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NAME    [Toc]    [Back]

     speaker, spkr -- console speaker device driver

SYNOPSIS    [Toc]    [Back]

     device speaker
     #include <machine/speaker.h>

DESCRIPTION    [Toc]    [Back]

     The speaker device driver allows applications to control the PC console
     speaker on an IBM-PC--compatible machine running FreeBSD.

     Only one process may have this device open at any given time; open(2) and
     close(2) 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(2) request 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(2) on a speaker file descriptor to control
     the speaker driver directly; definitions for the ioctl(2) interface are
     in <machine/speaker.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 ioctl(2) calls.  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 modeled on the PLAY statement conventions of
     IBM Advanced BASIC 2.0.  The MB, MF, and X primitives of PLAY are not
     useful in a timesharing environment and are omitted.  The `octave-tracking'
 feature and the slur mark are new.

     There are 84 accessible notes numbered 1-84 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 possible jump between notes.  Thus
		``olbc'' will be played as ``olb>c'', and ``olcb'' as
		``olc<b''.  Octave locking is disabled for one letter note
		following >, < and O[0123456].	(The octave-locking feature is
		not supported in IBM BASIC.)

     >		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,
		quarter or crotchet 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 n.  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
				      Adagio	      66-76
		      slow	      Adagietto
				      Andante	      76-108
		      medium	      Andantino
				      Moderato	      108-120
		      fast	      Allegretto
				      Allegro	      120-168
				      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 for 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 onehalf
 for each one.  Thus, a note dotted once is held for 3/2 of its
     undotted value; dotted twice, it is held 9/4, and three times would give

     A note and its sustain dots may also be followed by a slur mark (underscore).
  This causes the normal micro-rest after the note to be filled
     in, slurring it to the next one.  (The slur feature is not supported in
     IBM BASIC.)

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

BUGS    [Toc]    [Back]

     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.

     The action of two or more sustain dots does not reflect standard musical
     notation, in which each dot adds half the value of the previous dot modifier,
 not half the value of the note as modified.	Thus, a note dotted
     once is held for 3/2 of its undotted value; dotted twice, it is held 7/4,
     and three times would give 15/8.  The multiply-by-3/2 interpretation,
     however, is specified in the IBM BASIC manual and has been retained for

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

FILES    [Toc]    [Back]

     /dev/speaker    speaker device file

SEE ALSO    [Toc]    [Back]


AUTHORS    [Toc]    [Back]

     Eric S. Raymond <esr@snark.thyrsus.com> June 1990

PORTED BY    [Toc]    [Back]

     Andrew A. Chernov <ache@astral.msk.su>

HISTORY    [Toc]    [Back]

     The speaker device appeared in FreeBSD 1.0.

FreeBSD 5.2.1		       November 7, 1993 		 FreeBSD 5.2.1
[ Back ]
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