timing.h

00001 /**
00002  * \file timing.h
00003  *
00004  * \brief Portable interface to timeouts and to the CPU cycle counter
00005  */
00006 /*
00007  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
00008  *  SPDX-License-Identifier: Apache-2.0
00009  *
00010  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
00011  *  not use this file except in compliance with the License.
00012  *  You may obtain a copy of the License at
00013  *
00014  *  http://www.apache.org/licenses/LICENSE-2.0
00015  *
00016  *  Unless required by applicable law or agreed to in writing, software
00017  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
00018  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00019  *  See the License for the specific language governing permissions and
00020  *  limitations under the License.
00021  *
00022  *  This file is part of mbed TLS (https://tls.mbed.org)
00023  */
00024 #ifndef MBEDTLS_TIMING_H
00025 #define MBEDTLS_TIMING_H
00026 
00027 #if !defined(MBEDTLS_CONFIG_FILE)
00028 #include "config.h"
00029 #else
00030 #include MBEDTLS_CONFIG_FILE
00031 #endif
00032 
00033 #if !defined(MBEDTLS_TIMING_ALT)
00034 // Regular implementation
00035 //
00036 
00037 #include <stdint.h>
00038 
00039 #ifdef __cplusplus
00040 extern "C" {
00041 #endif
00042 
00043 /**
00044  * \brief          timer structure
00045  */
00046 struct mbedtls_timing_hr_time
00047 {
00048     unsigned char opaque[32];
00049 };
00050 
00051 /**
00052  * \brief          Context for mbedtls_timing_set/get_delay()
00053  */
00054 typedef struct
00055 {
00056     struct mbedtls_timing_hr_time   timer;
00057     uint32_t                        int_ms;
00058     uint32_t                        fin_ms;
00059 } mbedtls_timing_delay_context;
00060 
00061 extern volatile int mbedtls_timing_alarmed;
00062 
00063 /**
00064  * \brief          Return the CPU cycle counter value
00065  *
00066  * \warning        This is only a best effort! Do not rely on this!
00067  *                 In particular, it is known to be unreliable on virtual
00068  *                 machines.
00069  *
00070  * \note           This value starts at an unspecified origin and
00071  *                 may wrap around.
00072  */
00073 unsigned long mbedtls_timing_hardclock( void );
00074 
00075 /**
00076  * \brief          Return the elapsed time in milliseconds
00077  *
00078  * \param val      points to a timer structure
00079  * \param reset    If 0, query the elapsed time. Otherwise (re)start the timer.
00080  *
00081  * \return         Elapsed time since the previous reset in ms. When
00082  *                 restarting, this is always 0.
00083  *
00084  * \note           To initialize a timer, call this function with reset=1.
00085  *
00086  *                 Determining the elapsed time and resetting the timer is not
00087  *                 atomic on all platforms, so after the sequence
00088  *                 `{ get_timer(1); ...; time1 = get_timer(1); ...; time2 =
00089  *                 get_timer(0) }` the value time1+time2 is only approximately
00090  *                 the delay since the first reset.
00091  */
00092 unsigned long mbedtls_timing_get_timer( struct mbedtls_timing_hr_time *val, int reset );
00093 
00094 /**
00095  * \brief          Setup an alarm clock
00096  *
00097  * \param seconds  delay before the "mbedtls_timing_alarmed" flag is set
00098  *                 (must be >=0)
00099  *
00100  * \warning        Only one alarm at a time  is supported. In a threaded
00101  *                 context, this means one for the whole process, not one per
00102  *                 thread.
00103  */
00104 void mbedtls_set_alarm( int seconds );
00105 
00106 /**
00107  * \brief          Set a pair of delays to watch
00108  *                 (See \c mbedtls_timing_get_delay().)
00109  *
00110  * \param data     Pointer to timing data.
00111  *                 Must point to a valid \c mbedtls_timing_delay_context struct.
00112  * \param int_ms   First (intermediate) delay in milliseconds.
00113  *                 The effect if int_ms > fin_ms is unspecified.
00114  * \param fin_ms   Second (final) delay in milliseconds.
00115  *                 Pass 0 to cancel the current delay.
00116  *
00117  * \note           To set a single delay, either use \c mbedtls_timing_set_timer
00118  *                 directly or use this function with int_ms == fin_ms.
00119  */
00120 void mbedtls_timing_set_delay( void *data, uint32_t int_ms, uint32_t fin_ms );
00121 
00122 /**
00123  * \brief          Get the status of delays
00124  *                 (Memory helper: number of delays passed.)
00125  *
00126  * \param data     Pointer to timing data
00127  *                 Must point to a valid \c mbedtls_timing_delay_context struct.
00128  *
00129  * \return         -1 if cancelled (fin_ms = 0),
00130  *                  0 if none of the delays are passed,
00131  *                  1 if only the intermediate delay is passed,
00132  *                  2 if the final delay is passed.
00133  */
00134 int mbedtls_timing_get_delay( void *data );
00135 
00136 #ifdef __cplusplus
00137 }
00138 #endif
00139 
00140 #else  /* MBEDTLS_TIMING_ALT */
00141 #include "timing_alt.h"
00142 #endif /* MBEDTLS_TIMING_ALT */
00143 
00144 #ifdef __cplusplus
00145 extern "C" {
00146 #endif
00147 
00148 #if defined(MBEDTLS_SELF_TEST)
00149 /**
00150  * \brief          Checkup routine
00151  *
00152  * \return         0 if successful, or 1 if a test failed
00153  */
00154 int mbedtls_timing_self_test( int verbose );
00155 #endif
00156 
00157 #ifdef __cplusplus
00158 }
00159 #endif
00160 
00161 #endif /* timing.h */