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implement SIMPLE_STRUCT_POINTERS

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This commit is contained in:
David Rose 2002-03-19 01:53:14 +00:00
parent b24638521a
commit c82667c148
3 changed files with 44 additions and 2 deletions
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8
panda/src/putil/pipelineCycler.h
View File

@ -48,9 +48,15 @@
// same interface but with minimal runtime overhead.
// (Actually, this isn't true yet, but it will be one
// day.)
//
// We define this as a struct instead of a class to
// guarantee byte placement within the object, so that
// (particularly for the trivial implementation) the
// inherited struct's data is likely to be placed by the
// compiler at the "this" pointer.
////////////////////////////////////////////////////////////////////
template<class CycleDataType>
class PipelineCycler : public PipelineCyclerBase {
struct PipelineCycler : public PipelineCyclerBase {
public:
INLINE PipelineCycler(Pipeline *pipeline = NULL);
INLINE PipelineCycler(const PipelineCycler<CycleDataType> &copy);

20
panda/src/putil/pipelineCyclerBase.I
View File

@ -299,7 +299,11 @@ PipelineCyclerBase(CycleData *initial_data, Pipeline *) {
// If this turns out not to be true on a particular platform, we
// will have to store the pointer in this class, for a little bit of
// extra overhead.
#ifdef SIMPLE_STRUCT_POINTERS
nassertv(initial_data == (CycleData *)this);
#else
_data = initial_data;
#endif // SIMPLE_STRUCT_POINTERS
}
////////////////////////////////////////////////////////////////////
@ -339,7 +343,11 @@ INLINE PipelineCyclerBase::
////////////////////////////////////////////////////////////////////
INLINE const CycleData *PipelineCyclerBase::
read() const {
#ifdef SIMPLE_STRUCT_POINTERS
return (const CycleData *)this;
#else
return _data;
#endif // SIMPLE_STRUCT_POINTERS
}
////////////////////////////////////////////////////////////////////
@ -381,7 +389,11 @@ release_read(const CycleData *) const {
////////////////////////////////////////////////////////////////////
INLINE CycleData *PipelineCyclerBase::
write() {
#ifdef SIMPLE_STRUCT_POINTERS
return (CycleData *)this;
#else
return _data;
#endif // SIMPLE_STRUCT_POINTERS
}
////////////////////////////////////////////////////////////////////
@ -395,7 +407,11 @@ write() {
////////////////////////////////////////////////////////////////////
INLINE CycleData *PipelineCyclerBase::
elevate_read(const CycleData *) {
#ifdef SIMPLE_STRUCT_POINTERS
return (CycleData *)this;
#else
return _data;
#endif // SIMPLE_STRUCT_POINTERS
}
////////////////////////////////////////////////////////////////////
@ -467,7 +483,11 @@ release_write_stage(int, CycleData *) {
////////////////////////////////////////////////////////////////////
INLINE CycleData *PipelineCyclerBase::
cheat() const {
#ifdef SIMPLE_STRUCT_POINTERS
return (CycleData *)this;
#else
return _data;
#endif // SIMPLE_STRUCT_POINTERS
}
////////////////////////////////////////////////////////////////////

18
panda/src/putil/pipelineCyclerBase.h
View File

@ -29,8 +29,14 @@
// Class : PipelineCyclerBase
// Description : This is the non-template part of the implementation
// of PipelineCycler. See PipelineCycler.
//
// We define this as a struct instead of a class to
// guarantee byte placement within the object, so that
// (particularly for the trivial implementation) the
// inherited struct's data is likely to be placed by the
// compiler at the "this" pointer.
////////////////////////////////////////////////////////////////////
class EXPCL_PANDA PipelineCyclerBase {
struct EXPCL_PANDA PipelineCyclerBase {
public:
INLINE PipelineCyclerBase(CycleData *initial_data, Pipeline *pipeline = NULL);
INLINE PipelineCyclerBase(const PipelineCyclerBase &copy);
@ -63,6 +69,16 @@ private:
PT(CycleData) _data;
Pipeline *_pipeline;
short _read_count, _write_count;
#else // !DO_PIPELINING
// In a trivial implementation, we only need to store the CycleData
// pointer. Actually, we don't even need to do that, if we're lucky
// and the compiler doesn't do anything funny with the struct
// layout.
#ifndef SIMPLE_STRUCT_POINTERS
CycleData *_data;
#endif // SIMPLE_STRUCT_POINTERS
#endif // DO_PIPELINING
};