these storage locations
|
|
//overlap. This allows all of the bitfields to manipulate the same data
|
|
//without having to know about each other. More details are provided with the
|
|
//individual components.
|
|
|
|
//This namespace is for classes which implement the backend of the BitUnion
|
|
//stuff. Don't use any of this directly! Use the macros at the end instead.
|
|
namespace BitfieldBackend
|
|
{
|
|
//A base class for all bitfields. It instantiates the actual storage,
|
|
//and provides getBits and setBits functions for manipulating it. The
|
|
//Data template parameter is type of the underlying storage.
|
|
template<class Data>
|
|
class BitfieldBase
|
|
{
|
|
protected:
|
|
Data __data;
|
|
|
|
//This function returns a range of bits from the underlying storage.
|
|
//It relies on the "bits" function above. It's the user's
|
|
//responsibility to make sure that there is a properly overloaded
|
|
//version of this function for whatever type they want to overlay.
|
|
inline uint64_t
|
|
getBits(int first, int last)
|
|
{
|
|
return bits(__data, first, last);
|
|
}
|
|
|
|
//Similar to the above, but for settings bits with replaceBits.
|
|
inline void
|
|
setBits(int first, int last, uint64_t val)
|
|
{
|
|
replaceBits(__data, first, last, val);
|
|
}
|
|
};
|
|
|
|
//A class which specializes a given base so that it can only be read
|
|
//from. This is accomplished by only passing through the conversion
|
|
//operator and explicitly making sure the assignment operator is blocked.
|
|
template<class Type, class Base>
|
|
class _BitfieldRO : public Base
|
|
{
|
|
private:
|
|
const Type
|
|
operator=(const Type & _data);
|
|
|
|
public:
|
|
operator const Type ()
|
|
{
|
|
return *((Base *)this);
|
|
}
|
|
};
|
|
|
|
//Similar to the above, but only allows writing.
|
|
template<class Type, class Base>
|
|
class _BitfieldWO : public Base
|
|
{
|
|
private:
|
|
operator const Type ();
|
|
|
|
public:
|
|
const Type operator=(const Type & _data)
|
|
{
|
|
*((Base *)this) = _data;
|
|
return _data;
|
|
}
|
|
};
|
|
|
|
//This class implements ordinary bitfields, that is a span of bits
|
|
//who's msb is "first", and who's lsb is "last".
|
|
template<class Data, int first, int last=first>
|
|
class _Bitfield : public BitfieldBase<Data>
|
|
{
|
|
public:
|
|
operator const Data ()
|
|
{
|
|
return this->getBits(first, last);
|
|
}
|
|
|
|
const Data
|
|
operator=(const Data & _data)
|
|
{
|
|
this->setBits(first, last, _data);
|
|
return _data;
|
|
}
|
|
};
|
|
|
|
//When a BitUnion is set up, an underlying class is created which holds
|
|
//the actual union. This class then inherits from it, and provids the
|
|
//implementations for various operators. Setting things up this way
|
|
//prevents having to redefine these functions in every different BitUnion
|
|
//type. More operators could be implemented in the future, as the need
|
|
//arises.
|
|
template <class Type, class Base>
|
|
class BitUnionOperators : public Base
|
|
{
|
|
public:
|
|
operator const Type ()
|
|
{
|
|
return Base::__data;
|
|
}
|
|
|
|
const Type
|
|
operator=(const Type & _data)
|
|
{
|
|
Base::__data = _data;
|
|
}
|
|
|
|
bool
|
|
operator<(const Base & base)
|
|
{
|
|
return Base::__data < base.__data;
|
|
}
|
|
|
|
bool
|
|
operator==(const Base & base)
|
|
{
|
|
return Base::__data == base.__data;
|
|
}
|
|
};
|
|
}
|
|
|
|
//This macro is a backend for other macros that specialize it slightly.
|
|
//First, it creates/extends a namespace "BitfieldUnderlyingClasses" and
|
|
//sticks the class which has the actual union in it, which
|
|
//BitfieldOperators above inherits from. Putting these classes in a special
|
|
//namespace ensures that there will be no collisions with other names as long
|
|
//as the BitUnion names themselves are all distinct and nothing else uses
|
|
//the BitfieldUnderlyingClasses namespace, which is unlikely. The class itself
|
|
//creates a typedef of the "type" parameter called __DataType. This allows
|
|
//the type to propagate outside of the macro itself in a controlled way.
|
|
//Finally, the base storage is defined which BitfieldOperators will refer to
|
|
//in the operators it defines. This macro is intended to be followed by
|
|
//bitfield definitions which will end up inside it's union. As explained
|
|
//above, these is overlayed the __data member in its entirety by each of the
|
|
//bitfields which are defined in the union, creating shared storage with no
|
|
//overhead.
