alt_irq_register.c

nios中自定义指令集实现三角函数的软件部分。

/******************************************************************************
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/******************************************************************************
*                                                                             *
* THIS IS A LIBRARY READ-ONLY SOURCE FILE. DO NOT EDIT IT DIRECTLY.           *
*                                                                             *
* Overriding HAL Functions                                                    *
*                                                                             *
* To provide your own implementation of a HAL function, include the file in   *
* your Nios II IDE application project. When building the executable, the     *
* Nios II IDE finds your function first, and uses it in place of the HAL      *
* version.                                                                    *
*                                                                             *
******************************************************************************/

#include <errno.h>

#include "sys/alt_irq.h"
#include "os/alt_hooks.h"

#include "alt_types.h"

/*
 * The header, alt_irq_entry.h, contains the exception entry point, and is
 * provided by the processor component. It is included here, so that the code
 * will be added to the executable only if alt_irq_register() is present, i.e.
 * if no interrupts are registered - there's no need to provide any 
 * interrupt handling.
 */

#include "sys/alt_irq_entry.h"

/*
 * The header, alt_irq_table.h contains a table describing which function
 * handles each interrupt.
 */

#include "priv/alt_irq_table.h"

/*
 * alt_irq_handler() is called to register an interrupt handler. If the 
 * function is succesful, then the requested interrupt will be enabled upon 
 * return. Registering a NULL handler will disable the interrupt.
 *
 * The return value is 0 if the interrupt handler was registered and the 
 * interrupt was enabled, otherwise it is negative.
 */
 
int alt_irq_register (alt_u32 id, 
                      void* context, 
                      void (*handler)(void*, alt_u32))
{
  int rc = -EINVAL;  
  alt_irq_context status;

  if (id < ALT_NIRQ)
  {
    /* 
     * interrupts are disabled while the handler tables are updated to ensure
     * that an interrupt doesn't occur while the tables are in an inconsistant
     * state.
     */

    status = alt_irq_disable_all ();

    alt_irq[id].handler = handler;
    alt_irq[id].context = context;

    rc = (handler) ? alt_irq_enable (id): alt_irq_disable (id);

    alt_irq_enable_all(status);
  }
  return rc; 
}