> On 24 mei 2006, at 10:56, Пётр Косаревский wrote:
> > Is there high level operator/(inline)function for rotating bits?
> No.
> > Am I supposed to implement rotating bits (like ror/rol in i386 asm)
> > by inline assembler or some ugly workarounds (shifts and or-s)?
> Yes. I think there's already a feature request to provide these
> operations, but no one worked on it yet.
> Jonas_______________________________________________
Why don't use this code?
{$INLINE ON}
interface
{$IFDEF CPUI386}
function brol(b: byte; c: byte): byte; assembler; inline;
function wrol(w: word; c: byte): word; assembler; inline;
function lrol(l: longword; c: byte): longword; assembler; inline;
function bror(b: byte; c: byte): byte; assembler; inline;
function wror(w: word; c: byte): word; assembler; inline;
function lror(l: longword; c: byte): longword; assembler; inline;
{$ELSE}
function brol(b: byte; c: byte): byte; inline;
function wrol(w: word; c: byte): word; inline;
function lrol(l: longword; c: byte): longword; inline;
function bror(b: byte; c: byte): byte; inline;
function wror(w: word; c: byte): word; inline;
function lror(l: longword; c: byte): longword; inline;
{$ENDIF}
implementation
{$IFDEF CPUI386}
function brol(b: byte; c: byte): byte; assembler; inline;
asm
movb b,%al
movb c,%cl
rolb %cl,%al
movb %al,result
end ['al','cl'];
function wrol(w: word; c: byte): word; assembler; inline;
asm
movw w,%ax
movb c,%cl
rolw %cl,%ax
movw %ax,result
end ['ax','cl'];
function lrol(l: longword; c: byte): longword; assembler; inline;
asm
movl l,%eax
movb c,%cl
roll %cl,%eax
movl %eax,result
end ['eax','cl'];
function bror(b: byte; c: byte): byte; assembler; inline;
asm
movb b,%al
movb c,%cl
rorb %cl,%al
movb %al,result
end ['al','cl'];
function wror(w: word; c: byte): word; assembler; inline;
asm
movw w,%ax
movb c,%cl
rorw %cl,%ax
movw %ax,result
end ['ax','cl'];
function lror(l: longword; c: byte): longword; assembler; inline;
asm
movl l,%eax
movb c,%cl
rorl %cl,%eax
movl %eax,result
end ['eax','cl'];
{$ELSE}
function brol(b: byte; c: byte): byte; inline;
var s,r: byte;
begin
s:=c and $7;
r:=byte(b shl s);
r:=r or byte(b shr (8-s)); // c may be over 8 and should be processed
correctly
brol:=r; // "result" is not supported in inline procedures
end;
function wrol(w: word; c: byte): word; inline;
var s: byte; r: word;
begin
s:=c and $f;
r:=word(w shl s);
r:=r or word(w shr (16-s)); // c may be over 16 and should be processed
correctly
wrol:=r;
end;
function lrol(l: longword; c: byte): longword; inline;
var s: byte; r: longword;
begin
s:=c and $1f;
r:=longword(l shl s);
r:=r or longword(l shr (32-s)); // c may be over 32 and should be processed
correctly
lrol:=r;
end;
function bror(b: byte; c: byte): byte; inline;
var s,r: byte;
begin
s:=c and $7;
r:=byte(b shr s);
r:=r or byte(b shl (8-s)); // c may be over 8 and should be processed
correctly
bror:=r;
end;
function wror(w: word; c: byte): word; inline;
var s: byte; r: word;
begin
s:=c and $f;
r:=word(w shr s);
r:=r or word(w shl (16-s)); // c may be over 16 and should be processed
correctly
wror:=r;
end;
function lror(l: longword; c: byte): longword; inline;
var s: byte; r: longword;
begin
s:=c and $1f;
r:=longword(l shr s);
r:=r or longword(l shl (32-s)); // c may be over 32 and should be processed
correctly
lror:=r;
end;
{$ENDIF}
Comments:
I. style/consistency
I didn't use all needed {$if}s: current code should word with range
checks on both on i386 and not.
{$Asmmode} was not used either.
First symbol denotes type: while shl/shr emit longword, cyclic shifts
shouldn't
Endianness is not supported, because I don't understand, why it should be.
II. performance
"Result" is not supported in the inline mode.
I don't know how to use "ret" to achieve the same goal with fewer
commands.
Test:
{$INLINE ON}
program testb;
uses commonthingies;
var i: byte; b: byte; w: word; l: longword;
begin
write('Enter byte (dec):');readln(b);
for i:=0 to 16 do
writeln('Orig:',binstr(b,8),' Left:',binstr(brol(b,i),8),'
Right:',binstr(bror(b,i),8));
write('Enter word (dec):');readln(w);
for i:=0 to 32 do
writeln('Orig:',binstr(w,16),' Left:',binstr(wrol(w,i),16),'
Right:',binstr(wror(w,i),16));
write('Enter lw (dec) :');readln(l);
for i:=0 to 64 do
writeln('Orig:',binstr(l,32),' Left:',binstr(lrol(l,i),32),'
Right:',binstr(lror(l,i),32));
end.
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