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minor: Fix timeval_subtract() to const

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This commit is contained in:
Christian W. Zuckschwerdt 2024-03-04 23:16:08 +01:00
parent b2a9bf3816
commit 71b6566514
2 changed files with 16 additions and 13 deletions

2
include/compat_time.h
View file

@ -23,7 +23,7 @@
@param y second time value
@return 1 if the difference is negative, otherwise 0.
*/
int timeval_subtract(struct timeval *result, struct timeval *x, struct timeval *y);
int timeval_subtract(struct timeval *result, struct timeval const *x, struct timeval const *y);
// platform-specific functions

27
src/compat_time.c
View file

@ -35,24 +35,27 @@ int gettimeofday(struct timeval *tv, void *tz)
#endif // _WIN32
int timeval_subtract(struct timeval *result, struct timeval *x, struct timeval *y)
int timeval_subtract(struct timeval *result, struct timeval const *x, struct timeval const *y)
{
// Copy one input
struct timeval yy = *y;
// Perform the carry for the later subtraction by updating y
if (x->tv_usec < y->tv_usec) {
int nsec = (y->tv_usec - x->tv_usec) / 1000000 + 1;
y->tv_usec -= 1000000 * nsec;
y->tv_sec += nsec;
if (x->tv_usec < yy.tv_usec) {
int nsec = (yy.tv_usec - x->tv_usec) / 1000000 + 1;
yy.tv_usec -= 1000000 * nsec;
yy.tv_sec += nsec;
}
if (x->tv_usec - y->tv_usec > 1000000) {
int nsec = (x->tv_usec - y->tv_usec) / 1000000;
y->tv_usec += 1000000 * nsec;
y->tv_sec -= nsec;
if (x->tv_usec - yy.tv_usec > 1000000) {
int nsec = (x->tv_usec - yy.tv_usec) / 1000000;
yy.tv_usec += 1000000 * nsec;
yy.tv_sec -= nsec;
}
// Compute the time difference, tv_usec is certainly positive
result->tv_sec = x->tv_sec - y->tv_sec;
result->tv_usec = x->tv_usec - y->tv_usec;
result->tv_sec = x->tv_sec - yy.tv_sec;
result->tv_usec = x->tv_usec - yy.tv_usec;
// Return 1 if result is negative
return x->tv_sec < y->tv_sec;
return x->tv_sec < yy.tv_sec;
}