speaker(4) - NetBSD Manual Pages

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SPEAKER(4)              NetBSD Kernel Interfaces Manual             SPEAKER(4)


NAME

     speaker -- console speaker audio device driver


SYNOPSIS

     spkr0     at pcppi?
     #include <machine/spkr.h>
     /dev/speaker


DESCRIPTION

     The speaker device driver allows applications to control the console
     speaker on machines with a PC-like 8253 timer implementation.

     Only one process may have this device open at any given time; open() and
     close() are used to lock and relinquish it. An attempt to open() when
     another process has the device locked will return -1 with an EBUSY error
     indication. Writes to the device are interpreted as 'play strings' in a
     simple ASCII melody notation. An ioctl() for tone generation at arbitrary
     frequencies is also supported.

     Sound-generation does not monopolize the processor; in fact, the driver
     spends most of its time sleeping while the PC hardware is emitting tones.
     Other processes may emit beeps while the driver is running.

     Applications may call ioctl() on a speaker file descriptor to control the
     speaker driver directly; definitions for the ioctl() interface are in
     <machine/spkr.h>.  The tone_t structure used in these calls has two
     fields, specifying a frequency (in hz) and a duration (in 1/100ths of a
     second).  A frequency of zero is interpreted as a rest.

     At present there are two such ioctls. SPKRTONE accepts a pointer to a
     single tone structure as third argument and plays it. SPKRTUNE accepts a
     pointer to the first of an array of tone structures and plays them in
     continuous sequence; this array must be terminated by a final member with
     a zero duration.

     The play-string language is modelled on the PLAY statement conventions of
     IBM BASIC 2.0. The MB, MF and X primitives of PLAY are not useful in a
     UNIX environment and are omitted. The `octave-tracking' feature is also
     new.

     There are 84 accessible notes numbered 1-83 in 7 octaves, each running
     from C to B, numbered 0-6; the scale is equal-tempered A440 and octave 3
     starts with middle C. By default, the play function emits half-second
     notes with the last 1/16th second being `rest time'.

     Play strings are interpreted left to right as a series of play command
     groups; letter case is ignored. Play command groups are as follows:

     CDEFGAB -- letters A through G cause the corresponding note to be played
     in the current octave. A note letter may optionally be followed by an
     accidental sign, one of # + or -; the first two of these cause it to be
     sharped one half-tone, the last causes it to be flatted one half-tone. It
     may also be followed by a time value number and by sustain dots (see
     below). Time values are interpreted as for the L command below;.

     O <n> -- if <n> is numeric, this sets the current octave. <n> may also be
     one of 'L' or 'N' to enable or disable octave-tracking (it is disabled by
     default).  When octave-tracking is on, interpretation of a pair of letter
     notes will change octaves if necessary in order to make the smallest pos-
     sible jump between notes. Thus "olbc" will be played as "olb>c", and
     "olcb" as "olc<b". Octave locking is disabled for one letter note follow-
     ing by >, < and O[0123456].

     > -- bump the current octave up one.

     < -- drop the current octave down one.

     N <n> -- play note n, n being 1 to 84 or 0 for a rest of current time
     value.  May be followed by sustain dots.

     L <n> -- sets the current time value for notes. The default is L4, quar-
     ter notes. The lowest possible value is 1; values up to 64 are accepted.
     L1 sets whole notes, L2 sets half notes, L4 sets quarter notes, etc..

     P <n> -- pause (rest), with <n> interpreted as for L. May be followed by
     sustain dots. May also be written '~'.

     T <n> -- Sets the number of quarter notes per minute; default is 120.
     Musical names for common tempi are:

                          Tempo           Beats per Minute
           very slow      Larghissimo
                          Largo           40-60
                          Larghetto       60-66
                          Grave
                          Lento
                          Adagio          66-76
           slow           Adagietto
                          Andante         76-108
           medium         Andantino
                          Moderato        108-120
           fast           Allegretto
                          Allegro         120-168
                          Vivace
                          Veloce
                          Presto          168-208
           very fast      Prestissimo

     M[LNS] -- set articulation. MN (N for normal) is the default; the last
     1/8th of the note's value is rest time. You can set ML for legato (no
     rest space) or MS (staccato) 1/4 rest space.

     Notes (that is, CDEFGAB or N command character groups) may be followed by
     sustain dots. Each dot causes the note's value to be lengthened by one-
     half for each one. Thus, a note dotted once is held for 3/2 of its undot-
     ted value; dotted twice, it is held 9/4, and three times would give 27/8.

     Whitespace in play strings is simply skipped and may be used to separate
     melody sections.


FILES

     /dev/speaker


SEE ALSO

     pcppi(4)


AUTHORS

     Eric S. Raymond <esr@snark.thyrsus.com>


BUGS

     Due to roundoff in the pitch tables and slop in the tone-generation and
     timer hardware (neither of which was designed for precision), neither
     pitch accuracy nor timings will be mathematically exact.

     There is no volume control.

     In play strings which are very long (longer than your system's physical
     I/O blocks) note suffixes or numbers may occasionally be parsed incor-
     rectly due to crossing a block boundary.

NetBSD 5.1.2                    August 6, 1993                    NetBSD 5.1.2