__lsx_vmepatmsk_v

LSX intrinsic · group: Undocumented Intrinsics

Synopsis

__m128i __lsx_vmepatmsk_v (int mode, int uimm5)
#include <lsxintrin.h>
Instruction: vmepatmsk.v vr, mode, uimm5
CPU Flags: LSX

Description

Compute an 8-bit pattern selected by mode (0: repeating 0..3; 1: 0..3 shifted by 1 for each group; 2: 4..7 shifted by 1 for each group; 3: 0..15), then add uimm5 to each byte element.

Examples

__m128i __lsx_vmepatmsk_v(3, 1)
= 0x0807060504030201 0x100f0e0d0c0b0a09

Operation

if (mode == 0b00) {
  for (int i = 0; i < 16; i++) {
    dst.byte[i] = uimm5 + (i % 4); // [0 1 2 3 0 1 2 3 0 1 2 3 0 1 2 3]
  }
} else if (mode == 0b01) {
  for (int i = 0; i < 16; i++) {
    dst.byte[i] =
        uimm5 + (i / 4) + (i % 4); // [0 1 2 3 1 2 3 4 2 3 4 5 3 4 5 6]
  }
} else if (mode == 0b10) {
  for (int i = 0; i < 16; i++) {
    dst.byte[i] =
        uimm5 + (i / 4) + (i % 4) + 4; // [4 5 6 7 5 6 7 8 6 7 8 9 7 8 9 10]
  }
} else if (mode == 0b11) {
  for (int i = 0; i < 16; i++) {
    dst.byte[i] = uimm5 + i; // [0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15]
  }
} else {
  // illegal instruction
}

Tested on real machine.

Latency and Throughput

CPU	µarch	Latency	Throughput (IPC)
3C5000	LA464	N/A	2
3C6000	LA664	N/A	4
2K1000LA	LA264	N/A	1
2K3000	LA364E	N/A	1

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