[proxmark3-svn] / armsrc / util.c

//-----------------------------------------------------------------------------
// 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;
}

int32_t le24toh (uint8_t data[3])
{
    return (data[2] << 16) | (data[1] << 8) | data[0];
}

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\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(){
	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 * 2) / 3); //was  /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 iso14443 mode, 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 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 < 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 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;
	}
}


//  -------------------------------------------------------------------------
//  Timer for bitbanging,  or LF stuff when you need a very precis timer
//  1us = 1.5ticks
//  -------------------------------------------------------------------------
void StartTicks(void){
	//initialization of the timer
	// tc1 is higher 0xFFFF0000
	// tc0 is lower 0x0000FFFF
	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;
	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
	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 |
								AT91C_TC_ACPC_SET | AT91C_TC_ASWTRG_SET;
	AT91C_BASE_TC0->TC_RA = 1;
	AT91C_BASE_TC0->TC_RC = 0; 

	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;	// timer disable  
	AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_XC1; // from TC0
	
	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;
	
	// wait until timer becomes zero.
	while (AT91C_BASE_TC1->TC_CV > 0);
}


// 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 += GET_TICKS;	
	while (GET_TICKS < ticks);
}


// Wait / Spindelay in us (microseconds) 
// 1us = 1.5ticks.
void WaitUS(uint16_t us){
	if ( us == 0 ) return;
	WaitTicks( (uint32_t)us * 3 / 2 ) ;
}


void WaitMS(uint16_t ms){
	if (ms == 0) return;
	WaitTicks( (uint32_t)ms * 1500 );
}


