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/*

 * cpu.h,v

 *

 *  This include file contains information pertaining to the ARM

 *  processor.

 *

 *  Copyright (c) 2002 Advent Networks, Inc.

 *        Jay Monkman <jmonkman@adventnetworks.com>

 *

 *  COPYRIGHT (c) 2000 Canon Research Centre France SA.

 *  Emmanuel Raguet, mailto:raguet@crf.canon.fr

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 */

/* FIXME: finish commenting/cleaning up this file */

#ifndef __CPU_h

#define __CPU_h

#ifdef __cplusplus

extern "C" {

#endif

#include <rtems/score/arm.h>            /* pick up machine definitions */

#ifndef ASM

#include <rtems/score/types.h>

#endif

/* conditional compilation parameters */

/*

 *  Should the calls to _Thread_Enable_dispatch be inlined?

 *

 *  If TRUE, then they are inlined.

 *  If FALSE, then a subroutine call is made.

 *

 *  Basically this is an example of the classic trade-off of size

 *  versus speed.  Inlining the call (TRUE) typically increases the

 *  size of RTEMS while speeding up the enabling of dispatching.

 *  [NOTE: In general, the _Thread_Dispatch_disable_level will

 *  only be 0 or 1 unless you are in an interrupt handler and that

 *  interrupt handler invokes the executive.]  When not inlined

 *  something calls _Thread_Enable_dispatch which in turns calls

 *  _Thread_Dispatch.  If the enable dispatch is inlined, then

 *  one subroutine call is avoided entirely.]

 */

#define CPU_INLINE_ENABLE_DISPATCH       TRUE

/*

 *  Should the body of the search loops in _Thread_queue_Enqueue_priority

 *  be unrolled one time?  In unrolled each iteration of the loop examines

 *  two "nodes" on the chain being searched.  Otherwise, only one node

 *  is examined per iteration.

 *

 *  If TRUE, then the loops are unrolled.

 *  If FALSE, then the loops are not unrolled.

 *

 *  The primary factor in making this decision is the cost of disabling

 *  and enabling interrupts (_ISR_Flash) versus the cost of rest of the

 *  body of the loop.  On some CPUs, the flash is more expensive than

 *  one iteration of the loop body.  In this case, it might be desirable

 *  to unroll the loop.  It is important to note that on some CPUs, this

 *  code is the longest interrupt disable period in RTEMS.  So it is

 *  necessary to strike a balance when setting this parameter.

 */

#define CPU_UNROLL_ENQUEUE_PRIORITY      TRUE

/*

 *  Does RTEMS manage a dedicated interrupt stack in software?

 *

 *  If TRUE, then a stack is allocated in _Interrupt_Manager_initialization.

 *  If FALSE, nothing is done.

 *

 *  If the CPU supports a dedicated interrupt stack in hardware,

 *  then it is generally the responsibility of the BSP to allocate it

 *  and set it up.

 *

 *  If the CPU does not support a dedicated interrupt stack, then

 *  the porter has two options: (1) execute interrupts on the

 *  stack of the interrupted task, and (2) have RTEMS manage a dedicated

 *  interrupt stack.

 *

 *  If this is TRUE, CPU_ALLOCATE_INTERRUPT_STACK should also be TRUE.

 *

 *  Only one of CPU_HAS_SOFTWARE_INTERRUPT_STACK and

 *  CPU_HAS_HARDWARE_INTERRUPT_STACK should be set to TRUE.  It is

 *  possible that both are FALSE for a particular CPU.  Although it

 *  is unclear what that would imply about the interrupt processing

 *  procedure on that CPU.

 */

#define CPU_HAS_SOFTWARE_INTERRUPT_STACK FALSE

/*

 *  Does this CPU have hardware support for a dedicated interrupt stack?

 *

 *  If TRUE, then it must be installed during initialization.

 *  If FALSE, then no installation is performed.

 *

 *  If this is TRUE, CPU_ALLOCATE_INTERRUPT_STACK should also be TRUE.

 *

 *  Only one of CPU_HAS_SOFTWARE_INTERRUPT_STACK and

 *  CPU_HAS_HARDWARE_INTERRUPT_STACK should be set to TRUE.  It is

 *  possible that both are FALSE for a particular CPU.  Although it

 *  is unclear what that would imply about the interrupt processing

 *  procedure on that CPU.

