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162 lines
4.5 KiB
162 lines
4.5 KiB
/** @file mmelody.h
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@author M. P. Hayes, UCECE
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@date 20 April 2007
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@brief Play simple melodies.
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*/
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/* By default notes are in the scale C4 -> C5.
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Note the first 12 frets on a six string guitar covers 3 octaves
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from the pitch E2 (82.41 Hz) to the pitch E5 (659.26 Hz).
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Tunes are specified using a sequence of characters representing
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notes, periods, and control operations.
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A note consists of the note name, followed by the octave number.
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For example, middle C is C4.
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A simple melody could be represented by C4C5F4G4C4 but for brevity
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this can be simplified to C4C5F4GC where the previously specified
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octave number persists.
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A problem with this notation is the verbosity when we have
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something like B2C3B2C3. Most melodies will only require 2 and 3
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at the most octaves. In contrast, the ABC music notation uses
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CDEFGABcdefgabc'd'e'f'g'a'b'c' to denote 3 octaves from C2 to C5.
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This uses numbers to indicate note duration, for example, C2
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denotes a C of twice the standard duration.
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By default notes are crotchets (quarter notes) and tempos are
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defined in beats per minute. If we assume 4/4 time, then each beat
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has a quarter-note duration.
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The note duration can be halved with a comma suffix, e.g., A,
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The note duration can be extended by a half with a dot suffix, e.g., A.
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The note duration can be doubled with a slash suffix, e.g., A/
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The note duration can be trebled with two slash suffixes, e.g., A//
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(this can be continued to lengthen the note).
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If there are lots of quavers (eighth notes), then the default note
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duration can be switched using *8. *4 returns to quarter note timing.
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Rests are specified with a space character. The timing modifiers ,
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. and / can be used.
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<ABC> is equivalent to ABCABC
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<ABC>3 is equivalent to ABCABCABC
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ABC: performs an infinite repeat of ABC
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<ABC]1DE]2FG> represents ABCDEABCFG where ]n denotes alternate
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endings.
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A+ sounds an octave higher
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A- sounds an octave lower
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@120 sets the tempo to 120 beats per minute
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This could be made a lot more flexible but the orginal
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implementation had a tight memory constraint. Possible extensions:
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* For emphasis perhaps use ^ to indicate louder, for example, C^.
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Similarly, to make a note quieter it could have a v suffix.
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* Use | for bar markers; these can be ignored.
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* Time signatures.
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* Nested loops, e.g., <AB<ABC>>
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* Sixteenth notes? Perhaps A,,
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* Perhaps lower case for eighth notes?
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* Triplets and other irrational tuplets? A triplet quarter note
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has 2 / 3 the duration of a quarter note while a triplet eighth note
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has 2 / 3 the duration of of an eighth note. This can be achieved
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using *6 or *12.
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*/
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#ifndef MMELODY_H
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#define MMELODY_H
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#include "system.h"
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typedef uint8_t mmelody_speed_t;
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typedef uint8_t mmelody_scale_t;
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typedef uint8_t mmelody_note_t;
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typedef uint8_t mmelody_volume_t;
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enum {MMELODY_OCTAVE_DEFAULT = 4};
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enum {MMELODY_SPEED_DEFAULT = 200};
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typedef struct
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{
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uint16_t ticks1;
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uint8_t ticks2;
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uint8_t unit_ticks;
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uint8_t release_ticks;
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/* Pointer to current position in string. */
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const char *cur;
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/* Pointer to start of string. */
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const char *start;
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const char *loop_start;
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int8_t loop_count;
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/* Fraction of a whole note, e.g., 4 for quarter note. */
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uint8_t symbol_fraction;
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/* Last note emitted. */
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uint8_t note;
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/* Tempo in beats per minute. */
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mmelody_speed_t speed;
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mmelody_volume_t volume;
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uint8_t octave;
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void (* play_callback) (void *data, uint8_t note, uint8_t volume);
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void *play_callback_data;
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uint16_t poll_rate;
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} mmelody_private_t;
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typedef mmelody_private_t mmelody_obj_t;
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typedef mmelody_obj_t *mmelody_t;
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typedef void (* mmelody_callback_t) (void *data, uint8_t note, uint8_t volume);
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mmelody_t
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mmelody_init (mmelody_obj_t *dev,
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uint16_t poll_rate,
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mmelody_callback_t play_callback,
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void *play_callback_data);
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/** Start playing a new melody. */
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void
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mmelody_play (mmelody_t mmelody, const char *str);
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/** Update melody sequencer. */
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void
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mmelody_update (mmelody_t mmelody);
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/** Set (base) speed in beats per minute (BPM). */
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void
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mmelody_speed_set (mmelody_t mmelody, mmelody_speed_t speed);
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/** Set volume as percentage of maximum. */
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void
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mmelody_volume_set (mmelody_t mmelody, mmelody_volume_t volume);
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/** Return non-zero if playing. */
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bool
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mmelody_active_p (mmelody_t mmelody);
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#endif
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