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  */
  17 /*
  18  * XXX XXX XXX XXX  We should get DEVFS working so that we
  19  * don't have to do this, possibly sparse, array based junk.
  20  * XXX: We can do this now with cdev_t, that's even better.
  21  */
  22 /*
  23  * Extensible arrays: Use a realloc like implementation to permit
  24  * the arrays to be extend.
  25  */
  26 #include <sys/param.h>
  27 #include <sys/systm.h>
  28 #include <sys/kernel.h>
  29 #include <sys/malloc.h>
  30
  31 #include "cam_extend.h"
  32
  33 struct extend_array
  34 {
  35         int nelem;
  36         void **ps;
  37 };
  38
  39 /* EXTEND_CHUNK: Number of extend slots to allocate whenever we need a new
  40  * one.
  41  */
  42 #ifndef EXTEND_CHUNK
  43         #define EXTEND_CHUNK 8
  44 #endif
  45
  46 struct extend_array *
  47 cam_extend_new(void)
  48 {
  49         return(kmalloc(sizeof(struct extend_array), M_DEVBUF,
  50             M_INTWAIT | M_ZERO));
  51 }
  52
  53 void *
  54 cam_extend_set(struct extend_array *ea, int index, void *value)
  55 {
  56         if (index >= ea->nelem) {
  57                 void **space;
  58                 space = kmalloc(sizeof(void *) * (index + EXTEND_CHUNK),
  59                     M_DEVBUF, M_INTWAIT | M_ZERO);
  60
  61                 /* Make sure we have something to copy before we copy it */
  62                 if (ea->nelem) {
  63                         bcopy(ea->ps, space, sizeof(void *) * ea->nelem);
  64                         kfree(ea->ps, M_DEVBUF);
  65                 }
  66
  67                 ea->ps = space;
  68                 ea->nelem = index + EXTEND_CHUNK;
  69         }
  70         if (ea->ps[index]) {
  71                 kprintf("extend_set: entry %d already has storage.\n", index);
  72                 return 0;
  73         }
  74         else
  75                 ea->ps[index] = value;
  76
  77         return value;
  78 }
  79
  80 void *
  81 cam_extend_get(struct extend_array *ea,
  82                int index)
  83 {
  84         if (ea == NULL || index >= ea->nelem || index < 0)
  85                 return NULL;
  86         return ea->ps[index];
  87 }
  88
  89 void
  90 cam_extend_release(struct extend_array *ea, int index)
  91 {
  92         void *p = cam_extend_get(ea, index);
  93         if (p) {
  94                 ea->ps[index] = NULL;
  95         }
  96 }