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[/] [ao486/] [trunk/] [syn/] [soc/] [firmware/] [exe_bsp/] [HAL/] [src/] [alt_sbrk.c] - Blame information for rev 2

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/******************************************************************************
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*                                                                             *
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* License Agreement                                                           *
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*                                                                             *
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* Copyright (c) 2004 Altera Corporation, San Jose, California, USA.           *
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* All rights reserved.                                                        *
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*                                                                             *
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* Permission is hereby granted, free of charge, to any person obtaining a     *
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* copy of this software and associated documentation files (the "Software"),  *
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* to deal in the Software without restriction, including without limitation   *
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,    *
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* and/or sell copies of the Software, and to permit persons to whom the       *
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* Software is furnished to do so, subject to the following conditions:        *
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*                                                                             *
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* The above copyright notice and this permission notice shall be included in  *
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* all copies or substantial portions of the Software.                         *
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*                                                                             *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  *
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,    *
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE *
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER      *
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING     *
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER         *
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* DEALINGS IN THE SOFTWARE.                                                   *
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*                                                                             *
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* This agreement shall be governed in all respects by the laws of the State   *
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* of California and by the laws of the United States of America.              *
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*                                                                             *
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* Altera does not recommend, suggest or require that this reference design    *
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* file be used in conjunction or combination with any other product.          *
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******************************************************************************/
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#include <sys/types.h>
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#include "os/alt_syscall.h"
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#include "sys/alt_irq.h"
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#include "sys/alt_stack.h"
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#include "system.h"
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/*
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 * sbrk() is called to dynamically extend the data segment for the application.
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 * Thie input argument "incr" is the size of the block to allocate.
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 *
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 * This simple implementation does not perform any bounds checking. Memory will
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 * be allocated, even if the request region colides with the stack or overflows
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 * the available physical memory.
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 *
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 * ALT_SBRK is mapped onto the sbrk() system call in alt_syscall.h
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 *
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 * This function is called by the profiling code to allocate memory so must be
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 * safe if called from an interrupt context.  It must also not be instrumented
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 * because that would lead to an infinate loop.
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 */
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extern char __alt_heap_start[]; /* set by linker */
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extern char __alt_heap_limit[]; /* set by linker */
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static char *heap_end = __alt_heap_start;
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#if defined(ALT_EXCEPTION_STACK) && defined(ALT_STACK_CHECK)
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char * alt_exception_old_stack_limit = NULL;
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#endif
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caddr_t ALT_SBRK (int incr) __attribute__ ((no_instrument_function ));
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caddr_t ALT_SBRK (int incr)
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{
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  alt_irq_context context;
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  char *prev_heap_end;
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  context = alt_irq_disable_all();
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  /* Always return data aligned on a word boundary */
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  heap_end = (char *)(((unsigned int)heap_end + 3) & ~3);
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#ifdef ALT_MAX_HEAP_BYTES
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  /*
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   * User specified a maximum heap size.  Return -1 if it would
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   * be exceeded by this sbrk call.
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   */
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  if (((heap_end + incr) - __alt_heap_start) > ALT_MAX_HEAP_BYTES) {
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    alt_irq_enable_all(context);
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    return (caddr_t)-1;
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  }
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#else
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  if ((heap_end + incr) > __alt_heap_limit) {
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    alt_irq_enable_all(context);
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    return (caddr_t)-1;
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  }
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#endif
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  prev_heap_end = heap_end;
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  heap_end += incr;
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#ifdef ALT_STACK_CHECK
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  /*
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   * If the stack and heap are contiguous then extending the heap reduces the
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   * space available for the stack.  If we are still using the default stack
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   * then adjust the stack limit to note this, while checking for stack
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   * pointer overflow.
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   * If the stack limit isn't pointing at the top of the heap then the code
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   * is using a different stack so none of this needs to be done.
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   */
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  if (alt_stack_limit() == prev_heap_end)
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  {
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    if (alt_stack_pointer() <= heap_end)
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      alt_report_stack_overflow();
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    alt_set_stack_limit(heap_end);
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  }
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#ifdef ALT_EXCEPTION_STACK
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  /*
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   * If we are executing from the exception stack then compare against the
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   * stack we switched away from as well.  The exception stack is a fixed
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   * size so doesn't need to be checked.
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   */
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  if (alt_exception_old_stack_limit == prev_heap_end)
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  {
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    if (alt_exception_old_stack_limit <= heap_end)
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      alt_report_stack_overflow();
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    alt_exception_old_stack_limit = heap_end;
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  }
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#endif
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#endif
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  alt_irq_enable_all(context);
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  return (caddr_t) prev_heap_end;
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}

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