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lib/ucs2_string: Add ucs2 -> utf8 helper functions

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This adds ucs2_utf8size(), which tells us how big our ucs2 string is in
bytes, and ucs2_as_utf8, which translates from ucs2 to utf8..

Signed-off-by: Peter Jones <pjones@redhat.com>
Tested-by: Lee, Chun-Yi <jlee@suse.com>
Acked-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
This commit is contained in:
Peter Jones 2016-02-08 14:48:11 -05:00 committed by Matt Fleming
parent 59fd121456
commit 73500267c9
2 changed files with 66 additions and 0 deletions
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4
include/linux/ucs2_string.h
View File

@ -11,4 +11,8 @@ unsigned long ucs2_strlen(const ucs2_char_t *s);
unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);
unsigned long ucs2_utf8size(const ucs2_char_t *src);
unsigned long ucs2_as_utf8(u8 *dest, const ucs2_char_t *src,
unsigned long maxlength);
#endif /* _LINUX_UCS2_STRING_H_ */

62
lib/ucs2_string.c
View File

@ -49,3 +49,65 @@ ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
}
}
EXPORT_SYMBOL(ucs2_strncmp);
unsigned long
ucs2_utf8size(const ucs2_char_t *src)
{
unsigned long i;
unsigned long j = 0;
for (i = 0; i < ucs2_strlen(src); i++) {
u16 c = src[i];
if (c > 0x800)
j += 3;
else if (c > 0x80)
j += 2;
else
j += 1;
}
return j;
}
EXPORT_SYMBOL(ucs2_utf8size);
/*
* copy at most maxlength bytes of whole utf8 characters to dest from the
* ucs2 string src.
*
* The return value is the number of characters copied, not including the
* final NUL character.
*/
unsigned long
ucs2_as_utf8(u8 *dest, const ucs2_char_t *src, unsigned long maxlength)
{
unsigned int i;
unsigned long j = 0;
unsigned long limit = ucs2_strnlen(src, maxlength);
for (i = 0; maxlength && i < limit; i++) {
u16 c = src[i];
if (c > 0x800) {
if (maxlength < 3)
break;
maxlength -= 3;
dest[j++] = 0xe0 | (c & 0xf000) >> 12;
dest[j++] = 0x80 | (c & 0x0fc0) >> 8;
dest[j++] = 0x80 | (c & 0x003f);
} else if (c > 0x80) {
if (maxlength < 2)
break;
maxlength -= 2;
dest[j++] = 0xc0 | (c & 0xfe0) >> 5;
dest[j++] = 0x80 | (c & 0x01f);
} else {
maxlength -= 1;
dest[j++] = c & 0x7f;
}
}
if (maxlength)
dest[j] = '\0';
return j;
}
EXPORT_SYMBOL(ucs2_as_utf8);