git.cworth.org Git - scherzo/blob - pitch.h

   1 /* scherzo - Music notation training
   2  *
   3  *      pitch.h - Common structures and functions for pitches, etc.
   4  *
   5  * Copyright © 2010,2013 Carl Worth
   6  *
   7  * This program is free software: you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation, either version 3 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see http://www.gnu.org/licenses/ .
  19  */
  20
  21 #include <stdint.h>
  22
  23 #ifndef PITCH_H
  24 #define PITCH_H
  25
  26 typedef uint32_t pitch_t;
  27
  28 #define PITCH_ACCIDENTAL_SHIFT  (0)
  29 #define PITCH_ACCIDENTAL_MASK   (0x07 << PITCH_ACCIDENTAL_SHIFT)
  30
  31 #define PITCH_NAME_SHIFT        (3)
  32 #define PITCH_NAME_MASK         (0x07 << PITCH_NAME_SHIFT)
  33
  34 #define PITCH_OCTAVE_SHIFT      (6)
  35 #define PITCH_OCTAVE_MASK       (0x0F << PITCH_OCTAVE_SHIFT)
  36
  37 #define PITCH_ACCIDENTAL(pitch) \
  38     (((pitch) & PITCH_ACCIDENTAL_MASK) >> PITCH_ACCIDENTAL_SHIFT)
  39 #define PITCH_NAME(pitch)       \
  40     (((pitch) & PITCH_NAME_MASK) >> PITCH_NAME_SHIFT)
  41 #define PITCH_OCTAVE(pitch)     \
  42     (((pitch) & PITCH_OCTAVE_MASK) >> PITCH_OCTAVE_SHIFT)
  43
  44 #define PITCH(name, accidental, octave)           \
  45     (((octave) << PITCH_OCTAVE_SHIFT)           | \
  46      ((name) << PITCH_NAME_SHIFT)               | \
  47      ((accidental) << PITCH_ACCIDENTAL_SHIFT))
  48
  49 #define PITCH_LITERAL(literal_name, literal_accidental, octave) \
  50     PITCH(PITCH_NAME_##literal_name,                            \
  51           PITCH_ACCIDENTAL_##literal_accidental,                \
  52           octave)
  53
  54 #define PITCH_NATURAL(literal_name, octave) \
  55     PITCH_LITERAL(literal_name, NATURAL, octave)
  56
  57 /* PITCH_CLASS is useful for comparing pitches while ignoring any octave. */
  58 #define PITCH_CLASS(pitch) PITCH(PITCH_NAME(pitch), PITCH_ACCIDENTAL(pitch), 0)
  59
  60 #define PITCH_CLASS_LITERAL(literal_name, literal_accidental) \
  61     PITCH_LITERAL(literal_name, literal_accidental, 0)
  62
  63 #define PITCH_NOT_A_PITCH ((pitch_t) -1)
  64
  65 typedef enum pitch_accidental
  66 {
  67     PITCH_ACCIDENTAL_DOUBLE_FLAT,
  68     PITCH_ACCIDENTAL_FLAT,
  69     PITCH_ACCIDENTAL_NATURAL,
  70     PITCH_ACCIDENTAL_SHARP,
  71     PITCH_ACCIDENTAL_DOUBLE_SHARP
  72 } pitch_accidental_t;
  73
  74 typedef enum pitch_name
  75 {
  76     PITCH_NAME_C,
  77     PITCH_NAME_D,
  78     PITCH_NAME_E,
  79     PITCH_NAME_F,
  80     PITCH_NAME_G,
  81     PITCH_NAME_A,
  82     PITCH_NAME_B,
  83 } pitch_name_t;
  84
  85 /* Octave numbers are ISO octave numbers [0:8], (so Octave 4 is from
  86  * middle C to the B above middle C).
  87  */
  88
  89 /* Get a string representation of a pitch_t value.
  90  *
  91  * Note: The returned value is static to the pithc_string function and
  92  * may be modified by future calls to pitch_string. So the caller
  93  * should copy the value if needed. */
  94 const char *
  95 pitch_string (pitch_t pitch);
  96
  97 /* Return a new pitch, a number of octaves above 'pitch'
  98  *
  99  * Note: Maximum octave value is 8. A pitch with octave 8 will not be
 100  * raised.
 101  */
 102 pitch_t
 103 pitch_raise_by_octaves (pitch_t pitch, int octaves);
 104
 105 /* Return a new pitch, a number of octaves below 'pitch'
 106  *
 107  * Note: Minimum octave value is 9. A pitch with octave 8 will not be
 108  * lowered.
 109  */
 110 pitch_t
 111 pitch_lower_by_octaves (pitch_t pitch, int octaves);
 112
 113 /* Number of half steps from 'root' up to 'pitch' (that is, counting
 114  * the steps up a chromatic scale), within the same octave. */
 115 int
 116 pitch_from_root_in_half_steps (pitch_t pitch, pitch_t root);
 117
 118 /* Respell 'pitch' to have a name that matches the (diatonic) scale
 119  * 'degree' from 'root'.
 120  *
 121  * If the pitch is too distant from the specified degree to be
 122  * respelled, the original pitch will be returned unmodified.
 123  */
 124 pitch_t
 125 pitch_spell_as_degree (pitch_t pitch, pitch_t root, int degree);
 126
 127 /* Return a MIDI note value corresponding to 'pitch' */
 128 unsigned char
 129 pitch_to_midi (pitch_t pitch);
 130
 131 /* Return the pitch_t value corresponding to the given MIDI note value. */
 132 pitch_t
 133 pitch_from_midi (unsigned char midi_note);
 134
 135 /* Return true if 'a' and 'b' sound identical, (even if spelled differently)
 136  *
 137  * This comparison considers octaves as significant. So Bb and A# in
 138  * the same octave are considered enharmonic, but Bb and A# in
 139  * different octaves are not. */
 140 int
 141 pitch_enharmonic_to (pitch_t a, pitch_t b);
 142
 143 #endif /* PITCH_H */