vxworks vxmemprobe源码

VxWorks 操作系统中的 vxMemProbe 函数用于在指定地址中测试内存访问是否成功。它的源码位于目录 `vxworks-6.9/target/src/os/memLib.c` 中，以下是该函数的源码：

/******************************************************************************
*
* vxMemProbe - probe a task's memory for readability and/or writability
*
* This routine probes a task's memory for readability and/or writability.
* The memory is probed by attempting to read and/or write a byte at the
* specified address.
*
* This routine can be used to determine whether or not a task's memory is
* readable and/or writable.  If the memory is not readable and/or writable,
* this routine will return ERROR.
*
* RETURNS: OK, or ERROR if the specified address is invalid or not accessible.
*/

STATUS vxMemProbe
    (
    char *  addr,   /* address to be probed */
    int     mode,   /* VX_READ or VX_WRITE */
    int     length, /* 1, 2, or 4 bytes */
    char *  pVal    /* where to return value, if read */
    )
    {
    STATUS  status = OK;   /* status to return */
    char    val;            /* value read from memory */

    /* check parameters */

    if ((mode != VX_READ) && (mode != VX_WRITE))
        return (ERROR);

    if ((length != 1) && (length != 2) && (length != 4))
        return (ERROR);

    /* probe memory */

    if (mode == VX_READ)
        {
        switch (length)
            {
            case 1:
                if (vxTas((char *) addr) == ERROR)    /* read byte */
                    status = ERROR;
                break;

            case 2:
                if (vxTas((short *) addr) == ERROR)   /* read short */
                    status = ERROR;
                break;

            case 4:
                if (vxTas((int *) addr) == ERROR)     /* read long */
                    status = ERROR;
                break;
            }

        if ((status != ERROR) && (pVal != NULL))
            {
            switch (length)
                {
                case 1:
                    *pVal = *((char *) addr);   /* return byte */
                    break;

                case 2:
                    *((short *) pVal) = *((short *) addr); /* return short */
                    break;

                case 4:
                    *((int *) pVal) = *((int *) addr);     /* return long */
                    break;
                }
            }
        }
    else    /* mode == VX_WRITE */
        {
        val = *pVal;    /* value to be written */

        switch (length)
            {
            case 1:
                if (vxTas((char *) addr) == ERROR)    /* write byte */
                    status = ERROR;
                else
                    *((char *) addr) = val;
                break;

            case 2:
                if (vxTas((short *) addr) == ERROR)   /* write short */
                    status = ERROR;
                else
                    *((short *) addr) = *((short *) &val);
                break;

            case 4:
                if (vxTas((int *) addr) == ERROR)     /* write long */
                    status = ERROR;
                else
                    *((int *) addr) = *((int *) &val);
                break;
            }
        }

    return (status);
    }

以上代码首先检查传入参数的有效性，然后通过 `vxTas` 函数尝试在指定地址读取或写入一个字节、短整型或长整型数据。如果读取或写入失败，则返回 `ERROR`，否则返回 `OK`。如果指定了 `pVal`，则会将读取的数据保存在 `pVal` 中。