FIX: Even the US clock had the issues with not resetting properly. Now its always...

[proxmark3-svn] / armsrc / util.c

diff --git a/armsrc/util.c b/armsrc/util.c
index 74fba94b764db748cf6a377ba23b96f5d06bc304..37fe3f4396a79be827fd5216c28b1b5973f0c6ae 100644 (file)
--- a/armsrc/util.c
+++ b/armsrc/util.c
@@ -8,30 +8,28 @@
 // Utility functions used in many places, not specific to any piece of code.
 //-----------------------------------------------------------------------------
 
 // Utility functions used in many places, not specific to any piece of code.
 //-----------------------------------------------------------------------------
 

-#include "proxmark3.h"

 #include "util.h"
 #include "util.h"

-#include "string.h"
-#include "apps.h"
-#include "BigBuf.h"
-
-

 
 void print_result(char *name, uint8_t *buf, size_t len) {
 
 void print_result(char *name, uint8_t *buf, size_t len) {

-   uint8_t *p = buf;
+       uint8_t *p = buf;

 
 

-   if ( len % 16 == 0 ) {
-          for(; p-buf < len; p += 16)
-       Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
+       if ( len % 16 == 0 ) {
+               for(; p-buf < len; p += 16)
+                       Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",

                                name,
                                p-buf,
                                len,
                                p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]
                                name,
                                p-buf,
                                len,
                                p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7],p[8], p[9], p[10], p[11], p[12], p[13], p[14], p[15]

-          );
-   }
-   else {
-   for(; p-buf < len; p += 8)
-       Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x", name, p-buf, len, p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
-   }
+                       );
+       }
+       else {
+               for(; p-buf < len; p += 8)
+                       Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x",
+                               name,
+                               p-buf,
+                               len,
+                               p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
+       }

 }
 
 size_t nbytes(size_t nbits) {
 }
 
 size_t nbytes(size_t nbits) {


@@ -39,27 +37,40 @@ size_t nbytes(size_t nbits) {
 }
 
 uint32_t SwapBits(uint32_t value, int nrbits) {
 }
 
 uint32_t SwapBits(uint32_t value, int nrbits) {

-       int i;

        uint32_t newvalue = 0;
        uint32_t newvalue = 0;

-       for(i = 0; i < nrbits; i++) {
+       for(int i = 0; i < nrbits; i++) {

                newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
        }
        return newvalue;
 }
 
                newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
        }
        return newvalue;
 }
 

-void num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
-{
+/*
+ ref  http://www.csm.ornl.gov/~dunigan/crc.html
+ Returns the value v with the bottom b [0,32] bits reflected. 
+ Example: reflect(0x3e23L,3) == 0x3e26
+*/
+uint32_t reflect(uint32_t v, int b) {
+       uint32_t t = v;
+       for ( int i = 0; i < b; ++i) {
+               if (t & 1)
+                       v |=  BITMASK((b-1)-i);
+               else
+                       v &= ~BITMASK((b-1)-i);
+               t >>= 1;
+       }
+       return v;
+}
+
+void num_to_bytes(uint64_t n, size_t len, uint8_t* dest) {

        while (len--) {
                dest[len] = (uint8_t) n;
                n >>= 8;
        }
 }
 
        while (len--) {
                dest[len] = (uint8_t) n;
                n >>= 8;
        }
 }
 

-uint64_t bytes_to_num(uint8_t* src, size_t len)
-{
+uint64_t bytes_to_num(uint8_t* src, size_t len) {

        uint64_t num = 0;
        uint64_t num = 0;

-       while (len--)
-       {
+       while (len--) {

                num = (num << 8) | (*src);
                src++;
        }
                num = (num << 8) | (*src);
                src++;
        }


@@ -67,13 +78,14 @@ uint64_t bytes_to_num(uint8_t* src, size_t len)
 }
 
 // RotateLeft - Ultralight, Desfire
 }
 
 // RotateLeft - Ultralight, Desfire

-void rol(uint8_t *data, const size_t len){
+void rol(uint8_t *data, const size_t len) {

     uint8_t first = data[0];
     for (size_t i = 0; i < len-1; i++) {
         data[i] = data[i+1];
     }
     data[len-1] = first;
 }
     uint8_t first = data[0];
     for (size_t i = 0; i < len-1; i++) {
         data[i] = data[i+1];
     }
     data[len-1] = first;
 }

