On 03-05-12 13:27, Thomas Schatzl wrote:
...
function reverse(b : byte) : byte; assembler; nostackframe;
asm
rbit r0, r0
// rbit reverses the whole word, so now you have
// your value in bits 31-24... so shift right by that amount
// should fix this up (bits 23-0 contain junk, we shift that out
// anyway)
lsr r0, r0, #24
end;
However, this may not compile because fpc may not recognize the rbit
instruction.
Following is a version that encodes the instruction directly, retrieved
from disassembling some gcc code:
function reverse(b : byte) : byte; assembler; nostackframe;
asm
.long 0xe6ff0f30 // rbit r0, r0
lsr r0, r0, #24
end;
Thanks guys, I'll try and test this weekend.
Regards,
Koenraad Lelong.
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