| /* Get frequency of the system processor. IA-64/Linux version. |
| Copyright (C) 2001-2014 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 Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <ctype.h> |
| #include <fcntl.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <libc-internal.h> |
| |
| |
| hp_timing_t |
| __get_clockfreq (void) |
| { |
| /* We read the information from the /proc filesystem. It contains at |
| least one line like |
| itc MHz : 733.390988 |
| We search for this line and convert the number in an integer. */ |
| static hp_timing_t result; |
| int fd; |
| |
| /* If this function was called before, we know the result. */ |
| if (result != 0) |
| return result; |
| |
| 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, "itc MHz", 7); |
| |
| if (__builtin_expect (mhz != NULL, 1)) |
| { |
| char *endp = buf + n; |
| int seen_decpoint = 0; |
| int ndigits = 0; |
| |
| /* 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'; |
| if (seen_decpoint) |
| ++ndigits; |
| } |
| else if (*mhz == '.') |
| seen_decpoint = 1; |
| |
| ++mhz; |
| } |
| |
| /* Compensate for missing digits at the end. */ |
| while (ndigits++ < 6) |
| result *= 10; |
| } |
| } |
| |
| __close (fd); |
| } |
| |
| return result; |
| } |