sys/sys/sglist.h

   1 /*-
   2  * Copyright (c) 2008 Yahoo!, Inc.
   3  * All rights reserved.
   4  * Written by: John Baldwin <jhb@FreeBSD.org>
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the author nor the names of any co-contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  * $FreeBSD: src/sys/sys/sglist.h,v 1.2 2009/08/20 19:23:58 jhb Exp $
  31  */
  32
  33 /*
  34  * A scatter/gather list describes a group of physical address ranges.
  35  * Each physical address range consists of a starting address and a
  36  * length.
  37  */
  38
  39 #ifndef __SGLIST_H__
  40 #define __SGLIST_H__
  41
  42 #include <sys/refcount.h>
  43
  44 struct sglist_seg {
  45         vm_paddr_t      ss_paddr;
  46         size_t          ss_len;
  47 };
  48
  49 struct sglist {
  50         struct sglist_seg *sg_segs;
  51         int             sg_refs;
  52         u_short         sg_nseg;
  53         u_short         sg_maxseg;
  54 };
  55
  56 struct mbuf;
  57 struct uio;
  58
  59 static __inline void
  60 sglist_init(struct sglist *sg, u_short maxsegs, struct sglist_seg *segs)
  61 {
  62
  63         sg->sg_segs = segs;
  64         sg->sg_nseg = 0;
  65         sg->sg_maxseg = maxsegs;
  66         refcount_init(&sg->sg_refs, 1);
  67 }
  68
  69 static __inline void
  70 sglist_reset(struct sglist *sg)
  71 {
  72
  73         sg->sg_nseg = 0;
  74 }
  75
  76 static __inline struct sglist *
  77 sglist_hold(struct sglist *sg)
  78 {
  79
  80         refcount_acquire(&sg->sg_refs);
  81         return (sg);
  82 }
  83
  84 struct sglist *sglist_alloc(int nsegs, int mflags);
  85 int     sglist_append(struct sglist *sg, void *buf, size_t len);
  86 int     sglist_append_mbuf(struct sglist *sg, struct mbuf *m0);
  87 int     sglist_append_phys(struct sglist *sg, vm_paddr_t paddr,
  88             size_t len);
  89 int     sglist_append_uio(struct sglist *sg, struct uio *uio);
  90 int     sglist_append_user(struct sglist *sg, void *buf, size_t len,
  91             struct thread *td);
  92 struct sglist *sglist_build(void *buf, size_t len, int mflags);
  93 struct sglist *sglist_clone(struct sglist *sg, int mflags);
  94 int     sglist_consume_uio(struct sglist *sg, struct uio *uio, size_t resid);
  95 int     sglist_count(void *buf, size_t len);
  96 void    sglist_free(struct sglist *sg);
  97 int     sglist_join(struct sglist *first, struct sglist *second);
  98 size_t  sglist_length(struct sglist *sg);
  99 int     sglist_slice(struct sglist *original, struct sglist **slice,
 100             size_t offset, size_t length, int mflags);
 101 int     sglist_split(struct sglist *original, struct sglist **head,
 102             size_t length, int mflags);
 103
 104 #endif  /* !__SGLIST_H__ */