fix: introduced a stupid error when refactoring the start bit detector in MillerDecod...

[proxmark3-svn] / armsrc / iso14443a.c

diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index 06a134f6b56f519d076295ef15885461ed2c96bc..0bd681d9dc685d6f7748ae3f03301452a4520ad7 100644 (file)
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -232,13 +232,19 @@ void AppendCrc14443a(uint8_t* data, int len)
 static tUart Uart;
 
 // Lookup-Table to decide if 4 raw bits are a modulation.
-// We accept two or three consecutive "0" in any position with the rest "1"
+// We accept the following:
+// 0001  -   a 3 tick wide pause
+// 0011  -   a 2 tick wide pause, or a three tick wide pause shifted left
+// 0111  -   a 2 tick wide pause shifted left
+// 1001  -   a 2 tick wide pause shifted right
 const bool Mod_Miller_LUT[] = {
-       TRUE,  TRUE,  FALSE, TRUE,  FALSE, FALSE, FALSE, FALSE,
-       TRUE,  TRUE,  FALSE, FALSE, TRUE,  FALSE, FALSE, FALSE
+//    TRUE,  TRUE,  FALSE, TRUE,  FALSE, FALSE, FALSE, FALSE,
+//    TRUE,  TRUE,  FALSE, FALSE, TRUE,  FALSE, FALSE, FALSE
+       FALSE,  TRUE, FALSE, TRUE,  FALSE, FALSE, FALSE, TRUE,
+       FALSE,  TRUE, FALSE, FALSE, FALSE, FALSE, FALSE, FALSE
 };
-#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x00F0) >> 4])
-#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x000F)])
+#define IsMillerModulationNibble1(b) (Mod_Miller_LUT[(b & 0x000000F0) >> 4])
+#define IsMillerModulationNibble2(b) (Mod_Miller_LUT[(b & 0x0000000F)])
 
 void UartReset()
 {
@@ -248,7 +254,6 @@ void UartReset()
        Uart.parityLen = 0;                                     // number of decoded parity bytes
        Uart.shiftReg = 0;                                      // shiftreg to hold decoded data bits
        Uart.parityBits = 0;                            // holds 8 parity bits
-       Uart.fourBits = 0x00000000;                     // buffer for 4 Bits
        Uart.startTime = 0;
        Uart.endTime = 0;
 }
@@ -257,6 +262,7 @@ void UartInit(uint8_t *data, uint8_t *parity)
 {
        Uart.output = data;
        Uart.parity = parity;
+       Uart.fourBits = 0x00000000;                     // clear the buffer for 4 Bits
        UartReset();
 }
 
@@ -269,18 +275,21 @@ static RAMFUNC bool MillerDecoding(uint8_t bit, uint32_t non_real_time)
        if (Uart.state == STATE_UNSYNCD) {                                                                                      // not yet synced
        
                Uart.syncBit = 9999;                                                                                                    // not set
-               // we look for a ...xxxx1111111100x11111xxxxxx pattern 
-               // (unmodulated, followed by the start bit = 8 '1's followed by 2 '0's, eventually followed by another '0', followed by 5 '1's)
-#define ISO14443A_STARTBIT_MASK                0x007FEF80                                                                      // mask is    00000000 01111111 11101111 10000000
-#define ISO14443A_STARTBIT_PATTERN     0x007F8F80                                                                      // pattern is 00000000 01111111 10001111 10000000
-               if              ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 0 == ISO14443A_STARTBIT_PATTERN >> 0) Uart.syncBit = 7;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 1 == ISO14443A_STARTBIT_PATTERN >> 1) Uart.syncBit = 6;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 2 == ISO14443A_STARTBIT_PATTERN >> 2) Uart.syncBit = 5;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 3 == ISO14443A_STARTBIT_PATTERN >> 3) Uart.syncBit = 4;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 4 == ISO14443A_STARTBIT_PATTERN >> 4) Uart.syncBit = 3;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 5 == ISO14443A_STARTBIT_PATTERN >> 5) Uart.syncBit = 2;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 6 == ISO14443A_STARTBIT_PATTERN >> 6) Uart.syncBit = 1;
-               else if ((Uart.fourBits & ISO14443A_STARTBIT_MASK) >> 7 == ISO14443A_STARTBIT_PATTERN >> 7) Uart.syncBit = 0;
+               // The start bit is one ore more Sequence Y followed by a Sequence Z (... 11111111 00x11111). We need to distinguish from
+               // Sequence X followed by Sequence Y followed by Sequence Z (111100x1 11111111 00x11111)
+               // we therefore look for a ...xx11111111111100x11111xxxxxx... pattern 
+               // (12 '1's followed by 2 '0's, eventually followed by another '0', followed by 5 '1's)
+#define ISO14443A_STARTBIT_MASK                0x07FFEF80                                                                      // mask is    00000111 11111111 11101111 10000000
+#define ISO14443A_STARTBIT_PATTERN     0x07FF8F80                                                                      // pattern is 00000111 11111111 10001111 10000000
+               if              ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 0)) == ISO14443A_STARTBIT_PATTERN >> 0) Uart.syncBit = 7;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 1)) == ISO14443A_STARTBIT_PATTERN >> 1) Uart.syncBit = 6;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 2)) == ISO14443A_STARTBIT_PATTERN >> 2) Uart.syncBit = 5;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 3)) == ISO14443A_STARTBIT_PATTERN >> 3) Uart.syncBit = 4;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 4)) == ISO14443A_STARTBIT_PATTERN >> 4) Uart.syncBit = 3;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 5)) == ISO14443A_STARTBIT_PATTERN >> 5) Uart.syncBit = 2;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 6)) == ISO14443A_STARTBIT_PATTERN >> 6) Uart.syncBit = 1;
+               else if ((Uart.fourBits & (ISO14443A_STARTBIT_MASK >> 7)) == ISO14443A_STARTBIT_PATTERN >> 7) Uart.syncBit = 0;
+
                if (Uart.syncBit != 9999) {                                                                                             // found a sync bit
                        Uart.startTime = non_real_time?non_real_time:(GetCountSspClk() & 0xfffffff8);
                        Uart.startTime -= Uart.syncBit;
@@ -646,7 +655,7 @@ void RAMFUNC SnoopIso14443a(uint8_t param) {
                                                                                TRUE)) break;
                                        }
                                        /* And ready to receive another command. */
-                                       UartReset();
+                                       UartInit(receivedCmd, receivedCmdPar);
                                        /* And also reset the demod code, which might have been */
                                        /* false-triggered by the commands from the reader. */
                                        DemodReset();
@@ -2798,7 +2807,7 @@ void RAMFUNC SniffMifare(uint8_t param) {
                                        if (MfSniffLogic(receivedCmd, Uart.len, Uart.parity, Uart.bitCount, TRUE)) break;
 
                                        /* And ready to receive another command. */
-                                       UartReset();
+                                       UartInit(receivedCmd, receivedCmdPar);
                                        
                                        /* And also reset the demod code */
                                        DemodReset();