1 /**
2  * \file timing.h
3  *
4  * \brief Portable interface to timeouts and to the CPU cycle counter
5  */
6 /*
7  *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
8  *  SPDX-License-Identifier: Apache-2.0
9  *
10  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
11  *  not use this file except in compliance with the License.
12  *  You may obtain a copy of the License at
13  *
14  *  http://www.apache.org/licenses/LICENSE-2.0
15  *
16  *  Unless required by applicable law or agreed to in writing, software
17  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
18  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19  *  See the License for the specific language governing permissions and
20  *  limitations under the License.
21  *
22  *  This file is part of mbed TLS (https://tls.mbed.org)
23  */
24 #ifndef MBEDTLS_TIMING_H
25 #define MBEDTLS_TIMING_H
26 
27 #if !defined(MBEDTLS_CONFIG_FILE)
28 #include "config.h"
29 #else
30 #include MBEDTLS_CONFIG_FILE
31 #endif
32 
33 #include <stdint.h>
34 
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38 
39 #if !defined(MBEDTLS_TIMING_ALT)
40 // Regular implementation
41 //
42 
43 /**
44  * \brief          timer structure
45  */
46 struct mbedtls_timing_hr_time
47 {
48     unsigned char opaque[32];
49 };
50 
51 /**
52  * \brief          Context for mbedtls_timing_set/get_delay()
53  */
54 typedef struct mbedtls_timing_delay_context
55 {
56     struct mbedtls_timing_hr_time   timer;
57     uint32_t                        int_ms;
58     uint32_t                        fin_ms;
59 } mbedtls_timing_delay_context;
60 
61 #else  /* MBEDTLS_TIMING_ALT */
62 #include "timing_alt.h"
63 #endif /* MBEDTLS_TIMING_ALT */
64 
65 extern volatile int mbedtls_timing_alarmed;
66 
67 /**
68  * \brief          Return the CPU cycle counter value
69  *
70  * \warning        This is only a best effort! Do not rely on this!
71  *                 In particular, it is known to be unreliable on virtual
72  *                 machines.
73  *
74  * \note           This value starts at an unspecified origin and
75  *                 may wrap around.
76  */
77 unsigned long mbedtls_timing_hardclock( void );
78 
79 /**
80  * \brief          Return the elapsed time in milliseconds
81  *
82  * \param val      points to a timer structure
83  * \param reset    If 0, query the elapsed time. Otherwise (re)start the timer.
84  *
85  * \return         Elapsed time since the previous reset in ms. When
86  *                 restarting, this is always 0.
87  *
88  * \note           To initialize a timer, call this function with reset=1.
89  *
90  *                 Determining the elapsed time and resetting the timer is not
91  *                 atomic on all platforms, so after the sequence
92  *                 `{ get_timer(1); ...; time1 = get_timer(1); ...; time2 =
93  *                 get_timer(0) }` the value time1+time2 is only approximately
94  *                 the delay since the first reset.
95  */
96 unsigned long mbedtls_timing_get_timer( struct mbedtls_timing_hr_time *val, int reset );
97 
98 /**
99  * \brief          Setup an alarm clock
100  *
101  * \param seconds  delay before the "mbedtls_timing_alarmed" flag is set
102  *                 (must be >=0)
103  *
104  * \warning        Only one alarm at a time  is supported. In a threaded
105  *                 context, this means one for the whole process, not one per
106  *                 thread.
107  */
108 void mbedtls_set_alarm( int seconds );
109 
110 /**
111  * \brief          Set a pair of delays to watch
112  *                 (See \c mbedtls_timing_get_delay().)
113  *
114  * \param data     Pointer to timing data.
115  *                 Must point to a valid \c mbedtls_timing_delay_context struct.
116  * \param int_ms   First (intermediate) delay in milliseconds.
117  *                 The effect if int_ms > fin_ms is unspecified.
118  * \param fin_ms   Second (final) delay in milliseconds.
119  *                 Pass 0 to cancel the current delay.
120  *
121  * \note           To set a single delay, either use \c mbedtls_timing_set_timer
122  *                 directly or use this function with int_ms == fin_ms.
123  */
124 void mbedtls_timing_set_delay( void *data, uint32_t int_ms, uint32_t fin_ms );
125 
126 /**
127  * \brief          Get the status of delays
128  *                 (Memory helper: number of delays passed.)
129  *
130  * \param data     Pointer to timing data
131  *                 Must point to a valid \c mbedtls_timing_delay_context struct.
132  *
133  * \return         -1 if cancelled (fin_ms = 0),
134  *                  0 if none of the delays are passed,
135  *                  1 if only the intermediate delay is passed,
136  *                  2 if the final delay is passed.
137  */
138 int mbedtls_timing_get_delay( void *data );
139 
140 #if defined(MBEDTLS_SELF_TEST)
141 /**
142  * \brief          Checkup routine
143  *
144  * \return         0 if successful, or 1 if a test failed
145  */
146 int mbedtls_timing_self_test( int verbose );
147 #endif
148 
149 #ifdef __cplusplus
150 }
151 #endif
152 
153 #endif /* timing.h */
154