xio.h

实用的程序代码

/* $Id: xio.h,v 1.6 2002/06/28 17:13:45 moleres Exp $ */
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/*****************************************************************************/
/**
*
* @file cpu_ppc405/v1_00_a/src/xio.h
*
* This file contains the interface for the XIo component, which encapsulates
* the Input/Output functions for the PowerPC architecture.
*
* @note
*
* This file contains architecture-dependent items (memory mapped or non memory
* mapped I/O).
*
******************************************************************************/

#ifndef XIO_H           /* prevent circular inclusions */
#define XIO_H           /* by using protection macros */

/***************************** Include Files *********************************/

#include "xbasic_types.h"

/************************** Constant Definitions *****************************/


/**************************** Type Definitions *******************************/

/**
 * Typedef for an I/O address.  Typically correlates to the width of the
 * address bus.
 */
typedef Xuint32 XIo_Address;

/***************** Macros (Inline Functions) Definitions *********************/

/* The following macro is specific to the GNU compiler and PowerPC family. It
 * performs an EIEIO instruction such that I/O operations are synced correctly.
 * This macro is not necessarily portable across compilers since it uses
 * inline assembly.
 */
#define SYNCHRONIZE_IO __asm__(" eieio")


/* The following macros allow the software to be transportable across
 * processors which use big or little endian memory models.
 *
 * Defined first are processor-specific endian conversion macros specific to
 * the GNU compiler and the PowerPC family, as well as a no-op endian conversion
 * macro. These macros are not to be used directly by software. Instead, the
 * XIo_To/FromLittleEndianXX and XIo_To/FromBigEndianXX macros below are to be
 * used to allow the endian conversion to only be performed when necessary
 */
#define XIo_EndianSwap16(Source, DestPtr)  __asm__ __volatile__(\
                                           "sthbrx %0,0,%1\n"\
                                           : : "r" (Source), "r" (DestPtr)\
                                           )

#define XIo_EndianSwap32(Source, DestPtr)  __asm__ __volatile__(\
                                           "stwbrx %0,0,%1\n"\
                                           : : "r" (Source), "r" (DestPtr)\
                                           )

#define XIo_EndianNoop(Source, DestPtr)    (*DestPtr = Source)

#ifdef XLITTLE_ENDIAN
/* little-endian processor */

#define XIo_ToLittleEndian16                XIo_EndianNoop
#define XIo_ToLittleEndian32                XIo_EndianNoop
#define XIo_FromLittleEndian16              XIo_EndianNoop
#define XIo_FromLittleEndian32              XIo_EndianNoop

#define XIo_ToBigEndian16(Source, DestPtr)  XIo_EndianSwap16(Source, DestPtr)
#define XIo_ToBigEndian32(Source, DestPtr)  XIo_EndianSwap32(Source, DestPtr)
#define XIo_FromBigEndian16                 XIo_ToBigEndian16
#define XIo_FromBigEndian32                 XIo_ToBigEndian32

#else
/* big-endian processor */

#define XIo_ToLittleEndian16(Source, DestPtr) XIo_EndianSwap16(Source, DestPtr)
#define XIo_ToLittleEndian32(Source, DestPtr) XIo_EndianSwap32(Source, DestPtr)
#define XIo_FromLittleEndian16                XIo_ToLittleEndian16
#define XIo_FromLittleEndian32                XIo_ToLittleEndian32

#define XIo_ToBigEndian16                     XIo_EndianNoop
#define XIo_ToBigEndian32                     XIo_EndianNoop
#define XIo_FromBigEndian16                   XIo_EndianNoop
#define XIo_FromBigEndian32                   XIo_EndianNoop

#endif


/************************** Function Prototypes ******************************/

/* The following functions allow the software to be transportable across
 * processors which may use memory mapped I/O or I/O which is mapped into a
 * seperate address space such as X86.  The functions are better suited for
 * debugging and are therefore the default implementation. Macros can instead
 * be used if USE_IO_MACROS is defined.
 */
#ifndef USE_IO_MACROS

/* Functions */
Xuint8 XIo_In8(XIo_Address InAddress);
Xuint16 XIo_In16(XIo_Address InAddress);
Xuint32 XIo_In32(XIo_Address InAddress);

void XIo_Out8(XIo_Address OutAddress, Xuint8 Value);
void XIo_Out16(XIo_Address OutAddress, Xuint16 Value);
void XIo_Out32(XIo_Address OutAddress, Xuint32 Value);

#else

/* The following macros allow optimized I/O operations for memory mapped I/O */

#define XIo_In8(InputPtr)  (*(volatile Xuint8  *)(InputPtr)); SYNCHRONIZE_IO;
#define XIo_In16(InputPtr) (*(volatile Xuint16 *)(InputPtr)); SYNCHRONIZE_IO;
#define XIo_In32(InputPtr)  (*(volatile Xuint32 *)(InputPtr)); SYNCHRONIZE_IO;

#define XIo_Out8(OutputPtr, Value)  \
    { (*(volatile Xuint8  *)(OutputPtr) = Value); SYNCHRONIZE_IO; }
#define XIo_Out16(OutputPtr, Value) \
    { (*(volatile Xuint16 *)(OutputPtr) = Value); SYNCHRONIZE_IO; }
#define XIo_Out32(OutputPtr, Value) \
    { (*(volatile Xuint32 *)(OutputPtr) = Value); SYNCHRONIZE_IO; }

#endif


#endif          /* end of protection macro */