os_mem.c

一个著名的嵌入式实时操作系统源代码UCOS-

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*                                            MEMORY MANAGEMENT
*
*                          (c) Copyright 1992-2003, Jean J. Labrosse, Weston, FL
*                                           All Rights Reserved
*
* File    : OS_MEM.C
* By      : Jean J. Labrosse
* Version : V2.76
*********************************************************************************************************
*/

#ifndef  OS_MASTER_FILE
#include <ucos_ii.h>
#endif

#if (OS_MEM_EN > 0) && (OS_MAX_MEM_PART > 0)
/*
*********************************************************************************************************
*                                        CREATE A MEMORY PARTITION
*
* Description : Create a fixed-sized memory partition that will be managed by uC/OS-II.
*
* Arguments   : addr     is the starting address of the memory partition
*
*               nblks    is the number of memory blocks to create from the partition.
*
*               blksize  is the size (in bytes) of each block in the memory partition.
*
*               err      is a pointer to a variable containing an error message which will be set by
*                        this function to either:
*
*                        OS_NO_ERR            if the memory partition has been created correctly.
*                        OS_MEM_INVALID_ADDR  you are specifying an invalid address for the memory 
*                                             storage of the partition.
*                        OS_MEM_INVALID_PART  no free partitions available
*                        OS_MEM_INVALID_BLKS  user specified an invalid number of blocks (must be >= 2)
*                        OS_MEM_INVALID_SIZE  user specified an invalid block size
*                                             (must be greater than the size of a pointer)
* Returns    : != (OS_MEM *)0  is the partition was created
*              == (OS_MEM *)0  if the partition was not created because of invalid arguments or, no
*                              free partition is available.
*********************************************************************************************************
*/

OS_MEM  *OSMemCreate (void *addr, INT32U nblks, INT32U blksize, INT8U *err)
{
    OS_MEM    *pmem;
    INT8U     *pblk;
    void     **plink;
    INT32U     i;
#if OS_CRITICAL_METHOD == 3                           /* Allocate storage for CPU status register      */
    OS_CPU_SR  cpu_sr;



    cpu_sr = 0;                                       /* Prevent compiler warning                       */
#endif    
#if OS_ARG_CHK_EN > 0
    if (addr == (void *)0) {                          /* Must pass a valid address for the memory part. */
        *err = OS_MEM_INVALID_ADDR;
        return ((OS_MEM *)0);
    }
    if (nblks < 2) {                                  /* Must have at least 2 blocks per partition      */
        *err = OS_MEM_INVALID_BLKS;
        return ((OS_MEM *)0);
    }
    if (blksize < sizeof(void *)) {                   /* Must contain space for at least a pointer      */
        *err = OS_MEM_INVALID_SIZE;
        return ((OS_MEM *)0);
    }
#endif
    OS_ENTER_CRITICAL();
    pmem = OSMemFreeList;                             /* Get next free memory partition                */
    if (OSMemFreeList != (OS_MEM *)0) {               /* See if pool of free partitions was empty      */
        OSMemFreeList = (OS_MEM *)OSMemFreeList->OSMemFreeList;
    }
    OS_EXIT_CRITICAL();
    if (pmem == (OS_MEM *)0) {                        /* See if we have a memory partition             */
        *err = OS_MEM_INVALID_PART;
        return ((OS_MEM *)0);
    }
    plink = (void **)addr;                            /* Create linked list of free memory blocks      */
    pblk  = (INT8U *)((INT32U)addr + blksize);
    for (i = 0; i < (nblks - 1); i++) {
       *plink = (void *)pblk;                         /* Save pointer to NEXT block in CURRENT block   */
        plink = (void **)pblk;                        /* Position to  NEXT      block                  */
        pblk  = (INT8U *)((INT32U)pblk + blksize);    /* Point to the FOLLOWING block                  */
    }
    *plink              = (void *)0;                  /* Last memory block points to NULL              */
    pmem->OSMemAddr     = addr;                       /* Store start address of memory partition       */
    pmem->OSMemFreeList = addr;                       /* Initialize pointer to pool of free blocks     */
    pmem->OSMemNFree    = nblks;                      /* Store number of free blocks in MCB            */
    pmem->OSMemNBlks    = nblks;
    pmem->OSMemBlkSize  = blksize;                    /* Store block size of each memory blocks        */
    *err                = OS_NO_ERR;
    return (pmem);
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                          GET A MEMORY BLOCK
*
* Description : Get a memory block from a partition
*
* Arguments   : pmem    is a pointer to the memory partition control block
*
*               err     is a pointer to a variable containing an error message which will be set by this
*                       function to either:
*
*                       OS_NO_ERR           if the memory partition has been created correctly.
*                       OS_MEM_NO_FREE_BLKS if there are no more free memory blocks to allocate to caller
*                       OS_MEM_INVALID_PMEM if you passed a NULL pointer for 'pmem'
*
* Returns     : A pointer to a memory block if no error is detected
*               A pointer to NULL if an error is detected
*********************************************************************************************************
*/

