]> git.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/util.c
minor adjustment to askmandemod for lf search
[proxmark3-svn] / armsrc / util.c
index e6332a7b57615224a547792f6082e694aed6046e..5b68f5134cf16a1991aed51c463acb87b02994c8 100644 (file)
-//-----------------------------------------------------------------------------\r
-// Utility functions used in many places, not specific to any piece of code.\r
-// Jonathan Westhues, Sept 2005\r
-//-----------------------------------------------------------------------------\r
-#include <proxmark3.h>\r
-#include "apps.h"\r
-\r
-void *memcpy(void *dest, const void *src, int len)\r
-{\r
-       BYTE *d = dest;\r
-       const BYTE *s = src;\r
-       while((len--) > 0) {\r
-               *d = *s;\r
-               d++;\r
-               s++;\r
-       }\r
-       return dest;\r
-}\r
-\r
-void *memset(void *dest, int c, int len)\r
-{\r
-       BYTE *d = dest;\r
-       while((len--) > 0) {\r
-               *d = c;\r
-               d++;\r
-       }\r
-       return dest;\r
-}\r
-\r
-int memcmp(const void *av, const void *bv, int len)\r
-{\r
-       const BYTE *a = av;\r
-       const BYTE *b = bv;\r
-\r
-       while((len--) > 0) {\r
-               if(*a != *b) {\r
-                       return *a - *b;\r
-               }\r
-               a++;\r
-               b++;\r
-       }\r
-       return 0;\r
-}\r
-\r
-int strlen(char *str)\r
-{\r
-       int l = 0;\r
-       while(*str) {\r
-               l++;\r
-               str++;\r
-       }\r
-       return l;\r
-}\r
-\r
-char* strncat(char *dest, const char *src, unsigned int n)\r
-{\r
-       unsigned int dest_len = strlen(dest);\r
-       unsigned int i;\r
-       \r
-       for (i = 0 ; i < n && src[i] != '\0' ; i++)\r
-               dest[dest_len + i] = src[i];\r
-       dest[dest_len + i] = '\0';\r
-       \r
-       return dest;\r
-}\r
-\r
-void num_to_bytes(uint64_t n, size_t len, byte_t* dest)\r
-{\r
-       while (len--) {\r
-               dest[len] = (byte_t) n;\r
-               n >>= 8;\r
-       }\r
-}\r
-\r
-uint64_t bytes_to_num(byte_t* src, size_t len)\r
-{\r
-       uint64_t num = 0;\r
-       while (len--)\r
-       {\r
-               num = (num << 8) | (*src);\r
-               src++;\r
-       }\r
-       return num;\r
-}\r
-\r
-void LEDsoff()\r
-{\r
-       LED_A_OFF();\r
-       LED_B_OFF();\r
-       LED_C_OFF();\r
-       LED_D_OFF();\r
-}\r
-\r
-// LEDs: R(C) O(A) G(B) -- R(D) [1, 2, 4 and 8]\r
-void LED(int led, int ms)\r
-{\r
-       if (led & LED_RED)\r
-               LED_C_ON();\r
-       if (led & LED_ORANGE)\r
-               LED_A_ON();\r
-       if (led & LED_GREEN)\r
-               LED_B_ON();\r
-       if (led & LED_RED2)\r
-               LED_D_ON();\r
-\r
-       if (!ms)\r
-               return;\r
-\r
-       SpinDelay(ms);\r
-\r
-       if (led & LED_RED)\r
-               LED_C_OFF();\r
-       if (led & LED_ORANGE)\r
-               LED_A_OFF();\r
-       if (led & LED_GREEN)\r
-               LED_B_OFF();\r
-       if (led & LED_RED2)\r
-               LED_D_OFF();\r
-}\r
-\r
-\r
-// Determine if a button is double clicked, single clicked,\r
-// not clicked, or held down (for ms || 1sec)\r
-// In general, don't use this function unless you expect a\r
-// double click, otherwise it will waste 500ms -- use BUTTON_HELD instead\r
-int BUTTON_CLICKED(int ms)\r
-{\r
-       // Up to 500ms in between clicks to mean a double click\r
-       int ticks = (48000 * (ms ? ms : 1000)) >> 10;\r
-\r
-       // If we're not even pressed, forget about it!\r
-       if (!BUTTON_PRESS())\r
-               return BUTTON_NO_CLICK;\r
-\r
-       // Borrow a PWM unit for my real-time clock\r
-       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);\r
-       // 48 MHz / 1024 gives 46.875 kHz\r
-       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);\r
-       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;\r
-       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;\r
