www.pudn.com > 51ucosii.zip > OS_MEM.C, change:2002-04-14,size:10937b


/* 
********************************************************************************************************* 
*                                                uC/OS-II 
*                                          The Real-Time Kernel 
*                                            MEMORY MANAGEMENT 
* 
*                        (c) Copyright 1992-1998, Jean J. Labrosse, Plantation, FL 
*                                           All Rights Reserved 
* 
*                                                  V2.00 
* 
* File : OS_MEM.C 
* By   : Jean J. Labrosse 
********************************************************************************************************* 
*/ 
 
#ifndef  OS_MASTER_FILE 
#include "includes.h" 
#endif 
 
#if OS_MEM_EN && OS_MAX_MEM_PART >= 2 
/* 
********************************************************************************************************* 
*                                         LOCAL GLOBAL VARIABLES 
********************************************************************************************************* 
*/ 
 
static  OS_MEM      *OSMemFreeList;            /* Pointer to free list of memory partitions            */ 
static  OS_MEM       OSMemTbl[OS_MAX_MEM_PART];/* Storage for memory partition manager                 */ 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                        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_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)reentrant 
{ 
    OS_MEM  *pmem; 
    INT8U   *pblk; 
    void   **plink; 
    INT32U   i; 
 
 
    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); 
    } 
    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 *)addr + blksize; 
    for (i = 0; i < (nblks - 1); i++) { 
        *plink = (void *)pblk; 
        plink  = (void **)pblk; 
        pblk   = pblk + blksize; 
    } 
    *plink = (void *)0;                               /* Last memory block points to NULL              */ 
    OS_ENTER_CRITICAL(); 
    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        */ 
    OS_EXIT_CRITICAL(); 
    *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 
* 
* 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)reentrant 
{ 
    void    *pblk; 
 
 
    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            */ 
    } else { 
        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*/ 
/* 
********************************************************************************************************* 
*                                    INITIALIZE MEMORY PARTITION MANAGER 
* 
* Description : This function is called by uC/OS-II to initialize the memory partition manager.  Your 
*               application MUST NOT call this function. 
* 
* Arguments   : none 
* 
* Returns     : none 
********************************************************************************************************* 
*/ 
 
void OSMemInit (void)reentrant 
{ 
    OS_MEM  *pmem; 
    INT16U   i; 
 
 
    pmem = (OS_MEM *)&OSMemTbl[0];                    /* Point to memory control block (MCB)           */ 
    for (i = 0; i < (OS_MAX_MEM_PART - 1); i++) {     /* Init. list of free memory partitions          */ 
        pmem->OSMemFreeList = (void *)&OSMemTbl[i+1]; /* Chain list of free partitions                 */ 
        pmem->OSMemAddr     = (void *)0;              /* Store start address of memory partition       */ 
        pmem->OSMemNFree    = 0;                      /* No free blocks                                */ 
        pmem->OSMemNBlks    = 0;                      /* No blocks                                     */ 
        pmem->OSMemBlkSize  = 0;                      /* Zero size                                     */ 
        pmem++; 
    } 
    OSMemTbl[OS_MAX_MEM_PART - 1].OSMemFreeList = (void *)0; 
    OSMemFreeList                               = (OS_MEM *)&OSMemTbl[0]; 
} 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                         RELEASE A MEMORY BLOCK 
* 
* Description : Returns a memory block to a partition 
* 
* Arguments   : pmem    is a pointer to the memory partition control block 
* 
*               pblk    is a pointer to the memory block being released. 
* 
* Returns     : OS_NO_ERR         if the memory block was inserted into the partition 
*               OS_MEM_FULL       if you are returning a memory block to an already FULL memory partition 
*                                 (You freed more blocks than you allocated!) 
********************************************************************************************************* 
*/ 
 
INT8U OSMemPut (OS_MEM  *pmem, void *pblk)reentrant 
{ 
    OS_ENTER_CRITICAL(); 
    if (pmem->OSMemNFree >= pmem->OSMemNBlks) {  /* Make sure all blocks not already returned          */ 
        OS_EXIT_CRITICAL(); 
        return (OS_MEM_FULL);        
    } 
    *(void **)pblk      = pmem->OSMemFreeList;   /* Insert released block into free block list         */ 
    pmem->OSMemFreeList = pblk; 
    pmem->OSMemNFree++;                          /* One more memory block in this partition            */ 
    OS_EXIT_CRITICAL(); 
    return (OS_NO_ERR);                          /* Notify caller that memory block was released       */ 
} 
/*$PAGE*/ 
/* 
********************************************************************************************************* 
*                                          QUERY MEMORY PARTITION 
* 
* Description : This function is used to determine the number of free memory blocks and the number of  
*               used memory blocks from a memory partition. 
* 
* Arguments   : pmem    is a pointer to the memory partition control block 
* 
*               dataptr   is a pointer to a structure that will contain information about the memory 
*                       partition. 
* 
* Returns     : OS_NO_ERR         Always returns no error. 
********************************************************************************************************* 
*/ 
 
INT8U OSMemQuery (OS_MEM *pmem, OS_MEM_DATA *dataptr)reentrant 
{ 
    OS_ENTER_CRITICAL(); 
    dataptr->OSAddr     = pmem->OSMemAddr; 
    dataptr->OSFreeList = pmem->OSMemFreeList; 
    dataptr->OSBlkSize  = pmem->OSMemBlkSize; 
    dataptr->OSNBlks    = pmem->OSMemNBlks; 
    dataptr->OSNFree    = pmem->OSMemNFree; 
    OS_EXIT_CRITICAL(); 
    dataptr->OSNUsed    = dataptr->OSNBlks - dataptr->OSNFree; 
    return (OS_NO_ERR);                          
} 
#endif