apple2ix/src/video/gltouchjoy_kpad.c

/*
 * Apple // emulator for *ix
 *
 * This software package is subject to the GNU General Public License
 * version 3 or later (your choice) as published by the Free Software
 * Foundation.
 *
 * Copyright 2013-2015 Aaron Culliney
 *
 */

#include "video/gltouchjoy.h"

#if !INTERFACE_TOUCH
#error this is a touch interface module, possibly you mean to not compile this at all?
#endif

#define KEY_REPEAT_THRESHOLD_NANOS (NANOSECONDS_PER_SECOND / 4)
#define CALLBACK_LOCK_VALUE (1000)

// WARNING : this does not match the rosette left-right-down layout, but what is returned by atan2f()
typedef enum keypad_octant_t {
    OCTANT_WEST = 0,
    OCTANT_NORTHWEST,
    OCTANT_NORTH,
    OCTANT_NORTHEAST,
    OCTANT_EAST,
    OCTANT_SOUTHEAST,
    OCTANT_SOUTH,
    OCTANT_SOUTHWEST,
    ORIGIN,
} keypad_octant_t;

// Assuming radian value between -PI <-> PI
#define RADIANS_NORTHWEST ((-3.f * M_PI) / 4.f)
#define RADIANS_NORTH     ((-1.f * M_PI) / 2.f)
#define RADIANS_NORTHEAST ((-1.f * M_PI) / 4.f)
#define RADIANS_WEST_NEG  (-M_PI)
#define RADIANS_EAST      (0.f)
#define RADIANS_SOUTHWEST (( 3.f * M_PI) / 4.f)
#define RADIANS_SOUTH     (( 1.f * M_PI) / 2.f)
#define RADIANS_SOUTHEAST (( 1.f * M_PI) / 4.f)

typedef enum keypad_fire_t {
    REPEAT_AXIS = 0,
    REPEAT_AXIS_ALT,
    REPEAT_BUTTON,
    MAX_REPEATING,
} keypad_fire_t;

static struct {
    keypad_octant_t axisCurrentOctant;

    uint8_t currButtonDisplayChar;
    void (*buttonDrawCallback)(char newChar);

    // index of repeating scancodes to fire
    keypad_fire_t fireIdx;

    volatile int axisLock; // modified by both CPU thread and touch handling thread
    volatile int buttonLock; // modified by both CPU thread and touch handling thread

    int scancodes[MAX_REPEATING];
    struct timespec timingBegins[MAX_REPEATING];
    bool buttonBegan;
    bool axisBegan;
    int lastScancode;

    float repeatThresholdNanos;

    // axis rosette
    uint8_t  rosetteChars[ROSETTE_ROWS * ROSETTE_COLS];
    long rosetteScancodes[ROSETTE_ROWS * ROSETTE_COLS];

    // touch/swipe buttons
    touchjoy_button_type_t touchDownChar;
    int                    touchDownScancode;
    touchjoy_button_type_t northChar;
    int                    northScancode;
    touchjoy_button_type_t southChar;
    int                    southScancode;

} kpad = { 0 };

static GLTouchJoyVariant kpadJoy = { 0 };

// ----------------------------------------------------------------------------
// repeat key callback scheduling and unscheduling
//
// Assumptions :
//  - All touch sources run on a single thread
//  - callback itself runs on CPU thread

// unlock callback section
static inline void _callback_sourceUnlock(volatile int *source) {
    int val = __sync_add_and_fetch(source, (int)(CALLBACK_LOCK_VALUE));
    assert(val >= 0 && "inconsistent lock state for callback detected");
    (void)val;
}

// attempt to lock the critical section where we unschedule the function pointer callback
// there should be no outstanding touch sources being tracked
static inline bool _callback_sourceTryLock(volatile int *source) {
    int val = __sync_sub_and_fetch(source, (int)(CALLBACK_LOCK_VALUE));
    if (val == -CALLBACK_LOCK_VALUE) {
        return true;
    } else {
        _callback_sourceUnlock(source);
        return false;
    }
}

// touch source has ended
static inline void _touch_sourceEnd(volatile int *source) {
    __sync_sub_and_fetch(source, 1);
}

