The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/dev/sound/unit.c

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    1 /*-
    2  * Copyright (c) 2007 Ariff Abdullah <ariff@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  *
   26  * $FreeBSD$
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/systm.h>
   31 
   32 #include <dev/sound/unit.h>
   33 
   34 /*
   35  * Unit magic allocator for sound driver.
   36  *
   37  * 'u' = Unit of attached soundcards
   38  * 'd' = Device type
   39  * 'c' = Channel number
   40  *
   41  * eg: dsp0.p1  - u=0, d=p, c=1
   42  *     dsp1.vp0 - u=1, d=vp, c=0
   43  *     dsp0.10  - u=0, d=clone, c=allocated clone (see further explanation)
   44  *
   45  * Maximum unit of soundcards can be tuned through "hw.snd.maxunit", which
   46  * is between SND_UNIT_UMIN (16) and SND_UNIT_UMAX (2048). By design,
   47  * maximum allowable allocated channel is 256, with exception for clone
   48  * devices which doesn't have any notion of channel numbering. The use of
   49  * channel numbering in a clone device is simply to provide uniqueness among
   50  * allocated clones. This also means that the maximum allowable clonable
   51  * device is largely dependant and dynamically tuned depending on
   52  * hw.snd.maxunit.
   53  */
   54 
   55 /* Default width */
   56 static int snd_u_shift = 9;     /* 0 - 0x1ff :  512 distinct soundcards   */
   57 static int snd_d_shift = 5;     /* 0 - 0x1f  :   32 distinct device types */
   58 static int snd_c_shift = 10;    /* 0 - 0x3ff : 1024 distinct channels
   59                                                (256 limit "by design",
   60                                                except for clone devices)  */
   61 
   62 static int snd_unit_initialized = 0;
   63 
   64 #ifdef SND_DIAGNOSTIC
   65 #define SND_UNIT_ASSERT()       do {                                    \
   66         if (snd_unit_initialized == 0)                                  \
   67                 panic("%s(): Uninitialized sound unit!", __func__);     \
   68 } while(0)
   69 #else
   70 #define SND_UNIT_ASSERT()       KASSERT(snd_unit_initialized != 0,      \
   71                                 ("%s(): Uninitialized sound unit!",     \
   72                                 __func__))
   73 #endif
   74 
   75 #define MKMASK(x)       ((1 << snd_##x##_shift) - 1)
   76 
   77 int
   78 snd_max_u(void)
   79 {
   80         SND_UNIT_ASSERT();
   81 
   82         return (MKMASK(u));
   83 }
   84 
   85 int
   86 snd_max_d(void)
   87 {
   88         SND_UNIT_ASSERT();
   89 
   90         return (MKMASK(d));
   91 }
   92 
   93 int
   94 snd_max_c(void)
   95 {
   96         SND_UNIT_ASSERT();
   97 
   98         return (MKMASK(c));
   99 }
  100 
  101 int
  102 snd_unit2u(int unit)
  103 {
  104         SND_UNIT_ASSERT();
  105 
  106         return ((unit >> (snd_c_shift + snd_d_shift)) & MKMASK(u));
  107 }
  108 
  109 int
  110 snd_unit2d(int unit)
  111 {
  112         SND_UNIT_ASSERT();
  113 
  114         return ((unit >> snd_c_shift) & MKMASK(d));
  115 }
  116 
  117 int
  118 snd_unit2c(int unit)
  119 {
  120         SND_UNIT_ASSERT();
  121 
  122         return (unit & MKMASK(c));
  123 }
  124 
  125 int
  126 snd_u2unit(int u)
  127 {
  128         SND_UNIT_ASSERT();
  129 
  130         return ((u & MKMASK(u)) << (snd_c_shift + snd_d_shift));
  131 }
  132 
  133 int
  134 snd_d2unit(int d)
  135 {
  136         SND_UNIT_ASSERT();
  137 
  138         return ((d & MKMASK(d)) << snd_c_shift);
  139 }
  140 
  141 int
  142 snd_c2unit(int c)
  143 {
  144         SND_UNIT_ASSERT();
  145 
  146         return (c & MKMASK(c));
  147 }
  148 
  149 int
  150 snd_mkunit(int u, int d, int c)
  151 {
  152         SND_UNIT_ASSERT();
  153 
  154         return ((c & MKMASK(c)) | ((d & MKMASK(d)) << snd_c_shift) |
  155             ((u & MKMASK(u)) << (snd_c_shift + snd_d_shift)));
  156 }
  157 
  158 /*
  159  * This *must* be called first before any of the functions above!!!
  160  */
  161 void
  162 snd_unit_init(void)
  163 {
  164         int i;
  165 
  166         if (snd_unit_initialized != 0)
  167                 return;
  168 
  169         snd_unit_initialized = 1;
  170 
  171         if (getenv_int("hw.snd.maxunit", &i) != 0) {
  172                 if (i < SND_UNIT_UMIN)
  173                         i = SND_UNIT_UMIN;
  174                 else if (i > SND_UNIT_UMAX)
  175                         i = SND_UNIT_UMAX;
  176                 else
  177                         i = roundup2(i, 2);
  178 
  179                 for (snd_u_shift = 0; (i >> (snd_u_shift + 1)) != 0;
  180                     snd_u_shift++)
  181                         ;
  182 
  183                 /*
  184                  * Make room for channels/clones allocation unit
  185                  * to fit within 24bit MAXMINOR limit.
  186                  */
  187                 snd_c_shift = 24 - snd_u_shift - snd_d_shift;
  188         }
  189 
  190         if (bootverbose != 0)
  191                 printf("%s() u=0x%08x [%d] d=0x%08x [%d] c=0x%08x [%d]\n",
  192                     __func__, SND_U_MASK, snd_max_u() + 1,
  193                     SND_D_MASK, snd_max_d() + 1, SND_C_MASK, snd_max_c() + 1);
  194 }

Cache object: efd0b3c2239511a05e75dc309ebe22cc


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