FreeBSD Manual Pages
SPKR(4) Kernel Interfaces Manual 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 an- other process has the device locked will return -1 with an EBUSY error in- dication. Writes to the device are interpreted as `play strings' in a sim- ple ASCII melody notation. An ioctl(2) request for tone generation at ar- bitrary 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 <dev/speaker/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 ac- cepts 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 use- ful 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 inter- preted 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 dis- abled 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, quar- ter 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 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 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 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. A note and its sustain dots may also be followed by a slur mark (under- score). 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 BA- SIC.) 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 precision), neither pitch accuracy nor timings will be mathematically exact. There is no volume con- trol. 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 modi- fier, 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 compatibil- ity. 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. FreeBSD ports 15.quarterly November 10, 2005 SPKR(4)
NAME | SYNOPSIS | DESCRIPTION | FILES | SEE ALSO | HISTORY | AUTHORS | PORTED BY | BUGS
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