// touch source has begun
static inline void _touch_sourceBegin(volatile int *source) {
    do {
        int val = __sync_add_and_fetch(source, 1);
        if (val >= 0) {
            assert(val > 0 && "inconsistent lock state for touch source detected");
            return;
        }
        // spin waiting on callback critical
        _touch_sourceEnd(source);
    } while (1);
}

static void touchkpad_keyboardReadCallback(void) {
    ASSERT_ON_CPU_THREAD();

    // HACK FIXME TODO :
    //
    // There are a number of cases where the emulated software is reading the keyboard state but not using the value.
    // This is quite noticeable in a number of games that take keyboard input.
    //
    // This indicates that we are incorrectly emulating the keyboard hardware.  The proper fix for this touch keypad
    // joystick will be to properly emulate the original hardware timing, using the existing facility to count 65c02 CPU
    // machine cyles.
#warning FIXME TODO : implement proper keyboard repeat callback timing

    if (kpad.lastScancode >= 0) {
        c_keys_handle_input(kpad.lastScancode, /*pressed:*/false, /*ASCII:*/false);
        kpad.lastScancode = -1;
    }

    struct timespec now = { 0 };
    clock_gettime(CLOCK_MONOTONIC, &now);

    int fired = -1;
    for (unsigned int i=0; i<MAX_REPEATING; i++) {
        int scancode = kpad.scancodes[kpad.fireIdx];
        if (scancode >= 0) {
            struct timespec deltat = timespec_diff(kpad.timingBegins[kpad.fireIdx], now, NULL);
            if (deltat.tv_sec || deltat.tv_nsec > kpad.repeatThresholdNanos) {
                TOUCH_JOY_LOG("ACTIVE(%d,%d) REPEAT #%d/%lu/%lu: %d", kpad.axisLock, kpad.buttonLock, kpad.fireIdx, deltat.tv_sec, deltat.tv_nsec, scancode);
                c_keys_handle_input(scancode, /*pressed:*/true, /*ASCII:*/false);
                kpad.lastScancode = scancode;
                fired = kpad.fireIdx;
            }
        }
        ++kpad.fireIdx;
        if (kpad.fireIdx >= MAX_REPEATING) {
            kpad.fireIdx = 0;
        }
        if (fired >= 0) {
            break;
        }
    }

    bool lockedAxis = _callback_sourceTryLock(&kpad.axisLock);
    if (lockedAxis) {
        if (fired == REPEAT_AXIS || fired == REPEAT_AXIS_ALT) {
            TOUCH_JOY_LOG("RESETTING AXIS INDEX %d ...", fired);
            kpad.scancodes[fired] = -1;
        }
    }

    bool lockedButton = _callback_sourceTryLock(&kpad.buttonLock);
    if (lockedButton) {
        if (fired == REPEAT_BUTTON) {
            TOUCH_JOY_LOG("RESETTING BUTTON INDEX %d ...", fired);
            kpad.scancodes[fired] = -1;
        }
    }

    if (lockedButton && lockedAxis && fired < 0) {
        TOUCH_JOY_LOG("REPEAT KEY CALLBACK DONE ...");
        keydriver_keyboardReadCallback = NULL;
    }

    if (lockedAxis) {
        _callback_sourceUnlock(&kpad.axisLock);
    }
    if (lockedButton) {
        _callback_sourceUnlock(&kpad.buttonLock);
    }
}

// ----------------------------------------------------------------------------

static interface_device_t touchkpad_variant(void) {
    return TOUCH_DEVICE_JOYSTICK_KEYPAD;
}

static void touchkpad_resetState(void) {
    TOUCH_JOY_LOG("...");
    kpad.axisLock = 0;
    kpad.buttonLock = 0;
    keydriver_keyboardReadCallback = NULL;

    kpad.axisCurrentOctant = ORIGIN;
    kpad.lastScancode = -1;

    for (unsigned int i=0; i<MAX_REPEATING; i++) {
        kpad.scancodes[i] = -1;
        kpad.timingBegins[i] = (struct timespec){ 0 };
    }

    kpad.currButtonDisplayChar = ' ';
    kpad.axisBegan = false;
    kpad.buttonBegan = false;

    for (unsigned int i=0; i<ROSETTE_COLS; i++) {
        for (unsigned int j=0; j<ROSETTE_ROWS; j++) {
            c_keys_handle_input(kpad.rosetteScancodes[i], /*pressed:*/false, /*ASCII:*/false);
        }
    }

