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pullupmsg(9f) [freebsd man page]

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

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
pullupmsg() 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
pullupmsg() can be called from user or interrupt 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
pullupmsg() is not included in the DKI and will be removed from the system in a future release. Device driver writers are strongly encour- aged to use msgpullup(9F) instead of pullupmsg(). SunOS 5.10 11 Nov 1996 pullupmsg(9F)

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

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
The rmvb() function 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
The rmvb() function can be called from user, interrupt, or kernel 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 5.11 16 Jan 2006 rmvb(9F)
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