 */

#define CPU_HAS_HARDWARE_INTERRUPT_STACK TRUE

/*

 *  Does RTEMS allocate a dedicated interrupt stack in the Interrupt Manager?

 *

 *  If TRUE, then the memory is allocated during initialization.

 *  If FALSE, then the memory is allocated during initialization.

 *

 *  This should be TRUE is CPU_HAS_SOFTWARE_INTERRUPT_STACK is TRUE

 *  or CPU_INSTALL_HARDWARE_INTERRUPT_STACK is TRUE.

 */

#define CPU_ALLOCATE_INTERRUPT_STACK FALSE

/*

 *  Does the RTEMS invoke the user's ISR with the vector number and

 *  a pointer to the saved interrupt frame (1) or just the vector

 *  number (0)?

 */

#define CPU_ISR_PASSES_FRAME_POINTER 0

/*

 *  Does the CPU have hardware floating point?

 *

 *  If TRUE, then the RTEMS_FLOATING_POINT task attribute is supported.

 *  If FALSE, then the RTEMS_FLOATING_POINT task attribute is ignored.

 *

 *  If there is a FP coprocessor such as the i387 or mc68881, then

 *  the answer is TRUE.

 *

 *  The macro name "ARM_HAS_FPU" should be made CPU specific.

 *  It indicates whether or not this CPU model has FP support.  For

 *  example, it would be possible to have an i386_nofp CPU model

 *  which set this to false to indicate that you have an i386 without

 *  an i387 and wish to leave floating point support out of RTEMS.

 */

#if ( ARM_HAS_FPU == 1 )

#define CPU_HARDWARE_FP     TRUE

#else

#define CPU_HARDWARE_FP     FALSE

#endif

#define CPU_SOFTWARE_FP     FALSE

/*

 *  Are all tasks RTEMS_FLOATING_POINT tasks implicitly?

 *

 *  If TRUE, then the RTEMS_FLOATING_POINT task attribute is assumed.

 *  If FALSE, then the RTEMS_FLOATING_POINT task attribute is followed.

 *

 *  So far, the only CPU in which this option has been used is the

 *  HP PA-RISC.  The HP C compiler and gcc both implicitly use the

 *  floating point registers to perform integer multiplies.  If

 *  a function which you would not think utilize the FP unit DOES,

 *  then one can not easily predict which tasks will use the FP hardware.

 *  In this case, this option should be TRUE.

 *

 *  If CPU_HARDWARE_FP is FALSE, then this should be FALSE as well.

 */

#define CPU_ALL_TASKS_ARE_FP     FALSE

/*

 *  Should the IDLE task have a floating point context?

 *

 *  If TRUE, then the IDLE task is created as a RTEMS_FLOATING_POINT task

 *  and it has a floating point context which is switched in and out.

 *  If FALSE, then the IDLE task does not have a floating point context.

 *

 *  Setting this to TRUE negatively impacts the time required to preempt

 *  the IDLE task from an interrupt because the floating point context

 *  must be saved as part of the preemption.

 */

#define CPU_IDLE_TASK_IS_FP      FALSE

/*

 *  Should the saving of the floating point registers be deferred

 *  until a context switch is made to another different floating point

 *  task?

 *

 *  If TRUE, then the floating point context will not be stored until

 *  necessary.  It will remain in the floating point registers and not

 *  disturned until another floating point task is switched to.

 *

 *  If FALSE, then the floating point context is saved when a floating

 *  point task is switched out and restored when the next floating point

 *  task is restored.  The state of the floating point registers between

 *  those two operations is not specified.

 *

 *  If the floating point context does NOT have to be saved as part of

 *  interrupt dispatching, then it should be safe to set this to TRUE.

 *

 *  Setting this flag to TRUE results in using a different algorithm

 *  for deciding when to save and restore the floating point context.

 *  The deferred FP switch algorithm minimizes the number of times

 *  the FP context is saved and restored.  The FP context is not saved

 *  until a context switch is made to another, different FP task.

 *  Thus in a system with only one FP task, the FP context will never

 *  be saved or restored.

 */

#define CPU_USE_DEFERRED_FP_SWITCH   FALSE

/*

 *  Does this port provide a CPU dependent IDLE task implementation?