    c_keys_handle_input(kpad.touchDownScancode, /*pressed:*/false, /*ASCII:*/false);
    c_keys_handle_input(kpad.northScancode,     /*pressed:*/false, /*ASCII:*/false);
    c_keys_handle_input(kpad.southScancode,     /*pressed:*/false, /*ASCII:*/false);
}

static void touchkpad_setup(void (*buttonDrawCallback)(char newChar)) {
    kpad.buttonDrawCallback = buttonDrawCallback;
}

static void touchkpad_shutdown(void) {
    // ...
}

// ----------------------------------------------------------------------------
// axis key(s) state

static void touchkpad_axisDown(void) {
    TOUCH_JOY_LOG("...");
    if (!kpad.axisBegan) {
        // avoid multiple locks on extra axisDown()
        kpad.axisBegan = true;
        _touch_sourceBegin(&kpad.axisLock);
    }

    keydriver_keyboardReadCallback = &touchkpad_keyboardReadCallback;
    struct timespec now = { 0 };
    clock_gettime(CLOCK_MONOTONIC, &now);
    kpad.timingBegins[REPEAT_AXIS] = now;
    kpad.timingBegins[REPEAT_AXIS_ALT] = now;

    kpad.axisCurrentOctant = ORIGIN;
    if (kpad.rosetteScancodes[ROSETTE_CENTER] >= 0) {
        kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_CENTER];
        kpad.scancodes[REPEAT_AXIS_ALT] = -1;
    }
}

static void touchkpad_axisMove(int dx, int dy) {
    TOUCH_JOY_LOG("...");

    if ((dx > -joyglobals.switchThreshold) && (dx < joyglobals.switchThreshold) && (dy > -joyglobals.switchThreshold) && (dy < joyglobals.switchThreshold)) {
        kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_CENTER];
        kpad.scancodes[REPEAT_AXIS_ALT] = -1;
        return;
    }

    if (dx == 0 && dy == 0) {
        return;
    }

    do {

        // determine the octant of this dx/dy

        keypad_octant_t axisLastOctant = kpad.axisCurrentOctant;

        const float radians = atan2f(dy, dx);   // -180-180deg range
        float radnorm = radians + M_PI;         // 0-360deg range
        if (UNLIKELY(radnorm < 0.f)) {
            radnorm = 0.f;                      // clamp positive
        }
        float octant = radnorm + (M_PI/8.f);    // rotate to correct octant (+45deg)
        octant /= (M_PI/4.f);                   // divide to octant (/90deg)
        kpad.axisCurrentOctant = (keypad_octant_t) ((int)octant & 0x7);// integer modulo maps to enum

        if (kpad.axisCurrentOctant == axisLastOctant) {
            break;
        }

        TOUCH_JOY_LOG("radians:%f radnorm:%f octant:%f, currOctant:%d", radians, radnorm, octant, kpad.axisCurrentOctant);

        // Current implementation NOTE : four cardinal directions are handled slightly different than the intercardinal
        // ones.
        //  - The intercardinals might generate 2 scanscodes (for example north and west scancodes for a northwest axis)
        //    if there is not a specific scancode to handle it (e.g., the northwest scancode).
        //  - The cardinals will only ever generate one scancode (the cardinal in question if it's set, or the scancode
        //    of the adjacent intercardinal where the point lies).
        kpad.scancodes[REPEAT_AXIS_ALT] = -1;
        switch (kpad.axisCurrentOctant) {
            case OCTANT_NORTHWEST:
                if (kpad.rosetteScancodes[ROSETTE_NORTHWEST] >= 0) {
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHWEST];
                    TOUCH_JOY_LOG("XY : NORTHWEST, (%d)", kpad.rosetteScancodes[ROSETTE_WEST]);
                } else {
                    TOUCH_JOY_LOG("XY : WEST (%d) & NORTH (%d)", kpad.rosetteScancodes[ROSETTE_WEST], kpad.rosetteScancodes[ROSETTE_NORTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_WEST];
                    kpad.scancodes[REPEAT_AXIS_ALT] = kpad.rosetteScancodes[ROSETTE_NORTH];
                }
                break;

            case OCTANT_NORTH:
                if (kpad.rosetteScancodes[ROSETTE_NORTH] >= 0) {
                    TOUCH_JOY_LOG("Y : NORTH (%d)", kpad.rosetteScancodes[ROSETTE_NORTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTH];
                } else if (radians < RADIANS_NORTH) {
                    TOUCH_JOY_LOG("XY : NORTHWEST (%d)", kpad.rosetteScancodes[ROSETTE_NORTHWEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHWEST];
                } else {
                    TOUCH_JOY_LOG("XY : NORTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_NORTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHEAST];
                }
                break;

