AMD Typewriter x86 사용자 설명서

Copy Frequently De-referenced Pointer Arguments to Local Variables

AMD Athlon™ Processor x86 Code Optimization

22007E/0—November 1999

Example 1 (Avoid):

//assumes pointers are different and q!=r
void isqrt

( unsigned long a,

unsigned long *q,
unsigned long *r)

{
*q = a;
if (a > 0)

{
while (*q > (*r = a / *q))

{
*q = (*q + *r) >> 1;
}

}
*r = a - *q * *q;
}

Example 2 (Preferred):

//assumes pointers are different and q!=r
void isqrt

( unsigned long a,

unsigned long *q,
unsigned long *r)

{
unsigned long qq, rr;
qq = a;
if (a > 0)

{
while (qq > (rr = a / qq))

{
qq = (qq + rr) >> 1;
}

}
rr = a - qq * qq;
*q = qq;
*r = rr;
}