common_clock.cpp revision 232f869c99b8b33276ddad8054fc3e89e44852e5 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define __STDC_LIMIT_MACROS
18
19#define LOG_TAG "common_time"
20#include <utils/Log.h>
21
22#include <stdint.h>
23
24#include <utils/Errors.h>
25#include <utils/LinearTransform.h>
26
27#include "common_clock.h"
28
29namespace android {
30
31CommonClock::CommonClock() {
32    cur_slew_        = 0;
33    cur_trans_valid_ = false;
34
35    cur_trans_.a_zero = 0;
36    cur_trans_.b_zero = 0;
37    cur_trans_.a_to_b_numer = local_to_common_freq_numer_ = 1;
38    cur_trans_.a_to_b_denom = local_to_common_freq_denom_ = 1;
39}
40
41bool CommonClock::init(uint64_t local_freq) {
42    Mutex::Autolock lock(&lock_);
43
44    if (!local_freq)
45        return false;
46
47    uint64_t numer = kCommonFreq;
48    uint64_t denom = local_freq;
49
50    LinearTransform::reduce(&numer, &denom);
51    if ((numer > UINT32_MAX) || (denom > UINT32_MAX)) {
52        LOGE("Overflow in CommonClock::init while trying to reduce %lld/%lld",
53             kCommonFreq, local_freq);
54        return false;
55    }
56
57    cur_trans_.a_to_b_numer = local_to_common_freq_numer_ =
58        static_cast<uint32_t>(numer);
59    cur_trans_.a_to_b_denom = local_to_common_freq_denom_ =
60        static_cast<uint32_t>(denom);
61
62    return true;
63}
64
65status_t CommonClock::localToCommon(int64_t local, int64_t *common_out) const {
66    Mutex::Autolock lock(&lock_);
67
68    if (!cur_trans_valid_)
69        return INVALID_OPERATION;
70
71    if (!cur_trans_.doForwardTransform(local, common_out))
72        return INVALID_OPERATION;
73
74    return OK;
75}
76
77status_t CommonClock::commonToLocal(int64_t common, int64_t *local_out) const {
78    Mutex::Autolock lock(&lock_);
79
80    if (!cur_trans_valid_)
81        return INVALID_OPERATION;
82
83    if (!cur_trans_.doReverseTransform(common, local_out))
84        return INVALID_OPERATION;
85
86    return OK;
87}
88
89void CommonClock::setBasis(int64_t local, int64_t common) {
90    Mutex::Autolock lock(&lock_);
91
92    cur_trans_.a_zero = local;
93    cur_trans_.b_zero = common;
94    cur_trans_valid_ = true;
95}
96
97void CommonClock::resetBasis() {
98    Mutex::Autolock lock(&lock_);
99
100    cur_trans_.a_zero = 0;
101    cur_trans_.b_zero = 0;
102    cur_trans_valid_ = false;
103}
104
105status_t CommonClock::setSlew(int64_t change_time, int32_t ppm) {
106    Mutex::Autolock lock(&lock_);
107
108    int64_t new_local_basis;
109    int64_t new_common_basis;
110
111    if (cur_trans_valid_) {
112        new_local_basis = change_time;
113        if (!cur_trans_.doForwardTransform(change_time, &new_common_basis)) {
114            LOGE("Overflow when attempting to set slew rate to %d", ppm);
115            return INVALID_OPERATION;
116        }
117    } else {
118        new_local_basis = 0;
119        new_common_basis = 0;
120    }
121
122    cur_slew_ = ppm;
123    uint32_t n1 = local_to_common_freq_numer_;
124    uint32_t n2 = 1000000 + cur_slew_;
125
126    uint32_t d1 = local_to_common_freq_denom_;
127    uint32_t d2 = 1000000;
128
129    // n1/d1 has alredy been reduced, no need to do so here.
130    LinearTransform::reduce(&n1, &d2);
131    LinearTransform::reduce(&n2, &d1);
132    LinearTransform::reduce(&n2, &d2);
133
134    cur_trans_.a_zero = new_local_basis;
135    cur_trans_.b_zero = new_common_basis;
136    cur_trans_.a_to_b_numer = n1 * n2;
137    cur_trans_.a_to_b_denom = d1 * d2;
138
139    return OK;
140}
141
142}  // namespace android
143