cosmopolitan/libc/nt/API-MS-Win-Core-Realtime-l1-1-1/QueryInterruptTimePrecise.S
Justine Tunney dd8544c3bd
Delve into clock rabbit hole
The worst issue I had with consts.sh for clock_gettime is how it defined
too many clocks. So I looked into these clocks all day to figure out how
how they overlap in functionality. I discovered counter-intuitive things
such as how CLOCK_MONOTONIC should be CLOCK_UPTIME on MacOS and BSD, and
that CLOCK_BOOTTIME should be CLOCK_MONOTONIC on MacOS / BSD. Windows 10
also has some incredible new APIs, that let us simplify clock_gettime().

  - Linux CLOCK_REALTIME         -> GetSystemTimePreciseAsFileTime()
  - Linux CLOCK_MONOTONIC        -> QueryUnbiasedInterruptTimePrecise()
  - Linux CLOCK_MONOTONIC_RAW    -> QueryUnbiasedInterruptTimePrecise()
  - Linux CLOCK_REALTIME_COARSE  -> GetSystemTimeAsFileTime()
  - Linux CLOCK_MONOTONIC_COARSE -> QueryUnbiasedInterruptTime()
  - Linux CLOCK_BOOTTIME         -> QueryInterruptTimePrecise()

Documentation on the clock crew has been added to clock_gettime() in the
docstring and in redbean's documentation too. You can read that to learn
interesting facts about eight essential clocks that survived this purge.
This is original research you will not find on Google, OpenAI, or Claude

I've tested this change by porting *NSYNC to become fully clock agnostic
since it has extensive tests for spotting irregularities in time. I have
also included these tests in the default build so they no longer need to
be run manually. Both CLOCK_REALTIME and CLOCK_MONOTONIC are good across
the entire amd64 and arm64 test fleets.
2024-09-04 01:32:46 -07:00

20 lines
413 B
ArmAsm

#include "libc/nt/codegen.h"
.imp API-MS-Win-Core-Realtime-l1-1-1,__imp_QueryInterruptTimePrecise,QueryInterruptTimePrecise
.text.windows
.ftrace1
QueryInterruptTimePrecise:
.ftrace2
#ifdef __x86_64__
push %rbp
mov %rsp,%rbp
mov %rdi,%rcx
sub $32,%rsp
call *__imp_QueryInterruptTimePrecise(%rip)
leave
#elif defined(__aarch64__)
mov x0,#0
#endif
ret
.endfn QueryInterruptTimePrecise,globl
.previous