armsrc/Standalone/lf_em4100emul.c

   1 //-----------------------------------------------------------------------------
   2 // Artyom Gnatyuk, 2020
   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
   6 // the license.
   7 //-----------------------------------------------------------------------------
   8 // LF emul  -   Very simple mode. Simulate only predefined in low[] IDs
   9 //              Short click - select next slot and start simulation
  10 //-----------------------------------------------------------------------------
  11 #include "standalone.h"
  12 #include "proxmark3_arm.h"
  13 #include "appmain.h"
  14 #include "fpgaloader.h"
  15 #include "lfops.h"
  16 #include "util.h"
  17 #include "dbprint.h"
  18 #include "ticks.h"
  19 #include "string.h"
  20 #include "BigBuf.h"
  21 #include "commonutil.h"
  22
  23 #define MAX_IND 16 // 4 LEDs - 2^4 combinations
  24 #define LF_CLOCK 64 // for 125kHz
  25
  26 // low & high - array for storage IDs. Its length must be equal.
  27 // Predefined IDs must be stored in low[].
  28 static uint64_t low[] = {0x565A1140BE, 0x365A398149, 0x5555555555, 0xFFFFFFFFFF};
  29 static uint8_t slots_count;
  30 static int buflen;
  31
  32 void ModInfo(void) {
  33     DbpString("  LF EM4100 simulator standalone mode");
  34 }
  35
  36 static uint64_t rev_quads(uint64_t bits) {
  37     uint64_t result = 0;
  38     for (int i = 0; i < 16; i++) {
  39         result += ((bits >> (60 - 4 * i)) & 0xf) << (4 * i);
  40     }
  41     return result >> 24;
  42 }
  43
  44 static void fill_buff(uint8_t bit) {
  45     uint8_t *bba = BigBuf_get_addr();
  46     memset(bba + buflen, bit, LF_CLOCK / 2);
  47     buflen += (LF_CLOCK / 2);
  48     memset(bba + buflen, bit ^ 1, LF_CLOCK / 2);
  49     buflen += (LF_CLOCK / 2);
  50 }
  51
  52 static void construct_EM410x_emul(uint64_t id) {
  53
  54     int i, j;
  55     int binary[4] = {0, 0, 0, 0};
  56     int parity[4] = {0, 0, 0, 0};
  57     buflen = 0;
  58
  59     for (i = 0; i < 9; i++)
  60         fill_buff(1);
  61
  62     for (i = 0; i < 10; i++) {
  63         for (j = 3; j >= 0; j--, id /= 2)
  64             binary[j] = id % 2;
  65
  66         for (j = 0; j < 4; j++)
  67             fill_buff(binary[j]);
  68
  69         fill_buff(binary[0] ^ binary[1] ^ binary[2] ^ binary[3]);
  70         for (j = 0; j < 4; j++)
  71             parity[j] ^= binary[j];
  72     }
  73
  74     for (j = 0; j < 4; j++)
  75         fill_buff(parity[j]);
  76
  77     fill_buff(0);
  78 }
  79
  80 static void LED_Slot(int i) {
  81     LEDsoff();
  82     if (slots_count > 4) {
  83         LED(i % MAX_IND, 0); //binary indication for slots_count > 4
  84     } else {
  85         LED(1 << i, 0); //simple indication for slots_count <=4
  86     }
  87 }
  88
  89 void RunMod(void) {
  90     StandAloneMode();
  91     FpgaDownloadAndGo(FPGA_BITSTREAM_LF);
  92     Dbprintf("[=] >>  LF EM4100 simulator started  <<");
  93
  94     int selected = 0; //selected slot after start
  95     slots_count = ARRAYLEN(low);
  96     for (;;) {
  97         WDT_HIT();
  98         if (data_available()) break;
  99
 100         SpinDelay(100);
 101         SpinUp(100);
 102         LED_Slot(selected);
 103         construct_EM410x_emul(rev_quads(low[selected]));
 104         SimulateTagLowFrequency(buflen, 0, true);
 105         selected = (selected + 1) % slots_count;
 106     }
 107 }