On Tue, Apr 16, 2024 at 4:01 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio...@nec.com>
wrote:
> On 2024/04/16 15:49, Yulong Tang wrote:
> >> On Mon, Apr 15, 2024 at 2:32 PM HAGIO KAZUHITO(萩尾 一仁) <k-hagio-ab(a)
> nec.com>
> >> wrote:
> >>
> >>
> >> Sure. The macro '#if __BYTE_ORDER == __BIG_ENDIAN' takes effect on a
> >> big-endian machine. But it requires to include the header file
> 'byteswap.h'
> >> as below:
> >> #include <byteswap.h>
> >>
> >> In addition, there is a similar implementation, but I haven't tested it
> >> with Yulong's case. Can you help to check if this can work well for you?
> >> Yulong.
> >>
> >> static inline uint16_t
> >> get_unaligned_le16 (const uint8_t *p)
> >> {
> >> return p[0] | p[1] << 8;
> >> }
>
> Ah nice, this looks simple and better. If it works well on a big-endian
> machine too, let's go with this.
>
I tested these two functions with a test case, for example:
unsigned int x = 0x76543210;
big-endian machine:
call get_unaligned_le16_v1(): 0x5476
call get_unaligned_le16_v2(): 0x5476
little-endian machine:
call get_unaligned_le16_v1(): 0x3210
call get_unaligned_le16_v2(): 0x3210
---------------------------code---------------------------------------
static uint16_t get_unaligned_le16_v1(const void *p) {
uint16_t value;
memcpy(&value, p, sizeof(uint16_t));
#if __BYTE_ORDER == __BIG_ENDIAN
return bswap_16(value);
#else
return value;
#endif
}
static inline uint16_t
get_unaligned_le16_v2(const uint8_t *p)
{
return p[0] | p[1] << 8;
}
---------------------------code---------------------------------------
They have the same results on the little-endian/big-endian machine from my
side.
> >>
> >
> > Hi, Lianbo
> >
> > It works well in my case(little-endian). This looks promising, but I
> don't have a big-
Thank you for the confirmation, Yulong.
Thanks
Lianbo
endian machine to test it on.
>
> Thank you for testing, Yulong.
>
> Thanks,
> Kazu
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