SDL_strcasecmp (even when calling into a C runtime) does not work with
Unicode chars, and depending on the user's locale, might not work with
even basic ASCII strings.
This implements the function from scratch, using "case-folding,"
which is a more robust method that deals with various languages. It
involves a hashtable of a few hundred codepoints that are "uppercase" and
how to map them to lowercase equivalents (possibly increasing the size of
the string in the process). The vast majority of human languages (and
Unicode) do not have letters with different cases, but still, this static
table takes about 10 kilobytes on a 64-bit machine.
Even this will fail in one known case: the Turkish 'i' folds differently
if you're writing in Turkish vs other languages. Generally this is seen as
unfortunate collateral damage in cases where you can't specify the language
in use.
In addition to case-folding the codepoints, the new functions also know how
to decode the various formats to turn them into codepoints in the first
place, instead of blindly stepping by one byte (or one wchar_t) per
character.
Also included is casefolding.txt from the Unicode Consortium and a perl
script to generate the hashtable from that text file, so we can trivially
update this if new languages are added in the future.
A simple test using the new function:
```c
#include <SDL3/SDL.h>
int main(void)
{
const char *a = "α ε η";
const char *b = "Α Ε Η";
SDL_Log(" strcasecmp(\"%s\", \"%s\") == %d\n", a, b, strcasecmp(a, b));
SDL_Log("SDL_strcasecmp(\"%s\", \"%s\") == %d\n", a, b, SDL_strcasecmp(a, b));
return 0;
}
```
Produces:
```
INFO: strcasecmp("α ε η", "Α Ε Η") == 32
INFO: SDL_strcasecmp("α ε η", "Α Ε Η") == 0
```
glibc strcasecmp() fails to compare a Greek lowercase string to its uppercase
equivalent, even with a UTF-8 locale, but SDL_strcasecmp() works.
Other SDL_stdinc.h functions are changed to be more consistent, which is to
say they now ignore any C runtime and often dictate that only English-based
low-ASCII works with them.
Fixes Issue #9313.
Some POSIX platforms don't define macros to note the presence of the POSIX.1-2008 st_*tim timespec members of the stat struct, so check if this member exists during CMake configuration and conditionally enable it.
Apple platforms use st_*timespec naming, which is supported as of OSX 10.6. SDL3 requires 10.9+, so no fallback is needed.
Android only supports the POSIX.1-2008 semantics as of API version 26 or higher, so this has to be conditionally enabled in the makefile build via an API version definition check.
In other cases, file times fall back to the legacy path with second precision.
Adds functions to query the system's realtime clock, convert time intervals to/from a calendar date and time in either UTC or the local time, and perform time related calculations.
An SDL_Time type (a time interval represented in nanoseconds), and SDL_DateTime struct (broken down calendar date and time) were added to facilitate this functionality.
Querying the system time results in a value expressed in nanoseconds since the Unix epoch (Jan 1, 1970) in UTC +0000. Conversions to and from the various platform epochs and units are performed when required.
Any direct handling of timezones and DST were intentionally avoided. The offset from UTC is provided when converting from UTC to a local time by calculating the difference between the original UTC and the resulting local time, but no other timezone or DST information is used.
The preferred date formatting and 12/24 hour time for the system locale can be retrieved via global preferences.
Helper functions for obtaining the day of week or day or year for calendar date, and getting the number of days in a month in a given year are provided for convenience. These are simple, but useful for performing various time related calculations.
An automated test for time conversion is included, as is a simple standalone test to display the current system date and time onscreen along with a calendar, the rendering of which demonstrates the use of the utility functions (press up/down to increment or decrement the current month, and keys 1-5 to change the date and time formats).
Sam Lantinga
Petar Popovic
Ryan C. Gordon
SDL Wiki Bot
Susko3
Ozkan Sezer
Frank Praznik
Daniel Ludwig
Cameron Gutman
Anonymous Maarten