-\r
-       WORD start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-\r
-       int letoff = 0;\r
-       for(;;)\r
-       {\r
-               WORD now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-\r
-               // We haven't let off the button yet\r
-               if (!letoff)\r
-               {\r
-                       // We just let it off!\r
-                       if (!BUTTON_PRESS())\r
-                       {\r
-                               letoff = 1;\r
-\r
-                               // reset our timer for 500ms\r
-                               start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-                               ticks = (48000 * (500)) >> 10;\r
-                       }\r
-\r
-                       // Still haven't let it off\r
-                       else\r
-                               // Have we held down a full second?\r
-                               if (now == (WORD)(start + ticks))\r
-                                       return BUTTON_HOLD;\r
-               }\r
-\r
-               // We already let off, did we click again?\r
-               else\r
-                       // Sweet, double click!\r
-                       if (BUTTON_PRESS())\r
-                               return BUTTON_DOUBLE_CLICK;\r
-\r
-                       // Have we ran out of time to double click?\r
-                       else\r
-                               if (now == (WORD)(start + ticks))\r
-                                       // At least we did a single click\r
-                                       return BUTTON_SINGLE_CLICK;\r
-\r
-               WDT_HIT();\r
-       }\r
-\r
-       // We should never get here\r
-       return BUTTON_ERROR;\r
-}\r
-\r
-// Determine if a button is held down\r
-int BUTTON_HELD(int ms)\r
-{\r
-       // If button is held for one second\r
-       int ticks = (48000 * (ms ? ms : 1000)) >> 10;\r
-\r
-       // If we're not even pressed, forget about it!\r
-       if (!BUTTON_PRESS())\r
-               return BUTTON_NO_CLICK;\r
-\r
-       // Borrow a PWM unit for my real-time clock\r
-       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);\r
-       // 48 MHz / 1024 gives 46.875 kHz\r
-       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);\r
-       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;\r
-       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;\r
-\r
-       WORD start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-\r
-       for(;;)\r
-       {\r
-               WORD now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-\r
-               // As soon as our button let go, we didn't hold long enough\r
-               if (!BUTTON_PRESS())\r
-                       return BUTTON_SINGLE_CLICK;\r
-\r
-               // Have we waited the full second?\r
-               else\r
-                       if (now == (WORD)(start + ticks))\r
-                               return BUTTON_HOLD;\r
-\r
-               WDT_HIT();\r
-       }\r
-\r
-       // We should never get here\r
-       return BUTTON_ERROR;\r
-}\r
-\r
-// attempt at high resolution microsecond timer\r
-// beware: timer counts in 21.3uS increments (1024/48Mhz)\r
-void SpinDelayUs(int us)\r
-{\r
-       int ticks = (48*us) >> 10;\r
-\r
-       // Borrow a PWM unit for my real-time clock\r
-       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);\r
-       // 48 MHz / 1024 gives 46.875 kHz\r
-       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);\r
-       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;\r
-       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;\r
-\r
-       WORD start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-\r
-       for(;;) {\r
-               WORD now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;\r
-               if (now == (WORD)(start + ticks))\r
-                       return;\r
-\r
-               WDT_HIT();\r
