# st

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    commit 45b808b88ee63f21a188800ba3473a24a3c4b987
    parent 71328cbcdc88f4fdfbb62d8c0324938e245c8971
    Author: Damian Okrasa <dokrasa@gmail.com>
    Date:   Tue, 25 Mar 2014 20:20:26 +0100

    new utf decoder

    This patch replaces current utf decoder with a new one, which is ~50
    lines shorter and should be easier to understand. Parsing 5 and 6
    sequences, if necessary, requires trivial modification of UTF_SIZ
    constant and utfbyte, utfmask, utfmin, utfmax arrays.

    Diffstat:
    Mst.c | 214++++++++++++++++++++++++++++++-------------------------------------------------

    1 file changed, 81 insertions(+), 133 deletions(-)
    diff --git a/st.c b/st.c
    @@ -55,6 +55,7 @@ char *argv0;
     #define XEMBED_FOCUS_OUT 5

     /* Arbitrary sizes */
    +#define UTF_INVALID   0xFFFD
     #define UTF_SIZ       4
     #define ESC_BUF_SIZ   (128*UTF_SIZ)
     #define ESC_ARG_SIZ   16
    @@ -442,10 +443,12 @@ static void selcopy(void);
     static void selscroll(int, int);
     static void selsnap(int, int *, int *, int);

    -static int utf8decode(char *, long *);
    -static int utf8encode(long *, char *);
    -static int utf8size(char *);
    -static int isfullutf8(char *, int);
    +static size_t utf8decode(char *, long *, size_t);
    +static long utf8decodebyte(char, size_t *);
    +static size_t utf8encode(long, char *, size_t);
    +static char utf8encodebyte(long, size_t);
    +static size_t utf8len(char *);
    +static size_t utf8validate(long *, size_t);

     static ssize_t xwrite(int, char *, size_t);
     static void *xmalloc(size_t);
    @@ -490,6 +493,11 @@ static int oldbutton = 3; /* button event on startup: 3 = release */
     static char *usedfont = NULL;
     static double usedfontsize = 0;

    +static uchar utfbyte[UTF_SIZ + 1] = {0x80,    0, 0xC0, 0xE0, 0xF0};
    +static uchar utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
    +static long utfmin[UTF_SIZ + 1] = {       0,    0,  0x80,  0x800,  0x10000};
    +static long utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
    +
     /* Font Ring Cache */
     enum {
     	FRC_NORMAL,
    @@ -549,128 +557,69 @@ xstrdup(char *s) {
     	return p;
     }

    -int
    -utf8decode(char *s, long *u) {
    -	uchar c;
    -	int i, n, rtn;
    -
    -	rtn = 1;
    -	c = *s;
    -	if(~c & 0x80) { /* 0xxxxxxx */
    -		*u = c;
    -		return rtn;
    -	} else if((c & 0xE0) == 0xC0) { /* 110xxxxx */
    -		*u = c & 0x1F;
    -		n = 1;
    -	} else if((c & 0xF0) == 0xE0) { /* 1110xxxx */
    -		*u = c & 0x0F;
    -		n = 2;
    -	} else if((c & 0xF8) == 0xF0) { /* 11110xxx */
    -		*u = c & 0x07;
    -		n = 3;
    -	} else {
    -		goto invalid;
    -	}
    -
    -	for(i = n, ++s; i > 0; --i, ++rtn, ++s) {
    -		c = *s;
    -		if((c & 0xC0) != 0x80) /* 10xxxxxx */
    -			goto invalid;
    -		*u <<= 6;
    -		*u |= c & 0x3F;
    -	}
    -
    -	if((n == 1 && *u < 0x80) ||
    -	   (n == 2 && *u < 0x800) ||
    -	   (n == 3 && *u < 0x10000) ||
    -	   (*u >= 0xD800 && *u <= 0xDFFF)) {
    -		goto invalid;
    -	}
    -
    -	return rtn;
    -invalid:
    -	*u = 0xFFFD;
    -
    -	return rtn;
    -}
    +size_t
    +utf8decode(char *c, long *u, size_t clen) {
    +	size_t i, j, len, type;
    +	long udecoded;

    -int
    -utf8encode(long *u, char *s) {
    -	uchar *sp;
    -	ulong uc;
    -	int i, n;
    -
    -	sp = (uchar *)s;
    -	uc = *u;
    -	if(uc < 0x80) {
    -		*sp = uc; /* 0xxxxxxx */
    +	*u = UTF_INVALID;
    +	if(!clen)
    +		return 0;
    +	udecoded = utf8decodebyte(c[0], &len);
    +	if(!BETWEEN(len, 1, UTF_SIZ))
     		return 1;
    -	} else if(*u < 0x800) {
    -		*sp = (uc >> 6) | 0xC0; /* 110xxxxx */
    -		n = 1;
    -	} else if(uc < 0x10000) {
    -		*sp = (uc >> 12) | 0xE0; /* 1110xxxx */
    -		n = 2;
    -	} else if(uc <= 0x10FFFF) {
    -		*sp = (uc >> 18) | 0xF0; /* 11110xxx */
    -		n = 3;
    -	} else {
    -		goto invalid;
    +	for(i = 1, j = 1; i < clen && j < len; ++i, ++j) {
    +		udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
    +		if(type != 0)
    +			return j;
     	}
    +	if(j < len)
    +		return 0;
    +	*u = udecoded;
    +	utf8validate(u, len);
    +	return len;
    +}

