cam_extend.c

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    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  * $FreeBSD$
   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  */
   21 /*
   22  * Extensible arrays: Use a realloc like implementation to permit
   23  * the arrays to be extend.
   24  */
   25 #include <sys/param.h>
   26 #include <sys/systm.h>
   27 #include <sys/kernel.h>
   28 #include <sys/malloc.h>
   29 
   30 #include <cam/cam_extend.h>
   31 
   32 struct extend_array
   33 {
   34         int nelem;
   35         void **ps;
   36 };
   37 
   38 static void *
   39 cam_extend_alloc(size_t s)
   40 {
   41         void *p = malloc(s, M_DEVBUF, M_NOWAIT);
   42         if (!p)
   43                 panic("extend_alloc: malloc failed.");
   44         return p;
   45 }
   46 
   47 static void
   48 cam_extend_free(void *p)
   49 {
   50         free(p, M_DEVBUF);
   51 }
   52 
   53 /* EXTEND_CHUNK: Number of extend slots to allocate whenever we need a new
   54  * one.
   55  */
   56 #ifndef EXTEND_CHUNK
   57         #define EXTEND_CHUNK 8
   58 #endif
   59 
   60 struct extend_array *
   61 cam_extend_new(void)
   62 {
   63         struct extend_array *p = cam_extend_alloc(sizeof(*p));
   64         if (p) {
   65                 p->nelem = 0;
   66                 p->ps = 0;
   67         }
   68 
   69         return p;
   70 }
   71 
   72 void *
   73 cam_extend_set(struct extend_array *ea, int index, void *value)
   74 {
   75         if (index >= ea->nelem) {
   76                 void **space;
   77                 space = cam_extend_alloc(sizeof(void *) * (index + EXTEND_CHUNK));
   78                 bzero(space, sizeof(void *) * (index + EXTEND_CHUNK));
   79 
   80                 /* Make sure we have something to copy before we copy it */
   81                 if (ea->nelem) {
   82                         bcopy(ea->ps, space, sizeof(void *) * ea->nelem);
   83                         cam_extend_free(ea->ps);
   84                 }
   85 
   86                 ea->ps = space;
   87                 ea->nelem = index + EXTEND_CHUNK;
   88         }
   89         if (ea->ps[index]) {
   90                 printf("extend_set: entry %d already has storage.\n", index);
   91                 return 0;
   92         }
   93         else
   94                 ea->ps[index] = value;
   95 
   96         return value;
   97 }
   98 
   99 void *
  100 cam_extend_get(struct extend_array *ea,
  101                int index)
  102 {
  103         if (ea == NULL || index >= ea->nelem || index < 0)
  104                 return NULL;
  105         return ea->ps[index];
  106 }
  107 
  108 void
  109 cam_extend_release(struct extend_array *ea, int index)
  110 {
  111         void *p = cam_extend_get(ea, index);
  112         if (p) {
  113                 ea->ps[index] = 0;
  114         }
  115 }

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FreeBSD/Linux Kernel Cross Reference sys/cam/cam_extend.c

FreeBSD/Linux Kernel Cross Reference
sys/cam/cam_extend.c