 *

 *  If TRUE, then the routine _CPU_Thread_Idle_body

 *  must be provided and is the default IDLE thread body instead of

 *  _CPU_Thread_Idle_body.

 *

 *  If FALSE, then use the generic IDLE thread body if the BSP does

 *  not provide one.

 *

 *  This is intended to allow for supporting processors which have

 *  a low power or idle mode.  When the IDLE thread is executed, then

 *  the CPU can be powered down.

 *

 *  The order of precedence for selecting the IDLE thread body is:

 *

 *    1.  BSP provided

 *    2.  CPU dependent (if provided)

 *    3.  generic (if no BSP and no CPU dependent)

 */

#define CPU_PROVIDES_IDLE_THREAD_BODY    FALSE

/*

 *  Does the stack grow up (toward higher addresses) or down

 *  (toward lower addresses)?

 *

 *  If TRUE, then the grows upward.

 *  If FALSE, then the grows toward smaller addresses.

 */

#define CPU_STACK_GROWS_UP               FALSE

/*

 *  The following is the variable attribute used to force alignment

 *  of critical RTEMS structures.  On some processors it may make

 *  sense to have these aligned on tighter boundaries than

 *  the minimum requirements of the compiler in order to have as

 *  much of the critical data area as possible in a cache line.

 *

 *  The placement of this macro in the declaration of the variables

 *  is based on the syntactically requirements of the GNU C

 *  "__attribute__" extension.  For example with GNU C, use

 *  the following to force a structures to a 32 byte boundary.

 *

 *      __attribute__ ((aligned (32)))

 *

 *  NOTE:  Currently only the Priority Bit Map table uses this feature.

 *         To benefit from using this, the data must be heavily

 *         used so it will stay in the cache and used frequently enough

 *         in the executive to justify turning this on.

 */

#define CPU_STRUCTURE_ALIGNMENT  __attribute__ ((aligned (32)))

/*

 *  Define what is required to specify how the network to host conversion

 *  routines are handled.

 */

#define CPU_HAS_OWN_HOST_TO_NETWORK_ROUTINES     FALSE

#define CPU_BIG_ENDIAN                           FALSE

#define CPU_LITTLE_ENDIAN                        TRUE

/*

 *  The following defines the number of bits actually used in the

 *  interrupt field of the task mode.  How those bits map to the

 *  CPU interrupt levels is defined by the routine _CPU_ISR_Set_level().

 */

#define CPU_MODES_INTERRUPT_MASK   0x000000c0

/*

 *  Processor defined structures

 *

 *  Examples structures include the descriptor tables from the i386

 *  and the processor control structure on the i960ca.

 */

/* may need to put some structures here.  */

/*

 * Contexts

 *

 *  Generally there are 2 types of context to save.

 *     1. Interrupt registers to save

 *     2. Task level registers to save

 *

 *  This means we have the following 3 context items:

 *     1. task level context stuff::  Context_Control

 *     2. floating point task stuff:: Context_Control_fp

 *     3. special interrupt level context :: Context_Control_interrupt

 *

 *  On some processors, it is cost-effective to save only the callee

 *  preserved registers during a task context switch.  This means

 *  that the ISR code needs to save those registers which do not

 *  persist across function calls.  It is not mandatory to make this

 *  distinctions between the caller/callee saves registers for the

 *  purpose of minimizing context saved during task switch and on interrupts.

 *  If the cost of saving extra registers is minimal, simplicity is the

 *  choice.  Save the same context on interrupt entry as for tasks in

 *  this case.

 *

 *  Additionally, if gdb is to be made aware of RTEMS tasks for this CPU, then

 *  care should be used in designing the context area.

 *

 *  On some CPUs with hardware floating point support, the Context_Control_fp

 *  structure will not be used or it simply consist of an array of a

 *  fixed number of bytes.   This is done when the floating point context

 *  is dumped by a "FP save context" type instruction and the format

 *  is not really defined by the CPU.  In this case, there is no need

 *  to figure out the exact format -- only the size.  Of course, although

 *  this is enough information for RTEMS, it is probably not enough for

 *  a debugger such as gdb.  But that is another problem.