void  *OSMemGet (OS_MEM *pmem, INT8U *err)
{
    void      *pblk;
#if OS_CRITICAL_METHOD == 3                           /* Allocate storage for CPU status register      */
    OS_CPU_SR  cpu_sr;



    cpu_sr = 0;                                       /* Prevent compiler warning                       */
#endif    
#if OS_ARG_CHK_EN > 0
    if (pmem == (OS_MEM *)0) {                        /* Must point to a valid memory partition         */
        *err = OS_MEM_INVALID_PMEM;
        return ((OS_MEM *)0);
    }
#endif
    OS_ENTER_CRITICAL();
    if (pmem->OSMemNFree > 0) {                       /* See if there are any free memory blocks       */
        pblk                = pmem->OSMemFreeList;    /* Yes, point to next free memory block          */
        pmem->OSMemFreeList = *(void **)pblk;         /*      Adjust pointer to new free list          */
        pmem->OSMemNFree--;                           /*      One less memory block in this partition  */
        OS_EXIT_CRITICAL();
        *err = OS_NO_ERR;                             /*      No error                                 */
        return (pblk);                                /*      Return memory block to caller            */
    }
    OS_EXIT_CRITICAL();
    *err = OS_MEM_NO_FREE_BLKS;                       /* No,  Notify caller of empty memory partition  */
    return ((void *)0);                               /*      Return NULL pointer to caller            */
}
/*$PAGE*/
/*
*********************************************************************************************************
*                                   GET THE NAME OF A MEMORY PARTITION
*
* Description: This function is used to obtain the name assigned to a memory partition.
*
* Arguments  : pmem      is a pointer to the memory partition
*
*              pname     is a pointer to an ASCII string that will receive the name of the memory partition.
*
*              err       is a pointer to an error code that can contain one of the following values:
*
*                        OS_NO_ERR                  if the name was copied to 'pname'
*                        OS_MEM_INVALID_PMEM        if you passed a NULL pointer for 'pmem'
*                        OS_ERR_PNAME_NULL          You passed a NULL pointer for 'pname'
*
* Returns    : The length of the string or 0 if 'pmem' is a NULL pointer.
*********************************************************************************************************
*/

#if OS_MEM_NAME_SIZE > 1
INT8U  OSMemNameGet (OS_MEM *pmem, char *pname, INT8U *err)
{
    INT8U      len;
#if OS_CRITICAL_METHOD == 3                      /* Allocate storage for CPU status register           */
    OS_CPU_SR  cpu_sr;



    cpu_sr = 0;                                  /* Prevent compiler warning                           */
#endif    
    OS_ENTER_CRITICAL();
#if OS_ARG_CHK_EN > 0
    if (pmem == (OS_MEM *)0) {                   /* Is 'pmem' a NULL pointer?                          */
        OS_EXIT_CRITICAL();                      /* Yes                                                */
        *err = OS_MEM_INVALID_PMEM;
        return (0);
    }
    if (pname == (char *)0) {                    /* Is 'pname' a NULL pointer?                         */
        OS_EXIT_CRITICAL();                      /* Yes                                                */
        *err = OS_ERR_PNAME_NULL;
        return (0);
    }
#endif
    len  = OS_StrCopy(pname, pmem->OSMemName);   /* Copy name from OS_MEM                              */
    OS_EXIT_CRITICAL();
    *err = OS_NO_ERR;
    return (len);
}
#endif