text: #ifndef __ALT_EXCEPTIONS_H__
  #define __ALT_EXCEPTIONS_H__
  
  /******************************************************************************
  *                                                                             *
  * License Agreement                                                           *
  *                                                                             *
  * Copyright (c) 2008 Altera Corporation, San Jose, California, USA.           *
  * All rights reserved.                                                        *
  *                                                                             *
  * Permission is hereby granted, free of charge, to any person obtaining a     *
  * copy of this software and associated documentation files (the "Software"),  *
  * to deal in the Software without restriction, including without limitation   *
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,    *
  * and/or sell copies of the Software, and to permit persons to whom the       *
  * Software is furnished to do so, subject to the following conditions:        *
  *                                                                             *
  * The above copyright notice and this permission notice shall be included in  *
  * all copies or substantial portions of the Software.                         *
  *                                                                             *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *
  * DEALINGS IN THE SOFTWARE.                                                   *
  *                                                                             *
  * This agreement shall be governed in all respects by the laws of the State   *
  * of California and by the laws of the United States of America.              *
  *                                                                             *
  ******************************************************************************/
  #include "alt_types.h"
  #include "system.h"
  
  #ifdef __cplusplus
  extern "C"
  {
  #endif /* __cplusplus */
  
  /*
   * This file defines instruction-generated exception handling and registry
   * API, exception type enumeration, and handler return value enumeration for
   * Nios II.
   */
  
  /*
   * The following enumeration describes the value in the CPU EXCEPTION
   * register CAUSE bit field. Not all exception types will cause the
   * processor to go to the exception vector; these are provided for
   * reference.
   */
  enum alt_exception_cause_e {
    /* Exeption causes that will cause jump to exception vector */
    NIOS2_EXCEPTION_INTERRUPT                  = 2,
    NIOS2_EXCEPTION_TRAP_INST                  = 3,
    NIOS2_EXCEPTION_UNIMPLEMENTED_INST         = 4,
    NIOS2_EXCEPTION_ILLEGAL_INST               = 5,
    NIOS2_EXCEPTION_MISALIGNED_DATA_ADDR       = 6,
    NIOS2_EXCEPTION_MISALIGNED_TARGET_PC       = 7,
    NIOS2_EXCEPTION_DIVISION_ERROR             = 8,
    NIOS2_EXCEPTION_SUPERVISOR_ONLY_INST_ADDR  = 9,
    NIOS2_EXCEPTION_SUPERVISOR_ONLY_INST       = 10,
    NIOS2_EXCEPTION_SUPERVISOR_ONLY_DATA_ADDR  = 11,
    NIOS2_EXCEPTION_TLB_MISS                   = 12,
    NIOS2_EXCEPTION_TLB_EXECUTE_PERM_VIOLATION = 13,
    NIOS2_EXCEPTION_MPU_INST_REGION_VIOLATION  = 16,
  
    /* Exception causes that will NOT cause a jump to exception vector */
    NIOS2_EXCEPTION_RESET                      = 0,
    NIOS2_EXCEPTION_CPU_ONLY_RESET_REQUEST     = 1,
    NIOS2_EXCEPTION_TLB_READ_PERM_VIOLATION    = 14,
    NIOS2_EXCEPTION_TLB_WRITE_PERM_VIOLATION   = 15,
    NIOS2_EXCEPTION_MPU_DATA_REGION_VIOLATION  = 17,
    /*
     * This value is passed to an exception handler's cause argument if
     * "extra exceptions" information (EXECPTION) register is not
     * present in the processor hardware configuration.
     */
    NIOS2_EXCEPTION_CAUSE_NOT_PRESENT          = -1
  };
  typedef enum alt_exception_cause_e alt_exception_cause;
  
  /*
   * These define valid return values for a user-defined instruction-generated
   * exception handler. The handler should return one of these to indicate
   * whether to re-issue the instruction that triggered the exception, or to
   * skip it.
   */
  enum alt_exception_result_e {
    NIOS2_EXCEPTION_RETURN_REISSUE_INST = 0,
    NIOS2_EXCEPTION_RETURN_SKIP_INST    = 1
  };
  typedef enum alt_exception_result_e alt_exception_result;
  
  /*
   * alt_instruction_exception_register() can be used to register an exception
   * handler for instruction-generated exceptions that are not handled by the
   * built-in exception handler (i.e. for interrupts).
   *
   * The registry API is optionally enabled through the "Enable
   * Instruction-related Exception API" HAL BSP setting, which will
   * define the macro below.
   */
  #ifdef ALT_INCLUDE_INSTRUCTION_RELATED_EXCEPTION_API
  void alt_instruction_exception_register (
    alt_exception_result (*exception_handler)(
      alt_exception_cause cause,
      alt_u32 exception_pc,
      alt_u32 bad_addr) );
  #endif /*ALT_INCLUDE_INSTRUCTION_RELATED_EXCEPTION_API */
  
  /*
   * alt_exception_cause_generated_bad_addr() indicates whether a particular
   * exception cause value was from an exception-type that generated a valid
   * address in the BADADDR register. The contents of BADADDR is passed to
   * a user-registered exception handler in all cases, whether valid or not.
   * This routine should be called to validate the bad_addr argument to
   * your exception handler.
   */
  int alt_exception_cause_generated_bad_addr(alt_exception_cause cause);
  
  #ifdef __cplusplus
  }
  #endif /* __cplusplus */
  
  #endif /* __ALT_EXCEPTIONS_H__ */
  