ar_membox.c

Keil开发环境下ARM7内核单片机的ARTX RTOS内核源代码

/*----------------------------------------------------------------------------
 *      A R T X  -  K e r n e l
 *----------------------------------------------------------------------------
 *      Name:    AR_MEMBOX.C
 *      Purpose: Interface functions for fixed memory block management system
 *      Rev.:    V2.00 / 19-oct-2005
 *----------------------------------------------------------------------------
 *      This code is part of the ARTX-ARM kernel package of Keil Software.
 *      Copyright (c) 2004-2005 Keil Software. All rights reserved. 
 *---------------------------------------------------------------------------*/

#include "Kernel\ARTX_Config.h"

//-------------------------------------------------------------------------
//
//  Initialize memory block system
//
//  1.  create a memory structure
//    box_mem+0 : U32 : pointer to first free memory block
//    box_mem+4 : U32 : pointer to memory block end
//    box_mem+8 : U32 : blk_size
//
//  2.  link all free blocks using offsets
//-------------------------------------------------------------------------

struct bm  {
   void *free;
   void *end;
   U32  blk_size;
};

/*----------------------------------------------------------------------------
 *      Global Functions
 *---------------------------------------------------------------------------*/


/*--------------------------- _init_box -------------------------------------*/

int _init_box  (void *box_mem, U32 box_size, U32 blk_size) {
   /* Initialize memory block system, returns 0 if OK, 1 if fails. */
   void *end;
   void *blk;
   void *next;

   /* Create memory structure. */
   blk_size = (blk_size + 3) & ~3;
   if (blk_size == 0) {
      return 1;
   }
   if ((blk_size + sizeof (struct bm)) > box_size) {
       return 1;
   }
   blk = ((U8 *) box_mem) + sizeof (struct bm);
   ((struct bm *) box_mem)->free = blk;
   end = ((U8 *) box_mem) + box_size;
   ((struct bm *) box_mem)->end      = end;
   ((struct bm *) box_mem)->blk_size = blk_size;

   /* Link free blocks. */
   end = ((U8 *) end) - blk_size;
   while (1)  {
      next = ((U8 *) blk) + blk_size;
      if (next > end)  break;
      *((void **)blk) = next;
      blk = next;
   }
   /* end marker */
   *((void **)blk) = 0;
   return (0);
}


/*--------------------------- _alloc_box ------------------------------------*/

void *_alloc_box (void *box_mem)  __swi (6)  {
   /* Allocate a memory block and return start address. */
   void **free;

   free = ((struct bm *) box_mem)->free;
   if (free) {
      ((struct bm *) box_mem)->free = *free;
   }
   return (free);
}


/*--------------------------- _calloc_box -----------------------------------*/

void *_calloc_box (void *box_mem)  {
   /* Allocate a memory block, set it to 0, and return start address. */
   void *free;
   U32 *p;
   U32 i;

   free = _alloc_box (box_mem);
   if (free)  {
      p = free;
      for (i = ((struct bm *) box_mem)->blk_size; i; i -= 4)  {
         *p = 0;
         p++;
      }
   }
   return (free);
}


/*--------------------------- _free_box -------------------------------------*/

int _free_box (void *box_mem, void *box)  __swi (7) {
   /* Free a memory block, returns 0 if OK, 1 if box does not belong to box_mem */
   if (box < box_mem) {
      return (1);
   }
   if (box > ((struct bm *) box_mem)->end) {
      return (1);
   }
   *((void **)box) = ((struct bm *) box_mem)->free;
   ((struct bm *) box_mem)->free = box;
   return (0);
}

/*----------------------------------------------------------------------------
 * end of file
 *---------------------------------------------------------------------------*/