[U-Boot] [PATCH V2 1/3] memcpy: copy one word at a time if possible

[Chris Moore]

Mike Frysinger a écrit :
> On Friday 09 October 2009 06:11:16 Mark Jackson wrote:
>   
>> Chris Moore wrote:
>>     
>>> I agree wholeheartedly with the idea but shouldn't it be more like this
>>> (untested) code :
>>>
>>> void * memcpy(void *dest, const void *src, size_t count)
>>>
>>> {
>>> 	char *d8, *s8;
>>> 	unsigned long *dl = dest, *sl = src;
>>>       
>> In here, would it be overkill to add byte copying until data is aligned,
>>  and then fall into the aligned copy code.
>>     
>
> both addresses have to be unaligned the same ...
>
> if ((ulong)dl & (sizeof(*dl) - 1) == (ulong)sl & (sizeof(*sl) - 1))
>
>   
>> In that case, you'd still gain a speed increase if you're starting at an
>>  unaligned address ?
>>     
>
> now it's a question of how often does this come up and is it worth the code 
> size increase ?
>   

Like Mike I'm not sure if it is worth it for memcpy.
However it may be for memset where only the destination has to be aligned.

Chris