1 /*
2 * Copyright (C) 2018 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 #ifndef RIL_MNC_H
18 #define RIL_MNC_H
19
20 #include <climits>
21 #include <cstdio>
22 #include <string>
23
24 namespace ril {
25 namespace util {
26 namespace mnc {
27
28 /**
29 * Decode an MNC with an optional length indicator provided in the most-significant nibble.
30 *
31 * @param mnc an encoded MNC value; if no encoding is provided, then the string is returned
32 * as a minimum length string representing the provided integer.
33 *
34 * @return string representation of an encoded MNC or an empty string if the MNC is not a valid
35 * MNC value.
36 */
decode(int mnc)37 static inline std::string decode(int mnc) {
38 if (mnc == INT_MAX || mnc < 0) return "";
39 unsigned umnc = mnc;
40 char mncNumDigits = (umnc >> (sizeof(int) * 8 - 4)) & 0xF;
41
42 umnc = (umnc << 4) >> 4;
43 if (umnc > 999) return "";
44
45 char mncStr[4] = {0};
46 switch (mncNumDigits) {
47 case 0:
48 // Legacy MNC report hasn't set the number of digits; preserve current
49 // behavior and make a string of the minimum number of required digits.
50 return std::to_string(umnc);
51
52 case 2:
53 snprintf(mncStr, sizeof(mncStr), "%03.3u", umnc);
54 return mncStr + 1;
55
56 case 3:
57 snprintf(mncStr, sizeof(mncStr), "%03.3u", umnc);
58 return mncStr;
59
60 default:
61 // Error case
62 return "";
63 }
64
65 }
66
67 /**
68 * Encode an MNC of the given value and a given number of digits
69 *
70 * @param mnc an MNC value 0-999 or INT_MAX if unknown
71 * @param numDigits the number of MNC digits {2, 3} or 0 if unknown
72 *
73 * @return an encoded MNC with embedded length information
74 */
encode(int mnc,int numDigits)75 static inline int encode(int mnc, int numDigits) {
76 if (mnc > 999 || mnc < 0) return INT_MAX;
77 switch (numDigits) {
78 case 0: // fall through
79 case 2: // fall through
80 case 3:
81 break;
82
83 default:
84 return INT_MAX;
85 };
86
87 return (numDigits << (sizeof(int) * 8 - 4)) | mnc;
88 }
89
90 /**
91 * Encode an MNC of the given value
92 *
93 * @param mnc the string representation of the MNC, with the length equal to the length of the
94 * provided string.
95 *
96 * @return an encoded MNC with embedded length information
97 */
encode(const std::string & mnc)98 static inline int encode(const std::string & mnc) {
99 return encode(std::stoi(mnc), mnc.length());
100 }
101
102 // echo -e "#include \"hardware/ril/include/telephony/ril_mnc.h\"\nint main()"\
103 // "{ return ril::util::mnc::test(); }" > ril_test.cpp \
104 // && g++ -o /tmp/ril_test -DTEST_RIL_MNC ril_test.cpp; \
105 // rm ril_test.cpp; /tmp/ril_test && [ $? ] && echo "passed"
106 #ifdef TEST_RIL_MNC
test()107 static int test() {
108 const struct mnc_strings { const char * in; const char * out; } mncs[] = {
109 {"0001",""},
110 {"9999",""},
111 {"0",""},
112 {"9",""},
113 {"123","123"},
114 {"000","000"},
115 {"001","001"},
116 {"011","011"},
117 {"111","111"},
118 {"00","00"},
119 {"01","01"},
120 {"11","11"},
121 {"09","09"},
122 {"099","099"},
123 {"999", "999"}};
124
125 for (int i=0; i< sizeof(mncs) / sizeof(struct mnc_strings); i++) {
126 if (decode(encode(mncs[i].in)).compare(mncs[i].out)) return 1;
127 }
128
129 const struct mnc_ints { const int in; const char * out; } legacy_mncs[] = {
130 {INT_MAX, ""},
131 {1, "1"},
132 {11, "11"},
133 {111, "111"},
134 {0, "0"},
135 {9999, ""},
136 };
137
138 for (int i=0; i < sizeof(legacy_mncs) / sizeof(struct mnc_ints); i++) {
139 if (decode(legacy_mncs[i].in).compare(legacy_mncs[i].out)) return 1;
140 }
141
142 return 0;
143 }
144 #endif
145
146 }
147 }
148 }
149 #endif /* !defined(RIL_MNC_H) */
150