// Starts Clock and waits until its reset
void ResetTicks(void){
	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 > 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;
}
Commit	Line	Data
e30c654b	1	//-----------------------------------------------------------------------------
e30c654b	2	// Jonathan Westhues, Sept 2005
bd20f8f4	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	// Utility functions used in many places, not specific to any piece of code.
e30c654b	9	//-----------------------------------------------------------------------------
bd20f8f4	10
e30c654b	11	#include "proxmark3.h"
f7e3ed82	12	#include "util.h"
9ab7a6c7	13	#include "string.h"
9492e0b0	14	#include "apps.h"
7d5ebac9	15	#include "BigBuf.h"
e30c654b	16
787b5bd8	17
	18
	19	void print_result(char name, uint8_t buf, size_t len) {
	20	uint8_t *p = buf;
	21
	22	if ( len % 16 == 0 ) {
	23	for(; p-buf < len; p += 16)
	24	Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
	25	name,
	26	p-buf,
	27	len,
	28	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]
	29	);
	30	}
	31	else {
	32	for(; p-buf < len; p += 8)
	33	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]);
	34	}
	35	}
	36
195af472	37	size_t nbytes(size_t nbits) {
665775c8	38	return (nbits >> 3)+((nbits % 8) > 0);
195af472	39	}
195af472	40
81cd0474	41	uint32_t SwapBits(uint32_t value, int nrbits) {
	42	int i;
	43	uint32_t newvalue = 0;
	44	for(i = 0; i < nrbits; i++) {
	45	newvalue ^= ((value >> i) & 1) << (nrbits - 1 - i);
	46	}
	47	return newvalue;
	48	}
	49
f7e3ed82	50	void num_to_bytes(uint64_t n, size_t len, uint8_t* dest)
e30c654b	51	{
e30c654b	52	while (len--) {
f7e3ed82	53	dest[len] = (uint8_t) n;
e30c654b	54	n >>= 8;
	55	}
	56	}
	57
f7e3ed82	58	uint64_t bytes_to_num(uint8_t* src, size_t len)
e30c654b	59	{
	60	uint64_t num = 0;
	61	while (len--)
	62	{
	63	num = (num << 8) \| (*src);
	64	src++;
	65	}
	66	return num;
	67	}
	68
787b5bd8	69	// RotateLeft - Ultralight, Desfire
	70	void rol(uint8_t *data, const size_t len){
	71	uint8_t first = data[0];
	72	for (size_t i = 0; i < len-1; i++) {
	73	data[i] = data[i+1];
	74	}
	75	data[len-1] = first;
	76	}
	77	void lsl (uint8_t *data, size_t len) {
	78	for (size_t n = 0; n < len - 1; n++) {
	79	data[n] = (data[n] << 1) \| (data[n+1] >> 7);
	80	}
	81	data[len - 1] <<= 1;
	82	}
	83
	84	int32_t le24toh (uint8_t data[3])
	85	{
	86	return (data[2] << 16) \| (data[1] << 8) \| data[0];
	87	}
	88
e30c654b	89	void LEDsoff()
	90	{
	91	LED_A_OFF();
	92	LED_B_OFF();
	93	LED_C_OFF();
	94	LED_D_OFF();
	95	}
	96
	97	// LEDs: R(C) O(A) G(B) -- R(D) [1, 2, 4 and 8]
	98	void LED(int led, int ms)
	99	{
	100	if (led & LED_RED)
	101	LED_C_ON();
	102	if (led & LED_ORANGE)
	103	LED_A_ON();
	104	if (led & LED_GREEN)
	105	LED_B_ON();
	106	if (led & LED_RED2)
	107	LED_D_ON();
	108
	109	if (!ms)
	110	return;
	111
	112	SpinDelay(ms);
	113
	114	if (led & LED_RED)
	115	LED_C_OFF();
	116	if (led & LED_ORANGE)
	117	LED_A_OFF();
	118	if (led & LED_GREEN)
	119	LED_B_OFF();
	120	if (led & LED_RED2)
	121	LED_D_OFF();
	122	}
	123
	124
	125	// Determine if a button is double clicked, single clicked,
	126	// not clicked, or held down (for ms \|\| 1sec)
	127	// In general, don't use this function unless you expect a
	128	// double click, otherwise it will waste 500ms -- use BUTTON_HELD instead
	129	int BUTTON_CLICKED(int ms)
	130	{
	131	// Up to 500ms in between clicks to mean a double click
	132	int ticks = (48000 * (ms ? ms : 1000)) >> 10;
	133
	134	// If we're not even pressed, forget about it!
	135	if (!BUTTON_PRESS())
	136	return BUTTON_NO_CLICK;
	137
	138	// Borrow a PWM unit for my real-time clock
	139	AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
	140	// 48 MHz / 1024 gives 46.875 kHz
	141	AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
	142	AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
	143	AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
	144
f7e3ed82	145	uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