-       }\r
-}\r
-\r
-void SpinDelay(int ms)\r
-{\r
-  // convert to uS and call microsecond delay function\r
-       SpinDelayUs(ms*1000);\r
-}\r
-\r
-/* Similar to FpgaGatherVersion this formats stored version information\r
- * into a string representation. It takes a pointer to the struct version_information,\r
- * verifies the magic properties, then stores a formatted string, prefixed by\r
- * prefix in dst.\r
- */\r
-void FormatVersionInformation(char *dst, int len, const char *prefix, void *version_information)\r
-{\r
-       struct version_information *v = (struct version_information*)version_information;\r
-       dst[0] = 0;\r
-       strncat(dst, prefix, len);\r
-       if(v->magic != VERSION_INFORMATION_MAGIC) {\r
-               strncat(dst, "Missing/Invalid version information", len);\r
-               return;\r
-       }\r
-       if(v->versionversion != 1) {\r
-               strncat(dst, "Version information not understood", len);\r
-               return;\r
-       }\r
-       if(!v->present) {\r
-               strncat(dst, "Version information not available", len);\r
-               return;\r
-       }\r
-       \r
-       strncat(dst, v->svnversion, len);\r
-       if(v->clean == 0) {\r
-               strncat(dst, "-unclean", len);\r
-       } else if(v->clean == 2) {\r
-               strncat(dst, "-suspect", len);\r
-       }\r
-       \r
-       strncat(dst, " ", len);\r
-       strncat(dst, v->buildtime, len);\r
-}\r
+//-----------------------------------------------------------------------------
+// Jonathan Westhues, Sept 2005
+//
+// This code is licensed to you under the terms of the GNU GPL, version 2 or,
+// at your option, any later version. See the LICENSE.txt file for the text of
+// the license.
+//-----------------------------------------------------------------------------
+// Utility functions used in many places, not specific to any piece of code.
+//-----------------------------------------------------------------------------
+
+#include "proxmark3.h"
+#include "util.h"
+#include "string.h"
+#include "apps.h"
+
+size_t nbytes(size_t nbits) {
+       return (nbits/8)+((nbits%8)>0);
+}
+
+uint32_t SwapBits(uint32_t value, int nrbits) {
+       int i;
+       uint32_t newvalue = 0;
+       for(i = 0; i < nrbits; i++) {
+               newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
+       }
+       return newvalue;
+}
+
+void num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
+{
+       while (len--) {
+               dest[len] = (uint8_t) n;
+               n >>= 8;
+       }
+}
+
+uint64_t bytes_to_num(uint8_t* src, size_t len)
+{
+       uint64_t num = 0;
+       while (len--)
+       {
+               num = (num << 8) | (*src);
+               src++;
+       }
+       return num;
+}
+
+void LEDsoff()
+{
+       LED_A_OFF();
+       LED_B_OFF();
+       LED_C_OFF();
+       LED_D_OFF();
+}
+
+// LEDs: R(C) O(A) G(B) -- R(D) [1, 2, 4 and 8]
+void LED(int led, int ms)
+{
+       if (led & LED_RED)
+               LED_C_ON();
+       if (led & LED_ORANGE)
+               LED_A_ON();
+       if (led & LED_GREEN)
+               LED_B_ON();
+       if (led & LED_RED2)
+               LED_D_ON();
+
+       if (!ms)
+               return;
+
+       SpinDelay(ms);
+
+       if (led & LED_RED)
+               LED_C_OFF();
+       if (led & LED_ORANGE)
+               LED_A_OFF();
+       if (led & LED_GREEN)
+               LED_B_OFF();
+       if (led & LED_RED2)
+               LED_D_OFF();
+}
+
+
+// Determine if a button is double clicked, single clicked,
+// not clicked, or held down (for ms || 1sec)
+// In general, don't use this function unless you expect a
+// double click, otherwise it will waste 500ms -- use BUTTON_HELD instead
+int BUTTON_CLICKED(int ms)
+{
+       // Up to 500ms in between clicks to mean a double click
+       int ticks = (48000 * (ms ? ms : 1000)) >> 10;
+
+       // If we're not even pressed, forget about it!
