cosmopolitan/libc/intrin/pshufd.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ This program is free software; you can redistribute it and/or modify         │
│ it under the terms of the GNU General Public License as published by         │
│ the Free Software Foundation; version 2 of the License.                      │
│                                                                              │
│ This program is distributed in the hope that it will be useful, but          │
│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
│ General Public License for more details.                                     │
│                                                                              │
│ You should have received a copy of the GNU General Public License            │
│ along with this program; if not, write to the Free Software                  │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
│ 02110-1301 USA                                                               │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/pshufd.h"
#include "libc/str/str.h"

/**
 * Shuffles int vector.
 * @param 𝑚 needs to be a literal, constexpr, or embedding
 * @mayalias
 */
void(pshufd)(int32_t b[4], const int32_t a[4], uint8_t m) {
  int32_t t[4];
  t[0] = a[(m & 0b00000011) >> 0];
  t[1] = a[(m & 0b00001100) >> 2];
  t[2] = a[(m & 0b00110000) >> 4];
  t[3] = a[(m & 0b11000000) >> 6];
  memcpy(b, t, 16);
}