Implementation of some string.h function using SSE2 instructions

Wojciech Muła wojciech_mula@poczta.onet.pl
Wed Aug 8 20:19:00 GMT 2007


PaweÂł Sikora wrote:
>         {
>                 __m128i m1 = *( __m128i* )( s1 );
>                 __m128i m2 = *( __m128i* )( s2 );
>                 __m128i r1 = not( _mm_cmpeq_epi8( m1, m2 ) );
>                 __m128i zero = { 0 };
>                 __m128i r2 = _mm_cmpeq_epi8( m1, zero );
>                 __m128i r3 = _mm_cmpeq_epi8( m2, zero );
>                 __m128i r = _mm_or_si128( r1, _mm_or_si128( r2, r3 ) );
>                 mask = _mm_movemask_epi8( r );
>                 if ( mask )
>                 {
>                         unsigned index = __builtin_ffs( mask ) - 1;
>                         return ( s1[ index ] - s2[ index ] );
>                 }
>         }

BTW r3 isn't needed.



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