+       if (!BUTTON_PRESS())
+               return BUTTON_NO_CLICK;
+
+       // Borrow a PWM unit for my real-time clock
+       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
+       // 48 MHz / 1024 gives 46.875 kHz
+       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
+       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
+       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
+
+       uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+
+       int letoff = 0;
+       for(;;)
+       {
+               uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+
+               // We haven't let off the button yet
+               if (!letoff)
+               {
+                       // We just let it off!
+                       if (!BUTTON_PRESS())
+                       {
+                               letoff = 1;
+
+                               // reset our timer for 500ms
+                               start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+                               ticks = (48000 * (500)) >> 10;
+                       }
+
+                       // Still haven't let it off
+                       else
+                               // Have we held down a full second?
+                               if (now == (uint16_t)(start + ticks))
+                                       return BUTTON_HOLD;
+               }
+
+               // We already let off, did we click again?
+               else
+                       // Sweet, double click!
+                       if (BUTTON_PRESS())
+                               return BUTTON_DOUBLE_CLICK;
+
+                       // Have we ran out of time to double click?
+                       else
+                               if (now == (uint16_t)(start + ticks))
+                                       // At least we did a single click
+                                       return BUTTON_SINGLE_CLICK;
+
+               WDT_HIT();
+       }
+
+       // We should never get here
+       return BUTTON_ERROR;
+}
+
+// Determine if a button is held down
+int BUTTON_HELD(int ms)
+{
+       // If button is held for one second
+       int ticks = (48000 * (ms ? ms : 1000)) >> 10;
+
+       // If we're not even pressed, forget about it!
+       if (!BUTTON_PRESS())
+               return BUTTON_NO_CLICK;
+
+       // Borrow a PWM unit for my real-time clock
+       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
+       // 48 MHz / 1024 gives 46.875 kHz
+       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
+       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
+       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
+
+       uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+
+       for(;;)
+       {
+               uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+
+               // As soon as our button let go, we didn't hold long enough
+               if (!BUTTON_PRESS())
+                       return BUTTON_SINGLE_CLICK;
+
+               // Have we waited the full second?
+               else
+                       if (now == (uint16_t)(start + ticks))
+                               return BUTTON_HOLD;
+
+               WDT_HIT();
+       }
+
+       // We should never get here
+       return BUTTON_ERROR;
+}
+
+// attempt at high resolution microsecond timer
+// beware: timer counts in 21.3uS increments (1024/48Mhz)
+void SpinDelayUs(int us)
+{
+       int ticks = (48*us) >> 10;
+
+       // Borrow a PWM unit for my real-time clock
+       AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
+       // 48 MHz / 1024 gives 46.875 kHz
+       AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
+       AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
+       AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
+
+       uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+
+       for(;;) {
+               uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
+               if (now == (uint16_t)(start + ticks))
+                       return;
+
+               WDT_HIT();
+       }
+}
+
+void SpinDelay(int ms)
+{
+  // convert to uS and call microsecond delay function
+       SpinDelayUs(ms*1000);
+}
+
+/* Similar to FpgaGatherVersion this formats stored version information
+ * into a string representation. It takes a pointer to the struct version_information,
+ * verifies the magic properties, then stores a formatted string, prefixed by
+ * prefix in dst.