    -	for(i=n,++sp; i>0; --i,++sp)
    -		*sp = ((uc >> 6*(i-1)) & 0x3F) | 0x80; /* 10xxxxxx */
    -
    -	return n+1;
    -invalid:
    -	/* U+FFFD */
    -	*s++ = '\xEF';
    -	*s++ = '\xBF';
    -	*s = '\xBD';
    -
    -	return 3;
    +long
    +utf8decodebyte(char c, size_t *i) {
    +	for(*i = 0; *i < LEN(utfmask); ++(*i))
    +		if(((uchar)c & utfmask[*i]) == utfbyte[*i])
    +			return (uchar)c & ~utfmask[*i];
    +	return 0;
     }

    -/* use this if your buffer is less than UTF_SIZ, it returns 1 if you can decode
    -   UTF-8 otherwise return 0 */
    -int
    -isfullutf8(char *s, int b) {
    -	uchar *c1, *c2, *c3;
    +size_t
    +utf8encode(long u, char *c, size_t clen) {
    +	size_t len, i;

    -	c1 = (uchar *)s;
    -	c2 = (uchar *)++s;
    -	c3 = (uchar *)++s;
    -	if(b < 1) {
    +	len = utf8validate(&u, 0);
    +	if(clen < len)
     		return 0;
    -	} else if((*c1 & 0xE0) == 0xC0 && b == 1) {
    -		return 0;
    -	} else if((*c1 & 0xF0) == 0xE0 &&
    -	    ((b == 1) ||
    -	    ((b == 2) && (*c2 & 0xC0) == 0x80))) {
    -		return 0;
    -	} else if((*c1 & 0xF8) == 0xF0 &&
    -	    ((b == 1) ||
    -	    ((b == 2) && (*c2 & 0xC0) == 0x80) ||
    -	    ((b == 3) && (*c2 & 0xC0) == 0x80 && (*c3 & 0xC0) == 0x80))) {
    -		return 0;
    -	} else {
    -		return 1;
    +	for(i = len - 1; i != 0; --i) {
    +		c[i] = utf8encodebyte(u, 0);
    +		u >>= 6;
     	}
    +	c[0] = utf8encodebyte(u, len);
    +	return len;
     }

    -int
    -utf8size(char *s) {
    -	uchar c = *s;
    +char
    +utf8encodebyte(long u, size_t i) {
    +	return utfbyte[i] | (u & ~utfmask[i]);
    +}

    -	if(~c & 0x80) {
    -		return 1;
    -	} else if((c & 0xE0) == 0xC0) {
    -		return 2;
    -	} else if((c & 0xF0) == 0xE0) {
    -		return 3;
    -	} else {
    -		return 4;
    -	}
    +size_t
    +utf8len(char *c) {
    +	return utf8decode(c, &(long){0}, UTF_SIZ);
    +}
    +
    +size_t
    +utf8validate(long *u, size_t i) {
    +	if(!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
    +		*u = UTF_INVALID;
    +	for(i = 1; *u > utfmax[i]; ++i)
    +		;
    +	return i;
     }

     static void
    @@ -984,7 +933,7 @@ getsel(void) {
     				if(!selected(x, y) || (gp->mode & ATTR_WDUMMY))
     					continue;

    -				size = utf8size(gp->c);
    +				size = utf8len(gp->c);
     				memcpy(ptr, gp->c, size);
     				ptr += size;
     			}
    @@ -1298,7 +1247,7 @@ ttyread(void) {
     	char *ptr;
     	char s[UTF_SIZ];
     	int charsize; /* size of utf8 char in bytes */
    -	long utf8c;
    +	long unicodep;
     	int ret;

