chmemcore.c

/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                 2011,2012,2013 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @file    chmemcore.c
 * @brief   Core memory manager code.
 *
 * @addtogroup memcore
 * @details Core Memory Manager related APIs and services.
 *          <h2>Operation mode</h2>
 *          The core memory manager is a simplified allocator that only
 *          allows to allocate memory blocks without the possibility to
 *          free them.<br>
 *          This allocator is meant as a memory blocks provider for the
 *          other allocators such as:
 *          - C-Runtime allocator (through a compiler specific adapter module).
 *          - Heap allocator (see @ref heaps).
 *          - Memory pools allocator (see @ref pools).
 *          .
 *          By having a centralized memory provider the various allocators
 *          can coexist and share the main memory.<br>
 *          This allocator, alone, is also useful for very simple
 *          applications that just require a simple way to get memory
 *          blocks.
 * @pre     In order to use the core memory manager APIs the @p CH_USE_MEMCORE
 *          option must be enabled in @p chconf.h.
 * @{
 */

#include "ch.h"

#if CH_USE_MEMCORE || defined(__DOXYGEN__)

static uint8_t *nextmem;
static uint8_t *endmem, *realendmem;

/**
 * @brief   Low level memory manager initialization.
 *
 * @notapi
 */
void _core_init(void) {
#if CH_MEMCORE_SIZE == 0
  extern uint8_t __heap_base__[];
  extern uint8_t __heap_end__[];
  nextmem = (uint8_t *)MEM_ALIGN_NEXT(__heap_base__);
  endmem = (uint8_t *)MEM_ALIGN_PREV(__heap_end__);
#else
  static stkalign_t buffer[MEM_ALIGN_NEXT(CH_MEMCORE_SIZE)/MEM_ALIGN_SIZE];
  nextmem = (uint8_t *)&buffer[0];
  endmem = (uint8_t *)&buffer[MEM_ALIGN_NEXT(CH_MEMCORE_SIZE)/MEM_ALIGN_SIZE];
#endif
  realendmem = endmem;
}

/**
 * @brief   Allocates a memory block.
 * @details The size of the returned block is aligned to the alignment
 *          type so it is not possible to allocate less
 *          than <code>MEM_ALIGN_SIZE</code>.
 *
 * @param[in] size      the size of the block to be allocated
 * @return              A pointer to the allocated memory block.
 * @retval NULL         allocation failed, core memory exhausted.
 *
 * @api
 */
void *chCoreAlloc(size_t size) {
  void *p;

  chSysLock();
  p = chCoreAllocI(size);
  chSysUnlock();
  return p;
}

/**
 * @brief   Allocates a memory block.
 * @details The size of the returned block is aligned to the alignment
 *          type so it is not possible to allocate less than
 *          <code>MEM_ALIGN_SIZE</code>.
 *
 * @param[in] size      the size of the block to be allocated.
 * @return              A pointer to the allocated memory block.
 * @retval NULL         allocation failed, core memory exhausted.
 *
 * @iclass
 */
void *chCoreAllocI(size_t size) {
  void *p;

  chDbgCheckClassI();

  size = MEM_ALIGN_NEXT(size);
  if ((size_t)(endmem - nextmem) < size)
    return NULL;
  p = nextmem;
  nextmem += size;
  return p;
}

/**
 * @brief   Core memory status.
 *
 * @return              The size, in bytes, of the free core memory.
 *
 * @api
 */
size_t chCoreStatus(void) {

  return (size_t)(endmem - nextmem);
}

void *chCoreTrim(size_t size) {
  void *p;

  chSysLock();
  p = chCoreTrimI(size);
  chSysUnlock();
  return p;
}

void *chCoreTrimI(size_t size) {
  uint8_t *p;

  chDbgCheckClassI();

  p = (uint8_t *)MEM_ALIGN_PREV(endmem - size);
  if (p < nextmem)
    return NULL;
  endmem = p;
  return (void *)p;
}

void chCoreGrow(size_t size) {

  chSysLock();
  chCoreGrowI(size);
  chSysUnlock();
}

void chCoreGrowI(size_t size) {

  chDbgCheckClassI();
  size = MEM_ALIGN_NEXT(size);
  chDbgCheck(endmem + size <= realendmem, "chCoreGrowI");
  endmem += size;
}
#endif /* CH_USE_MEMCORE */

/** @} */