+ */
+void FormatVersionInformation(char *dst, int len, const char *prefix, void *version_information)
+{
+       struct version_information *v = (struct version_information*)version_information;
+       dst[0] = 0;
+       strncat(dst, prefix, len-1);
+       if(v->magic != VERSION_INFORMATION_MAGIC) {
+               strncat(dst, "Missing/Invalid version information", len - strlen(dst) - 1);
+               return;
+       }
+       if(v->versionversion != 1) {
+               strncat(dst, "Version information not understood", len - strlen(dst) - 1);
+               return;
+       }
+       if(!v->present) {
+               strncat(dst, "Version information not available", len - strlen(dst) - 1);
+               return;
+       }
+
+       strncat(dst, v->gitversion, len - strlen(dst) - 1);
+       if(v->clean == 0) {
+               strncat(dst, "-unclean", len - strlen(dst) - 1);
+       } else if(v->clean == 2) {
+               strncat(dst, "-suspect", len - strlen(dst) - 1);
+       }
+
+       strncat(dst, " ", len - strlen(dst) - 1);
+       strncat(dst, v->buildtime, len - strlen(dst) - 1);
+}
+
+//  -------------------------------------------------------------------------
+//  timer lib
+//  -------------------------------------------------------------------------
+//  test procedure:
+//
+//     ti = GetTickCount();
+//     SpinDelay(1000);
+//     ti = GetTickCount() - ti;
+//     Dbprintf("timer(1s): %d t=%d", ti, GetTickCount());
+
+void StartTickCount()
+{
+//  must be 0x40, but on my cpu - included divider is optimal
+//  0x20 - 1 ms / bit 
+//  0x40 - 2 ms / bit
+
+       AT91C_BASE_RTTC->RTTC_RTMR = AT91C_RTTC_RTTRST + 0x001D; // was 0x003B
+}
+
+/*
+* Get the current count.
+*/
+uint32_t RAMFUNC GetTickCount(){
+       return AT91C_BASE_RTTC->RTTC_RTVR;// was * 2;
+}
+
+//  -------------------------------------------------------------------------
+//  microseconds timer 
+//  -------------------------------------------------------------------------
+void StartCountUS()
+{
+       AT91C_BASE_PMC->PMC_PCER |= (0x1 << 12) | (0x1 << 13) | (0x1 << 14);
+//     AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC1XC1S_TIOA0;
+       AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE | AT91C_TCB_TC1XC1S_TIOA0 | AT91C_TCB_TC2XC2S_NONE;
+
+       // fast clock
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS; // timer disable
+       AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK | // MCK(48MHz)/32 -- tick=1.5mks
+                                                                                                               AT91C_TC_WAVE | AT91C_TC_WAVESEL_UP_AUTO | AT91C_TC_ACPA_CLEAR |
+                                                                                                               AT91C_TC_ACPC_SET | AT91C_TC_ASWTRG_SET;
+       AT91C_BASE_TC0->TC_RA = 1;
+       AT91C_BASE_TC0->TC_RC = 0xBFFF + 1; // 0xC000
+       
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; // timer disable  
+       AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_XC1; // from timer 0
+       
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN;
+       AT91C_BASE_TCB->TCB_BCR = 1;
+       }
+
+uint32_t RAMFUNC GetCountUS(){
+       return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV / 15) * 10);
+}
+
+static uint32_t GlobalUsCounter = 0;
+
+uint32_t RAMFUNC GetDeltaCountUS(){
+       uint32_t g_cnt = GetCountUS();
+       uint32_t g_res = g_cnt - GlobalUsCounter;
+       GlobalUsCounter = g_cnt;
+       return g_res;
+}
+
+
+//  -------------------------------------------------------------------------
+//  Timer for iso14443 commands. Uses ssp_clk from FPGA 
+//  -------------------------------------------------------------------------
+void StartCountSspClk()
+{
+       AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0) | (1 << AT91C_ID_TC1) | (1 << AT91C_ID_TC2);  // Enable Clock to all timers
+       AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_TIOA1               // XC0 Clock = TIOA1
+                                                       | AT91C_TCB_TC1XC1S_NONE                // XC1 Clock = none
+                                                       | AT91C_TCB_TC2XC2S_TIOA0;              // XC2 Clock = TIOA0
+
+       // configure TC1 to create a short pulse on TIOA1 when a rising edge on TIOB1 (= ssp_clk from FPGA) occurs:
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;                               // disable TC1
+       AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK // TC1 Clock = MCK(48MHz)/2 = 24MHz
+                                                       | AT91C_TC_CPCSTOP                              // Stop clock on RC compare
+                                                       | AT91C_TC_EEVTEDG_RISING               // Trigger on rising edge of Event
