1 //-----------------------------------------------------------------------------
2 // Copyright (C) 2018 grauerfuchs
3 //
4 // This code is licensed to you under the terms of the GNU GPL, version 2 or,
5 // at your option, any later version. See the LICENSE.txt file for the text of
7 //-----------------------------------------------------------------------------
8 // HID card format packing/unpacking support functions
9 //-----------------------------------------------------------------------------
11 #include <stdbool.h>
12 #include <stdint.h>
13 #include <stdio.h>
14 #include <string.h>
15 #include "hidcardformatutils.h"
16 #include "ui.h"
18 bool get_bit_by_position(/* in */hidproxmessage_t* data, /* in */uint8_t pos){
19 if (pos >= data->Length) return false;
20 pos = (data->Length - pos) - 1; // invert ordering; Indexing goes from 0 to 1. Subtract 1 for weight of bit.
21 bool result = false;
22 if (pos > 95)
23 result = false;
24 else if (pos > 63)
25 result = (data->top >> (pos - 64)) & 1;
26 else if (pos > 31)
27 result = (data->mid >> (pos - 32)) & 1;
28 else
29 result = (data->bot >> pos) & 1;
30 return result;
31 }
32 bool set_bit_by_position(/* inout */hidproxmessage_t* data, /* in */bool value, /* in */uint8_t pos){
33 if (pos >= data->Length) return false;
34 pos = (data->Length - pos) - 1; // invert ordering; Indexing goes from 0 to 1. Subtract 1 for weight of bit.
35 if (pos > 95) {
36 return false;
37 } else if (pos > 63) {
38 if (value)
39 data->top |= (1 << (pos - 64));
40 else
41 data->top &= ~(1 << (pos - 64));
42 return true;
43 } else if (pos > 31) {
44 if (value)
45 data->mid |= (1 << (pos - 32));
46 else
47 data->mid &= ~(1 << (pos - 32));
48 return true;
49 } else {
50 if (value)
51 data->bot |= (1 << pos);
52 else
53 data->bot &= ~(1 << pos);
54 return true;
55 }
56 }
57 /**
58 * Safeguard the data by doing a manual deep copy
59 *
60 * At the time of the initial writing, the struct does not contain pointers. That doesn't
61 * mean it won't eventually contain one, however. To prevent memory leaks and erroneous
62 * aliasing, perform the copy function manually instead. Hence, this function.
63 *
64 * If the definition of the hidproxmessage struct changes, this function must also
65 * be updated to match.
66 */
67 void proxmessage_datacopy(/*in*/hidproxmessage_t* src, /*out*/hidproxmessage_t* dest){
68 dest->bot = src->bot;
69 dest->mid = src->mid;
70 dest->top = src->top;
71 dest->Length = src->Length;
72 }
73 /**
74 *
75 * Yes, this is horribly inefficient for linear data.
76 * The current code is a temporary measure to have a working function in place
77 * until all the bugs shaken from the block/chunk version of the code.
78 *
79 */
80 uint64_t get_linear_field(/* in */hidproxmessage_t* data, uint8_t firstBit, uint8_t length){
81 uint64_t result = 0;
82 for (uint8_t i = 0; i < length; i++ ) {
83 result = (result << 1) | get_bit_by_position(data, firstBit + i);
84 }
85 return result;
86 }
87 bool set_linear_field(/* inout */hidproxmessage_t* data, uint64_t value, uint8_t firstBit, uint8_t length){
88 hidproxmessage_t tmpdata;
89 proxmessage_datacopy(data, &tmpdata);
90 bool result = true;
91 for (int i = 0; i < length; i++){
92 result &= set_bit_by_position(&tmpdata, (value >> ((length - i) - 1)) & 1, firstBit + i);
93 }
94 if (result) proxmessage_datacopy(&tmpdata, data);
95 return result;
96 }
98 uint64_t get_nonlinear_field(/* in */hidproxmessage_t* data, uint8_t numBits, uint8_t* bits){
99 uint64_t result = 0;
100 for (int i = 0; i < numBits; i++){
101 result = (result << 1) | (get_bit_by_position(data, *(bits+i)) & 1);
102 }
103 return result;
104 }
105 bool set_nonlinear_field(/* inout */hidproxmessage_t* data, uint64_t value, uint8_t numBits, uint8_t* bits){
106 hidproxmessage_t tmpdata;
107 proxmessage_datacopy(data, &tmpdata);
108 bool result = true;
109 for (int i = 0; i < numBits; i++){
110 result &= set_bit_by_position(&tmpdata, (value >> ((numBits - i) - 1)) & 1, *(bits + i));
111 }
112 if (result) proxmessage_datacopy(&tmpdata, data);
113 return result;
114 }
116 uint8_t get_length_from_header(/* inout */hidproxmessage_t* data) {
117 uint8_t len = 0;
119 uint32_t hFmt; // for calculating card length
120 if ((data->top & 0x000FFFFF) > 0) { // > 64 bits
121 hFmt = data->top & 0x000FFFFF;
122 len = 64;
123 } else if ((data->mid & 0xFFFFFFC0) > 0) { // < 63-38 bits
124 hFmt = data->mid & 0xFFFFFFC0;
125 len = 32;
126 } else if ((data->mid & 0x00000020) == 0) { // 37 bits
127 hFmt = 0;
128 len = 37;
129 } else if ((data->mid & 0x0000001F) > 0){ // 36-32 bits
130 hFmt = data->mid & 0x0000001F;
131 len = 32;
132 } else { // <32 bits
133 hFmt = data->bot;
134 len = 0;
135 }
137 while (hFmt > 1) {
138 hFmt >>= 1;
139 len++;
140 }
141 return len;
142 }
144 hidproxmessage_t initialize_proxmessage_object(uint32_t top, uint32_t mid, uint32_t bot){
145 struct hidproxmessage_s result;
146 memset(&result, 0, sizeof(hidproxmessage_t));
147 result.top = top;
148 result.mid = mid;
149 result.bot = bot;
151 return result;
152 }
154 if (data->Length > 84 || data->Length == 0) return false; // Invalid value
156 if (data->Length >= 64){
157 data->top |= 1 << (data->Length - 64); // leading 1: start bit
158 data->top |= 0x09e00000; // Extended-length header
159 } else if (data->Length > 37){
160 data->mid |= 1 << (data->Length - 32); // leading 1: start bit
161 data->top |= 0x09e00000; // Extended-length header
162 } else if (data->Length == 37){