            case OCTANT_NORTHEAST:
                if (kpad.rosetteScancodes[ROSETTE_NORTHEAST] >= 0) {
                    TOUCH_JOY_LOG("XY : NORTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_NORTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHEAST];
                } else {
                    TOUCH_JOY_LOG("XY : EAST (%d) & NORTH (%d)", kpad.rosetteScancodes[ROSETTE_EAST], kpad.rosetteScancodes[ROSETTE_NORTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_EAST];
                    kpad.scancodes[REPEAT_AXIS_ALT] = kpad.rosetteScancodes[ROSETTE_NORTH];
                }
                break;

            case OCTANT_WEST:
                if (kpad.rosetteScancodes[ROSETTE_WEST] >= 0) {
                    TOUCH_JOY_LOG("Y : WEST (%d)", kpad.rosetteScancodes[ROSETTE_WEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_WEST];
                } else if (radians > RADIANS_WEST_NEG && radians < 0) {
                    TOUCH_JOY_LOG("XY : NORTHWEST (%d)", kpad.rosetteScancodes[ROSETTE_NORTHWEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHWEST];
                } else {
                    TOUCH_JOY_LOG("XY : SOUTHWEST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHWEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHWEST];
                }
                break;

            case OCTANT_EAST:
                if (kpad.rosetteScancodes[ROSETTE_EAST] >= 0) {
                    TOUCH_JOY_LOG("Y : EAST (%d)", kpad.rosetteScancodes[ROSETTE_EAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_EAST];
                } else if (radians < RADIANS_EAST) {
                    TOUCH_JOY_LOG("XY : NORTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_NORTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_NORTHEAST];
                } else {
                    TOUCH_JOY_LOG("XY : SOUTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHEAST];
                }
                break;

            case OCTANT_SOUTHWEST:
                if (kpad.rosetteScancodes[ROSETTE_SOUTHWEST] >= 0) {
                    TOUCH_JOY_LOG("XY : SOUTHWEST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHWEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHWEST];
                } else {
                    TOUCH_JOY_LOG("XY : WEST (%d) & SOUTH (%d)", kpad.rosetteScancodes[ROSETTE_WEST], kpad.rosetteScancodes[ROSETTE_SOUTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_WEST];
                    kpad.scancodes[REPEAT_AXIS_ALT] = kpad.rosetteScancodes[ROSETTE_SOUTH];
                }
                break;

            case OCTANT_SOUTH:
                if (kpad.rosetteScancodes[ROSETTE_SOUTH] >= 0) {
                    TOUCH_JOY_LOG("Y : SOUTH (%d)", kpad.rosetteScancodes[ROSETTE_SOUTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTH];
                } else if (radians > RADIANS_SOUTH) {
                    TOUCH_JOY_LOG("XY : SOUTHWEST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHWEST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHWEST];
                } else {
                    TOUCH_JOY_LOG("XY : SOUTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHEAST];
                }
                break;

            case OCTANT_SOUTHEAST:
                if (kpad.rosetteScancodes[ROSETTE_SOUTHEAST] >= 0) {
                    TOUCH_JOY_LOG("XY : SOUTHEAST (%d)", kpad.rosetteScancodes[ROSETTE_SOUTHEAST]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_SOUTHEAST];
                } else {
                    TOUCH_JOY_LOG("XY : EAST (%d) & SOUTH (%d)", kpad.rosetteScancodes[ROSETTE_EAST], kpad.rosetteScancodes[ROSETTE_SOUTH]);
                    kpad.scancodes[REPEAT_AXIS] = kpad.rosetteScancodes[ROSETTE_EAST];
                    kpad.scancodes[REPEAT_AXIS_ALT] = kpad.rosetteScancodes[ROSETTE_SOUTH];
                }
                break;

            default:
                assert(false && "should not happen");
                break;
        }

    } while (0);
}

static void touchkpad_axisUp(int dx, int dy) {
    TOUCH_JOY_LOG("...");
    touchkpad_axisMove(dx, dy);
    kpad.axisCurrentOctant = ORIGIN;
    kpad.timingBegins[REPEAT_AXIS] = (struct timespec){ 0 };
    kpad.timingBegins[REPEAT_AXIS_ALT] = (struct timespec){ 0 };
    if (kpad.axisBegan) {
        kpad.axisBegan = false;
        _touch_sourceEnd(&kpad.axisLock);
    }
}

