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/* wc_avx - Count the number of newlines with avx2 instructions.
Copyright (C) 2021-2025 Free Software Foundation, Inc.
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, either version 3 of the License, or
(at your option) any later version.
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, see <https://www.gnu.org/licenses/>. */
#include <config.h>
#include "wc.h"
#include "system.h"
#include "ioblksize.h"
#include <x86intrin.h>
/* Read FD and return a summary. */
extern struct wc_lines
wc_lines_avx2 (int fd)
{
intmax_t lines = 0;
intmax_t bytes = 0;
__m256i endlines = _mm256_set1_epi8 ('\n');
while (true)
{
__m256i avx_buf[IO_BUFSIZE / sizeof (__m256i)];
ssize_t bytes_read = read (fd, avx_buf, sizeof avx_buf);
if (bytes_read <= 0)
return (struct wc_lines) { bytes_read == 0 ? 0 : errno, lines, bytes };
bytes += bytes_read;
__m256i *datap = avx_buf;
while (bytes_read >= 32)
{
__m256i to_match = _mm256_load_si256 (datap);
__m256i matches = _mm256_cmpeq_epi8 (to_match, endlines);
int mask = _mm256_movemask_epi8 (matches);
lines += __builtin_popcount (mask);
datap += 1;
bytes_read -= 32;
}
/* Finish up any left over bytes */
char *end = (char *) datap + bytes_read;
for (char *p = (char *) datap; p < end; p++)
lines += *p == '\n';
}
}
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