loginx Code

// This file is part of the loginx project
//
// Copyright (c) 2013 by Mike Sharov <msharov@users.sourceforge.net>
// This file is free software, distributed under the ISC license.

#include "utf8.h"

// Returns the number of bytes in the character whose first char is c
static unsigned utf8_ibytes (char c)
{
    // Count the leading bits. Header bits are 1 * nBytes followed by a 0.
    //	0 - single byte character. Take 7 bits (0xff >> 1)
    //	1 - error, in the middle of the character. Take 6 bits (0xff >> 2)
    //	    so you will keep reading invalid entries until you hit the next character.
    //	>2 - multibyte character. Take remaining bits, and get the next bytes.
    //
    unsigned n = 0u;
    for (uint8_t mask = 0x80; c & mask; ++n)
	mask >>= 1;
    return n+!n; // A sequence is always at least 1 byte.
}

static wchar_t utf8_next (const char** pt)
{
    const char* i = *pt;
    unsigned n = utf8_ibytes (*i);
    wchar_t v = *i & (0xff >> n);	// First byte contains bits after the header.
    while (--n && *++i)			// Each subsequent byte has 6 bits.
	v = (v << 6) | (*i & 0x3f);
    *pt = ++i;
    return v;
}

unsigned utf8_length (const char* s)
{
    unsigned l = 0;
    while (utf8_next (&s))
	++l;
    return l;
}

unsigned utf8_range_length (const char* f, const char* l)
{
    unsigned rl = 0;
    while (f < l && utf8_next (&f))
	++rl;
    return rl;
}

void waddn_utf8 (WINDOW* w, const char* s, unsigned n)
{
    #if NCURSES_WIDECHAR
	attr_t attr = 0;
	short cpair = 0;
	attr_get (&attr, &cpair, NULL);

	wchar_t wchzs[2] = { 0, 0 };
	cchar_t ch = {};

	while (n-- && (wchzs[0] = utf8_next (&s))) {
	    setcchar (&ch, wchzs, attr, cpair, NULL);
	    wadd_wch (w, &ch);
	}
    #else
	wchar_t wc;
	while (n-- && (wc = utf8_next (&s)))
	    waddch (w, wc < CHAR_MAX ? (char) wc : '?');
    #endif
}

void wadd_utf8 (WINDOW* w, const char* s)
{
    int x = getcurx (w);
    unsigned ww = getmaxx (w);
    waddn_utf8 (w, s, ww-x);
}

void mvwaddn_utf8 (WINDOW* w, int y, int x, const char* s, unsigned n)
{
    wmove (w, y, x);
    waddn_utf8 (w, s, n);
}

void mvwadd_utf8 (WINDOW* w, int y, int x, const char* s)
{
    wmove (w, y, x);
    wadd_utf8 (w, s);
}