// ----------------------------------------------------------------------------
// button key state

static void _set_current_button_state(touchjoy_button_type_t theButtonChar, int theButtonScancode) {
    TOUCH_JOY_LOG("...");
    if (theButtonChar >= 0) {
        kpad.currButtonDisplayChar = theButtonChar;
        kpad.scancodes[REPEAT_BUTTON] = theButtonScancode;
    } else {
        kpad.currButtonDisplayChar = ' ';
        kpad.scancodes[REPEAT_BUTTON] = -1;
    }
    kpad.buttonDrawCallback(kpad.currButtonDisplayChar);
}

static void touchkpad_buttonDown(void) {
    if (!kpad.buttonBegan) {
        kpad.buttonBegan = true;
        _touch_sourceBegin(&kpad.buttonLock);
    }
    _set_current_button_state(kpad.touchDownChar, kpad.touchDownScancode);
    if (kpad.scancodes[REPEAT_BUTTON] >= 0) {
        TOUCH_JOY_LOG("->BUTT : %d/'%c'", kpad.scancodes[REPEAT_BUTTON], kpad.currButtonDisplayChar);
        clock_gettime(CLOCK_MONOTONIC, &kpad.timingBegins[REPEAT_BUTTON]);
        keydriver_keyboardReadCallback = &touchkpad_keyboardReadCallback;
    }
}

static void touchkpad_buttonMove(int dx, int dy) {
    // Currently this is the same logic as the "regular" joystick variant ... but we could likely be more creative here
    // in a future revision, like having a full octant of key possibilities ... (for example, playing Bolo with a friend
    // on the same tablet, one driving, the other shooting and controlling the turret)
    if ((dy < -joyglobals.switchThreshold) || (dy > joyglobals.switchThreshold)) {
        touchjoy_button_type_t theButtonChar = -1;
        int theButtonScancode = -1;
        if (dy < 0) {
            theButtonChar = kpad.northChar;
            theButtonScancode = kpad.northScancode;
        } else {
            theButtonChar = kpad.southChar;
            theButtonScancode = kpad.southScancode;
        }
        _set_current_button_state(theButtonChar, theButtonScancode);
    }
}

static void touchkpad_buttonUp(int dx, int dy) {
    TOUCH_JOY_LOG("...");
    touchkpad_buttonMove(dx, dy);
    kpad.timingBegins[REPEAT_BUTTON] = (struct timespec){ 0 };
    if (kpad.buttonBegan) {
        kpad.buttonBegan = false;
        _touch_sourceEnd(&kpad.buttonLock);
    }
}

static void touchkpad_prefsChanged(const char *domain) {
    assert(video_isRenderThread());

    float fVal = 0.f;
    long lVal = 0;

    kpad.repeatThresholdNanos = prefs_parseFloatValue(domain, PREF_KPAD_REPEAT_THRESH,    &fVal)              ? fVal*NANOSECONDS_PER_SECOND : NANOSECONDS_PER_SECOND;

    kpad.touchDownChar        = prefs_parseLongValue (domain, PREF_KPAD_TOUCHDOWN_CHAR,   &lVal, /*base:*/10) ? lVal : ICONTEXT_SPACE_VISUAL;
    kpad.touchDownScancode    = prefs_parseLongValue (domain, PREF_KPAD_TOUCHDOWN_SCAN,   &lVal, /*base:*/10) ? lVal : c_keys_ascii_to_scancode(' ');

    kpad.southChar            = prefs_parseLongValue (domain, PREF_KPAD_SWIPE_SOUTH_CHAR, &lVal, /*base:*/10) ? lVal : ICONTEXT_NONACTIONABLE;
    kpad.southScancode        = prefs_parseLongValue (domain, PREF_KPAD_SWIPE_SOUTH_SCAN, &lVal, /*base:*/10) ? lVal : -1;

    kpad.northChar            = prefs_parseLongValue (domain, PREF_KPAD_SWIPE_NORTH_CHAR, &lVal, /*base:*/10) ? lVal : ICONTEXT_NONACTIONABLE;
    kpad.northScancode        = prefs_parseLongValue (domain, PREF_KPAD_SWIPE_NORTH_SCAN, &lVal, /*base:*/10) ? lVal : -1;

