Hi Jiří,
Jiří Zárevúcky <[email protected]> wrote:
> Hi Miroslav,
> supporting the atomic operations you need is a simple matter of adding the
> missing functions to uspace/lib/c/arch/arm32/src/atomic.c
>
> I wouldn't worry too much about it. Use what you need, I'll help sort out the
> missing stuff if needed. :)
Thanks, I didn't know about that. I wrote implementations for:
- __atomic_compare_exchange_1 [1]
- __atomic_{load,store}_8 [2]
Could you please review them?
Other functions in uspace/lib/c/arch/arm32/src/atomic.c seem to not have a
clobber argument
"memory", even though they modify memory [3]. (I don't know if they are needed
at all:
https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#Clobbers-and-Scratch-Registers-1)
Another question: in `__atomic_fetch_add_2()' (same file) there is an `unsigned
short ret',
to which there is a *word* written to in the inline assembly RAS (Restartable
Atomic Seqeunce)
prologue, while the `ret' is half-word. Does the compiler internally promote it
to 32-bits
for the `str', `ldr', or it doesn't care as it is a register anyway? That's
also the reason
I let the `ret' in [1] be an `unsigned', instead of `unsigned char'.
... and I tried mips32 as well, the 8 byte stores and loads are missing there,
but there
is no uspace/lib/c/arch/mips32/src/atomic.c, is it technically possible to add
it?
[1]:
- branch: arm32-atomic_cmpexchg_1
(https://github.com/mcimerman/helenos/tree/arm32-atomic_cmpexchg_1)
- commit:
https://github.com/mcimerman/helenos/commit/a2332a14639bbc3b179b56366ddf2805ca2863d6
[2]:
- branch: arm32-atomic_ldr_str_8
(https://github.com/mcimerman/helenos/tree/arm32-atomic_ldr_str_8)
- commit:
https://github.com/mcimerman/helenos/commit/977df1a63f1409c1c3da4dd4a8b2e2da8fc8f634
[3]:
- branch: arm32-atomic-mem-fix
(https://github.com/mcimerman/helenos/tree/arm32-atomic-mem-fix)
- commit:
https://github.com/mcimerman/helenos/commit/958f62d64d06cdcafaf0e00fc713b455743cb58d
Thanks.
--
mc
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