 */

typedef struct {

    unsigned32 register_cpsr;

    unsigned32 register_r4;

    unsigned32 register_r5;

    unsigned32 register_r6;

    unsigned32 register_r7;

    unsigned32 register_r8;

    unsigned32 register_r9;

    unsigned32 register_r10;

    unsigned32 register_fp;

    unsigned32 register_sp;

    unsigned32 register_lr;

    unsigned32 register_pc;

} Context_Control;

typedef struct {

    double      some_float_register;

} Context_Control_fp;

typedef struct {

    unsigned32 register_r0;

    unsigned32 register_r1;

    unsigned32 register_r2;

    unsigned32 register_r3;

    unsigned32 register_ip;

    unsigned32 register_lr;

} CPU_Exception_frame;

typedef void (*cpuExcHandlerType) (CPU_Exception_frame*);

extern cpuExcHandlerType _currentExcHandler;

extern void rtems_exception_init_mngt();

/*

 *  The following structure defines the set of information saved

 *  on the current stack by RTEMS upon receipt of each interrupt

 *  that will lead to re-enter the kernel to signal the thread.

 */

typedef CPU_Exception_frame CPU_Interrupt_frame;

/*

 *  The following table contains the information required to configure

 *  the XXX processor specific parameters.

 */

typedef struct {

  void       (*pretasking_hook)( void );

  void       (*predriver_hook)( void );

  void       (*postdriver_hook)( void );

  void       (*idle_task)( void );

  boolean      do_zero_of_workspace;

  unsigned32   idle_task_stack_size;

  unsigned32   interrupt_stack_size;

  unsigned32   extra_mpci_receive_server_stack;

  void *     (*stack_allocate_hook)( unsigned32 );

  void       (*stack_free_hook)( void* );

  /* end of fields required on all CPUs */

}   rtems_cpu_table;

/*

 *  Macros to access required entires in the CPU Table are in

 *  the file rtems/system.h.

 */

/*

 *  Macros to access ARM specific additions to the CPU Table

 *

 *  none required

 */

/* There are no CPU specific additions to the CPU Table for this port. */

/*

 *  This variable is optional.  It is used on CPUs on which it is difficult

 *  to generate an "uninitialized" FP context.  It is filled in by

 *  _CPU_Initialize and copied into the task's FP context area during

 *  _CPU_Context_Initialize.

 */

SCORE_EXTERN Context_Control_fp  _CPU_Null_fp_context;

/*

 *  The size of the floating point context area.  On some CPUs this

 *  will not be a "sizeof" because the format of the floating point

 *  area is not defined -- only the size is.  This is usually on

 *  CPUs with a "floating point save context" instruction.

 */

#define CPU_CONTEXT_FP_SIZE sizeof( Context_Control_fp )

/*

 *  Amount of extra stack (above minimum stack size) required by

 *  MPCI receive server thread.  Remember that in a multiprocessor

 *  system this thread must exist and be able to process all directives.

 */

#define CPU_MPCI_RECEIVE_SERVER_EXTRA_STACK 0

/*

 *  This defines the number of entries in the ISR_Vector_table managed

 *  by RTEMS.

 */

#define CPU_INTERRUPT_NUMBER_OF_VECTORS      8

#define CPU_INTERRUPT_MAXIMUM_VECTOR_NUMBER  (CPU_INTERRUPT_NUMBER_OF_VECTORS - 1)

/*

 *  This is defined if the port has a special way to report the ISR nesting

 *  level.  Most ports maintain the variable _ISR_Nest_level.

 */

#define CPU_PROVIDES_ISR_IS_IN_PROGRESS FALSE

/*

 *  Should be large enough to run all RTEMS tests.  This insures

 *  that a "reasonable" small application should not have any problems.

 */

#define CPU_STACK_MINIMUM_SIZE          (1024*4)

/*

 *  CPU's worst alignment requirement for data types on a byte boundary.  This

 *  alignment does not take into account the requirements for the stack.

 */

#define CPU_ALIGNMENT              4

/*

 *  This number corresponds to the byte alignment requirement for the

 *  heap handler.  This alignment requirement may be stricter than that

 *  for the data types alignment specified by CPU_ALIGNMENT.  It is

 *  common for the heap to follow the same alignment requirement as

 *  CPU_ALIGNMENT.  If the CPU_ALIGNMENT is strict enough for the heap,

 *  then this should be set to CPU_ALIGNMENT.

 *

 *  NOTE:  This does not have to be a power of 2.  It does have to

 *         be greater or equal to than CPU_ALIGNMENT.

