VocalEasel/Sources/VLPitchGrid.cpp

//
// File: VLPitchGrid.h - Translate between (MIDI) pitches and their vertical position
//
// Author(s):
//
//      (MN)    Matthias Neeracher
//
// Copyright © 2011 Matthias Neeracher
//

#include "VLPitchGrid.h"
#include "VLModel.h"

#define P(x) (1<<x)

static inline bool IsBasicNote(int semi) 
{
    //
    // Bitmap of basic notes, padded left and right by two positions
    //                              B     C     D     E     F     G     A     B     C 
    const uint16_t kBasicNotes = P( 1)|P( 2)|P( 4)|P( 6)|P( 7)|P( 9)|P(11)|P(13)|P(14);
    
    return kBasicNotes & (1<<(semi+2));
}

static inline bool HasFlat(int semi, int key)
{
    const uint16_t kFMajor  =     P(1) | P(13);         // Bb
    const uint16_t kBbMajor = kFMajor  | P(6);          // Eb
    const uint16_t kEbMajor = kBbMajor | P(11);         // Ab
    const uint16_t kAbMajor = kEbMajor | P(4);          // Db
    const uint16_t kDbMajor = kAbMajor | P(9);          // Gb
    const uint16_t kGbMajor = kDbMajor | P(2) | P(14);  // Cb
    
    static const uint16_t sFlats[] = 
        {kFMajor, kBbMajor, kEbMajor, kAbMajor, kDbMajor, kGbMajor};
    
    return sFlats[-1-key] & (1<<(semi+2));
}

static inline bool HasSharp(int semi, int key)
{
    const uint16_t kGMajor  =           P(7);           // F#
    const uint16_t kDMajor  = kGMajor | P(2) | P(14);   // C#
    const uint16_t kAMajor  = kDMajor | P(9);           // G#
    const uint16_t kEMajor  = kAMajor | P(4);           // D#
    const uint16_t kBMajor  = kEMajor | P(11);          // A#
    const uint16_t kFsMajor = kBMajor | P(6);           // E#
    
    static const uint16_t sSharps[] = 
        {kGMajor, kDMajor, kAMajor, kEMajor, kBMajor, kFsMajor};
    
    return sSharps[key-1] & (1<<(semi+2));
}

static inline int8_t SemiToStep(int semi)
{
    static const int8_t sSteps[] = 
    //   Bb  B C   D   E F   G   A   B C
        {-1,-1,0,0,1,1,2,3,3,4,4,5,5,6,7,7};

    return sSteps[semi+2];
}

static inline int8_t StepToSemi(int step)
{
    //                             C D E F G A B
    static const int8_t sSemi[] = {0,2,4,5,7,9,11};
    
    return sSemi[step];
}

int VLPitchToGrid(int8_t pitch, uint16_t & visual, int key)
{
    int semi    = pitch % 12;
    int octave  = (pitch/12)-5;
    
    if ((visual &= VLNote::kAccidentalsMask)) {
        //
        // The user expressed a preference, try to match it
        //
        switch (visual) {
        case VLNote::kWantNatural:
            if (!IsBasicNote(semi))
                break;
            visual = 0; // Don't draw naturals unless needed 
            goto computePosition;
        case VLNote::kWant2Flat:
            if (IsBasicNote(semi+2)) {
                semi    +=  2;
                goto computePosition;
            } 
            visual = VLNote::kWantFlat;
            goto flatIsPossible;
        case VLNote::kWantFlat:
            if (!IsBasicNote(semi+1)) 
                break;
        flatIsPossible:
            semi    +=  1;
			if (key < 0 && HasFlat(semi, key))
				visual = 0;
            goto computePosition;
        case VLNote::kWant2Sharp:
            if (IsBasicNote(semi-2)) {
                semi    -=  2;
                goto computePosition;
            } 
            visual = VLNote::kWantSharp;
            goto sharpIsPossible;
        case VLNote::kWantSharp:
            if (!IsBasicNote(semi-1)) 
                break;
        sharpIsPossible:
            semi    -=  1;
            if (key > 0 && HasSharp(semi, key))
                visual = 0;
            goto computePosition;
        }
    }
    //
    // No visuals, or no match
    //
    visual = 0;
    if (IsBasicNote(semi)) {
        if (key < 0 ? HasFlat(semi, key) : key > 0 && HasSharp(semi, key))
            visual  = VLNote::kWantNatural;
    } else if (key < 0) {
        semi       += 1;
        if (!HasFlat(semi, key))
            visual  = VLNote::kWantFlat;
    } else if (key > 0) {
        semi       -= 1;
        if (!HasSharp(semi, key))
            visual  = VLNote::kWantSharp;
    } else {
        semi       += 1;
        visual      = VLNote::kWantFlat;
    }
computePosition:
    return SemiToStep(semi)+7*octave;
}

int8_t  VLGridToPitch(int gridPos, uint16_t visual, int key)
{
    int octave = VLNote::kMiddleC;
    
    while (gridPos > 6) {
        octave  +=  12;
        gridPos -=   7;
    }
    while (gridPos < 0) {
        octave  -=  12;
        gridPos +=   7;
    }
    int semi        = StepToSemi(gridPos);
    int accidental;
    switch (visual) {
    case VLNote::kWantFlat:
        accidental  = -1;
        break;
    case VLNote::kWant2Flat:
        accidental  = -2;
        break;
    case VLNote::kWantSharp:
        accidental  = 1;
        break;
    case VLNote::kWant2Sharp:
        accidental  = 2;
        break;
    case VLNote::kWantNatural:
        accidental  = 0;
        break;
    default:
        if (key > 0 && HasSharp(semi, key))
            accidental = 1;
        else if (key < 0 && HasFlat(semi, key))
            accidental = -1;
        else
            accidental = 0;
        break;
    }
    return octave+semi+accidental;
}

VLVisualFilter::VLVisualFilter(int key)
{
    memset(&fKeyState[0], 0, 7*sizeof(fKeyState[0]));
    switch (key) { // Almost every state falls through
    case -6:
        fKeyState[0]   = VLNote::kWantFlat;
    case -5:
        fKeyState[5]   = VLNote::kWantFlat;
    case -4:
        fKeyState[1]   = VLNote::kWantFlat;
    case -3:
        fKeyState[4]   = VLNote::kWantFlat;
    case -2:
        fKeyState[2]   = VLNote::kWantFlat;
    case -1:
        fKeyState[6]   = VLNote::kWantFlat;
    case 0:
        break;
    case 6:
        fKeyState[2]   = VLNote::kWantSharp;
    case 5:
        fKeyState[5]   = VLNote::kWantSharp;
    case 4:
        fKeyState[1]   = VLNote::kWantSharp;
    case 3:
        fKeyState[4]   = VLNote::kWantSharp;
    case 2:
        fKeyState[0]   = VLNote::kWantSharp;
    case 1:
        fKeyState[3]   = VLNote::kWantSharp;
    default:
        break;
    }
    memcpy(fState, fKeyState, 7*sizeof(fKeyState[0]));
}

uint16_t VLVisualFilter::operator()(int gridPos, uint16_t visual)
{
    gridPos %= 12;
    if (!visual)
        visual = fKeyState[gridPos];
    if (visual != fState[gridPos])
        if (!fState[gridPos] && visual == VLNote::kWantNatural) {
            visual = 0;
        } else {
            if (!visual)
                visual = VLNote::kWantNatural;
            fState[gridPos] = visual==VLNote::kWantNatural ? 0 : visual;
        }
    else
        visual = 0;
    return visual;
}