sys/bus/cam/cam_extend.c

   1 /*
   2  * Written by Julian Elischer (julian@tfs.com)
   3  * for TRW Financial Systems for use under the MACH(2.5) operating system.
   4  *
   5  * TRW Financial Systems, in accordance with their agreement with Carnegie
   6  * Mellon University, makes this software available to CMU to distribute
   7  * or use in any manner that they see fit as long as this message is kept with
   8  * the software. For this reason TFS also grants any other persons or
   9  * organisations permission to use or modify this software.
  10  *
  11  * TFS supplies this software to be publicly redistributed
  12  * on the understanding that TFS is not responsible for the correct
  13  * functioning of this software in any circumstances.
  14  *
  15  * $FreeBSD: src/sys/cam/cam_extend.c,v 1.3 1999/08/28 00:40:39 peter Exp $
  16  * $DragonFly: src/sys/bus/cam/cam_extend.c,v 1.8 2006/12/22 23:12:16 swildner Exp $
  17  */
  18 /*
  19  * XXX XXX XXX XXX  We should get DEVFS working so that we
  20  * don't have to do this, possibly sparse, array based junk.
  21  * XXX: We can do this now with cdev_t, that's even better.
  22  */
  23 /*
  24  * Extensible arrays: Use a realloc like implementation to permit
  25  * the arrays to be extend.
  26  */
  27 #include <sys/param.h>
  28 #include <sys/systm.h>
  29 #include <sys/kernel.h>
  30 #include <sys/malloc.h>
  31
  32 #include "cam_extend.h"
  33
  34 struct extend_array
  35 {
  36         int nelem;
  37         void **ps;
  38 };
  39
  40 /* EXTEND_CHUNK: Number of extend slots to allocate whenever we need a new
  41  * one.
  42  */
  43 #ifndef EXTEND_CHUNK
  44         #define EXTEND_CHUNK 8
  45 #endif
  46
  47 struct extend_array *
  48 cam_extend_new(void)
  49 {
  50         return(kmalloc(sizeof(struct extend_array), M_DEVBUF,
  51             M_INTWAIT | M_ZERO));
  52 }
  53
  54 void *
  55 cam_extend_set(struct extend_array *ea, int index, void *value)
  56 {
  57         if (index >= ea->nelem) {
  58                 void **space;
  59                 space = kmalloc(sizeof(void *) * (index + EXTEND_CHUNK),
  60                     M_DEVBUF, M_INTWAIT | M_ZERO);
  61
  62                 /* Make sure we have something to copy before we copy it */
  63                 if (ea->nelem) {
  64                         bcopy(ea->ps, space, sizeof(void *) * ea->nelem);
  65                         kfree(ea->ps, M_DEVBUF);
  66                 }
  67
  68                 ea->ps = space;
  69                 ea->nelem = index + EXTEND_CHUNK;
  70         }
  71         if (ea->ps[index]) {
  72                 kprintf("extend_set: entry %d already has storage.\n", index);
  73                 return 0;
  74         }
  75         else
  76                 ea->ps[index] = value;
  77
  78         return value;
  79 }
  80
  81 void *
  82 cam_extend_get(struct extend_array *ea,
  83                int index)
  84 {
  85         if (ea == NULL || index >= ea->nelem || index < 0)
  86                 return NULL;
  87         return ea->ps[index];
  88 }
  89
  90 void
  91 cam_extend_release(struct extend_array *ea, int index)
  92 {
  93         void *p = cam_extend_get(ea, index);
  94         if (p) {
  95                 ea->ps[index] = 0;
  96         }
  97 }