 */

#define CPU_HEAP_ALIGNMENT         CPU_ALIGNMENT

/*

 *  This number corresponds to the byte alignment requirement for memory

 *  buffers allocated by the partition manager.  This alignment requirement

 *  may be stricter than that for the data types alignment specified by

 *  CPU_ALIGNMENT.  It is common for the partition to follow the same

 *  alignment requirement as CPU_ALIGNMENT.  If the CPU_ALIGNMENT is strict

 *  enough for the partition, then this should be set to CPU_ALIGNMENT.

 *

 *  NOTE:  This does not have to be a power of 2.  It does have to

 *         be greater or equal to than CPU_ALIGNMENT.

 */

#define CPU_PARTITION_ALIGNMENT    CPU_ALIGNMENT

/*

 *  This number corresponds to the byte alignment requirement for the

 *  stack.  This alignment requirement may be stricter than that for the

 *  data types alignment specified by CPU_ALIGNMENT.  If the CPU_ALIGNMENT

 *  is strict enough for the stack, then this should be set to 0.

 *

 *  NOTE:  This must be a power of 2 either 0 or greater than CPU_ALIGNMENT.

 */

#define CPU_STACK_ALIGNMENT        4

/* ISR handler macros */

/*

 *  Support routine to initialize the RTEMS vector table after it is allocated.

 */

#define _CPU_Initialize_vectors() 

/*

 *  Disable all interrupts for an RTEMS critical section.  The previous

 *  level is returned in _level.

 */

#define _CPU_ISR_Disable( _level )                \

  {                                               \

    int reg;                                       \

    asm volatile ("MRS  %0, cpsr \n"               \

                  "ORR  %1, %0, #0xc0 \n"          \

                  "MSR  cpsr, %1 \n"               \

                   : "=&r" (_level), "=&r" (reg)); \

  }

/*

 *  Enable interrupts to the previous level (returned by _CPU_ISR_Disable).

 *  This indicates the end of an RTEMS critical section.  The parameter

 *  _level is not modified.

 */

#define _CPU_ISR_Enable( _level )               \

  {                                             \

    asm volatile ("MSR  cpsr, %0 \n"            \

                  : : "r" (_level));            \

  }

/*

 *  This temporarily restores the interrupt to _level before immediately

 *  disabling them again.  This is used to divide long RTEMS critical

 *  sections into two or more parts.  The parameter _level is not

 * modified.

 */

#define _CPU_ISR_Flash( _level ) \

  { \

    int reg;                                    \

    asm volatile ("MRS  %0, cpsr \n"            \

                  "MSR  cpsr, %1 \n"            \

                  "MSR  cpsr, %0 \n"            \

                  : "=&r" (reg)                 \

                  : "r" (_level));              \

  }

/*

 *  Map interrupt level in task mode onto the hardware that the CPU

 *  actually provides.  Currently, interrupt levels which do not

 *  map onto the CPU in a generic fashion are undefined.  Someday,

 *  it would be nice if these were "mapped" by the application

 *  via a callout.  For example, m68k has 8 levels 0 - 7, levels

 *  8 - 255 would be available for bsp/application specific meaning.

 *  This could be used to manage a programmable interrupt controller

 *  via the rtems_task_mode directive.

 *

 *  The get routine usually must be implemented as a subroutine.

 */

#define _CPU_ISR_Set_level( new_level )         \

  {                                             \

    int reg;                                    \

    asm volatile ("MRS  %0, cpsr \n"            \

                  "BIC  %0, %0, #0xc0 \n"       \

                  "ORR  %0, %0, %2 \n"          \

                  "MSR  cpsr_c, %0 \n"          \

                  : "=r" (reg)                  \

                  : "r" (reg), "0" (reg));      \

  }

unsigned32 _CPU_ISR_Get_level( void );

/* end of ISR handler macros */

/* Context handler macros */

/*

 *  Initialize the context to a state suitable for starting a

 *  task after a context restore operation.  Generally, this

 *  involves:

 *

 *     - setting a starting address

 *     - preparing the stack

 *     - preparing the stack and frame pointers

 *     - setting the proper interrupt level in the context

 *     - initializing the floating point context

 *

 *  This routine generally does not set any unnecessary register

 *  in the context.  The state of the "general data" registers is

 *  undefined at task start time.

