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/****************************************************************************
* mm/mm_sbrk.c
*
* Copyright (C) 2014 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/arch.h>
#include <nuttx/mm.h>
#include <nuttx/pgalloc.h>
#ifdef CONFIG_ARCH_ADDRENV
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: mm_sbrk
*
* Description:
* The sbrk() function is used to change the amount of space allocated
* for the calling process. The change is made by resetting the process'
* break value and allocating the appropriate amount of space. The amount
* of allocated space increases as the break value increases.
*
* The sbrk() function adds 'incr' bytes to the break value and changes
* the allocated space accordingly. If incr is negative, the amount of
* allocated space is decreased by incr bytes. The current value of the
* program break is returned by sbrk(0).
*
* Input Parameters:
* incr - Specifies the number of bytes to add or to remove from the
* space allocated for the process.
*
* Returned Value:
* Upon successful completion, sbrk() returns the prior break value.
* Otherwise, it returns (void *)-1 and sets errno to indicate the
* error:
*
* ENOMEM - The requested change would allocate more space than
* allowed under system limits.
* EAGAIN - The total amount of system memory available for allocation
* to this process is temporarily insufficient. This may occur even
* though the space requested was less than the maximum data segment
* size.
*
****************************************************************************/
FAR void *mm_sbrk(FAR struct mm_heap_s *heap, intptr_t incr,
uintptr_t maxbreak)
{
uintptr_t brkaddr;
uintptr_t allocbase;
unsigned int pgincr;
size_t bytesize;
int err;
DEBUGASSERT(incr >= 0);
if (incr < 0)
{
err = ENOSYS;
goto errout;
}
/* Get the current break address (NOTE: assumes region 0). If
* the memory manager is uninitialized, mm_brkaddr() will return
* zero.
*/
brkaddr = (uintptr_t)mm_brkaddr(heap, 0);
if (incr > 0)
{
/* Convert the increment to multiples of the page size */
pgincr = MM_NPAGES(incr);
/* Check if this increment would exceed the maximum break value */
if ((brkaddr > 0) && ((maxbreak - brkaddr) < (pgincr << MM_PGSHIFT)))
{
err = ENOMEM;
goto errout;
}
/* Allocate the requested number of pages and map them to the
* break address. If we provide a zero brkaddr to pgalloc(), it
* will create the first block in the correct virtual address
* space and return the start address of that block.
*/
allocbase = pgalloc(brkaddr, pgincr);
if (allocbase == 0)
{
err = EAGAIN;
goto errout;
}
/* Has the been been initialized? brkaddr will be zero if the
* memory manager has not yet been initialized.
*/
bytesize = pgincr << MM_PGSHIFT;
if (brkaddr != 0)
{
/* No... then initialize it now */
mm_initialize(heap, (FAR void *)allocbase, bytesize);
}
else
{
/* Extend the heap (region 0) */
mm_extend(heap, (FAR void *)allocbase, bytesize, 0);
}
}
return (FAR void *)brkaddr;
errout:
set_errno(err);
return (FAR void *)-1;
}
#endif /* CONFIG_ARCH_ADDRENV */
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