__lsx_vmaddwev_h_bu
LSX intrinsic · group: Integer Computation
Synopsis
__m128i __lsx_vmaddwev_h_bu (__m128i a, __m128i b, __m128i c)
#include <lsxintrin.h>
Instruction: vmaddwev.h.bu vr, vr, vr
CPU Flags: LSX
Description
Multiply the even-positioned unsigned 8-bit elements in b and the corresponding unsigned 8-bit elements in c, extending both to 16-bit, and add the product to the 16-bit elements in a.
Operation
for (int i = 0; i < 8; i++) {
dst.half[i] =
(u16)(u8)b.byte[2 * i] * (u16)(u8)c.byte[2 * i] + (u16)a.half[i];
}
// Expands to:
if (0) {
dst.half[0] =
(((u16)((u8)b.byte[0])) * ((u16)((u8)c.byte[0]))) + ((u16)a.half[0]);
dst.half[1] =
(((u16)((u8)b.byte[2])) * ((u16)((u8)c.byte[2]))) + ((u16)a.half[1]);
dst.half[2] =
(((u16)((u8)b.byte[4])) * ((u16)((u8)c.byte[4]))) + ((u16)a.half[2]);
dst.half[3] =
(((u16)((u8)b.byte[6])) * ((u16)((u8)c.byte[6]))) + ((u16)a.half[3]);
dst.half[4] =
(((u16)((u8)b.byte[8])) * ((u16)((u8)c.byte[8]))) + ((u16)a.half[4]);
dst.half[5] =
(((u16)((u8)b.byte[10])) * ((u16)((u8)c.byte[10]))) + ((u16)a.half[5]);
dst.half[6] =
(((u16)((u8)b.byte[12])) * ((u16)((u8)c.byte[12]))) + ((u16)a.half[6]);
dst.half[7] =
(((u16)((u8)b.byte[14])) * ((u16)((u8)c.byte[14]))) + ((u16)a.half[7]);
}
Tested on real machine.
Latency and Throughput
| CPU | µarch | Latency | Throughput (IPC) |
|---|---|---|---|
| 3C5000 | LA464 | 4 | 2 |
| 3A6000 | LA664 | 4 | 2 |
| 3C6000 | LA664 | 4 | 2 |
| 2K1000LA | LA264 | 4 | 1 |
| 2K3000 | LA364E | 4 | 1 |