| /* Get frequency of the system processor. powerpc/Linux version. |
| Copyright (C) 2000, 2001, 2005 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, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <ctype.h> |
| #include <fcntl.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <libc-internal.h> |
| #include <sysdep.h> |
| #include <bits/libc-vdso.h> |
| |
| hp_timing_t |
| __get_clockfreq (void) |
| { |
| /* We read the information from the /proc filesystem. /proc/cpuinfo |
| contains at least one line like: |
| timebase : 33333333 |
| We search for this line and convert the number into an integer. */ |
| static hp_timing_t timebase_freq; |
| hp_timing_t result = 0L; |
| |
| /* If this function was called before, we know the result. */ |
| if (timebase_freq != 0) |
| return timebase_freq; |
| |
| /* If we can use the vDSO to obtain the timebase even better. */ |
| #ifdef SHARED |
| INTERNAL_SYSCALL_DECL (err); |
| timebase_freq = INTERNAL_VSYSCALL_NO_SYSCALL_FALLBACK (get_tbfreq, err, 0); |
| if (INTERNAL_SYSCALL_ERROR_P (timebase_freq, err) |
| && INTERNAL_SYSCALL_ERRNO (timebase_freq, err) == ENOSYS) |
| #endif |
| { |
| int fd = open ("/proc/cpuinfo", O_RDONLY); |
| |
| if (__builtin_expect (fd != -1, 1)) |
| { |
| /* The timebase will be in the 1st 1024 bytes for systems with up |
| to 8 processors. If the first read returns less then 1024 |
| bytes read, we have the whole cpuinfo and can start the scan. |
| Otherwise we will have to read more to insure we have the |
| timebase value in the scan. */ |
| char buf[1024]; |
| ssize_t n; |
| |
| n = read (fd, buf, sizeof (buf)); |
| if (n == sizeof (buf)) |
| { |
| /* We are here because the 1st read returned exactly sizeof |
| (buf) bytes. This implies that we are not at EOF and may |
| not have read the timebase value yet. So we need to read |
| more bytes until we know we have EOF. We copy the lower |
| half of buf to the upper half and read sizeof (buf)/2 |
| bytes into the lower half of buf and repeat until we |
| reach EOF. We can assume that the timebase will be in |
| the last 512 bytes of cpuinfo, so two 512 byte half_bufs |
| will be sufficient to contain the timebase and will |
| handle the case where the timebase spans the half_buf |
| boundry. */ |
| const ssize_t half_buf = sizeof (buf) / 2; |
| while (n >= half_buf) |
| { |
| memcpy (buf, buf + half_buf, half_buf); |
| n = read (fd, buf + half_buf, half_buf); |
| } |
| if (n >= 0) |
| n += half_buf; |
| } |
| |
| if (__builtin_expect (n, 1) > 0) |
| { |
| char *mhz = memmem (buf, n, "timebase", 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; |
| } |
| } |
| timebase_freq = result; |
| } |
| close (fd); |
| } |
| } |
| |
| return timebase_freq; |
| } |