+                                                       | AT91C_TC_EEVT_TIOB                    // Event-Source: TIOB1 (= ssp_clk from FPGA = 13,56MHz/16)
+                                                       | AT91C_TC_ENETRG                               // Enable external trigger event
+                                                       | AT91C_TC_WAVESEL_UP                   // Upmode without automatic trigger on RC compare
+                                                       | AT91C_TC_WAVE                                 // Waveform Mode
+                                                       | AT91C_TC_AEEVT_SET                    // Set TIOA1 on external event
+                                                       | AT91C_TC_ACPC_CLEAR;                  // Clear TIOA1 on RC Compare
+       AT91C_BASE_TC1->TC_RC = 0x04;                                                   // RC Compare value = 0x04
+
+       // use TC0 to count TIOA1 pulses
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;                               // disable TC0
+       AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_XC0                              // TC0 clock = XC0 clock = TIOA1
+                                                       | AT91C_TC_WAVE                                 // Waveform Mode
+                                                       | AT91C_TC_WAVESEL_UP                   // just count
+                                                       | AT91C_TC_ACPA_CLEAR                   // Clear TIOA0 on RA Compare
+                                                       | AT91C_TC_ACPC_SET;                    // Set TIOA0 on RC Compare
+       AT91C_BASE_TC0->TC_RA = 1;                                                              // RA Compare value = 1; pulse width to TC2
+       AT91C_BASE_TC0->TC_RC = 0;                                                              // RC Compare value = 0; increment TC2 on overflow
+
+       // use TC2 to count TIOA0 pulses (giving us a 32bit counter (TC0/TC2) clocked by ssp_clk)
+       AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKDIS;                               // disable TC2  
+       AT91C_BASE_TC2->TC_CMR = AT91C_TC_CLKS_XC2                              // TC2 clock = XC2 clock = TIOA0
+                                                       | AT91C_TC_WAVE                                 // Waveform Mode
+                                                       | AT91C_TC_WAVESEL_UP;                  // just count
+       
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN;                                // enable TC0
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN;                                // enable TC1
+       AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN;                                // enable TC2
+
+       //
+       // synchronize the counter with the ssp_frame signal. Note: FPGA must be in any iso14446 mode, otherwise the frame signal would not be present 
+       //
+       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME));   // wait for ssp_frame to go high (start of frame)
+       while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME);              // wait for ssp_frame to be low
+       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK));     // wait for ssp_clk to go high
+       // note: up to now two ssp_clk rising edges have passed since the rising edge of ssp_frame
+       // it is now safe to assert a sync signal. This sets all timers to 0 on next active clock edge
+       AT91C_BASE_TCB->TCB_BCR = 1;                                                    // assert Sync (set all timers to 0 on next active clock edge)
+       // at the next (3rd) ssp_clk rising edge, TC1 will be reset (and not generate a clock signal to TC0)
+       // at the next (4th) ssp_clk rising edge, TC0 (the low word of our counter) will be reset. From now on,
+       // whenever the last three bits of our counter go 0, we can be sure to be in the middle of a frame transfer.
+       // (just started with the transfer of the 4th Bit).
+       // The high word of the counter (TC2) will not reset until the low word (TC0) overflows. Therefore need to wait quite some time before
+       // we can use the counter.
+       while (AT91C_BASE_TC0->TC_CV < 0xFFF0);
+}
+
+
+uint32_t RAMFUNC GetCountSspClk(){
+       uint32_t tmp_count;
+       tmp_count = (AT91C_BASE_TC2->TC_CV << 16) | AT91C_BASE_TC0->TC_CV;
+       if ((tmp_count & 0x0000ffff) == 0) { //small chance that we may have missed an increment in TC2
+               return (AT91C_BASE_TC2->TC_CV << 16);
+       } 
+       else {
+               return tmp_count;
+       }
+}
+
+
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