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overhaul utf8decode()

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this changes the utf8decode function to:

* report when an error occurs
* report how many bytes to advance on error

these will be useful in the next commit to render invalid utf8
sequences.

the new implementation is also shorter and more direct.
This commit is contained in:
NRK 2024-07-04 21:25:37 +00:00 committed by Hiltjo Posthuma
parent 7be720cc88
commit 51e32d49b5
1 changed files with 31 additions and 45 deletions
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76
drw.c
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@ -9,54 +9,40 @@
#include "util.h"
#define UTF_INVALID 0xFFFD
#define UTF_SIZ 4
static const unsigned char utfbyte[UTF_SIZ + 1] = {0x80, 0, 0xC0, 0xE0, 0xF0};
static const unsigned char utfmask[UTF_SIZ + 1] = {0xC0, 0x80, 0xE0, 0xF0, 0xF8};
static const long utfmin[UTF_SIZ + 1] = { 0, 0, 0x80, 0x800, 0x10000};
static const long utfmax[UTF_SIZ + 1] = {0x10FFFF, 0x7F, 0x7FF, 0xFFFF, 0x10FFFF};
static long
utf8decodebyte(const char c, size_t *i)
static int
utf8decode(const char *s_in, long *u, int *err)
{
for (*i = 0; *i < (UTF_SIZ + 1); ++(*i))
if (((unsigned char)c & utfmask[*i]) == utfbyte[*i])
return (unsigned char)c & ~utfmask[*i];
return 0;
}
static const unsigned char lens[] = {
/* 0XXXX */ 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
/* 10XXX */ 0, 0, 0, 0, 0, 0, 0, 0, /* invalid */
/* 110XX */ 2, 2, 2, 2,
/* 1110X */ 3, 3,
/* 11110 */ 4,
/* 11111 */ 0, /* invalid */
};
static const unsigned char leading_mask[] = { 0x7F, 0x1F, 0x0F, 0x07 };
static const unsigned int overlong[] = { 0x0, 0x80, 0x0800, 0x10000 };
static size_t
utf8validate(long *u, size_t i)
{
if (!BETWEEN(*u, utfmin[i], utfmax[i]) || BETWEEN(*u, 0xD800, 0xDFFF))
const unsigned char *s = (const unsigned char *)s_in;
int len = lens[*s >> 3];
*u = UTF_INVALID;
for (i = 1; *u > utfmax[i]; ++i)
;
return i;
}
static size_t
utf8decode(const char *c, long *u, size_t clen)
{
size_t i, j, len, type;
long udecoded;
*u = UTF_INVALID;
if (!clen)
return 0;
udecoded = utf8decodebyte(c[0], &len);
if (!BETWEEN(len, 1, UTF_SIZ))
*err = 1;
if (len == 0)
return 1;
for (i = 1, j = 1; i < clen && j < len; ++i, ++j) {
udecoded = (udecoded << 6) | utf8decodebyte(c[i], &type);
if (type)
return j;
}
if (j < len)
return 0;
*u = udecoded;
utf8validate(u, len);
long cp = s[0] & leading_mask[len - 1];
for (int i = 1; i < len; ++i) {
if (s[i] == '\0' || (s[i] & 0xC0) != 0x80)
return i;
cp = (cp << 6) | (s[i] & 0x3F);
}
/* out of range, surrogate, overlong encoding */
if (cp > 0x10FFFF || (cp >> 11) == 0x1B || cp < overlong[len - 1])
return len;
*err = 0;
*u = cp;
return len;
}
@ -242,7 +228,7 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lp
unsigned int tmpw, ew, ellipsis_w = 0, ellipsis_len, hash, h0, h1;
XftDraw *d = NULL;
Fnt *usedfont, *curfont, *nextfont;
int utf8strlen, utf8charlen, render = x || y || w || h;
int utf8strlen, utf8charlen, utf8err, render = x || y || w || h;
long utf8codepoint = 0;
const char *utf8str;
FcCharSet *fccharset;
@ -272,11 +258,11 @@ drw_text(Drw *drw, int x, int y, unsigned int w, unsigned int h, unsigned int lp
if (!ellipsis_width && render)
ellipsis_width = drw_fontset_getwidth(drw, "...");
while (1) {
ew = ellipsis_len = utf8strlen = 0;
ew = ellipsis_len = utf8err = utf8charlen = utf8strlen = 0;
utf8str = text;
nextfont = NULL;
while (*text) {
utf8charlen = utf8decode(text, &utf8codepoint, UTF_SIZ);
utf8charlen = utf8decode(text, &utf8codepoint, &utf8err);
for (curfont = drw->fonts; curfont; curfont = curfont->next) {
charexists = charexists || XftCharExists(drw->dpy, curfont->xfont, utf8codepoint);
if (charexists) {