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mblkl(9f) [sunos man page]

MBLKHEAD(9F)						   Kernel Functions for Drivers 					      MBLKHEAD(9F)

NAME

       MBLKHEAD, MBLKIN, MBLKL, MBLKSIZE, MBLKTAIL - Message block utility macros

SYNOPSIS

       #include <sys/stream.h>
       #include <sys/strsun.h>

       int MBLKHEAD(mblk_t *mp);

       int MBLKTAIL(mblk_t *mp);

       int MBLKSIZE(mblk_t *mp);

       int MBLKL(mblk_t *mp);

       int MBLKIN(mblk_t *mp, int offset, int len);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI).

PARAMETERS

       mp	       Message to be examined.

       offset	       Offset from mp->b_rptr from which to start examining.

       len	       Number of bytes to examine.

DESCRIPTION

       The  MBLKHEAD()	macro  calculates  the	number	of  bytes  between the first byte and the first unread byte of the message block, that is:
       mp->b_rptr - mp->b_datap->db_base.

       The MBLKTAIL() macro calculates the number of bytes between the first unwritten byte and the last byte  of  the	message  block,  that  is:
       mp->b_datap->db_lim - mp->b_wptr.

       The MBLKSIZE() macros calculates the total size of the message block, that is: mp->b_datap->db_lim - mp->b_datap->db_base.

       The MBLKL() macro calculates the length of the message block, that is: mp->b_wptr - mp->b_rptr.

       The MBLKIN() macro checks whether the byte range specified by offset and len resides entirely within the message block.

RETURN VALUES

       The  MBLKHEAD(),  MBLKTAIL(),  MBLKL() and MBLKSIZE() functions all return the appropriate byte count, as specified above. MBLKIN() returns
       non-zero if the check succeeds, or zero if it fails.

CONTEXT

       These functions can be called from user, kernel or interrupt context.

NOTES

       These macros may evaluate any of their arguments more than once. This precludes passing arguments with side effects.

       These macros assume the message itself is well formed, that is: mp->b_datap->db_base <= mp->b_rptr <= mp->b_wptr <= mp->b_datap->db_lim.

SEE ALSO

       msgb(9S)

       STREAMS Programming Guide

SunOS 5.10							    9 June 2004 						      MBLKHEAD(9F)

Check Out this Related Man Page

rmvb(9F)						   Kernel Functions for Drivers 						  rmvb(9F)

NAME

       rmvb - remove a message block from a message

SYNOPSIS

       #include <sys/stream.h>

       mblk_t *rmvb(mblk_t *mp, mblk_t *bp);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       mp	Message from which a block is to be removed. mblk_t is an instance of the
		 msgb(9S) structure.

       bp	Message block to be removed.

DESCRIPTION

       rmvb()  removes	a  message  block  (bp) from a message (mp), and returns a pointer to the altered message. The message block is not freed,
       merely removed from the message. It is the module or driver's responsibility to free the message block.

RETURN VALUES

       If successful, a pointer to the message (minus the removed block) is returned. The pointer is  NULL if bp was the only block of the message
       before
	rmvb() was called. If the designated message block (bp) does not exist, -1 is returned.

CONTEXT

       rmvb() can be called from user or interrupt context.

EXAMPLES

       This  routine  removes  all zero-length M_DATA message blocks from the given message.  For each message block in the message, save the next
       message block (line 10). If the current message block is of type M_DATA and has no data in its buffer (line 11), then remove  it  from  the
       message (line 12) and free it (line 13). In either case, continue with the next message block in the message (line 16).

	1  void
	2  xxclean(mp)
	3      mblk_t *mp;
	4  {
	5	   mblk_t *tmp;
	6	   mblk_t *nmp;
	7
	8	   tmp = mp;
	9	   while (tmp) {
       10		    nmp = tmp->b_cont;
       11		    if ((tmp->b_datap->db_type == M_DATA) &&
				  (tmp->b_rptr == tmp->b_wptr)) {
       12			 (void) rmvb(mp, tmp);
       13			 freeb(tmp);
       14		    }
       15		    tmp = nmp;
       16	   }
       17  }

SEE ALSO

       freeb(9F), msgb(9S)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.10							    11 Apr 1991 							  rmvb(9F)
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