PureBasic Forums - English

Hello,

Just out of curiosity, I've looked at the /COMMENTED ASM output, and noticed the following :

; CopyMemory(*Fromaddr, *Toaddr, 5)
PUSH dword 5
PUSH dword [esp+PS28+4]
PUSH dword [esp+PS28+12]
CALL _PB_CopyMemory@12

Isn't it possible to copy directly the memory in pure ASM ?
MOV eax, Fromaddr
MOV Toaddr, eax

I'm sure it's not that simple, it would have already been implemented if it was Just wondering if it's possible to do it only in ASM, and if yes (and how) is there any speed gain ?
I found on the forum a post about an optimised CopyMemory for AMD processors, but it was rather complex.

Nothing urgent, but if you know the answer... thanks you in advance

newbie wrote:Hello,

Just out of curiosity, I've looked at the /COMMENTED ASM output, and noticed the following :

; CopyMemory(*Fromaddr, *Toaddr, 5)
PUSH dword 5
PUSH dword [esp+PS28+4]
PUSH dword [esp+PS28+12]
CALL _PB_CopyMemory@12

Not sure how PB's code is, but I assume Fred made his own code for it.

newbie wrote:Isn't it possible to copy directly the memory in pure ASM ?
MOV eax, Fromaddr
MOV Toaddr, eax

That would just copy the pointers.

newbie wrote:I'm sure it's not that simple, it would have already been implemented if it was Just wondering if it's possible to do it only in ASM, and if yes (and how) is there any speed gain ?
I found on the forum a post about an optimised CopyMemory for AMD processors, but it was rather complex.

Nothing urgent, but if you know the answer... thanks you in advance

Your own asm copymem if it was to work on any x86 cpu would be limited to 4 bytes (32bit) and would be a asm loop somewhat similar to the above.
One can get a larger speedup using asm and mmx registers though.
I'm not sure if PB has a mmx optimized routine or not available. (cpu choice in compile options) though...