path: root/src/wc_avx2.c

/* 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. */externstruct 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';}}