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https://github.com/jart/cosmopolitan.git
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f4f4caab0e
I wanted a tiny scriptable meltdown proof way to run userspace programs and visualize how program execution impacts memory. It helps to explain how things like Actually Portable Executable works. It can show you how the GCC generated code is going about manipulating matrices and more. I didn't feel fully comfortable with Qemu and Bochs because I'm not smart enough to understand them. I wanted something like gVisor but with much stronger levels of assurances. I wanted a single binary that'll run, on all major operating systems with an embedded GPL barrier ZIP filesystem that is tiny enough to transpile to JavaScript and run in browsers too. https://justine.storage.googleapis.com/emulator625.mp4
83 lines
3.9 KiB
C
83 lines
3.9 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/bits.h"
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#include "libc/bits/safemacros.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timeval.h"
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#include "libc/conv/conv.h"
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#include "libc/dce.h"
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#include "libc/mach.h"
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#include "libc/nt/struct/filetime.h"
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#include "libc/nt/struct/systemtime.h"
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#include "libc/nt/synchronization.h"
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#include "libc/sysv/consts/clock.h"
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#include "libc/sysv/consts/fileno.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/time/time.h"
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/**
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* Returns nanosecond time.
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*
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* This is a high-precision timer that supports multiple definitions of
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* time. Among the more popular is CLOCK_MONOTONIC. This function has a
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* zero syscall implementation of that on modern x86.
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*
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* @param clockid can be CLOCK_REALTIME, CLOCK_MONOTONIC, etc. noting
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* that on Linux CLOCK_MONOTONIC is redefined to use the monotonic
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* clock that's actually monotonic lool
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* @param out_ts is where the nanoseconds are stored if non-NULL
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* @return 0 on success or -1 w/ errno on error
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* @error ENOSYS if clockid isn't available; in which case this function
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* guarantees an ordinary timestamp is still stored to out_ts; and
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* errno isn't restored to its original value, to detect prec. loss
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* @see strftime(), gettimeofday()
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* @asyncsignalsafe
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*/
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int clock_gettime(int clockid, struct timespec *out_ts) {
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/* TODO(jart): Just ignore O/S for MONOTONIC and measure RDTSC on start */
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if (!IsWindows()) {
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if (!IsXnu()) {
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if (out_ts) {
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out_ts->tv_sec = 0;
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out_ts->tv_nsec = 0;
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}
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return clock_gettime$sysv(clockid, out_ts);
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} else {
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int rc;
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static_assert(sizeof(struct timeval) == sizeof(struct timespec));
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if (out_ts) {
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out_ts->tv_sec = 0;
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out_ts->tv_nsec = 0;
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}
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rc = gettimeofday$sysv((struct timeval *)out_ts, NULL);
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if (out_ts) {
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out_ts->tv_nsec *= 1000;
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}
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return rc;
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}
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} else {
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struct NtFileTime ft;
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GetSystemTimeAsFileTime(&ft);
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*out_ts = filetimetotimespec(ft);
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return 0;
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}
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}
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