what is faster?

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f0dder

Joined: 19 Feb 2004
Posts: 3170
Location: Denmark

f0dder

edfed wrote:

Mode 13h is good enough.

Suuuuuuuuuuuuuuuuuuuuuuuuuuuuuure thing Smile

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- carpe noctem

28 Feb 2011, 22:14

Teehee

Joined: 05 Aug 2009
Posts: 570
Location: Brazil

Teehee

Hi.

i made this function (32bits):

Code:

    drawchar:
        ;mov   ebx,a
        add   edi,1280*4*(8-1)-4
        mov   eax,ebx
        add   ebx,8*8-1
  .nxty:mov   ecx,8
  .nxtx:cmp   byte[ebx],0
        je    @f
        mov   dword[edi+ecx*4],-1 ; set pixel color
     @@:dec   ebx
        dec   ecx
        jnz  .nxtx
        sub   edi,1280*4
        cmp   ebx,eax
        jnbe .nxty
        ret

Is it good for performance to change some registers to a small ones? like (just a example, idunno if its right):

Code:

    drawchar:
        ;mov   bx,a
        add   edi,1280*4*(8-1)-4
        mov   ax,bx
        add   bx,8*8-1
  .nxty:mov   cl,8
  .nxtx:cmp   byte[bx],0
        je    @f
        mov   dword[edi+ecx*4],-1 ; set pixel color
     @@:dec   bx
        dec   cl
        jnz  .nxtx
        sub   edi,1280*4
        cmp   bx,ax
        jnbe .nxty
        ret

07 Mar 2011, 19:52

Teehee

Joined: 05 Aug 2009
Posts: 570
Location: Brazil

Teehee

please i really would like to know that.

08 Mar 2011, 15:52

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 18844
Location: In your JS exploiting you and your system

revolution

Teehee wrote:

Is it good for performance to change some registers to a small ones?

Have you read some of the posts about "which is faster"? To answer your question accurately: No one knows. The reason no one knows is that the answer depends upon so many factors that it is impossible to say what is, or is not, good for performance. Here is a suggestion though: test it. If you find it is faster for you, in your system, with your setup, etc. then go ahead and use it.

24 Mar 2011, 02:00

iic2

Joined: 26 Jun 2008
Posts: 122

iic2

Quote:

Teehee wrote: Is it good for performance to change some registers to a small ones?

I been looking for this on my machine for over a week. Come to find it's in the new version of masm32. Those doc's apply here also. The author always said that by the byte can be quicker than dword. I tested before and it's true. A flare will hit 1000 feet long before Apollo even leave the ground. So smaller can be faster. You got to test these days darn near along because nothing is standard anymore but this should still serve as an base-line at the very lease.

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06 Apr 2011, 11:07

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