diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/i386/get_clockfreq.c')
-rw-r--r-- | sysdeps/unix/sysv/linux/i386/get_clockfreq.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/i386/get_clockfreq.c b/sysdeps/unix/sysv/linux/i386/get_clockfreq.c new file mode 100644 index 0000000000..28f56c8fc3 --- /dev/null +++ b/sysdeps/unix/sysv/linux/i386/get_clockfreq.c @@ -0,0 +1,73 @@ +/* Get frequency of the system processor. i386/Linux version. + Copyright (C) 2000 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <ctype.h> +#include <fcntl.h> +#include <unistd.h> + + +unsigned long long int +__get_clockfreq (void) +{ + /* We read the information from the /proc filesystem. It contains at + least one line like + cpu MHz : 497.840237 + We search for this line and convert the number in an integer. */ + unsigned long long int result = 0ull; + int fd; + + fd = open ("/proc/cpuinfo", O_RDONLY); + if (__builtin_expect (fd != -1, 1)) + { + /* XXX AFAIK the /proc filesystem can generate "files" only up + to a size of 4096 bytes. */ + char buf[4096]; + ssize_t n; + + n = read (fd, buf, sizeof buf); + if (__builtin_expect (n, 1) > 0) + { + char *mhz = memmem (buf, n, "cpu MHz", 7); + + if (__builtin_expect (mhz != NULL, 1)) + { + char *endp = buf + n; + + /* Search for the beginning of the string. */ + while (mhz < endp && (*mhz < '0' || *mhz > '9') && *mhz != '\n') + ++mhz; + + while (mhz < endp && *mhz != '\n') + { + if (*mhz >= '0' && *mhz <= '9') + { + result *= 10; + result += *mhz - '0'; + } + + ++mhz; + } + } + } + + close (fd); + } + + return result; +} |