_mm_insert_ps
Microsoft Specific
Emits the Streaming SIMD Extensions 4 (SSE4) instruction insertps. This instruction insets a 32-bit integer into a 128-bit parameter.
__m128 _mm_insert_ps( __m128 a, __m128 b, const int sel );
A 128-bit parameter that is a copy of the input parameter a, with a couple of exceptions. A value from b will be copied into an index indicated by sel. Also, sel may indicate that specific index values should be set to 0.
This can be expressed with the following equations:
sx := sel6-7 sval := (sx == 0) ? b0 : ((sx == 1) ? b1 : ((sx == 2) ? b2 : b3)) dx := sel4-5 r0 := (dx == 0) ? sval : a0 r1 := (dx == 1) ? sval : a1 r2 := (dx == 2) ? sval : a2 r3 := (dx == 3) ? sval : a3 zmask := sel0-3 r0 := (zmask0 == 1) ? +0.0 : r0 r1 := (zmask1 == 1) ? +0.0 : r1 r2 := (zmask2 == 1) ? +0.0 : r2 r3 := (zmask3 == 1) ? +0.0 : r3
r0-r3, a0-a3, and b0-b3 are the sequentially ordered 32-bit components of return value r and parameters a and b, respectively. r0, a0, and b0 are the least significant 32 bits.
seli and zmaski denote bit i of parameter sel and temporary value zmask, with bit 0 being the least significant bit.
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;
const int sel = 0xD9;
// The D means that b3 will be stored in r1
// The 9 means that r0 and r3 will be set to 0
a.m128_f32[0] = 1.0;
a.m128_f32[1] = -1.0;
a.m128_f32[2] = 1.5;
a.m128_f32[3] = 105.5;
b.m128_f32[0] = -5.0;
b.m128_f32[1] = 10;
b.m128_f32[2] = -325.0625;
b.m128_f32[3] = 81.125;
__m128 res = _mm_insert_ps(a, b, sel);
printf_s("res0 should equal 0: %f\nres1 should equal %f: %f\n",
res.m128_f32[0], b.m128_f32[3], res.m128_f32[1]);
printf_s("res2 should equal %f: %f\nres3 should equal 0: %f\n",
a.m128_f32[2], res.m128_f32[2], res.m128_f32[3]);
return 0;
}
