[fpc-pascal] inline assembler procedure

[Florian Klaempfl]

Пётр Косаревский wrote:
> How can I write inline assembler procedure?
> 
> (FPC accepts the word "inline", but generates "call" instruction etc.)

Inline is only a recommendation.

> 
> If there is a way, could anyone point to an example, please?

Inlining assembler procedures efficently is rather hard, so we don't do
so currently.

> 
> 
> 
> 
> 
> 
> Or just remember rotating bits in fpc-devel (if I get it right, they were not implemented):
> 
> (it's i386, cyclic bitwise longword l shift to the left by c bits; c may be over 32)
> 
> function lrol(l: longword; c: byte): longword; assembler; inline; // this thing is not really inline
>    asm
>    movb  %dl,%cl
>    roll  %cl,%eax
>    end; // calling register conventions: l->eax, c->dl
> 
> (it generates
> .globl	P$P_LROL$LONGWORD$BYTE$$LONGWORD
> P$P_LROL$LONGWORD$BYTE$$LONGWORD:
> # Temps allocated between ebp-4 and ebp-4
> 	# Register ebp allocated
> 	pushl	%ebp
> 	movl	%esp,%ebp
> 	subl	$4,%esp
> # Var l located in register
> # Var c located in register
> # Temp -4,4 allocated
> # Var $result located at ebp-4
> 	# Register eax,ecx,edx allocated
> # [97] movb  %dl,%cl
> 	movb	%dl,%cl
> # [98] roll  %cl,%eax
> 	roll	%cl,%eax
> 	# Register eax,ecx,edx released
> # Temp -4,4 released
> 	leave
> 	# Register ebp released
> 	ret
> 	# Register eax released
> 
> 
> and
> 
>       (moving variables, which could already be in registers)
> 	call	P$P_LROL$LONGWORD$BYTE$$LONGWORD
> 
> where it is expected to be inlined)
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