opensolaris man page for pullupmsg

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

NAME
       pullupmsg - concatenate bytes in a message

SYNOPSIS
       #include <sys/stream.h>

       int pullupmsg(mblk_t *mp, ssize_t len);

INTERFACE LEVEL
       Architecture independent level 1 (DDI/DKI).

PARAMETERS
       mp     Pointer to the message whose blocks are to be concatenated. mblk_t is an instance of the msgb(9S) structure.

       len    Number of bytes to concatenate.

DESCRIPTION
       The  pullupmsg() function tries to combine multiple data blocks into a single block. pullupmsg() concatenates and aligns the first len data
       bytes of the message pointed to by mp. If len equals -1, all data are concatenated. If len bytes of the same message type cannot be  found,
       pullupmsg() fails and returns 0.

RETURN VALUES
       On success, 1 is returned; on failure, 0 is returned.

CONTEXT
       The pullupmsg() function can be called from user, interrupt, or kernel context.

EXAMPLES
       Example 1 Using pullupmsg()

       This  is a driver write srv(9E) (service) routine for a device that does not support scatter/gather DMA. For all  M_DATA messages, the data
       will be transferred to the device with DMA. First, try to pull up the message into one message block with the  pullupmsg()  function  (line
       12).  If successful, the transfer can be accomplished in one DMA job. Otherwise, it must be done one message block at a time (lines 19-22).
       After the data has been transferred to the device, free the message and continue processing messages on the queue.

	  1 xxxwsrv(q)
	  2    queue_t *q;
	  3 {
	  4	  mblk_t *mp;
	  5	  mblk_t *tmp;
	  6	  caddr_t dma_addr;
	  7	ssize_t dma_len;
	  8
	  9	  while ((mp = getq(q)) != NULL) {
	 10		  switch (mp->b_datap->db_type) {
	 11		case M_DATA:
	 12			 if (pullupmsg(mp, -1)) {
	 13			       dma_addr = vtop(mp->b_rptr);
	 14				 dma_len = mp->b_wptr - mp->b_rptr;
	 15				 xxx_do_dma(dma_addr, dma_len);
	 16				 freemsg(mp);
	 17				 break;
	 18			 }
	 19			 for (tmp = mp; tmp; tmp = tmp->b_cont) {
	 20			       dma_addr = vtop(tmp->b_rptr);
	 21			       dma_len = tmp->b_wptr - tmp->b_rptr;
	 22			       xxx_do_dma(dma_addr, dma_len);
	 23		       }
	 24			 freemsg(mp);
	 25			 break;
		    . . .
	 26		   }
	 27	  }
	 28 }

SEE ALSO
       srv(9E), allocb(9F), msgpullup(9F), msgb(9S)

       Writing Device Drivers

       STREAMS Programming Guide

NOTES
       The pullupmsg() function is not included in the DKI and will be removed from the system in a future  release.  Device  driver  writers  are
       strongly encouraged to use msgpullup(9F) instead of pullupmsg().

SunOS 5.11							    16 Jan 2006 						     pullupmsg(9F)