     	/* append read bytes to unprocessed bytes */
    @@ -1308,9 +1257,8 @@ ttyread(void) {
     	/* process every complete utf8 char */
     	buflen += ret;
     	ptr = buf;
    -	while(buflen >= UTF_SIZ || isfullutf8(ptr,buflen)) {
    -		charsize = utf8decode(ptr, &utf8c);
    -		utf8encode(&utf8c, s);
    +	while(charsize = utf8decode(ptr, &unicodep, buflen)) {
    +		utf8encode(unicodep, s, UTF_SIZ);
     		tputc(s, charsize);
     		ptr += charsize;
     		buflen -= charsize;
    @@ -2414,14 +2362,14 @@ void
     tputc(char *c, int len) {
     	uchar ascii = *c;
     	bool control = ascii < '\x20' || ascii == 0177;
    -	long u8char;
    +	long unicodep;
     	int width;

     	if(len == 1) {
     		width = 1;
     	} else {
    -		utf8decode(c, &u8char);
    -		width = wcwidth(u8char);
    +		utf8decode(c, &unicodep, UTF_SIZ);
    +		width = wcwidth(unicodep);
     	}

     	if(IS_SET(MODE_PRINT))
    @@ -3150,7 +3098,7 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
     	int frcflags;
     	int u8fl, u8fblen, u8cblen, doesexist;
     	char *u8c, *u8fs;
    -	long u8char;
    +	long unicodep;
     	Font *font = &dc.font;
     	FcResult fcres;
     	FcPattern *fcpattern, *fontpattern;
    @@ -3293,11 +3241,11 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
     		oneatatime = font->width != xw.cw;
     		for(;;) {
     			u8c = s;
    -			u8cblen = utf8decode(s, &u8char);
    +			u8cblen = utf8decode(s, &unicodep, UTF_SIZ);
     			s += u8cblen;
     			bytelen -= u8cblen;

    -			doesexist = XftCharExists(xw.dpy, font->match, u8char);
    +			doesexist = XftCharExists(xw.dpy, font->match, unicodep);
     			if(oneatatime || !doesexist || bytelen <= 0) {
     				if(oneatatime || bytelen <= 0) {
     					if(doesexist) {
    @@ -3329,7 +3277,7 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {

     		/* Search the font cache. */
     		for(i = 0; i < frclen; i++) {
    -			if(XftCharExists(xw.dpy, frc[i].font, u8char)
    +			if(XftCharExists(xw.dpy, frc[i].font, unicodep)
     					&& frc[i].flags == frcflags) {
     				break;
     			}
    @@ -3351,7 +3299,7 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
     			fcpattern = FcPatternDuplicate(font->pattern);
     			fccharset = FcCharSetCreate();

    -			FcCharSetAddChar(fccharset, u8char);
    +			FcCharSetAddChar(fccharset, unicodep);
     			FcPatternAddCharSet(fcpattern, FC_CHARSET,
     					fccharset);
     			FcPatternAddBool(fcpattern, FC_SCALABLE,
    @@ -3387,7 +3335,7 @@ xdraws(char *s, Glyph base, int x, int y, int charlen, int bytelen) {
     				xp, winy + frc[i].font->ascent,
     				(FcChar8 *)u8c, u8cblen);

    -		xp += xw.cw * wcwidth(u8char);
    +		xp += xw.cw * wcwidth(unicodep);
     	}

     	/*
    @@ -3430,7 +3378,7 @@ xdrawcursor(void) {
     	memcpy(g.c, term.line[term.c.y][term.c.x].c, UTF_SIZ);

     	/* remove the old cursor */
    -	sl = utf8size(term.line[oldy][oldx].c);
    +	sl = utf8len(term.line[oldy][oldx].c);
     	width = (term.line[oldy][oldx].mode & ATTR_WIDE)? 2 : 1;
     	xdraws(term.line[oldy][oldx].c, term.line[oldy][oldx], oldx,
     			oldy, width, sl);
    @@ -3444,7 +3392,7 @@ xdrawcursor(void) {
     				g.bg = defaultfg;
     			}

    -			sl = utf8size(g.c);
    +			sl = utf8len(g.c);
     			width = (term.line[term.c.y][curx].mode & ATTR_WIDE)\
     				? 2 : 1;
     			xdraws(g.c, g, term.c.x, term.c.y, width, sl);
    @@ -3516,7 +3464,7 @@ drawregion(int x1, int y1, int x2, int y2) {
     	Glyph base, new;
     	char buf[DRAW_BUF_SIZ];
     	bool ena_sel = sel.ob.x != -1;
    -	long u8char;
    +	long unicodep;

     	if(sel.alt ^ IS_SET(MODE_ALTSCREEN))
     		ena_sel = 0;
    @@ -3548,7 +3496,7 @@ drawregion(int x1, int y1, int x2, int y2) {
     				base = new;
     			}

    -			sl = utf8decode(new.c, &u8char);
    +			sl = utf8decode(new.c, &unicodep, UTF_SIZ);
     			memcpy(buf+ib, new.c, sl);
     			ib += sl;
     			ic += (new.mode & ATTR_WIDE)? 2 : 1;
    @@ -3707,7 +3655,7 @@ kpress(XEvent *ev) {
     		if(IS_SET(MODE_8BIT)) {
     			if(*buf < 0177) {
     				c = *buf | 0x80;
    -				len = utf8encode(&c, buf);
    +				len = utf8encode(c, buf, UTF_SIZ);
     			}
     		} else {
     			buf[1] = buf[0];