    const unsigned long rosetteCount = ROSETTE_ROWS*ROSETTE_COLS;

    do {
        const int rosetteChars[ROSETTE_ROWS*ROSETTE_COLS] = {
            ICONTEXT_NONACTIONABLE, 'I', ICONTEXT_NONACTIONABLE,
            'J', ICONTEXT_NONACTIONABLE, 'K',
            ICONTEXT_NONACTIONABLE, 'M', ICONTEXT_NONACTIONABLE,
        };
        const int rosetteScans[ROSETTE_ROWS*ROSETTE_COLS] = {
            -1, c_keys_ascii_to_scancode('I'), -1,
            c_keys_ascii_to_scancode('J'), -1, c_keys_ascii_to_scancode('K'),
            -1, c_keys_ascii_to_scancode('M'), -1,
        };
        for (unsigned long i=0; i<rosetteCount; i++) {
            kpad.rosetteChars[i] = rosetteChars[i];
            kpad.rosetteScancodes[i] = rosetteScans[i];
        }
    } while (0);

    // ASCII : "rosetteChars" : [ 121, 127, 130,  100, 101, 121,  132, 120, 99 ]
    JSON_ref array = NULL;
    do {
        if (!prefs_copyJSONValue(domain, PREF_KPAD_ROSETTE_CHAR_ARRAY, &array)) {
            LOG("could not parse touch keypad rosette");
            break;
        }
        long count = 0;
        if (!json_arrayCount(array, &count)) {
            LOG("rosette is not an array!");
            break;
        }
        if (count != rosetteCount) {
            LOG("rosette count unexpected : %lu!", rosetteCount);
            break;
        }
        for (unsigned long i=0; i<rosetteCount; i++) {
            kpad.rosetteChars[i] = json_arrayParseLongValueAtIndex(array, i, &lVal, /*base:*/10) ? (uint8_t)lVal : ' ';
        }
    } while (0);

    json_destroy(&array);

    // long : "rosetteScancodes" : [ -1, 100, -1,  99, -1, 96,  -1, 101, -1 ]
    do {
        if (!prefs_copyJSONValue(domain, PREF_KPAD_ROSETTE_SCAN_ARRAY, &array)) {
            LOG("could not parse touch keypad rosette");
            break;
        }
        long count = 0;
        if (!json_arrayCount(array, &count)) {
            LOG("rosette is not an array!");
            break;
        }
        if (count != rosetteCount) {
            LOG("rosette count unexpected : %lu!", rosetteCount);
            break;
        }
        for (unsigned long i=0; i<rosetteCount; i++) {
            kpad.rosetteScancodes[i] = json_arrayParseLongValueAtIndex(array, i, &lVal, /*base:*/10) ? lVal : -1;
        }
    } while (0);

    json_destroy(&array);
}

static uint8_t *touchkpad_rosetteChars(void) {
    return kpad.rosetteChars;
}

// ----------------------------------------------------------------------------

static void _init_gltouchjoy_kpad(void) {
    LOG("Registering OpenGL software touch joystick (keypad variant)");

    for (unsigned int i=0; i<MAX_REPEATING; i++) {
        kpad.scancodes[i] = -1;
    }

    kpad.currButtonDisplayChar = ' ';

    kpadJoy.variant = &touchkpad_variant;
    kpadJoy.resetState = &touchkpad_resetState;
    kpadJoy.setup = &touchkpad_setup;
    kpadJoy.shutdown = &touchkpad_shutdown;

    kpadJoy.prefsChanged = &touchkpad_prefsChanged;

    kpadJoy.buttonDown = &touchkpad_buttonDown;
    kpadJoy.buttonMove = &touchkpad_buttonMove;
    kpadJoy.buttonUp = &touchkpad_buttonUp;

    kpadJoy.axisDown = &touchkpad_axisDown;
    kpadJoy.axisMove = &touchkpad_axisMove;
    kpadJoy.axisUp = &touchkpad_axisUp;

    kpadJoy.rosetteChars = &touchkpad_rosetteChars;

    gltouchjoy_registerVariant(TOUCH_DEVICE_JOYSTICK_KEYPAD, &kpadJoy);
}

static __attribute__((constructor)) void __init_gltouchjoy_kpad(void) {
    emulator_registerStartupCallback(CTOR_PRIORITY_EARLY, &_init_gltouchjoy_kpad);
}