e30c654b	146
	147	int letoff = 0;
	148	for(;;)
	149	{
f7e3ed82	150	uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
e30c654b	151
	152	// We haven't let off the button yet
	153	if (!letoff)
	154	{
	155	// We just let it off!
	156	if (!BUTTON_PRESS())
	157	{
	158	letoff = 1;
	159
	160	// reset our timer for 500ms
	161	start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
	162	ticks = (48000 * (500)) >> 10;
	163	}
	164
	165	// Still haven't let it off
	166	else
	167	// Have we held down a full second?
f7e3ed82	168	if (now == (uint16_t)(start + ticks))
e30c654b	169	return BUTTON_HOLD;
	170	}
	171
	172	// We already let off, did we click again?
	173	else
	174	// Sweet, double click!
	175	if (BUTTON_PRESS())
	176	return BUTTON_DOUBLE_CLICK;
	177
	178	// Have we ran out of time to double click?
	179	else
f7e3ed82	180	if (now == (uint16_t)(start + ticks))
e30c654b	181	// At least we did a single click
	182	return BUTTON_SINGLE_CLICK;
	183
	184	WDT_HIT();
	185	}
	186
	187	// We should never get here
	188	return BUTTON_ERROR;
	189	}
	190
	191	// Determine if a button is held down
	192	int BUTTON_HELD(int ms)
	193	{
	194	// If button is held for one second
	195	int ticks = (48000 * (ms ? ms : 1000)) >> 10;
	196
	197	// If we're not even pressed, forget about it!
	198	if (!BUTTON_PRESS())
	199	return BUTTON_NO_CLICK;
	200
	201	// Borrow a PWM unit for my real-time clock
	202	AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
	203	// 48 MHz / 1024 gives 46.875 kHz
	204	AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
	205	AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
	206	AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
	207
f7e3ed82	208	uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
e30c654b	209
	210	for(;;)
	211	{
f7e3ed82	212	uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
e30c654b	213
	214	// As soon as our button let go, we didn't hold long enough
	215	if (!BUTTON_PRESS())
	216	return BUTTON_SINGLE_CLICK;
	217
	218	// Have we waited the full second?
	219	else
f7e3ed82	220	if (now == (uint16_t)(start + ticks))
e30c654b	221	return BUTTON_HOLD;
	222
	223	WDT_HIT();
	224	}
	225
	226	// We should never get here
	227	return BUTTON_ERROR;
	228	}
	229
	230	// attempt at high resolution microsecond timer
	231	// beware: timer counts in 21.3uS increments (1024/48Mhz)
	232	void SpinDelayUs(int us)
	233	{
	234	int ticks = (48*us) >> 10;
	235
	236	// Borrow a PWM unit for my real-time clock
	237	AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);
	238	// 48 MHz / 1024 gives 46.875 kHz
	239	AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);
	240	AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;
	241	AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;
	242
f7e3ed82	243	uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
e30c654b	244
e30c654b	245	for(;;) {
f7e3ed82	246	uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
f7e3ed82	247	if (now == (uint16_t)(start + ticks))
e30c654b	248	return;
	249
	250	WDT_HIT();
	251	}
	252	}
	253
	254	void SpinDelay(int ms)
	255	{
	256	// convert to uS and call microsecond delay function
	257	SpinDelayUs(ms*1000);
	258	}
	259
	260	/* Similar to FpgaGatherVersion this formats stored version information
	261	* into a string representation. It takes a pointer to the struct version_information,
	262	* verifies the magic properties, then stores a formatted string, prefixed by
	263	* prefix in dst.
	264	*/
	265	void FormatVersionInformation(char dst, int len, const char prefix, void *version_information)
	266	{
	267	struct version_information v = (struct version_information)version_information;
	268	dst[0] = 0;
2ed270a8	269	strncat(dst, prefix, len-1);
e30c654b	270	if(v->magic != VERSION_INFORMATION_MAGIC) {
8e074056	271	strncat(dst, "Missing/Invalid version information\n", len - strlen(dst) - 1);
e30c654b	272	return;
	273	}
	274	if(v->versionversion != 1) {