|
|
#define __BitUnion(type, name) \
|
|
namespace BitfieldUnderlyingClasses \
|
|
{ \
|
|
class name; \
|
|
} \
|
|
class BitfieldUnderlyingClasses::name { \
|
|
public: \
|
|
typedef type __DataType; \
|
|
union { \
|
|
type __data;\
|
|
|
|
//This closes off the class and union started by the above macro. It is
|
|
//followed by a typedef which makes "name" refer to a BitfieldOperator
|
|
//class inheriting from the class and union just defined, which completes
|
|
//building up the type for the user.
|
|
#define EndBitUnion(name) \
|
|
}; \
|
|
}; \
|
|
typedef BitfieldBackend::BitUnionOperators< \
|
|
BitfieldUnderlyingClasses::name::__DataType, \
|
|
BitfieldUnderlyingClasses::name> name;
|
|
|
|
//This sets up a bitfield which has other bitfields nested inside of it. The
|
|
//__data member functions like the "underlying storage" of the top level
|
|
//BitUnion. Like everything else, it overlays with the top level storage, so
|
|
//making it a regular bitfield type makes the entire thing function as a
|
|
//regular bitfield when referred to by itself. The operators are defined in
|
|
//the macro itself instead of a class for technical reasons. If someone
|
|
//determines a way to move them to one, please do so.
|
|
#define __SubBitUnion(type, name) \
|
|
union { \
|
|
type __data; \
|
|
inline operator const __DataType () \
|
|
{ return __data; } \
|
|
\
|
|
inline const __DataType operator = (const __DataType & _data) \
|
|
{ __data = _data; }
|
|
|
|
//This closes off the union created above and gives it a name. Unlike the top
|
|
//level BitUnion, we're interested in creating an object instead of a type.
|
|
#define EndSubBitUnion(name) } name;
|
|
|
|
//The preprocessor will treat everything inside of parenthesis as a single
|
|
//argument even if it has commas in it. This is used to pass in templated
|
|
//classes which typically have commas to seperate their parameters.
|
|
#define wrap(guts) guts
|
|
|
|
//Read only bitfields
|
|
//This wraps another bitfield class inside a _BitfieldRO class using
|
|
//inheritance. As explained above, the _BitfieldRO class only passes through
|
|
//the conversion operator, so the underlying bitfield can then only be read
|
|
//from.
|
|
#define __BitfieldRO(base) \
|
|
BitfieldBackend::_BitfieldRO<__DataType, base>
|
|
#define __SubBitUnionRO(name, base) \
|
|
__SubBitUnion(wrap(_BitfieldRO<__DataType, base>), name)
|
|
|
|
//Write only bitfields
|
|
//Similar to above, but for making write only versions of bitfields with
|
|
//_BitfieldWO.
|
|
#define __BitfieldWO(base) \
|
|
BitfieldBackend::_BitfieldWO<__DataType, base>
|
|
#define __SubBitUnionWO(name, base) \
|
|
__SubBitUnion(wrap(_BitfieldWO<__DataType, base>), name)
|
|
|
|
//Regular bitfields
|
|
//This uses all of the above to define macros for read/write, read only, and
|
|
//write only versions of regular bitfields.
|
|
#define Bitfield(first, last) \
|
|
BitfieldBackend::_Bitfield<__DataType, first, last>
|
|
#define SubBitUnion(name, first, last) \
|
|
__SubBitUnion(Bitfield(first, last), name)
|
|
#define BitfieldRO(first, last) __BitfieldRO(Bitfield(first, last))
|
|
#define SubBitUnionRO(name, first, last) \
|
|
__SubBitUnionRO(Bitfield(first, last), name)
|
|
#define BitfieldWO(first, last) __BitfieldWO(Bitfield(first, last))
|
|
#define SubBitUnionWO(name, first, last) \
|
|
__SubBitUnionWO(Bitfield(first, last), name)
|
|
|
|
//Use this to define an arbitrary type overlayed with bitfields.
|
|
#define BitUnion(type, name) __BitUnion(type, name)
|
|
|
|
//Use this to define conveniently sized values overlayed with bitfields.
|
|
#define BitUnion64(name) __BitUnion(uint64_t, name)
|
|
#define BitUnion32(name) __BitUnion(uint32_t, name)
|
|
#define BitUnion16(name) __BitUnion(uint16_t, name)
|
|
#define BitUnion8(name) __BitUnion(uint8_t, name)
|
|
|
|
#endif // __BASE_BITFIELD_HH__
|