__lsx_vsrarni_h_w
LSX intrinsic · group: Shift
Synopsis
__m128i __lsx_vsrarni_h_w (__m128i a, __m128i b, imm0_31 imm)
#include <lsxintrin.h>
Instruction: vsrarni.h.w vr, vr, imm
CPU Flags: LSX
Description
Arithmetic right shift with rounding the signed 32-bit elements in a and b by imm, write the lower 16 bits of the shifted result into the lower half of each 128-bit lane of dst, and zero the upper half.
Operation
for (int i = 0; i < 8; i++) {
if (i < 4) {
if (imm == 0) {
dst.half[i] = (s16)(s32)b.word[i];
} else {
dst.half[i] = (s16)(((s32)b.word[i] >> imm) +
(((s32)b.word[i] >> (imm - 1)) & 0x1));
}
} else {
if (imm == 0) {
dst.half[i] = (s16)(s32)a.word[i - 4];
} else {
dst.half[i] = (s16)(((s32)a.word[i - 4] >> imm) +
(((s32)a.word[i - 4] >> (imm - 1)) & 0x1));
}
}
}
Tested on real machine.
Latency and Throughput
| CPU | µarch | Latency | Throughput (IPC) |
|---|---|---|---|
| 3C5000 | LA464 | 4 | 1 |
| 3A6000 | LA664 | 4 | 2 |
| 3C6000 | LA664 | 4 | 2 |
| 2K1000LA | LA264 | 3 | 0.5(1/2) |
| 2K3000 | LA364E | 3 | 0.5(1/2) |