[XviD-devel] "restrict" keyword

[Christoph Lampert]

Hi,

does MSVC++ know about "restrict"? 

That's a new qualifier for pointer types in C99 which 
tells the compiler that the data referenced by two pointers
do not overlap. This can be interesting for optimization, 
because you know e.g. that write to an address does not change 
the value of where the other pointer points to, so you don't have to read
that value again. It's also important for memcpy() stuff.

void
fcpy(float *restrict a, float *restrict b,
     float *restrict aa, float *restrict bb, int n)
{
int i;
for(i = 0; i < n; i++) {
aa[i]=a[i];
bb[i]=b[i];
}
}

means these copy loops can be done "in parallel", because e.g. aa != b 

gcc accepts it when --std=c99 is active. 

gruel