The `_mm_set1_ps` function is an intrinsic in the SSE (Streaming...

The _mm_set1_ps function is an intrinsic in the SSE (Streaming SIMD Extensions) intrinsics library provided by Intel. Specifically, it is part of the SSE instruction set for working with 128-bit SIMD (Single Instruction, Multiple Data) operations.

What it does:

_mm_set1_ps sets all four single-precision floating-point values in a 128-bit SIMD register (__m128) to the same specified value. In other words, it broadcasts (duplicates) a single float into all four elements of the SIMD register.

Syntax:

__m128 _mm_set1_ps(float a);

Explanation:

• Input: A single float value a.
• Output: A __m128 register where all four slots (elements) are filled with the value of a.

Example in code:

#include <xmmintrin.h>
#include <stdio.h>

int main() {
    float value = 3.14f;
    __m128 result = _mm_set1_ps(value);

    // Printing the result (cast to an array for demonstration purposes)
    float array[4];
    _mm_storeu_ps(array, result); // Store the SIMD register values into a normal array for printing

    printf("Result: %f %f %f %f\n", array[0], array[1], array[2], array[3]);
    return 0;
}

Output:

Result: 3.140000 3.140000 3.140000 3.140000

Use case:

This is typically used in situations where you want to initialize all elements of a SIMD register to the same value for parallelized computations in programs that benefit from vectorized processing (e.g., graphics, scientific computing, game development, etc.).