.FOR built in JWasm

[Gunther]

Good to know habran.  :t

Gunther

[habran]

I have modified code to work exactly as C

[frktons]

I have modified code to work exactly as C

Interesting stuff. JWasm is written in C, and now we can use JWasm as C in some
of its features. At least I hope the JWasm version is faster/smarter/smaller/...er than
C counterpart.   :t

[habran]

"Frankly" it's well optimized
I've wished someone gave me a feedback after testing it

thanks Frank

[jj2007]

 :icon_confused:

I've wished someone gave me a feedback after testing it

JWasm32 told me that MSVCR110.dll was missing (on Win7-32). After fixing this, here are some timings:
AMD Athlon(tm) Dual Core Processor 4450B (SSE3)

22317   cycles for 100 * C style for loop
31539   cycles for 100 * Basic style for loop

14      bytes for C style for loop
30      bytes for Basic style for loop

So your code is really competitive :t
Here are the two loops compared:

        m2m eax, 40
        .for (ecx = 0¦ecx<=eax¦ecx+=1)
                inc edx        ; inc eax hangs
        .endfor

        m2m eax, 41
        For_ ecx=0 To eax-1
                inc eax        ; inc eax OK
        Next

The Basic loop is a bit more flexible, as it can handle eax+whatever, and references to the initial eax (or whatever) while looping. On the other hand, the C loop is shorter and faster. In real life, if speed was an issue, I would use a .Repeat ... .Until construct anyway, but I guess for C coders your add-on to JWasm is really handy :t

P.S.: I made a little test with Pelles C:

      int n=100;
      __asm int 3;
      __asm nop;
         for (jjc=0; jjc<n; jjc++) {
         n++;
      }
      __asm nop;

00401DD5  |.  90            nop
00401DD6  |.  31C0          xor eax, eax
00401DD8  |.  BA 64000000   mov edx, 64
00401DDD  |>  42            /inc edx
00401DDE  |.  40            |inc eax
00401DDF  |.  39D0          |cmp eax, edx
00401DE1  |.^ 7C FA         \jl short 00401DDD
00401DE3  |.  90            nop

Heavily optimised (bravo, Pelle :t), and it seems indeed that C keeps referring to the current loop counter, i.e. this loop stops only for edx = 80000000h 8)

[habran]

thanks JJ for testing it
if you write it like this:

Code: [Select]

       
         .for (ecx = 0¦ecx<=40¦ecx++)
                inc eax       
        .endfor

you will get:

Code: [Select]

004C879  xor     ecx,ecx
004C87B  jmp    004C87Fh
004C87D  inc     ecx 
004C87F  cmp    ecx,28h
004C882  ja      004C888h
004C884  inc     eax 
004C886  jmp    004C87Dh

I have optimized it so that:
  ++ will be transformed to INC
  -- will be transformed to DEC
but:
 += is ADD
and:
 -= is SUB

[frktons]

thanks JJ for testing it
if you write it like this:

Code: [Select]

       
         .for (ecx = 0¦ecx<=40¦ecx++)
                inc eax       
        .endfor

you will get:

Code: [Select]

004C879  xor     ecx,ecx
004C87B  jmp    004C87Fh
004C87D  inc     ecx 
004C87F  cmp    ecx,28h
004C882  ja      004C888h
004C884  inc     eax 
004C886  jmp    004C87Dh


Compliments habran, a really good job.   

[habran]

Thanks Frank

One who can see quality of others, posses quality himself
    who wrote that? :shock:
      habran himself  :lol:

[habran]

I added Jwasm.zip with 32 bits version with /MT option

needs at least Windows version 6
(Japheth)

however, you have a source code and can build for your system if it is older

[japheth]

I added Jwasm.zip with 32 bits version with /MT option

It should be noted that the binary is marked as "needs at least Windows version 6" ( which is Vista ). With XP, you get a message box saying that jwasm.exe "is not a valid Win32 application".

[jj2007]

 :redface:

thanks JJ for testing it
if you write it like this:

Code: [Select]

       
         .for (ecx = 0¦ecx<=40¦ecx++)
                inc eax       
        .endfor


Habran,

The immediate case ecx<=40 is trivial. More tricky is what happens when you pass the bounds in (volatile/non-volatile) registers:
        ; assume eax was set somewhere else, as a return value:
        .for (ecx = 0¦ecx<=eax¦ecx+=1)
                inc eax        ; hangs in C/your JWasm version, in contrast to BASIC/MasmBasic
        .endfor

The point is that ecx<=eax is not checked only at the beginning, but rather for every loop. Which implies that in practice you cannot use eax, ecx, edx for bounds if calls are inside the loops.

In MasmBasic it's possible, which is the reason why it is some cycles slower. Speed against convenience, as usual 

[habran]

thanks Japheth I was not aware of that
I don't have Xp nor Vista I have Windos 7 on all computers

jj2007 it is possible to write this:

Code: [Select]

LIMIT EQU 40
THE_BREAK EQU 20
.for (ecx = 0,eax=LIMIT,edx=THE_BREAK¦ecx<=eax¦ecx++)
                ;inc eax      it is illogical to increase a LIMIT especially with the same step
                                  ;of course it will hang
                .break .if (ecx > edx)
        .endfor

 

[jj2007]

                ;inc eax      it is illogical to increase a LIMIT especially with the same step

It depends on where you come from. For C coders, it may look illogical, but assembler coders might want to use return values directly...

include \masm32\MasmBasic\MasmBasic.inc        ; download
        Init
        GetFiles \Masm32\m32lib\*to*        ; list conversion to something algos please

        ; # of files found is returned in eax, as usual
        For_ ebx=0 To eax-1        ; it is illogical to forbid the use of eax inside the loop
                Print Str$(ebx), Tb$, Files$(ebx), CrLf$
        Next

        Inkey
        Exit
end start

And no, I don't want you to change your logic

[japheth]

The point is that ecx<=eax is not checked only at the beginning, but rather for every loop.

Yes, of course. Anything else would be VERY unintuitive ( at least for non-BASIC coders ).

In MasmBasic it's possible, which is the reason why it is some cycles slower. Speed against convenience, as usual

... another MB promotion thread ...  :icon_rolleyes:

[jj2007]

Yes, of course. Anything else would be VERY unintuitive

japheth,

Take it easy. Assembler != C, and assuming some"logic" is a source of difficult to chase bugs. Remember the debate about Switch/Case and falling thru? VERY unintuitive what C does, at least for the rest of the programming world.