8e074056	275	strncat(dst, "Version information not understood\n", len - strlen(dst) - 1);
e30c654b	276	return;
	277	}
	278	if(!v->present) {
8e074056	279	strncat(dst, "Version information not available\n", len - strlen(dst) - 1);
e30c654b	280	return;
	281	}
	282
cba867f2	283	strncat(dst, v->gitversion, len - strlen(dst) - 1);
e30c654b	284	if(v->clean == 0) {
cba867f2	285	strncat(dst, "-unclean", len - strlen(dst) - 1);
e30c654b	286	} else if(v->clean == 2) {
cba867f2	287	strncat(dst, "-suspect", len - strlen(dst) - 1);
e30c654b	288	}
e30c654b	289
cba867f2 MHS	290	strncat(dst, " ", len - strlen(dst) - 1);
cba867f2 MHS	291	strncat(dst, v->buildtime, len - strlen(dst) - 1);
8e074056	292	strncat(dst, "\n", len - strlen(dst) - 1);
e30c654b	293	}
9ca155ba	294
4058a2d7	295
9ca155ba M	296	// -------------------------------------------------------------------------
	297	// timer lib
	298	// -------------------------------------------------------------------------
	299	// test procedure:
	300	//
	301	// ti = GetTickCount();
	302	// SpinDelay(1000);
	303	// ti = GetTickCount() - ti;
	304	// Dbprintf("timer(1s): %d t=%d", ti, GetTickCount());
	305
	306	void StartTickCount()
	307	{
bfb01844	308	// This timer is based on the slow clock. The slow clock frequency is between 22kHz and 40kHz.
	309	// We can determine the actual slow clock frequency by looking at the Main Clock Frequency Register.
	310	uint16_t mainf = AT91C_BASE_PMC->PMC_MCFR & 0xffff; // = 16 * main clock frequency (16MHz) / slow clock frequency
	311	// set RealTimeCounter divider to count at 1kHz:
	312	AT91C_BASE_RTTC->RTTC_RTMR = AT91C_RTTC_RTTRST \| ((256000 + (mainf/2)) / mainf);
	313	// note: worst case precision is approx 2.5%
9ca155ba M	314	}
9ca155ba M	315
4058a2d7	316
9ca155ba M	317	/*
	318	* Get the current count.
	319	*/
	320	uint32_t RAMFUNC GetTickCount(){
8f51ddb0	321	return AT91C_BASE_RTTC->RTTC_RTVR;// was * 2;
9ca155ba M	322	}
9ca155ba M	323
4058a2d7	324
8f51ddb0 M	325	// -------------------------------------------------------------------------
	326	// microseconds timer
	327	// -------------------------------------------------------------------------
	328	void StartCountUS()
	329	{
	330	AT91C_BASE_PMC->PMC_PCER \|= (0x1 << 12) \| (0x1 << 13) \| (0x1 << 14);
	331	// AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC1XC1S_TIOA0;
	332	AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE \| AT91C_TCB_TC1XC1S_TIOA0 \| AT91C_TCB_TC2XC2S_NONE;
	333
	334	// fast clock
	335	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS; // timer disable
	336	AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK \| // MCK(48MHz)/32 -- tick=1.5mks
	337	AT91C_TC_WAVE \| AT91C_TC_WAVESEL_UP_AUTO \| AT91C_TC_ACPA_CLEAR \|
	338	AT91C_TC_ACPC_SET \| AT91C_TC_ASWTRG_SET;
	339	AT91C_BASE_TC0->TC_RA = 1;
	340	AT91C_BASE_TC0->TC_RC = 0xBFFF + 1; // 0xC000
	341
	342	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; // timer disable
	343	AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_XC1; // from timer 0
1c611bbd	344
8f51ddb0 M	345	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN;
	346	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN;
	347	AT91C_BASE_TCB->TCB_BCR = 1;
1c611bbd	348	}
8f51ddb0	349
4058a2d7	350
8f51ddb0	351	uint32_t RAMFUNC GetCountUS(){
e04475c4	352	return (AT91C_BASE_TC1->TC_CV * 0x8000) + ((AT91C_BASE_TC0->TC_CV * 2) / 3); //was /15) * 10);
8f51ddb0 M	353	}
8f51ddb0 M	354
4058a2d7	355
8f51ddb0 M	356	static uint32_t GlobalUsCounter = 0;
	357
	358	uint32_t RAMFUNC GetDeltaCountUS(){
	359	uint32_t g_cnt = GetCountUS();
	360	uint32_t g_res = g_cnt - GlobalUsCounter;
	361	GlobalUsCounter = g_cnt;
	362	return g_res;
	363	}
	364
	365
1c611bbd	366	// -------------------------------------------------------------------------
7bc95e2e	367	// Timer for iso14443 commands. Uses ssp_clk from FPGA
1c611bbd	368	// -------------------------------------------------------------------------
7bc95e2e	369	void StartCountSspClk()
