Xkb: как преобразовать код ключа в keysym

Я просто пытаюсь взять код ключа и маску модификатора и преобразовать его в KeySym с помощью расширения Xkb. Я не могу понять, почему это не работает. Понятно, что модификаторы не совпадают, но я не знаю, почему. Я даже не знаю, правильно ли я преобразовываю группу.

#include <stdio.h>
#include <stdlib.h>
#include <X11/X.h>
#include <X11/XKBlib.h>

void check(XkbDescPtr keyboard_map, KeyCode keycode, unsigned int mask) {
    //What the hell is diff between XkbKeyGroupInfo and XkbKeyNumGroups?
    unsigned char info = XkbKeyGroupInfo(keyboard_map, keycode);
    int num_groups = XkbKeyNumGroups(keyboard_map, keycode);

    int key_width = XkbKeyGroupsWidth(keyboard_map, keycode);
    //int num_syms = XkbKeyNumSyms(keyboard_map, keycode);

    //Get the group
    unsigned int group = 0; // What should this default to?
    switch (XkbOutOfRangeGroupAction(info)) {
        case XkbRedirectIntoRange:
            /* If the RedirectIntoRange flag is set, the four least significant 
            * bits of the groups wrap control specify the index of a group to 
            * which all illegal groups correspond. If the specified group is 
            * also out of range, all illegal groups map to Group1.
            */
            printf("XkbRedirectIntoRangen");
            group = XkbOutOfRangeGroupInfo(info);
            if (group >= num_groups) {
                group = 0;
            }
        break;

        case XkbClampIntoRange:
            /* If the ClampIntoRange flag is set, out-of-range groups correspond 
            * to the nearest legal group. Effective groups larger than the 
            * highest supported group are mapped to the highest supported group; 
            * effective groups less than Group1 are mapped to Group1 . For 
            * example, a key with two groups of symbols uses Group2 type and 
            * symbols if the global effective group is either Group3 or Group4.
            */
            printf("XkbClampIntoRangen");
            group = num_groups - 1;
        break;

        case XkbWrapIntoRange:
            /* If neither flag is set, group is wrapped into range using integer 
            * modulus. For example, a key with two groups of symbols for which 
            * groups wrap uses Group1 symbols if the global effective group is 
            * Group3 or Group2 symbols if the global effective group is Group4.
            */
            printf("XkbWrapIntoRangen");
        default:
            printf("Defaultn");
            if (num_groups != 0) {
                group %= num_groups;
            }
        break;
    }
    printf("Group Info %d, %d, %dn", group, num_groups, key_width);
    //printf("Mask Info %d, %d, %d, %d, %d, %d, %d, %dn", ShiftMask, LockMask, ControlMask, Mod1Mask, Mod2Mask, Mod3Mask, Mod4Mask, Mod5Mask);

    XkbKeyTypePtr key_type = XkbKeyKeyType(keyboard_map, keycode, group);

    KeySym keysym = NoSymbol;
    int i;
    for (i = 0; i < key_type->map_count; i++) {
        if (key_type->map[i].active &&  key_type->map[i].mods.mask == mask) {
            keysym = XkbKeySymEntry(keyboard_map, keycode, i, group);
        }
    }

    //printf("%sn", XKeysymToString(keysym));
    printf("KeyCode: %dn", (int) keycode);
    printf("KeySym:  %dn", (int) keysym);
}

int main(int argc, const char * argv[]) {
    Display * display;

    //Try to attach to the default X11 display.
    display = XOpenDisplay(NULL);
    if(display == NULL) {
        printf("Error: Could not open display!n");
        return EXIT_FAILURE;
    }

    //Get the map
    XkbDescPtr keyboard_map = XkbGetMap(display, XkbAllClientInfoMask, XkbUseCoreKbd);

    KeyCode keycode = 56; // b
    check(keyboard_map, keycode, ShiftMask | LockMask | ControlMask);

    //Close the connection to the selected X11 display.
    XCloseDisplay(display);

    return EXIT_SUCCESS;
}