Re: Endian swapping with C code on ARM

[Robert Dewar <dewar at gnat dot com>]

Joel Sherrill <joel@OARcorp.com> wrote:

> How about just using inline assembly like this from the RTEMS ARM port?
>
> unsigned int CPU_swap_u32(
>   unsigned int value
> )
> {
>     uint32_t   tmp = value;
>     asm volatile ("EOR   %1, %0, %0, ROR #16\n"
>                   "BIC   %1, %1, #0xff0000\n"
>                   "MOV   %0, %0, ROR #8\n"
>                   "EOR   %0, %0, %1, LSR #8\n"
>                   : "=r" (value), "=r" (tmp)
>                   : "0" (value), "1" (tmp));
>
>     return value;
> }

This is such a common operation. It seems a shame to render a program
severely target dependent just because it wants to do endianness
conversion.