144 lines
4 KiB
C
144 lines
4 KiB
C
/* Megumin LED display firmware
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* Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "global.h"
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#define RTC_INITIALIZED_REGISTER BKP->DR1
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#define RTC_INITIALIZED_FLAG 1
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uint32_t pcg32_random_r() {
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// *Really* minimal PCG32 code / (c) 2014 M.E. O'Neill / pcg-random.org
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// Licensed under Apache License 2.0 (NO WARRANTY, etc. see website)
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static uint64_t state = 0xbc422715d3aef60f;
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static uint64_t inc = 0x6605e3bc6d1a869b;
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uint64_t oldstate = state;
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// Advance internal state
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state = oldstate * 6364136223846793005ULL + (inc|1);
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// Calculate output function (XSH RR), uses old state for max ILP
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uint32_t xorshifted = ((oldstate >> 18u) ^ oldstate) >> 27u;
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uint32_t rot = oldstate >> 59u;
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return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
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}
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unsigned char dumb_random() {
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static unsigned char x=0x66, a=0x05, b=0xe3, c=0xbc;
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x++; //x is incremented every round and is not affected by any other variable
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a = (a ^ c ^ x); //note the mix of addition and XOR
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b = (b + a); //And the use of very few instructions
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c = (((c + (b >> 1)) ^ a)); // the AES S-Box Operation ensures an even distributon of entropy
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return (c);
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}
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void rtc_write(volatile uint32_t *reg, uint32_t val) {
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while (!(RTC->CRL & RTC_CRL_RTOFF)) ;
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RTC->CRL |= RTC_CRL_CNF;
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reg[0] = val>>16;
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reg[1] = val&0xffff;
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RTC->CRL &= ~RTC_CRL_CNF;
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while (!(RTC->CRL & RTC_CRL_RTOFF)) ;
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}
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void rtc_bus_sync(void) {
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RTC->CRL &= ~RTC_CRL_RSF;
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while (!(RTC->CRL & RTC_CRL_RSF)) ;
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}
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void rtc_alarm_reset(void) {
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RTC->CRL &= ~RTC_CRL_ALRF;
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}
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void rtc_init(void) {
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rtc_bus_sync();
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RTC->CRH = 0;
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if (!(RTC_INITIALIZED_REGISTER & RTC_INITIALIZED_FLAG)) {
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rtc_write(&RTC->PRLH, 32768-1);
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rtc_write(&RTC->CNTH, 0);
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RTC_INITIALIZED_REGISTER = RTC_INITIALIZED_FLAG;
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}
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}
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void rtc_set_alarm_sec(uint32_t value) {
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rtc_write(&RTC->ALRH, value);
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}
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void rtc_set_alarm_rel_sec(uint32_t value) {
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uint32_t now = RTC->CNTH<<16 | RTC->CNTL;
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rtc_set_alarm_sec(now + value);
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}
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int main(void){
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/* We're starting out from HSI@8MHz */
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SystemCoreClockUpdate();
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SCB->SCR &= (~SCB_SCR_SLEEPONEXIT_Msk) & SCB_SCR_SLEEPDEEP_Msk; /* Disable for now */
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for (int i=0; i<1000000; i++) /* about 5s */
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asm volatile ("nop");
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/* Turn on lots of neat things */
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RCC->APB2ENR |= RCC_APB2ENR_IOPCEN;
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RCC->APB1ENR |= RCC_APB1ENR_BKPEN | RCC_APB1ENR_PWREN;
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PWR->CR = PWR_CR_PDDS | PWR_CR_DBP;
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RCC->BDCR = RCC_BDCR_RTCEN | (1<<RCC_BDCR_RTCSEL_Pos) | RCC_BDCR_LSEON;
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while (!(RCC->BDCR & RCC_BDCR_LSERDY)) ;
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GPIOC->CRH |=
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(0<<GPIO_CRH_CNF13_Pos) | (2<<GPIO_CRH_MODE13_Pos); /* PC13 - LED */
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GPIOC->ODR |= 1<<13;
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rtc_init();
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rtc_set_alarm_rel_sec(2);
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SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk; /* Use deep sleep mode */
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GPIOC->ODR &= ~(1<<13);
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for (int i=0; i<100000; i++)
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asm volatile ("nop");
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GPIOC->ODR |= 1<<13;
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asm volatile ("wfe");
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return 42;
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}
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void gdb_dump(void) {
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/* debugger hook */
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}
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void NMI_Handler(void) {
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asm volatile ("bkpt");
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}
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void HardFault_Handler(void) __attribute__((naked));
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void HardFault_Handler() {
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asm volatile ("bkpt");
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}
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void SVC_Handler(void) {
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asm volatile ("bkpt");
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}
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void PendSV_Handler(void) {
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asm volatile ("bkpt");
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}
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void SysTick_Handler(void) {
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asm volatile ("bkpt");
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}
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