+

 void lsl (uint8_t *data, size_t len) {
     for (size_t n = 0; n < len - 1; n++) {
         data[n] = (data[n] << 1) | (data[n+1] >> 7);
 void lsl (uint8_t *data, size_t len) {
     for (size_t n = 0; n < len - 1; n++) {
         data[n] = (data[n] << 1) | (data[n+1] >> 7);


@@ -81,13 +93,11 @@ void lsl (uint8_t *data, size_t len) {
     data[len - 1] <<= 1;
 }
 
     data[len - 1] <<= 1;
 }
 

-int32_t le24toh (uint8_t data[3])
-{
+int32_t le24toh (uint8_t data[3]) {

     return (data[2] << 16) | (data[1] << 8) | data[0];
 }
 
     return (data[2] << 16) | (data[1] << 8) | data[0];
 }
 

-void LEDsoff()
-{
+void LEDsoff() {

        LED_A_OFF();
        LED_B_OFF();
        LED_C_OFF();
        LED_A_OFF();
        LED_B_OFF();
        LED_C_OFF();


@@ -95,8 +105,7 @@ void LEDsoff()
 }
 
 // LEDs: R(C) O(A) G(B) -- R(D) [1, 2, 4 and 8]
 }
 
 // LEDs: R(C) O(A) G(B) -- R(D) [1, 2, 4 and 8]

-void LED(int led, int ms)
-{
+void LED(int led, int ms) {

        if (led & LED_RED)
                LED_C_ON();
        if (led & LED_ORANGE)
        if (led & LED_RED)
                LED_C_ON();
        if (led & LED_ORANGE)


@@ -121,13 +130,11 @@ void LED(int led, int ms)
                LED_D_OFF();
 }
 
                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
 // 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)
-{
+int BUTTON_CLICKED(int ms) {

        // Up to 500ms in between clicks to mean a double click
        int ticks = (48000 * (ms ? ms : 1000)) >> 10;
 
        // Up to 500ms in between clicks to mean a double click
        int ticks = (48000 * (ms ? ms : 1000)) >> 10;
 


@@ -189,8 +196,7 @@ int BUTTON_CLICKED(int ms)
 }
 
 // Determine if a button is held down
 }
 
 // Determine if a button is held down

-int BUTTON_HELD(int ms)
-{
+int BUTTON_HELD(int ms) {

        // If button is held for one second
        int ticks = (48000 * (ms ? ms : 1000)) >> 10;
 
        // If button is held for one second
        int ticks = (48000 * (ms ? ms : 1000)) >> 10;
 


@@ -229,8 +235,7 @@ int BUTTON_HELD(int ms)
 
 // attempt at high resolution microsecond timer
 // beware: timer counts in 21.3uS increments (1024/48Mhz)
 
 // attempt at high resolution microsecond timer
 // beware: timer counts in 21.3uS increments (1024/48Mhz)

-void SpinDelayUs(int us)
-{
+void SpinDelayUs(int us) {

        int ticks = (48*us) >> 10;
 
        // Borrow a PWM unit for my real-time clock
        int ticks = (48*us) >> 10;
 
        // Borrow a PWM unit for my real-time clock


@@ -251,8 +256,7 @@ void SpinDelayUs(int us)
        }
 }
 
        }
 }
 

-void SpinDelay(int ms)
-{
+void SpinDelay(int ms) {

   // convert to uS and call microsecond delay function
        SpinDelayUs(ms*1000);
 }
   // convert to uS and call microsecond delay function
        SpinDelayUs(ms*1000);
 }


@@ -262,21 +266,20 @@ void SpinDelay(int ms)
  * verifies the magic properties, then stores a formatted string, prefixed by
  * prefix in dst.
  */
  * 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)
-{
+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) {
        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);
+               strncat(dst, "Missing/Invalid version information\n", len - strlen(dst) - 1);

                return;
        }
        if(v->versionversion != 1) {
                return;
        }
        if(v->versionversion != 1) {

-               strncat(dst, "Version information not understood", len - strlen(dst) - 1);
+               strncat(dst, "Version information not understood\n", len - strlen(dst) - 1);

                return;
        }
        if(!v->present) {
                return;
        }
        if(!v->present) {