 *

 *  NOTE: This is_fp parameter is TRUE if the thread is to be a floating

 *        point thread.  This is typically only used on CPUs where the

 *        FPU may be easily disabled by software such as on the SPARC

 *        where the PSR contains an enable FPU bit.

 */

void _CPU_Context_Initialize(

  Context_Control  *the_context,

  unsigned32       *stack_base,

  unsigned32        size,

  unsigned32        new_level,

  void             *entry_point,

  boolean           is_fp

);

/*

 *  This routine is responsible for somehow restarting the currently

 *  executing task.  If you are lucky, then all that is necessary

 *  is restoring the context.  Otherwise, there will need to be

 *  a special assembly routine which does something special in this

 *  case.  Context_Restore should work most of the time.  It will

 *  not work if restarting self conflicts with the stack frame

 *  assumptions of restoring a context.

 */

#define _CPU_Context_Restart_self( _the_context ) \

   _CPU_Context_restore( (_the_context) );

/*

 *  The purpose of this macro is to allow the initial pointer into

 *  a floating point context area (used to save the floating point

 *  context) to be at an arbitrary place in the floating point

 *  context area.

 *

 *  This is necessary because some FP units are designed to have

 *  their context saved as a stack which grows into lower addresses.

 *  Other FP units can be saved by simply moving registers into offsets

 *  from the base of the context area.  Finally some FP units provide

 *  a "dump context" instruction which could fill in from high to low

 *  or low to high based on the whim of the CPU designers.

 */

#define _CPU_Context_Fp_start( _base, _offset ) \

   ( (void *) _Addresses_Add_offset( (_base), (_offset) ) )

/*

 *  This routine initializes the FP context area passed to it to.

 *  There are a few standard ways in which to initialize the

 *  floating point context.  The code included for this macro assumes

 *  that this is a CPU in which a "initial" FP context was saved into

 *  _CPU_Null_fp_context and it simply copies it to the destination

 *  context passed to it.

 *

 *  Other models include (1) not doing anything, and (2) putting

 *  a "null FP status word" in the correct place in the FP context.

 */

#define _CPU_Context_Initialize_fp( _destination ) \

  { \

   *((Context_Control_fp *) *((void **) _destination)) = _CPU_Null_fp_context; \

  }

/* end of Context handler macros */

/* Fatal Error manager macros */

/*

 *  This routine copies _error into a known place -- typically a stack

 *  location or a register, optionally disables interrupts, and

 *  halts/stops the CPU.

 */

#define _CPU_Fatal_halt( _error )           \

   do {                                     \

     int _level;                            \

     _CPU_ISR_Disable( _level );            \

     asm volatile ("mov r0, %0\n"           \

                   : "=r" (_error)          \

                   : "0" (_error)           \

                   : "r0" );                \

     while(1) ;                             \

   } while(0);

/* end of Fatal Error manager macros */

/* Bitfield handler macros */

/*

 *  This routine sets _output to the bit number of the first bit

 *  set in _value.  _value is of CPU dependent type Priority_Bit_map_control.

 *  This type may be either 16 or 32 bits wide although only the 16

 *  least significant bits will be used.

 *

 *  There are a number of variables in using a "find first bit" type

 *  instruction.

 *

 *    (1) What happens when run on a value of zero?

 *    (2) Bits may be numbered from MSB to LSB or vice-versa.

 *    (3) The numbering may be zero or one based.

 *    (4) The "find first bit" instruction may search from MSB or LSB.

 *

 *  RTEMS guarantees that (1) will never happen so it is not a concern.

 *  (2),(3), (4) are handled by the macros _CPU_Priority_mask() and

 *  _CPU_Priority_bits_index().  These three form a set of routines

 *  which must logically operate together.  Bits in the _value are

 *  set and cleared based on masks built by _CPU_Priority_mask().

 *  The basic major and minor values calculated by _Priority_Major()

 *  and _Priority_Minor() are "massaged" by _CPU_Priority_bits_index()

 *  to properly range between the values returned by the "find first bit"

 *  instruction.  This makes it possible for _Priority_Get_highest() to

 *  calculate the major and directly index into the minor table.

 *  This mapping is necessary to ensure that 0 (a high priority major/minor)

 *  is the first bit found.

