spkr(4)

NAME

speaker, spkr - console speaker device driver

SYNOPSIS

device speaker
#include <dev/speaker/speaker.h>

DESCRIPTION

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 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 ac

cepts 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 struc

tures 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 option

ally 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-track

ing (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 ``ol

cb'' as
``olc<b''. Octave locking is disabled for one

letter note
following >, < and O[0123456]. (The octave-lock

ing 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 de

fault 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; de

fault 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 de

fault; 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
27/8.

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.

FILES

/dev/speaker speaker device file

SEE ALSO

spkrtest(8)

HISTORY

The speaker device appeared in FreeBSD 1.0.

AUTHORS

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

PORTED BY

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

BUGS

Due to roundoff in the pitch tables and slop in the tone

generation and
timer hardware (neither of which was designed for preci

sion), 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 pre

vious 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 inter

pretation,
however, is specified in the IBM BASIC manual and has been

retained for
compatibility.

In play strings which are very long (longer than your sys

tem's physical
I/O blocks) note suffixes or numbers may occasionally be

parsed incorrectly due to crossing a block boundary.

BSD November 10, 2005

BSD