On 4/24/19 8:30 AM, AKASHI Takahiro wrote:
u16_strncmp() works like u16_strcmp() but only at most n characters (in u16) are compared. This function will be used in a later patch.
Signed-off-by: AKASHI Takahiro takahiro.akashi@linaro.org
include/charset.h | 5 +++++ lib/charset.c | 13 +++++++++++++ 2 files changed, 18 insertions(+)
diff --git a/include/charset.h b/include/charset.h index 747a9b376c03..49842a88bc8b 100644 --- a/include/charset.h +++ b/include/charset.h @@ -171,6 +171,11 @@ s32 utf_to_upper(const s32 code); */ int u16_strcmp(const u16 *s1, const u16 *s2);
+/*
- u16_strncmp() - strncmp() for u16 strings
* u16_strncmp() - compare two u16 string * * @s1: first string to compare * @s2: second string to compare * @n1: maximum number of u16 to compare * Return: 0 if the first n u16 are the same in s1 and s2 * < 0 if the first different u16 in s1 is less than the * corresponding u16 in s2 * > 0 if the first different u16 in s1 is greater than the * corresponding u16 in s2
- */
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n);
- /**
- u16_strlen - count non-zero words
diff --git a/lib/charset.c b/lib/charset.c index 4a25ac0bdb9c..85f08db68fe2 100644 --- a/lib/charset.c +++ b/lib/charset.c @@ -345,6 +345,19 @@ int u16_strcmp(const u16 *s1, const u16 *s2) return (*(uint16_t *)s1 - *(uint16_t *)s2); }
+int u16_strncmp(const u16 *s1, const u16 *s2, size_t n) +{
- while ((n-- > 0) && (*s1 == *s2++)) {
if (*s1++ == 0)return 0;if (!n)return 0;- }
- --s2;
For u16_strncmp() called with n = 0 I would prefer to see 0 as return value instead of the result of an illegal memory access.
- return (*(uint16_t *)s1 - *(uint16_t *)s2);
No need for a conversion here.
Let's avoid the superfluous increment/decrement, provide 0 for n = 0, and make sure that the compiler calculates the difference only once per loop:
int u16_strncmp(const u16 *s1, const u16 *s2, size_t n) { int ret = 0;
for (; n; --n, ++s1, ++s2) { ret = *s1 - *s2; if (ret || !*s1) break; } return ret; }
I would like to see a unit test in test/unicode_ut.c. The test should include the n = 0 case.
Best regards
Heinrich
+}
- size_t u16_strlen(const u16 *in) { size_t i;