-               strncat(dst, "Version information not available", len - strlen(dst) - 1);
+               strncat(dst, "Version information not available\n", len - strlen(dst) - 1);

                return;
        }
 
                return;
        }
 


@@ -289,6 +292,7 @@ void FormatVersionInformation(char *dst, int len, const char *prefix, void *vers
 
        strncat(dst, " ", len - strlen(dst) - 1);
        strncat(dst, v->buildtime, len - strlen(dst) - 1);
 
        strncat(dst, " ", len - strlen(dst) - 1);
        strncat(dst, v->buildtime, len - strlen(dst) - 1);

+       strncat(dst, "\n", len - strlen(dst) - 1);

 }
 
 //  -------------------------------------------------------------------------
 }
 
 //  -------------------------------------------------------------------------


@@ -301,13 +305,13 @@ void FormatVersionInformation(char *dst, int len, const char *prefix, void *vers
 //     ti = GetTickCount() - ti;
 //     Dbprintf("timer(1s): %d t=%d", ti, GetTickCount());
 
 //     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
+void StartTickCount() {
+       // This timer is based on the slow clock. The slow clock frequency is between 22kHz and 40kHz.
+       // We can determine the actual slow clock frequency by looking at the Main Clock Frequency Register.
+    uint16_t mainf = AT91C_BASE_PMC->PMC_MCFR & 0xffff;                // = 16 * main clock frequency (16MHz) / slow clock frequency
+       // set RealTimeCounter divider to count at 1kHz:
+       AT91C_BASE_RTTC->RTTC_RTMR = AT91C_RTTC_RTTRST | ((256000 + (mainf/2)) / mainf);
+       // note: worst case precision is approx 2.5%

 }
 
 /*
 }
 
 /*


@@ -320,8 +324,7 @@ uint32_t RAMFUNC GetTickCount(){
 //  -------------------------------------------------------------------------
 //  microseconds timer 
 //  -------------------------------------------------------------------------
 //  -------------------------------------------------------------------------
 //  microseconds timer 
 //  -------------------------------------------------------------------------

-void StartCountUS()
-{
+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;
        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;


@@ -329,38 +332,49 @@ void StartCountUS()
        // 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
        // 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_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_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_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;

        AT91C_BASE_TCB->TCB_BCR = 1;
        AT91C_BASE_TCB->TCB_BCR = 1;

-       }
+       
+       while (AT91C_BASE_TC1->TC_CV >= 1);
+}

 
 uint32_t RAMFUNC GetCountUS(){
 
 uint32_t RAMFUNC GetCountUS(){

-       return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV / 15) * 10);
+       //return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV / 15) * 10);
+       //  By suggestion from PwPiwi, http://www.proxmark.org/forum/viewtopic.php?pid=17548#p17548
+       //return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV * 2) / 3); 
+       return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV << 1) / 3); 
+       //return (AT91C_BASE_TC1->TC_CV << 16) | ((AT91C_BASE_TC0->TC_CV << 1) / 3); 
+}
+void ResetUSClock(void) {      
+       //enable clock of timer and software trigger
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       while (AT91C_BASE_TC1->TC_CV >= 1);

 }
 
 }
 

-static uint32_t GlobalUsCounter = 0;
+// 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;
-}
+// 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 
 //  -------------------------------------------------------------------------
 
 
 //  -------------------------------------------------------------------------
 //  Timer for iso14443 commands. Uses ssp_clk from FPGA 
 //  -------------------------------------------------------------------------

-void StartCountSspClk()
-{
+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_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


@@ -394,17 +408,17 @@ void StartCountSspClk()
        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_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 
-       //
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;                               // enable and reset TC0
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;                               // enable and reset TC1
+       AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;                               // enable and reset TC2
+
+       // synchronize the counter with the ssp_frame signal. 
+       // Note: FPGA must be in any iso14443 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
        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)
        // 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)


@@ -412,20 +426,22 @@ void StartCountSspClk()
        // 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).
        // 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);
-}

 
 

+       // 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_TC2->TC_CV >= 1);
+}
+void ResetSspClk(void) {       
+       //enable clock of timer and software trigger
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+}

 
 uint32_t RAMFUNC GetCountSspClk(){
 
 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
+       uint32_t 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);
                return (AT91C_BASE_TC2->TC_CV << 16);

-       } 
-       else {
-               return tmp_count;
-       }
+       return tmp_count;

 }
 
 }