War diese Seite hilfreich?
Ihr Feedback ist uns wichtig. Teilen Sie uns Ihre Meinung mit.
Weiteres Feedback?
1500 verbleibende Zeichen
Exportieren (0) Drucken
Alle erweitern
Erweitern Minimieren
Wichtig Dieses Dokument enthält ggf. nicht die bewährten Methoden für die aktuelle Entwicklung. Außerdem sind Links zu Downloads und anderen Ressourcen u. U. nicht mehr gültig. Die aktuell empfohlene Version finden Sie hier.


Microsoft Specific

Emits the Streaming SIMD Extensions 4 (SSE4) instruction roundss. This instruction rounds a parameter down. The rounded value replaces the lower 64 bits of the other parameter.

__m128 _mm_floor_ss( 
   __m128 a,
   __m128 b

[in] a

A 128-bit parameter that contains four 32-bit floating point values.

[in] b

A 128-bit parameter that contains a floating point value in the lowest 32 bits.

The result can be expressed with the following equations:

r0 := FLOOR(b0)
r1 := a1
r2 := a2
r3 := a3




x86, x64

Header file <smmintrin.h>

r0-r3, a0-a3, and b0-b3 are the sequentially ordered 32-bit components of return value r and parameters a and b. r0, a0, and b0 denote the least significant 32 bits.

This function is implemented as a macro that invokes intrinsic _mm_round_ss.

Before you use this intrinsic, software must ensure that the processor supports the instruction.

#include <stdio.h>
#include <smmintrin.h>

int main ()
    __m128 a, b;

    a.m128_f32[0] = 0.0;
    a.m128_f32[1] = 3.5;
    a.m128_f32[2] = 500;
    a.m128_f32[3] = 25.25;
    b.m128_f32[0] = -1.625;
    b.m128_f32[1] = 0.0;
    b.m128_f32[2] = 0.0;
    b.m128_f32[3] = 0.0;

    __m128 res = _mm_floor_ss(a, b);
    printf_s("Original a: %f\t%f\t%f\t%f\nOriginal b: %f\t%f\t%f\t%f\n",
                a.m128_f32[0], a.m128_f32[1], a.m128_f32[2], a.m128_f32[3],
                b.m128_f32[0], b.m128_f32[1], b.m128_f32[2], b.m128_f32[3]);
    printf_s("Result res: %f\t%f\t%f\t%f\n",
                res.m128_f32[0], res.m128_f32[1], res.m128_f32[2], res.m128_f32[3]);

    return 0;
Original a: 0.000000    3.500000        500.000000      25.250000
Original b: -1.625000   0.000000        0.000000        0.000000
Result res: -2.000000   3.500000        500.000000      25.250000


© 2015 Microsoft