• Helmut Leitner (8/8) Apr 12 2003 What is the reason that D uses a different ordering (left->right, right-...
• Walter (7/12) Apr 12 2003 right->left)
• Charles Banas (8/10) Apr 12 2003 but when interfacing with separate assembler files, this is critical
• Nic Tiger (8/19) Apr 13 2003 You certainly can declare your D func as extern(C) and interface it from...
• Walter (9/18) Apr 13 2003 best
• Charles Banas (6/12) Apr 13 2003 there are a handful of (obscure) cases where this is neither preferable ...
• Helmut Leitner (12/26) Apr 13 2003 Well, yes, I know.
• Ilya Minkov (10/15) Apr 13 2003 Sure, in current mode (if i understood it correctly), when varargs are
• Helmut Leitner (8/21) Apr 13 2003 I hope to understand the advantage of Pascal calling conventions under

Helmut Leitner <helmut.leitner chello.at> writes:

What is the reason that D uses a different ordering (left->right, right->left)
of parameters for 
   - functions/methods having fixed parameter lists (e.g. func(i,j))
   - functions/methods having variable parameter lists (e. g. func(fmt,...)
?

--
Helmut Leitner    leitner hls.via.at   
Graz, Austria   www.hls-software.com

"Walter" <walter digitalmars.com> writes:

"Helmut Leitner" <helmut.leitner chello.at> wrote in message
news:3E9848DB.BB70783 chello.at...
 What is the reason that D uses a different ordering (left->right,

right->left)
 of parameters for
    - functions/methods having fixed parameter lists (e.g. func(i,j))

It varies depending on the function type (C, Windows, D, etc.). It's best
not to rely on a particular order.

    - functions/methods having variable parameter lists (e. g.

func(fmt,...)
 ?

For compatibility with C, and the normal way C accesses variable arguments.

Charles Banas <greywolf greyfade.net> writes:

On Sat, 12 Apr 2003 13:08:03 -0700, Walter <walter digitalmars.com> wrote:

 It varies depending on the function type (C, Windows, D, etc.). It's best
 not to rely on a particular order.

but when interfacing with separate assembler files, this is critical 
knowledge in most cases.  after a quick look through the specs, i don't see 
if it's documented anywhere, which IMHO, is a problem.  if i were to write 
a snippet of ASM code and needed to call a D function with parameters, how 
would i do this?

-- 
Charles "grey wolf" Banas

"Nic Tiger" <nictiger progtech.ru> writes:

You certainly can declare your D func as extern(C) and interface it from ASM
as usual C function (BTW, no mangling weirdness and other).
I think it is possible in most cases.

Nic Tiger.

"Charles Banas" <greywolf greyfade.net> ???????/???????? ? ????????
?????????: news:oprnj09xca8ctebf news.digitalmars.com...
 On Sat, 12 Apr 2003 13:08:03 -0700, Walter <walter digitalmars.com> wrote:

 It varies depending on the function type (C, Windows, D, etc.). It's


best
 not to rely on a particular order.

 but when interfacing with separate assembler files, this is critical
 knowledge in most cases.  after a quick look through the specs, i don't

see
 if it's documented anywhere, which IMHO, is a problem.  if i were to write
 a snippet of ASM code and needed to call a D function with parameters, how
 would i do this?

 --
 Charles "grey wolf" Banas

"Walter" <walter digitalmars.com> writes:

"Charles Banas" <greywolf greyfade.net> wrote in message
news:oprnj09xca8ctebf news.digitalmars.com...
 On Sat, 12 Apr 2003 13:08:03 -0700, Walter <walter digitalmars.com> wrote:

 It varies depending on the function type (C, Windows, D, etc.). It's


best
 not to rely on a particular order.

 but when interfacing with separate assembler files, this is critical
 knowledge in most cases.  after a quick look through the specs, i don't

see
 if it's documented anywhere, which IMHO, is a problem.  if i were to write
 a snippet of ASM code and needed to call a D function with parameters, how
 would i do this?

Two choices:

1) declare the function as extern (C) and write your asm function like it
was connecting to a C function.

2) use the inline assembler, which will get the right stack offsets for the
parameters automatically.

Charles Banas <greywolf greyfade.net> writes:

On Sun, 13 Apr 2003 14:13:27 -0700, Walter <walter digitalmars.com> wrote:

 Two choices:

 1) declare the function as extern (C) and write your asm function like it
 was connecting to a C function.

thank you.  i really should learn to think more in depth.

 2) use the inline assembler, which will get the right stack offsets for 
 the
 parameters automatically.

there are a handful of (obscure) cases where this is neither preferable nor 
desirable.  though, if the compiler properly inlines, helpful.


-- 
Charles "grey wolf" Banas

Helmut Leitner <helmut.leitner chello.at> writes:

Walter wrote:
 
 "Helmut Leitner" <helmut.leitner chello.at> wrote in message
 news:3E9848DB.BB70783 chello.at...
 What is the reason that D uses a different ordering (left->right,

 right->left)
 of parameters for
    - functions/methods having fixed parameter lists (e.g. func(i,j))

 It varies depending on the function type (C, Windows, D, etc.). It's best
 not to rely on a particular order.

Well, yes, I know. 
 
    - functions/methods having variable parameter lists (e. g.

 func(fmt,...)
 ?

 
 For compatibility with C, and the normal way C accesses variable arguments.

I understand this. 

Still I do not understand the need to have two different orderings within D 
itself. If there is a single cycle of performance you get out of this, ok.

But otherwise I would refer to Occam's racor not to deviate from C ordering
and not to introduce a piece of complexity unneeded.

The way it is makes general fp / dg call interfaces more difficult to construct.

--
Helmut Leitner    leitner hls.via.at   
Graz, Austria   www.hls-software.com

Ilya Minkov <midiclub 8ung.at> writes:

Helmut Leitner wrote:
 I understand this.
 
 Still I do not understand the need to have two different orderings
 within D itself. If there is a single cycle of performance you get
 out of this, ok.

Sure, in current mode (if i understood it correctly), when varargs are
used, D uses C calling convention, and when not, a Pascal-like
convention, where the called function cleans up the stack, as opposed to
C, where the caller does. This results in faster calls and less object
code size.

The D calling convention is also subject to change to allow for further
optimisation. To get a well-defined calling convention, use "extern" C
or Pascal option.

-i.

Helmut Leitner <helmut.leitner chello.at> writes:

Ilya Minkov wrote:
 
 Helmut Leitner wrote:
 I understand this.

 Still I do not understand the need to have two different orderings
 within D itself. If there is a single cycle of performance you get
 out of this, ok.

 
 Sure, in current mode (if i understood it correctly), when varargs are
 used, D uses C calling convention, and when not, a Pascal-like
 convention, where the called function cleans up the stack, as opposed to
 C, where the caller does. This results in faster calls and less object
 code size.

I hope to understand the advantage of Pascal calling conventions under
certain circumstances. But I think the advantage comes from having a 
fixed size parameter list, not from ordering the parameters (a,b,c) 
instead of (c,b,a).

--
Helmut Leitner    leitner hls.via.at   
Graz, Austria   www.hls-software.com