 *

 *  This entire "find first bit" and mapping process depends heavily

 *  on the manner in which a priority is broken into a major and minor

 *  components with the major being the 4 MSB of a priority and minor

 *  the 4 LSB.  Thus (0 << 4) + 0 corresponds to priority 0 -- the highest

 *  priority.  And (15 << 4) + 14 corresponds to priority 254 -- the next

 *  to the lowest priority.

 *

 *  If your CPU does not have a "find first bit" instruction, then

 *  there are ways to make do without it.  Here are a handful of ways

 *  to implement this in software:

 *

 *    - a series of 16 bit test instructions

 *    - a "binary search using if's"

 *    - _number = 0

 *      if _value > 0x00ff

 *        _value >>=8

 *        _number = 8;

 *

 *      if _value > 0x0000f

 *        _value >=8

 *        _number += 4

 *

 *      _number += bit_set_table[ _value ]

 *

 *    where bit_set_table[ 16 ] has values which indicate the first

 *      bit set

 */

#if (ARM_HAS_CLZ == 0)

#  define CPU_USE_GENERIC_BITFIELD_CODE TRUE

#  define CPU_USE_GENERIC_BITFIELD_DATA TRUE

#else 

#  define CPU_USE_GENERIC_BITFIELD_CODE FALSE

#  define CPU_USE_GENERIC_BITFIELD_DATA FALSE

#  define _CPU_Bitfield_Find_first_bit( _value, _output ) \

   { \

     (_output) = 0;   /* do something to prevent warnings */ \

   }

/* end of Bitfield handler macros */

/*

 *  This routine builds the mask which corresponds to the bit fields

 *  as searched by _CPU_Bitfield_Find_first_bit().  See the discussion

 *  for that routine.

 */

#  define _CPU_Priority_Mask( _bit_number ) \

   ( 1 << (_bit_number) )

/*

 *  This routine translates the bit numbers returned by

 *  _CPU_Bitfield_Find_first_bit() into something suitable for use as

 *  a major or minor component of a priority.  See the discussion

 *  for that routine.

 */

#  define _CPU_Priority_bits_index( _priority ) \

   (_priority)

#  error "Implement CLZ verson of priority bit functions for ARMv5"

#endif

/* end of Priority handler macros */

/* functions */

/*

 *  _CPU_Initialize

 *

 *  This routine performs CPU dependent initialization.

 */

void _CPU_Initialize(

  rtems_cpu_table  *cpu_table,

  void      (*thread_dispatch)

);

typedef enum {

  ARM_EXCEPTION_RESET      = 0,

  ARM_EXCEPTION_UNDEF      = 1,

  ARM_EXCEPTION_SWI        = 2,

  ARM_EXCEPTION_PREF_ABORT = 3,

  ARM_EXCEPTION_DATA_ABORT = 4,

  ARM_EXCEPTION_RESERVED   = 5,

  ARM_EXCEPTION_IRQ        = 6,

  ARM_EXCEPTION_FIQ        = 7,

  MAX_EXCEPTIONS           = 8

} Arm_symbolic_exception_name;

/*

 *  _CPU_ISR_install_vector

 *

 *  This routine installs an interrupt vector.

 */

void _CPU_ISR_install_vector(

  unsigned32  vector,

  proc_ptr    new_handler,

  proc_ptr   *old_handler

);

/*

 *  _CPU_Install_interrupt_stack

 *

 *  This routine installs the hardware interrupt stack pointer.

 *

 *  NOTE:  It need only be provided if CPU_HAS_HARDWARE_INTERRUPT_STACK

 *         is TRUE.

 */

void _CPU_Install_interrupt_stack( void );

/*

 *  _CPU_Context_switch

 *

 *  This routine switches from the run context to the heir context.

 */

void _CPU_Context_switch(

  Context_Control  *run,

  Context_Control  *heir

);

/*

 *  _CPU_Context_restore

 *

 *  This routine is generally used only to restart self in an

 *  efficient manner.  It may simply be a label in _CPU_Context_switch.

 *

 *  NOTE: May be unnecessary to reload some registers.

 */

void _CPU_Context_restore(

  Context_Control *new_context

);

#if (ARM_HAS_FPU == 1)

/*

 *  _CPU_Context_save_fp

 *

 *  This routine saves the floating point context passed to it.

 */

void _CPU_Context_save_fp(

  void **fp_context_ptr

);

/*

 *  _CPU_Context_restore_fp

 *