// -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil; -*-
// Copyright (C) 2013 Henner Zeller <h.zeller@acm.org>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation version 2.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://gnu.org/licenses/gpl-2.0.txt>
#ifndef RPI_GRAPHICS_UTF8_H
#define RPI_GRAPHICS_UTF8_H

#include <stdint.h>

// Utility function that reads UTF-8 encoded codepoints from byte iterator.
// No error checking, we assume string is UTF-8 clean.
template <typename byte_iterator>
uint32_t utf8_next_codepoint(byte_iterator &it) {
    uint32_t cp = *it++;
    if (cp < 0x80) {
        return cp;   // iterator already incremented.
    }
    else if ((cp & 0xE0) == 0xC0) {
        cp = ((cp & 0x1F) << 6) + (*it & 0x3F);
    }
    else if ((cp & 0xF0) == 0xE0) {
        cp = ((cp & 0x0F) << 12) + ((*it & 0x3F) << 6);
        cp += (*++it & 0x3F);
    }
    else if ((cp & 0xF8) == 0xF0) {
        cp = ((cp & 0x07) << 18) + ((*it & 0x3F) << 12);
        cp += (*++it & 0x3F) << 6;
        cp += (*++it & 0x3F);
    }
    else if ((cp & 0xFC) == 0xF8) {
        cp = ((cp & 0x03) << 24) + ((*it & 0x3F) << 18);
        cp += (*++it & 0x3F) << 12;
        cp += (*++it & 0x3F) << 6;
        cp += (*++it & 0x3F);
    }
    else if ((cp & 0xFE) == 0xFC) {
        cp = ((cp & 0x01) << 30) + ((*it & 0x3F) << 24);
        cp += (*++it & 0x3F) << 18;
        cp += (*++it & 0x3F) << 12;
        cp += (*++it & 0x3F) << 6;
        cp += (*++it & 0x3F);
    }
    ++it;
    return cp;
}

#endif  // RPI_GRAPHICS_UTF8_H
