On 03/02/2010 10:34 AM, Pjotr Kourzanov wrote:
>> int duff4_fails(char * dst,const char * src,const size_t n)
>> {
>> const size_t rem=n % 4, a=rem + (!rem)*4;
>> char * d=dst+=a;
>> const char * s=src+=a;
>> /* gcc bug? dst+=n; */
>>
>> switch (rem) {
>> case 0: for(dst+=n;d<dst;d+=4,s+=4) {
>> /*case 0:*/ d[-4]=s[-4];
>> case 3: d[-3]=s[-3];
>> case 2: d[-2]=s[-2];
>> case 1: d[-1]=s[-1];
>> }
>> }
>> return 0;
>> }
>> The first time around the loop the initializer (d+=n) is jumped around, so
>> d == dst. At the end of the loop, d+=4, so d > dst. Therefore the loop
>> exits.
>
> And its wrong since it shouldn't jump around the initializer.
Sure it should. On entry to that loop, rem == 3.
Andrew.
