If you want to go assembly:
function ReverseBits(const Value: LongWord): LongWord; register; assembler;
asm
BSWAP EAX
MOV EDX, EAX
AND EAX, 0AAAAAAAAh
SHR EAX, 1
AND EDX, 055555555h
SHL EDX, 1
OR EAX, EDX
MOV EDX, EAX
AND EAX, 0CCCCCCCCh
SHR EAX, 2
AND EDX, 033333333h
SHL EDX, 2
OR EAX, EDX
MOV EDX, EAX
AND EAX, 0F0F0F0F0h
SHR EAX, 4
AND EDX, 00F0F0F0Fh
SHL EDX, 4
OR EAX, EDX
end;
On Thu, May 3, 2012 at 9:10 AM, Koenraad Lelong <
fpas...@brouwerij.homelinux.net> wrote:
> Hi,
>
> I'm porting a driver, originally written in C, for an LCD to be used with
> an embedded arm-processor (STM32).
> The original driver uses SPI, my driver will use a USART in synchronous
> mode because the STM32 has no SPI for 9-bit. Unfortunately, the bit-order
> is reversed between SPI and USART transmission.
> Does anyone knows an efficient way to reverse bit-order of a byte for the
> arm-processor ? I'm going to look into the assembly language of the
> arm-processor, but maybe someone knows this immediately.
> For old processors like 8085 or Z80 I know how to do this, but
> arm-assembler is new to me.
>
> Thanks for any hints.
>
> Koenraad Lelong.
> ______________________________**_________________
> fpc-pascal maillist -
> fpc-pascal@lists.freepascal.**org<fpc-pascal@lists.freepascal.org>
> http://lists.freepascal.org/**mailman/listinfo/fpc-pascal<http://lists.freepascal.org/mailman/listinfo/fpc-pascal>
>
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