[Git][freetype/freetype-demos][master] * src/common.c (utf8_next): Use more efficient algorithm.

[Alexei Podtelezhnikov (@apodtele)]

Alexei Podtelezhnikov pushed to branch master at FreeType / FreeType Demo Programs

Commits:

• 2e32dc9f
  by Alexei Podtelezhnikov at 2022-08-15T22:51:11-04:00

  * src/common.c (utf8_next): Use more efficient algorithm.
  

1 changed file:

• src/common.c

Changes:

src/common.c

---

...	...	@@ -77,49 +77,31 @@
77	77	{
78	78	const unsigned char* p = (const unsigned char*)*pcursor;
79	79	int ch;
	80	+ int mask = 0x80; /* the first decision bit */
80	81
81	82
82		- if ( (const char*)p >= end ) /* end of stream */
83		- return -1;
	83	+ if ( (const char*)p >= end || ( *p & 0xc0 ) == 0x80 )
	84	+ goto BAD_DATA;
84	85
85	86	ch = *p++;
86		- if ( ch >= 0x80 )
87		- {
88		- int len;
89		-
90	87
91		- if ( ch < 0xc0 ) /* malformed data */
92		- goto BAD_DATA;
93		- else if ( ch < 0xe0 )
94		- {
95		- len = 1;
96		- ch &= 0x1f;
97		- }
98		- else if ( ch < 0xf0 )
99		- {
100		- len = 2;
101		- ch &= 0x0f;
102		- }
103		- else
104		- {
105		- len = 3;
106		- ch &= 0x07;
107		- }
	88	+ if ( ch & mask )
	89	+ {
	90	+ mask = 0x40;
108	91
109		- while ( len > 0 )
	92	+ do
110	93	{
111		- if ( (const char*)p >= end || ( p[0] & 0xc0 ) != 0x80 )
	94	+ if ( (const char*)p >= end || ( *p & 0xc0 ) != 0x80 )
112	95	goto BAD_DATA;
113	96
114		- ch = ( ch << 6 ) | ( p[0] & 0x3f );
115		- p += 1;
116		- len -= 1;
117		- }
	97	+ ch = ( ch << 6 ) | ( *p++ & 0x3f );
	98	+ mask <<= 5; /* the next decision bit after shift */
	99	+ } while ( ch & mask && mask <= 0x200000 );
118	100	}
119	101
120	102	*pcursor = (const char*)p;
121	103
122		- return ch;
	104	+ return ch & ( mask - 1 ); /* dropping the decision bits */
123	105
124	106	BAD_DATA:
125	107	return -1;

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