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updated to accomodate what I shouldnt have forgotten about strict aliasing

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This commit is contained in:
Jeff Hill
2006-11-28 23:07:06 +00:00
parent b61e4bcb59
commit de19586072
1 changed files with 76 additions and 41 deletions
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src/libCom/osi/os/default/osiWireFormat.h
+76 -41
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@@ -36,10 +36,15 @@
// for this file if that assumption is wrong.
//
/*
* Here are the definitions for architecture dependent byte ordering
* and floating point format.
*/
//
// Here are the definitions for architecture dependent byte ordering
// and floating point format.
//
// Perhaps the definition of EPICS_BIG_ENDIAN, EPICS_LITTLE_ENDIAN,
// and EPICS_32107654_FP_ENDIAN should be left to the build system
// so that this file need not be modified when adding support for a
// new architecture?
//
#if defined (_M_IX86) || defined (_X86_) || defined (__i386__) || defined (_X86_64_)
# define EPICS_LITTLE_ENDIAN
#elif ( defined (__ALPHA) || defined (__alpha) )
@@ -50,20 +55,20 @@
# define EPICS_BIG_ENDIAN
#endif
/*
* EPICS_CONVERSION_REQUIRED is set if either the byte order
* or the floating point are not exactly big endian and ieee fp.
* This can be set by hand above for a specific architecture
* should there be an architecture that is a weird middle endian
* ieee floating point format that is also big endian integer.
*/
//
// EPICS_CONVERSION_REQUIRED is set if either the byte order
// or the floating point are not exactly big endian and ieee fp.
// This can be set by hand above for a specific architecture
// should there be an architecture that is a weird middle endian
// ieee floating point format that is also big endian integer.
//
#if ! defined ( EPICS_BIG_ENDIAN ) && ! defined ( EPICS_CONVERSION_REQUIRED )
# define EPICS_CONVERSION_REQUIRED
#endif
/*
* some architecture sanity checks
*/
//
// some architecture sanity checks
//
#if defined(EPICS_BIG_ENDIAN) && defined(EPICS_LITTLE_ENDIAN)
# error defined(EPICS_BIG_ENDIAN) && defined(EPICS_LITTLE_ENDIAN)
#endif
@@ -113,51 +118,69 @@ inline epicsUInt32 byteSwap ( const epicsUInt32 & src )
# endif
}
inline epicsInt16 byteSwap ( const epicsInt16 & src )
inline epicsInt16 byteSwap ( const epicsInt16 & in )
{
return static_cast < epicsInt16 > (
byteSwap ( * reinterpret_cast < const epicsUInt16 * > ( & src ) ) );
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsUInt16 _u;
epicsInt16 _i;
} tmp;
tmp._i = in;
tmp._u = byteSwap ( tmp._u );
return tmp._i;
}
inline epicsInt32 byteSwap ( const epicsInt32 & src )
inline epicsInt32 byteSwap ( const epicsInt32 & in )
{
return static_cast < epicsInt32 > (
byteSwap ( * reinterpret_cast < const epicsUInt32 * > ( & src ) ) );
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsUInt32 _u;
epicsInt32 _i;
} tmp;
tmp._i = in;
tmp._u = byteSwap ( tmp._u );
return tmp._i;
}
inline epicsFloat32 byteSwap ( const epicsFloat32 & src )
inline epicsFloat32 byteSwap ( const epicsFloat32 & in )
{
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsUInt32 _u;
epicsFloat32 _f;
} tmp;
tmp._u = byteSwap ( * reinterpret_cast < const epicsUInt32 * > ( & src ) );
tmp._f = in;
tmp._u = byteSwap ( tmp._u );
return tmp._f;
}
inline epicsFloat64 byteSwap ( const epicsFloat64 & src )
inline epicsFloat64 byteSwap ( const epicsFloat64 & in )
{
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union Swapper {
epicsUInt32 _u[2];
epicsFloat64 _f;
};
# if defined ( EPICS_32107654_FP_ENDIAN )
union {
epicsUInt32 _u[2];
epicsFloat64 _f;
} tmp;
const epicsUInt32 * pSrc =
reinterpret_cast < const epicsUInt32 * > ( & src );
tmp._u[0] = byteSwap ( pSrc[0] );
tmp._u[1] = byteSwap ( pSrc[1] );
Swapper tmp;
tmp._f = in;
tmp._u[0] = byteSwap ( tmp._u[0] );
tmp._u[1] = byteSwap ( tmp._u[1] );
return tmp._f;
# elif defined ( EPICS_LITTLE_ENDIAN )
union {
epicsUInt32 _u[2];
epicsFloat64 _f;
} tmp;
const epicsUInt32 * pSrc =
reinterpret_cast < const epicsUInt32 * > ( & src );
epicsUInt32 tmpUInt32 = byteSwap ( pSrc[0] );
tmp._u[0] = byteSwap ( pSrc[1] );
tmp._u[1] = tmpUInt32;
return tmp._f;
Swapper src, dst;
src._f = in;
dst._u[0] = byteSwap ( src._u[1] );
dst._u[1] = byteSwap ( src._u[0] );
return dst._f;
# elif defined ( EPICS_BIG_ENDIAN )
return src;
# else
@@ -267,6 +290,9 @@ inline epicsUInt32 WireGetUInt32 ( const epicsUInt8 * pWireSrc )
}
inline epicsFloat32 WireGetFloat32 ( const epicsUInt8 * pWireSrc )
{
// extra copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) also allows for extra copy to be optimized away
union {
epicsFloat32 _f;
epicsUInt32 _u;
@@ -276,6 +302,9 @@ inline epicsFloat32 WireGetFloat32 ( const epicsUInt8 * pWireSrc )
}
inline epicsFloat64 WireGetFloat64 ( const epicsUInt8 * pWireSrc )
{
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsFloat64 _f;
epicsUInt32 _u[2];
@@ -306,6 +335,9 @@ inline void WireSetUInt32 ( const epicsUInt32 src, epicsUInt8 * pWireDst )
}
inline void WireSetFloat32 ( const epicsFloat32 src, epicsUInt8 * pWireDst )
{
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsFloat32 _f;
epicsUInt32 _u;
@@ -315,6 +347,9 @@ inline void WireSetFloat32 ( const epicsFloat32 src, epicsUInt8 * pWireDst )
}
inline void WireSetFloat64 ( const epicsFloat64 & src, epicsUInt8 * pWireDst )
{
// copy through union here
// a) prevents over-aggresive optimization under strict aliasing rules
// b) doesnt preclude extra copy operation being optimized away
union {
epicsFloat64 _f;
epicsUInt32 _u[2];