Developer Guide and Reference


Programming Example

This sample program uses the
class to average the elements of a twenty element floating point array.
//Include Intel® Streaming SIMD Extension (Intel® SSE) Class Definitions  #include <fvec.h> //Shuffle any two single precision floating point from a //into low two SP FP and shuffle any two SP FP from b //into high two SP FP of destination   #define SHUFFLE(a,b,i) (F32vec4)_mm_shuffle_ps(a,b,i) #include <stdio.h> #define SIZE 20 //Global variables  float result; _MM_ALIGN16 float array[SIZE]; //***************************************************** // Function: Add20ArrayElements // Add all the elements of a twenty element array //***************************************************** void Add20ArrayElements (F32vec4 *array, float *result) {    F32vec4 vec0, vec1;    vec0 = _mm_load_ps ((float *) array); // Load array's first four floats    //*****************************************************    // Add all elements of the array, four elements at a time    //******************************************************    vec0 += array[1]; // Add elements 5-8    vec0 += array[2]; // Add elements 9-12    vec0 += array[3]; // Add elements 13-16    vec0 += array[4]; // Add elements 17-20    //*****************************************************    // There are now four partial sums.    // Add the two lowers to the two raises,    // then add those two results together    //*****************************************************    vec1 = SHUFFLE(vec1, vec0, 0x40);    vec0 += vec1;    vec1 = SHUFFLE(vec1, vec0, 0x30);    vec0 += vec1;    vec0 = SHUFFLE(vec0, vec0, 2);    _mm_store_ss (result, vec0); // Store the final sum } void main(int argc, char *argv[]) {    int i;   //Initialize the array    for (i=0; i < SIZE; i++) { array[i] = (float) i; } //Call function to add all array elements    Add20ArrayElements (array, &result); //Print average array element value    printf ("Average of all array values = %f\n", result/20.);    printf ("The correct answer is %f\n\n\n", 9.5); }

Product and Performance Information


Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804