#include <stdint.h>
#include <xkbcommon/xkbcommon.h>

enum
{
	ShiftMask = 1<<0,
	LockMask = 1<<1,
	GroupShift = 13,
	GroupMask = 3,
};

uint32_t
keymaplookup(const uint32_t *syms, int nsyms, uint16_t state)
{
	uint32_t lo, hi, lower, upper;
	int col, group, shift;

	if(syms == NULL || nsyms <= 0)
		return XKB_KEY_NoSymbol;
	group = (state >> GroupShift) & GroupMask;
	col = group * 2;
	if(col >= nsyms || syms[col] == XKB_KEY_NoSymbol)
		col = 0;
	lo = syms[col];
	if(lo == XKB_KEY_NoSymbol)
		return XKB_KEY_NoSymbol;
	hi = col + 1 < nsyms ? syms[col + 1] : XKB_KEY_NoSymbol;
	lower = xkb_keysym_to_lower(lo);
	upper = xkb_keysym_to_upper(lo);
	if(hi == XKB_KEY_NoSymbol)
		hi = lower != upper ? upper : lo;
	shift = (state & ShiftMask) != 0;
	/* Lock reverses Shift only for keys with an alphabetic case pair. */
	if((state & LockMask) && lower != upper)
		shift = !shift;
	return shift ? hi : lo;
}