Справочник Пользователя для AMD 250

25112

Rev. 3.06

September 2005

Dynamic memory allocation—accomplished through the use of the 

malloc

 library function in C—

should always return a pointer that is suitably aligned for the largest base type (quadword alignment). 
Where this aligned pointer cannot be guaranteed, use the technique shown in the following code to 
make the pointer quadword aligned, if needed. This code assumes that it is possible to cast the pointer 
to a 

long

.

double *p;

double *np;

p  = (double *)malloc(sizeof(double) * number_of_doubles + 7L);

np = (double *)((((long)(p)) + 7L) & (-8L));

Then use 

np

 instead of 

p

 to access the data. The pointer 

p

 is still needed in order to deallocate the 

storage.

This optimization applies to:

•

32-bit software

•

64-bit software