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#define _WASI_EMULATED_PROCESS_CLOCKS
#include <time.h>
#include <wasi/api.h>
#include <common/time.h>
_Static_assert(
CLOCKS_PER_SEC == NSEC_PER_SEC,
"This implementation assumes that `clock` is in nanoseconds"
);
// Snapshot of the monotonic clock at the start of the program.
static __wasi_timestamp_t start;
// Use a priority of 10 to run fairly early in the implementation-reserved
// constructor priority range.
__attribute__((constructor(10)))
static void init(void) {
(void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &start);
}
// Define the libc symbol as `__clock` so that we can reliably call it
// from elsewhere in libc.
clock_t __clock(void) {
// Use `MONOTONIC` instead of `PROCESS_CPUTIME_ID` since WASI doesn't have
// an inherent concept of a process. Note that this means we'll incorrectly
// include time from other processes, so this function is only declared by
// the headers if `_WASI_EMULATED_PROCESS_CLOCKS` is defined.
__wasi_timestamp_t now = 0;
(void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &now);
return now - start;
}
// Define a user-visible alias as a weak symbol.
__attribute__((__weak__, __alias__("__clock")))
clock_t clock(void);
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