/* Megumin LED display firmware
 * Copyright (C) 2018 Sebastian Götte <code@jaseg.net>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "global.h"
#include "i2c.h"
#include "mpu6050.h"

uint32_t pcg32_random_r() {
    // *Really* minimal PCG32 code / (c) 2014 M.E. O'Neill / pcg-random.org
    // Licensed under Apache License 2.0 (NO WARRANTY, etc. see website)
    static uint64_t state = 0xbc422715d3aef60f;
    static uint64_t inc = 0x6605e3bc6d1a869b; 
    uint64_t oldstate = state;
    // Advance internal state
    state = oldstate * 6364136223846793005ULL + (inc|1);
    // Calculate output function (XSH RR), uses old state for max ILP
    uint32_t xorshifted = ((oldstate >> 18u) ^ oldstate) >> 27u;
    uint32_t rot = oldstate >> 59u;
    return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
}

unsigned char dumb_random() {
    static unsigned char x=0x66, a=0x05, b=0xe3, c=0xbc;
    x++; //x is incremented every round and is not affected by any other variable
    a = (a ^ c ^ x); //note the mix of addition and XOR
    b = (b + a); //And the use of very few instructions
    c = ((c + (b >> 1) ^ a)); // the AES S-Box Operation ensures an even distributon of entropy
    return (c);
}

int main(void) {
    /* We're starting out from HSI@8MHz */
    SystemCoreClockUpdate();

    /* Turn on lots of neat things */
    RCC->AHBENR  |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;

    GPIOA->MODER |=
          (1<<GPIO_MODER_MODER1_Pos)|   /* PA1    - Port 1 */
          (1<<GPIO_MODER_MODER2_Pos)|   /* PA2    - Port 2 */
          (1<<GPIO_MODER_MODER3_Pos)|   /* PA3    - Port 3 */
          (1<<GPIO_MODER_MODER4_Pos)|   /* PA4    - Port 4 */
          (1<<GPIO_MODER_MODER9_Pos);   /* PA9    - LED */

    //GPIOA->OTYPER |= (1<<1) | (1<<2) | (1<<3) | (1<<4) | (1<<9);

    int idx = 0;
    while (1) {
        GPIOA->ODR ^= (1<<9);
        GPIOA->ODR &= ~(0xf<<1);
        GPIOA->ODR |= 1<<(idx+1);
        idx += 1;
        if (idx > 3)
            idx = 0;

        for (size_t j=0; j<100000; j++) {
            asm volatile ("nop");
        }
    }
}

void gdb_dump(void) {
    /* debugger hook */
}

void NMI_Handler(void) {
    asm volatile ("bkpt");
}

void HardFault_Handler(void) __attribute__((naked));
void HardFault_Handler() {
    asm volatile ("bkpt");
}

void SVC_Handler(void) {
    asm volatile ("bkpt");
}


void PendSV_Handler(void) {
    asm volatile ("bkpt");
}

void SysTick_Handler(void) {
    asm volatile ("bkpt");
}