]> cvs.zerfleddert.de Git - proxmark3-svn/blobdiff - armsrc/util.c
Fix some printf/scanf format strings
[proxmark3-svn] / armsrc / util.c
index b3f0e76e4df5b5127e68042e26f45899b4633231..b0cd181824a977e0ffa2410c68ba65cb521db275 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
+//-----------------------------------------------------------------------------
+// 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"
+#include "BigBuf.h"
+
+
+
+void print_result(char *name, uint8_t *buf, size_t len) {
+   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",
+                               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]);
+   }
+}
+
+size_t nbytes(size_t nbits) {
+       return (nbits >> 3)+((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;
+}
+
+// RotateLeft - Ultralight, Desfire
+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;
+}
+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);
+       }
+       data[len - 1] <<= 1;
+}
+
+void LEDsoff()
+{
+       LED_A_OFF();
+       LED_B_OFF();
+       LED_C_OFF();
+       LED_D_OFF();
+}
+
+void LEDson()
+{
+       LED_A_ON();
+       LED_B_ON();
+       LED_C_ON();
+       LED_D_ON();
+}
+
+void LEDsinvert()
+{
+       LED_A_INV();
+       LED_B_INV();
+       LED_C_INV();
+       LED_D_INV();
+}
+
+// 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\n", len - strlen(dst) - 1);
+               return;
+       }
+       if(v->versionversion != 1) {
+               strncat(dst, "Version information not understood\n", len - strlen(dst) - 1);
+               return;
+       }
+       if(!v->present) {
+               strncat(dst, "Version information not available\n", 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);
+       strncat(dst, "\n", 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() {
+       // 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%
+}
+
+
+/*
+* Get the current count.
+*/
+uint32_t RAMFUNC GetTickCount(void) {
+       return AT91C_BASE_RTTC->RTTC_RTVR;// was * 2;
+}
+
+
+//  -------------------------------------------------------------------------
+//  microseconds timer
+//  -------------------------------------------------------------------------
+void StartCountUS(void) {
+       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(void) {
+       return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV * 2) / 3); //was  /15) * 10);
+}
+
+
+static uint32_t GlobalUsCounter = 0;
+
+uint32_t RAMFUNC GetDeltaCountUS(void) {
+       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(void) {
+       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 ... 13,56MHz/4)
+                                                       | 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 = 1;                              // RC Compare value = 1; pulse width to TC0
+
+       // 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 a FPGA mode with SSC transfer, otherwise SSC_FRAME and SSC_CLK signals would not be present
+       //
+       while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME);      // wait for ssp_frame to be low
+       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_CLK));     // wait for ssp_clk to go high; 1st ssp_clk after start of frame
+       while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);        // wait for ssp_clk to go low;
+       while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK));     // wait for ssp_clk to go high; 2nd ssp_clk after start of frame
+       if ((AT91C_BASE_SSC->SSC_RFMR & SSC_FRAME_MODE_BITS_IN_WORD(32)) == SSC_FRAME_MODE_BITS_IN_WORD(16)) { // 16bit frame
+               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);    // wait for ssp_clk to go low;
+               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)); // wait for ssp_clk to go high; 3rd ssp_clk after start of frame
+               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);    // wait for ssp_clk to go low;
+               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)); // wait for ssp_clk to go high; 4th ssp_clk after start of frame
+               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);    // wait for ssp_clk to go low;
+               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)); // wait for ssp_clk to go high; 5th ssp_clk after start of frame
+               while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK);    // wait for ssp_clk to go low;
+               while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)); // wait for ssp_clk to go high; 6th ssp_clk after start of 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/7th) ssp_clk rising edge, TC1 will be reset (and not generate a clock signal to TC0)
+       // at the next (4th/8th) ssp_clk rising edge, TC0 (the low word of our counter) will be reset. From now on,
+       // whenever the last three/four bits of our counter go 0, we can be sure to be in the middle of a frame transfer.
+
+       // 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 < 0xFFFF);
+       // Note: needs one more SSP_CLK cycle (1.18 us) until TC2 resets. Don't call GetCountSspClk() that soon.
