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https://github.com/apache/nuttx.git
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61caf7cce9
in arm64 Let's see how the following code looks like in assembly
volatile cpu_set_t g_cpu_set;
cpu_set_t set_cpu_set_t_set(int cpu) {
g_cpu_set &= ~(1 << cpu);
return g_cpu_set;
}
when
typedef volatile uint32_t cpu_set_t;
Dump of assembler code for function set_cpu_set_t_set:
0x0000000040288570 <+0>: adrp x2, 0x403ce000 <g_irqvector+1160>
0x0000000040288574 <+4>: ldr w3, [x2, #2368]
0x0000000040288578 <+8>: mov w1, #0x1
0x000000004028857c <+12>: lsl w1, w1, w0
0x0000000040288580 <+16>: bic w1, w3, w1
0x0000000040288584 <+20>: str w1, [x2, #2368]
0x0000000040288588 <+24>: ldr w0, [x2, #2368]
0x000000004028858c <+28>: ret
when
typedef volatile uint8_t cpu_set_t;
Dump of assembler code for function set_cpu_set_t_set:
0x000000004028856c <+0>: adrp x2, 0x403ce000 <g_irqvector+1192>
0x0000000040288570 <+4>: ldrb w3, [x2, #2336]
0x0000000040288574 <+8>: mov w1, #0x1
0x0000000040288578 <+12>: and w3, w3, #0xff // At this time, there will be one more instruction
0x000000004028857c <+16>: lsl w1, w1, w0
0x0000000040288580 <+20>: bic w1, w3, w1
0x0000000040288584 <+24>: strb w1, [x2, #2336]
0x0000000040288588 <+28>: ldrb w0, [x2, #2336]
0x000000004028858c <+32>: ret
test:
We can use qemu for testing.
compiling
make distclean -j20; ./tools/configure.sh -l qemu-armv8a:nsh_smp ;make -j20
running
qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic -machine virt,virtualization=on,gic-version=3 -net none -chardev stdio,id=con,mux=on -serial chardev:con -mon chardev=con,mode=readline -kernel ./nuttx
Signed-off-by: hujun5 <hujun5@xiaomi.com>
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| .. | ||
| android | ||
| arpa | ||
| crypto | ||
| cxx | ||
| net | ||
| netinet | ||
| netpacket | ||
| nuttx | ||
| ssp | ||
| sys | ||
| .gitignore | ||
| aio.h | ||
| alloca.h | ||
| assert.h | ||
| byteswap.h | ||
| ctype.h | ||
| debug.h | ||
| dirent.h | ||
| dlfcn.h | ||
| dsp.h | ||
| dspb16.h | ||
| elf.h | ||
| elf32.h | ||
| elf64.h | ||
| endian.h | ||
| err.h | ||
| errno.h | ||
| execinfo.h | ||
| fcntl.h | ||
| fixedmath.h | ||
| fnmatch.h | ||
| ftw.h | ||
| getopt.h | ||
| glob.h | ||
| grp.h | ||
| hex2bin.h | ||
| iconv.h | ||
| ifaddrs.h | ||
| inttypes.h | ||
| iso646.h | ||
| langinfo.h | ||
| libgen.h | ||
| libintl.h | ||
| limits.h | ||
| locale.h | ||
| lzf.h | ||
| malloc.h | ||
| mqueue.h | ||
| netdb.h | ||
| nl_types.h | ||
| nxflat.h | ||
| obstack.h | ||
| poll.h | ||
| pthread.h | ||
| pty.h | ||
| pwd.h | ||
| regex.h | ||
| resolv.h | ||
| sched.h | ||
| search.h | ||
| semaphore.h | ||
| signal.h | ||
| spawn.h | ||
| stdbool.h | ||
| stddef.h | ||
| stdint.h | ||
| stdio.h | ||
| stdlib.h | ||
| stdnoreturn.h | ||
| string.h | ||
| strings.h | ||
| syscall.h | ||
| syslog.h | ||
| termios.h | ||
| threads.h | ||
| time.h | ||
| unistd.h | ||
| utime.h | ||
| uuid.h | ||
| wchar.h | ||
| wctype.h | ||