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/******************************************************************************

*                                                                             *

* License Agreement                                                           *

*                                                                             *

* Copyright (c) 2004 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.              *

*                                                                             *

* Altera does not recommend, suggest or require that this reference design    *

* file be used in conjunction or combination with any other product.          *

******************************************************************************/

#include <sys/types.h>

#include "os/alt_syscall.h"

#include "sys/alt_irq.h"

#include "sys/alt_stack.h"

#include "system.h"

/*

 * sbrk() is called to dynamically extend the data segment for the application.

 * Thie input argument "incr" is the size of the block to allocate.

 *

 * This simple implementation does not perform any bounds checking. Memory will

 * be allocated, even if the request region colides with the stack or overflows

 * the available physical memory.

 *

 * ALT_SBRK is mapped onto the sbrk() system call in alt_syscall.h

 *

 * This function is called by the profiling code to allocate memory so must be

 * safe if called from an interrupt context.  It must also not be instrumented

 * because that would lead to an infinate loop.

 */

extern char __alt_heap_start[]; /* set by linker */

extern char __alt_heap_limit[]; /* set by linker */

static char *heap_end = __alt_heap_start;

#if defined(ALT_EXCEPTION_STACK) && defined(ALT_STACK_CHECK)

char * alt_exception_old_stack_limit = NULL;

#endif

caddr_t ALT_SBRK (int incr) __attribute__ ((no_instrument_function ));

caddr_t ALT_SBRK (int incr)

{

  alt_irq_context context;

  char *prev_heap_end;

  context = alt_irq_disable_all();

  /* Always return data aligned on a word boundary */

  heap_end = (char *)(((unsigned int)heap_end + 3) & ~3);

#ifdef ALT_MAX_HEAP_BYTES

  /*

   * User specified a maximum heap size.  Return -1 if it would

   * be exceeded by this sbrk call.

   */

  if (((heap_end + incr) - __alt_heap_start) > ALT_MAX_HEAP_BYTES) {

    alt_irq_enable_all(context);

    return (caddr_t)-1;

  }

#else

  if ((heap_end + incr) > __alt_heap_limit) {

    alt_irq_enable_all(context);

    return (caddr_t)-1;

  }

#endif

  prev_heap_end = heap_end;

  heap_end += incr;

#ifdef ALT_STACK_CHECK

  /*

   * If the stack and heap are contiguous then extending the heap reduces the

   * space available for the stack.  If we are still using the default stack

   * then adjust the stack limit to note this, while checking for stack

   * pointer overflow.

   * If the stack limit isn't pointing at the top of the heap then the code

   * is using a different stack so none of this needs to be done.

   */

  if (alt_stack_limit() == prev_heap_end)

  {

    if (alt_stack_pointer() <= heap_end)

      alt_report_stack_overflow();

    alt_set_stack_limit(heap_end);

  }

#ifdef ALT_EXCEPTION_STACK

  /*

   * If we are executing from the exception stack then compare against the

   * stack we switched away from as well.  The exception stack is a fixed

   * size so doesn't need to be checked.

   */

  if (alt_exception_old_stack_limit == prev_heap_end)

  {

    if (alt_exception_old_stack_limit <= heap_end)

      alt_report_stack_overflow();

    alt_exception_old_stack_limit = heap_end;

  }

#endif

#endif

  alt_irq_enable_all(context);

  return (caddr_t) prev_heap_end;

}