+}
+
+
+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;
+       while (AT91C_BASE_TC2->TC_CV > 0);
+}
+
+uint32_t GetCountSspClk(){
+       uint32_t hi, lo;
+
+       do { 
+               hi = AT91C_BASE_TC2->TC_CV;
+               lo = AT91C_BASE_TC0->TC_CV;
+       } while (hi != AT91C_BASE_TC2->TC_CV);
+       
+       return (hi << 16) | lo;
+}
+
+//  -------------------------------------------------------------------------
+//  Timer for bitbanging, or LF stuff when you need a very precis timer
+//  1us = 1.5ticks
+//  -------------------------------------------------------------------------
+void StartTicks(void){
+       // initialization of the timer
+       AT91C_BASE_PMC->PMC_PCER |= (1 << AT91C_ID_TC0) | (1 << AT91C_ID_TC1);
+       AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE | AT91C_TCB_TC1XC1S_TIOA0 | AT91C_TCB_TC2XC2S_NONE;
+
+       // disable TC0 and TC1 for re-configuration
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+
+       // first configure TC1 (higher, 0xFFFF0000) 16 bit counter
+       AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_XC1; // just connect to TIOA0 from TC0
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; // re-enable timer and wait for TC0
+
+       // second configure TC0 (lower, 0x0000FFFF) 16 bit counter
+       AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK | // MCK(48MHz) / 32
+                                                        AT91C_TC_WAVE | AT91C_TC_WAVESEL_UP_AUTO |
+                                                        AT91C_TC_ACPA_CLEAR | // RA comperator clears TIOA (carry bit)
+                                                        AT91C_TC_ACPC_SET |   // RC comperator sets TIOA (carry bit)
+                                                        AT91C_TC_ASWTRG_SET;  // SWTriger sets TIOA (carry bit)
+       AT91C_BASE_TC0->TC_RC  = 0; // set TIOA (carry bit) on overflow, return to zero
+       AT91C_BASE_TC0->TC_RA  = 1; // clear carry bit on next clock cycle
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG; // reset and re-enable timer
+
+       // synchronized startup procedure
+       while (AT91C_BASE_TC0->TC_CV > 0); // wait until TC0 returned to zero
+       while (AT91C_BASE_TC0->TC_CV < 2); // and has started (TC_CV > TC_RA, now TC1 is cleared)
+
+       // return to zero
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_SWTRG;
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_SWTRG;
+       while (AT91C_BASE_TC0->TC_CV > 0);
+}
+
+
+uint32_t GetTicks(void) {
+       uint32_t hi, lo;
+
+       do {
+               hi = AT91C_BASE_TC1->TC_CV;
+               lo = AT91C_BASE_TC0->TC_CV;
+       } while(hi != AT91C_BASE_TC1->TC_CV);
+
+       return (hi << 16) | lo;
+}
+
+
+// Wait - Spindelay in ticks.
+// if called with a high number, this will trigger the WDT...
+void WaitTicks(uint32_t ticks){
+       if ( ticks == 0 ) return;
+       ticks += GetTicks();
+       while (GetTicks() < ticks);
+}
+
+
+// Wait / Spindelay in us (microseconds)
+// 1us = 1.5ticks.
+void WaitUS(uint16_t us){
+       WaitTicks( (uint32_t)us * 3 / 2 ) ;
+}
+
+
+void WaitMS(uint16_t ms){
+       WaitTicks( (uint32_t)ms * 1500 );
+}
+
+
+// Starts Clock and waits until its reset
+void ResetTicks(void){
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       while (AT91C_BASE_TC0->TC_CV > 0);
+}
+
+
+void ResetTimer(AT91PS_TC timer){
+       timer->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+       while(timer->TC_CV > 0) ;
+}
+
+
+// stop clock
+void StopTicks(void){
+       AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
+       AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
+}
+
+
+static uint64_t next_random = 1;
+
+/* Generates a (non-cryptographically secure) 32-bit random number.
+ *
+ * We don't have an implementation of the "rand" function or a clock to seed it
+ * with, so we just call GetTickCount the first time to seed ourselves.
+ */
+uint32_t prand() {
+       if (next_random == 1) {
+               next_random = GetTickCount();
+       }
+
+       next_random = next_random * 6364136223846793005 + 1;
+       return (uint32_t)(next_random >> 32) % 0xffffffff;
+}
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