Add documentation for `time_get`

parser.c

@@ -13,12 +13,14 @@ unreachable(char *file, size_t line)
 	exit(EXIT_FAILURE);
 }
-bool str_eq(Str a, Str b)
+bool
+str_eq(Str a, Str b)
 {
 	return a.len == b.len && memcmp(a.str, b.str, a.len) == 0;
 }
-int str_cmp(Str a, Str b)
+int
+str_cmp(Str a, Str b)
 {
 	int cmp = memcmp(a.str, b.str, a.len < b.len ? a.len : b.len);
 	return cmp == 0 ? (a.len > b.len) - (b.len > a.len) : cmp;

parser.h

@@ -17,7 +17,7 @@
 // See the bottom of this file for parser API.
 // This header mainly defines the AST emitted by the reference FML parser and
-// a few utility types.
+// a few utility types and functions.
 typedef uint8_t  u8;
 typedef uint16_t u16;
@@ -46,9 +46,26 @@ bool str_eq(Str a, Str b);
 //  - a positive number if the first string is greater than the second
 int str_cmp(Str a, Str b);
-// Get current time and save it into `ts`.
+
+// Get current time and save it into `ts`. Platform details may differ, but
+// `struct timespec` should be at least similar to the following:
+//
+//         struct timespec {
+//                 long long tv_sec; /* seconds */
+//                 long tv_nsec; /* nanoseconds */
+//         }
+//
+// An example of use:
+//
+//         struct timespec ts;
+//         if (!time_get(&ts)) {
+//         	exit(1);
+//         }
+//         printf("%lld%09ld\n", ts.tv_sec, ts.tv_nsec);
+//
 bool time_get(struct timespec *ts);
+
 // See https://courses.fit.cvut.cz/NI-RUN/specs/ast.html for details about the
 // AST.