1c611bbd	370	{
	371	AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0) \| (1 << AT91C_ID_TC1) \| (1 << AT91C_ID_TC2); // Enable Clock to all timers
	372	AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_TIOA1 // XC0 Clock = TIOA1
	373	\| AT91C_TCB_TC1XC1S_NONE // XC1 Clock = none
	374	\| AT91C_TCB_TC2XC2S_TIOA0; // XC2 Clock = TIOA0
	375
	376	// configure TC1 to create a short pulse on TIOA1 when a rising edge on TIOB1 (= ssp_clk from FPGA) occurs:
	377	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; // disable TC1
	378	AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_TIMER_DIV1_CLOCK // TC1 Clock = MCK(48MHz)/2 = 24MHz
	379	\| AT91C_TC_CPCSTOP // Stop clock on RC compare
	380	\| AT91C_TC_EEVTEDG_RISING // Trigger on rising edge of Event
7bc95e2e	381	\| AT91C_TC_EEVT_TIOB // Event-Source: TIOB1 (= ssp_clk from FPGA = 13,56MHz/16)
1c611bbd	382	\| AT91C_TC_ENETRG // Enable external trigger event
	383	\| AT91C_TC_WAVESEL_UP // Upmode without automatic trigger on RC compare
	384	\| AT91C_TC_WAVE // Waveform Mode
	385	\| AT91C_TC_AEEVT_SET // Set TIOA1 on external event
	386	\| AT91C_TC_ACPC_CLEAR; // Clear TIOA1 on RC Compare
	387	AT91C_BASE_TC1->TC_RC = 0x04; // RC Compare value = 0x04
	388
	389	// use TC0 to count TIOA1 pulses
7bc95e2e	390	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS; // disable TC0
1c611bbd	391	AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_XC0 // TC0 clock = XC0 clock = TIOA1
	392	\| AT91C_TC_WAVE // Waveform Mode
	393	\| AT91C_TC_WAVESEL_UP // just count
	394	\| AT91C_TC_ACPA_CLEAR // Clear TIOA0 on RA Compare
	395	\| AT91C_TC_ACPC_SET; // Set TIOA0 on RC Compare
	396	AT91C_BASE_TC0->TC_RA = 1; // RA Compare value = 1; pulse width to TC2
	397	AT91C_BASE_TC0->TC_RC = 0; // RC Compare value = 0; increment TC2 on overflow
	398
	399	// use TC2 to count TIOA0 pulses (giving us a 32bit counter (TC0/TC2) clocked by ssp_clk)
	400	AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKDIS; // disable TC2
	401	AT91C_BASE_TC2->TC_CMR = AT91C_TC_CLKS_XC2 // TC2 clock = XC2 clock = TIOA0
	402	\| AT91C_TC_WAVE // Waveform Mode
	403	\| AT91C_TC_WAVESEL_UP; // just count
	404
1c611bbd	405	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN; // enable TC0
	406	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN; // enable TC1
	407	AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN; // enable TC2
9492e0b0	408
7bc95e2e	409	//
4058a2d7	410	// synchronize the counter with the ssp_frame signal. Note: FPGA must be in any iso14443 mode, otherwise SSC_FRAME and SSC_CLK signals would not be present
7bc95e2e	411	//
7bc95e2e	412	while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME)); // wait for ssp_frame to go high (start of frame)
9492e0b0	413	while(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_FRAME); // wait for ssp_frame to be low
7bc95e2e	414	while(!(AT91C_BASE_PIOA->PIO_PDSR & GPIO_SSC_CLK)); // wait for ssp_clk to go high
	415	// note: up to now two ssp_clk rising edges have passed since the rising edge of ssp_frame
	416	// it is now safe to assert a sync signal. This sets all timers to 0 on next active clock edge
1c611bbd	417	AT91C_BASE_TCB->TCB_BCR = 1; // assert Sync (set all timers to 0 on next active clock edge)
7bc95e2e	418	// at the next (3rd) ssp_clk rising edge, TC1 will be reset (and not generate a clock signal to TC0)
	419	// at the next (4th) ssp_clk rising edge, TC0 (the low word of our counter) will be reset. From now on,
	420	// whenever the last three bits of our counter go 0, we can be sure to be in the middle of a frame transfer.
	421	// (just started with the transfer of the 4th Bit).
	422	// The high word of the counter (TC2) will not reset until the low word (TC0) overflows. Therefore need to wait quite some time before
	423	// we can use the counter.
4058a2d7	424	while (AT91C_BASE_TC0->TC_CV < 0xFFFF);
4058a2d7	425	// Note: needs one more SSP_CLK cycle (1.18 us) until TC2 resets. Don't call GetCountSspClk() that soon.
