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/*************************************************************************
* Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Sandglass Library. *
* *
* The Sandglass 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 *
* 3 of the License, or (at your option) any later version. *
* *
* The Sandglass 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 this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
#include "sandglass_impl.h"
#include "sandglass.h"
#include <unistd.h>
#include <time.h>
#include <errno.h>
static int sandglass_real_create(sandglass_t *sandglass,
const sandglass_attributes_t *attr);
/* Create a timer */
int
sandglass_create(sandglass_t *sandglass,
const sandglass_attributes_t *min,
const sandglass_attributes_t *max)
{
sandglass_attributes_t realmin, realmax;
/* Get our real min and max values */
if (min)
realmin = *min;
else {
/* min defaults to { SANDGLASS_INTROSPECTIVE, SANDGLASS_SYSTEM } */
realmin.incrementation = SANDGLASS_INTROSPECTIVE;
realmin.resolution = SANDGLASS_SYSTEM;
}
if (max)
realmax = *max;
else {
/* max defaults to the greater of min and { SANDGLASS_INTROSPECTIVE,
SANDGLASS_CPUTIME } */
if (realmin.incrementation > SANDGLASS_INTROSPECTIVE
|| (realmin.incrementation == SANDGLASS_INTROSPECTIVE
&& realmin.resolution > SANDGLASS_CPUTIME))
realmax = realmin;
else {
realmax.incrementation = SANDGLASS_INTROSPECTIVE;
realmax.resolution = SANDGLASS_CPUTIME;
}
}
/* Ensure max >= min */
if (realmax.incrementation < realmin.incrementation
|| (realmax.incrementation == realmin.incrementation
&& realmax.resolution < realmin.resolution))
{
errno = EINVAL;
return -1;
}
/* Now search for available timers, starting from max */
while (sandglass_real_create(sandglass, &realmax) != 0) {
/* Once we reach the minimum attributes, bail out */
if (realmax.incrementation == realmin.incrementation
&& realmax.resolution == realmin.resolution)
{
errno = ENOTSUP;
return -1;
}
/* Try the next lowest allowable settings */
if (realmax.resolution)
--realmax.resolution;
else {
if (realmax.incrementation) {
--realmax.incrementation;
realmax.resolution = SANDGLASS_CPUTIME;
} else {
errno = ENOTSUP;
return -1;
}
}
}
return 0;
}
static int
sandglass_real_create(sandglass_t *sandglass,
const sandglass_attributes_t *attr)
{
switch (attr->incrementation) {
case SANDGLASS_MONOTONIC:
switch (attr->resolution) {
case SANDGLASS_REALTICKS:
#ifdef SANDGLASS_TSC
sandglass->resolution = sandglass_tsc_resolution();
sandglass->loops = sandglass_tsc_loops();
break;
#else
return -1;
#endif
case SANDGLASS_CPUTIME:
#ifdef SANDGLASS_TSC
sandglass->resolution = sandglass_tsc_resolution();
sandglass->loops = 1;
break;
#else
return -1;
#endif
case SANDGLASS_SYSTEM:
sandglass->resolution = 1e9;
sandglass->loops = 1;
break;
default:
return -1;
}
break;
case SANDGLASS_INTROSPECTIVE:
switch (attr->resolution) {
case SANDGLASS_REALTICKS:
/* No such thing as an introspective raw TSC */
return -1;
case SANDGLASS_CPUTIME:
if (sysconf(_SC_THREAD_CPUTIME) > 0 || sysconf(_SC_CPUTIME) > 0) {
sandglass->resolution = 1e9;
sandglass->loops = 1;
} else
return -1;
break;
case SANDGLASS_SYSTEM:
sandglass->resolution = CLOCKS_PER_SEC;
sandglass->loops = 1;
break;
default:
return -1;
}
break;
default:
return -1;
}
sandglass->attributes = *attr;
return 0;
}
/* Store a timer value in sandglass->grains */
static int sandglass_real_gettime(sandglass_t *sandglass);
/* Start timing */
int
sandglass_begin(sandglass_t *sandglass)
{
return sandglass_real_gettime(sandglass);
}
/* Finish timing */
int
sandglass_elapse(sandglass_t *sandglass)
{
long oldgrains = sandglass->grains;
if (sandglass_real_gettime(sandglass) != 0)
return -1;
sandglass->grains -= oldgrains;
/* Magical correction for timespec-based grains */
if (sandglass->grains < 0)
sandglass->grains += sandglass->adjustment;
sandglass->grains /= sandglass->loops;
return 0;
}
/* Store a timer value in sandglass->grains */
static int
sandglass_real_gettime(sandglass_t *sandglass)
{
struct timespec ts;
clock_t clock_ticks;
switch (sandglass->attributes.incrementation) {
case SANDGLASS_MONOTONIC:
switch (sandglass->attributes.resolution) {
case SANDGLASS_REALTICKS:
#ifdef SANDGLASS_TSC
sandglass->grains = sandglass_get_tsc();
break;
#else
return -1;
#endif
case SANDGLASS_CPUTIME:
#ifdef SANDGLASS_TSC
sandglass->grains = sandglass_get_tsc();
break;
#else
return -1;
#endif
case SANDGLASS_SYSTEM:
if (sysconf(_SC_MONOTONIC_CLOCK) > 0) {
if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0)
return -1;
} else {
if (clock_gettime(CLOCK_REALTIME, &ts) != 0)
return -1;
}
sandglass->grains = ts.tv_nsec;
sandglass->adjustment = 1000000000L;
break;
default:
return -1;
}
break;
case SANDGLASS_INTROSPECTIVE:
switch (sandglass->attributes.resolution) {
case SANDGLASS_REALTICKS:
/* No such thing as an introspective raw TSC */
return -1;
case SANDGLASS_CPUTIME:
if (sysconf(_SC_THREAD_CPUTIME) > 0) {
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts) != 0)
return -1;
} else if (sysconf(_SC_CPUTIME) > 0) {
if (clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &ts) != 0)
return -1;
} else
return -1;
sandglass->grains = ts.tv_nsec;
sandglass->adjustment = 1000000000L;
break;
case SANDGLASS_SYSTEM:
if ((clock_ticks = clock()) == -1)
return -1;
sandglass->grains = clock();
break;
default:
return -1;
}
break;
default:
return -1;
}
return 0;
}
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