Date: Thu, 23 Feb 1995 20:12:54 -0500 (CDT)
From: Aaron Ucko <UCKO AT VAX1 DOT ROCKHURST DOT EDU>
Subject: Re: Inline asm and structs
To: ldoan1 AT osf1 DOT gmu DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Organization: Rockhurst College; Kansas City, MO

>> 	long	x;
>> 
>> 	asm(
>> 	"movl	$0, _x\n"
>> 	::);
>> 
>> (provided x is global/static), but how can I do the equivalent of C
>> 
>> typedef struct
>> {
>> 	long	first;
>> 	long	second;
>> } vector;
>> 
>> vector	data[10];
>> 
>> for (x=0; x < 10; x++)
>> {
>> 	data[x].first = 0;
>> }
>
>I'm not sure if this works, but give it a try:

Why do you want to do this in the first place?  GCC generally produces
rather efficient code; if part of your program is too slow, it's more
likely due to a bad algorithm than to a suboptimal implementation of a
good one.  Look at the assembly generated by GCC (with the `-S' flag)
before trying to optimize it.  

NB:  These opinions are regurgitated but seem reasonable to me.

>
>  asm ("\n\
>        push %eax               \n\
>        push %ebx               \n\
>        push %ecx               \n\
>        movl _data, %ebx        \n\
>        xorl %eax, %eax         \n\
>        xorl %ecx, %ecx         \n\
>L_jump_label:                   \n\
>        movl $0x0, (%ebx, %eax,)\n\
>        addl $0x8, %eax         \n\
>        addl $0x1, %ecx         \n\
>        cmp  $0xa, %ecx         \n\
>        jnz  L_jump_label       \n\
>        pop  %ecx               \n\
>        pop  %ebx               \n\
>        pop  %eax               \n\
>       ");
>
>Hope that helps,
>Long.
>         
>
>+--------------------------------------------------------+
>| Long Doan                          ldoan1 AT osf1 DOT gmu DOT edu |
>|                                          ld AT netrix DOT com |
>+--------------------------------------------------------+
>




--- Aaron Ucko (ucko AT vax1 DOT rockhurst DOT edu; finger for PGP public key) -=- httyp!
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