1c611bbd	426	}
4058a2d7	427
4058a2d7	428
e04475c4	429	void ResetSspClk(void) {
	430	//enable clock of timer and software trigger
	431	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	432	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	433	AT91C_BASE_TC2->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	434	while (AT91C_BASE_TC2->TC_CV > 0);
	435	}
4058a2d7	436
4058a2d7	437
7bc95e2e	438	uint32_t RAMFUNC GetCountSspClk(){
1c611bbd	439	uint32_t tmp_count;
1c611bbd	440	tmp_count = (AT91C_BASE_TC2->TC_CV << 16) \| AT91C_BASE_TC0->TC_CV;
7bc95e2e	441	if ((tmp_count & 0x0000ffff) == 0) { //small chance that we may have missed an increment in TC2
1c611bbd	442	return (AT91C_BASE_TC2->TC_CV << 16);
	443	}
	444	else {
	445	return tmp_count;
	446	}
	447	}
7bc95e2e	448
4058a2d7	449
e04475c4	450	// -------------------------------------------------------------------------
	451	// Timer for bitbanging, or LF stuff when you need a very precis timer
	452	// 1us = 1.5ticks
	453	// -------------------------------------------------------------------------
	454	void StartTicks(void){
	455	//initialization of the timer
	456	// tc1 is higher 0xFFFF0000
	457	// tc0 is lower 0x0000FFFF
	458	AT91C_BASE_PMC->PMC_PCER \|= (1 << AT91C_ID_TC0) \| (1 << AT91C_ID_TC1);
	459	AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE \| AT91C_TCB_TC1XC1S_TIOA0 \| AT91C_TCB_TC2XC2S_NONE;
	460	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
	461	AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV3_CLOCK \| // MCK(48MHz) / 32
	462	AT91C_TC_WAVE \| AT91C_TC_WAVESEL_UP_AUTO \| AT91C_TC_ACPA_CLEAR \|
	463	AT91C_TC_ACPC_SET \| AT91C_TC_ASWTRG_SET;
	464	AT91C_BASE_TC0->TC_RA = 1;
	465	AT91C_BASE_TC0->TC_RC = 0;
	466
	467	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS; // timer disable
	468	AT91C_BASE_TC1->TC_CMR = AT91C_TC_CLKS_XC1; // from TC0
	469
	470	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	471	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	472	AT91C_BASE_TCB->TCB_BCR = 1;
	473
	474	// wait until timer becomes zero.
	475	while (AT91C_BASE_TC1->TC_CV > 0);
	476	}
	477
4058a2d7	478
e04475c4	479	// Wait - Spindelay in ticks.
	480	// if called with a high number, this will trigger the WDT...
	481	void WaitTicks(uint32_t ticks){
	482	if ( ticks == 0 ) return;
	483	ticks += GET_TICKS;
	484	while (GET_TICKS < ticks);
	485	}
4058a2d7	486
4058a2d7	487
e04475c4	488	// Wait / Spindelay in us (microseconds)
	489	// 1us = 1.5ticks.
	490	void WaitUS(uint16_t us){
	491	if ( us == 0 ) return;
913a54a8	492	WaitTicks( (uint32_t)us * 3 / 2 ) ;
e04475c4	493	}
4058a2d7	494
4058a2d7	495
e04475c4	496	void WaitMS(uint16_t ms){
e04475c4	497	if (ms == 0) return;
913a54a8	498	WaitTicks( (uint32_t)ms * 1500 );
e04475c4	499	}
4058a2d7	500
4058a2d7	501
e04475c4	502	// Starts Clock and waits until its reset
	503	void ResetTicks(void){
	504	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	505	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	506	while (AT91C_BASE_TC1->TC_CV > 0);
	507	}
4058a2d7	508
4058a2d7	509
e04475c4	510	void ResetTimer(AT91PS_TC timer){
	511	timer->TC_CCR = AT91C_TC_CLKEN \| AT91C_TC_SWTRG;
	512	while(timer->TC_CV > 0) ;
	513	}
4058a2d7	514
4058a2d7	515
e04475c4	516	// stop clock
	517	void StopTicks(void){
	518	AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
	519	AT91C_BASE_TC1->TC_CCR = AT91C_TC_CLKDIS;
	520	}
	521
4058a2d7	522
f9c1dcd9 MF	523	static uint64_t next_random = 1;
	524
	525	/* Generates a (non-cryptographically secure) 32-bit random number.
	526	*
	527	* We don't have an implementation of the "rand" function or a clock to seed it
	528	* with, so we just call GetTickCount the first time to seed ourselves.
	529	*/
	530	uint32_t prand() {
	531	if (next_random == 1) {
	532	next_random = GetTickCount();
	533	}
	534
	535	next_random = next_random * 6364136223846793005 + 1;
	536	return (uint32_t)(next_random >> 32) % 0xffffffff;
	537	}