X-Git-Url: http://git.zerfleddert.de/cgi-bin/gitweb.cgi/proxmark3-svn/blobdiff_plain/bf7ebb7b208a3b95f28a9a40f2e560a56e121794..refs/pull/938/head:/armsrc/util.c?ds=inline diff --git a/armsrc/util.c b/armsrc/util.c index 8576ddce..b0cd1818 100644 --- a/armsrc/util.c +++ b/armsrc/util.c @@ -21,7 +21,7 @@ void print_result(char *name, uint8_t *buf, size_t len) { 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", + Dbprintf("[%s:%d/%d] %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x", name, p-buf, len, @@ -30,7 +30,7 @@ void print_result(char *name, uint8_t *buf, size_t len) { } 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]); + 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]); } } @@ -68,22 +68,17 @@ uint64_t bytes_to_num(uint8_t* src, size_t len) // 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; + 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]; + for (size_t n = 0; n < len - 1; n++) { + data[n] = (data[n] << 1) | (data[n+1] >> 7); + } + data[len - 1] <<= 1; } void LEDsoff() @@ -94,6 +89,22 @@ void LEDsoff() 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) { @@ -126,8 +137,7 @@ void LED(int led, int ms) // 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; @@ -189,8 +199,7 @@ int BUTTON_CLICKED(int ms) } // 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; @@ -207,8 +216,7 @@ int BUTTON_HELD(int ms) uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR; - for(;;) - { + for(;;) { uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR; // As soon as our button let go, we didn't hold long enough @@ -216,8 +224,7 @@ int BUTTON_HELD(int ms) return BUTTON_SINGLE_CLICK; // Have we waited the full second? - else - if (now == (uint16_t)(start + ticks)) + else if (now == (uint16_t)(start + ticks)) return BUTTON_HOLD; WDT_HIT(); @@ -229,8 +236,7 @@ int BUTTON_HELD(int ms) // 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 @@ -251,8 +257,7 @@ void SpinDelayUs(int us) } } -void SpinDelay(int ms) -{ +void SpinDelay(int ms) { // convert to uS and call microsecond delay function SpinDelayUs(ms*1000); } @@ -292,39 +297,41 @@ void FormatVersionInformation(char *dst, int len, const char *prefix, void *vers 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() -{ -// 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 +// 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(){ +uint32_t RAMFUNC GetTickCount(void) { return AT91C_BASE_RTTC->RTTC_RTVR;// was * 2; } + // ------------------------------------------------------------------------- -// microseconds timer +// microseconds timer // ------------------------------------------------------------------------- -void StartCountUS() -{ +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_TC1XC1S_TIOA0; AT91C_BASE_TCB->TCB_BMR = AT91C_TCB_TC0XC0S_NONE | AT91C_TCB_TC1XC1S_TIOA0 | AT91C_TCB_TC2XC2S_NONE; // fast clock @@ -334,22 +341,24 @@ void StartCountUS() 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_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); + +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(){ +uint32_t RAMFUNC GetDeltaCountUS(void) { uint32_t g_cnt = GetCountUS(); uint32_t g_res = g_cnt - GlobalUsCounter; GlobalUsCounter = g_cnt; @@ -358,75 +367,201 @@ uint32_t RAMFUNC GetDeltaCountUS(){ // ------------------------------------------------------------------------- -// Timer for iso14443 commands. Uses ssp_clk from FPGA +// Timer for iso14443 commands. Uses ssp_clk from FPGA // ------------------------------------------------------------------------- -void StartCountSspClk() -{ +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 + 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_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 + | 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 + 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 + 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 + // 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 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 + 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) 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). + 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 < 0xFFF0); + 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. } -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; - } +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; +}