I use this for cross plattform:
function shr_int32(i ,shift : longint ) : longint; inline;
begin
Result:= i div (1 shl shift);
end;
Am 09.03.2012 08:46, schrieb Graeme Geldenhuys:
Hi,
Can anybody with Assembly knowledge help convert 3 methods in AggPas
(<lcl>/components/aggpas/src) so that it could work under x86_64
systems?
The three methods are shr_int6(), shr_int16() and shr_int32() defined
inside the agg_basics.pas unit.
For example, here is a one method that is often called, but because
there is no 64-bit x86_64 implementation, the agg output is not
correct (compared to the 32-bit version of my program).
function shr_int32;
begin
{$IFDEF AGG_CPU_386 }
asm
mov eax ,dword ptr [i ]
mov ecx ,dword ptr [shift ]
sar eax ,cl
mov dword ptr [result ] ,eax
end;
{$ENDIF }
{$IFDEF AGG_CPU_PPC }
asm
lwz r3,i
lwz r2,shift
sraw r3,r3,r2
stw r3,result
end;
{$ENDIF }
end;
I know FPC has built-in 'shr' functionality, but it seems Agg needs a
specific implementation to be compatible with the C compilers. As
noted by the code comment in the agg_basic.pas unit.
// SHR for signed integers is differently implemented in pascal compilers
// than in c++ compilers. On the assembler level, c++ is using the SAR and
// pascal is using SHR. That gives completely different result, when the
// number is negative. We have to be compatible with c++ implementation,
// thus instead of directly using SHR we emulate c++ solution.
Any help would be very much appreciated, thanks.
--
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