// The Potato Processor Benchmark Applications
// (c) Kristian Klomsten Skordal 2015-2023 <kristian.skordal@wafflemail.net>
// Report bugs and issues on <https://github.com/skordal/potato/issues>

#include <stdbool.h>
#include <stdint.h>

#include "platform.h"
#include "potato.h"

#include "gpio.h"
#include "icerror.h"
#include "timer.h"
#include "uart.h"

#include "sha256.h"

static struct gpio gpio0;
static struct uart uart0;
static struct timer timer0;
static struct timer timer1;
static struct icerror icerror0;

static uint8_t led_status = 0x01;
static volatile unsigned int hashes_per_second = 0;
static volatile bool reset_counter = true;

// Converts an integer to a string:
static void int2string(int i, char * s);
// Converts an unsigned 32 bit integer to a hexadecimal string:
static void int2hex32(uint32_t i, char * s);

void exception_handler(uint32_t mcause, uint32_t mepc, uint32_t sp)
{
	if((mcause & (1 << POTATO_MCAUSE_INTERRUPT_BIT)) && (mcause & (1 << POTATO_MCAUSE_IRQ_BIT)))
	{
		uint8_t irq = mcause & 0x0f;

		switch(irq)
		{
			case PLATFORM_IRQ_TIMER0:
			{
				// Print the number of hashes since last interrupt:
				char hps_dec[11];
				int2string(hashes_per_second, hps_dec);
				uart_tx_string(&uart0, hps_dec);
				uart_tx_string(&uart0, " H/s\n\r");
				reset_counter = true;

				timer_clear(&timer0);
				break;
			}
			case PLATFORM_IRQ_TIMER1:
			{
				led_status >>= 1;
				if((led_status & 0xf) == 0)
					led_status = 0x8;

				// Read the switches to determine which LEDs should be used:
				uint32_t switch_mask = (gpio_get_input(&gpio0) >> 4) & 0xf;

				// Read the buttons and turn on the corresponding LED regardless of the switch settings:
				uint32_t button_mask = gpio_get_input(&gpio0) & 0xf;

				// Set the LEDs:
				gpio_set_output(&gpio0, ((led_status & switch_mask) | button_mask) << 8);
				timer_clear(&timer1);
				break;
			}
			case PLATFORM_IRQ_BUS_ERROR:
			{
				uart_tx_string(&uart0, "Bus error!\n\r");

				enum icerror_access_type access = icerror_get_access_type(&icerror0);
				switch(access)
				{
					case ICERROR_ACCESS_READ:
					{
						uart_tx_string(&uart0, "\tType: read\n\r");

						uart_tx_string(&uart0, "\tAddress: ");
						char address_buffer[9];
						int2hex32(icerror_get_read_address(&icerror0), address_buffer);
						uart_tx_string(&uart0, address_buffer);
						uart_tx_string(&uart0, "\n\r");
						break;
					}
					case ICERROR_ACCESS_WRITE:
					{
						uart_tx_string(&uart0, "\tType: write\n\r");

						char address_buffer[9];
						int2hex32(icerror_get_write_address(&icerror0), address_buffer);
						uart_tx_string(&uart0, address_buffer);
						uart_tx_string(&uart0, "\n\r");
						break;
					}
					case ICERROR_ACCESS_NONE:
						// fallthrough
					default:
						break;
				}

				potato_disable_interrupts();
				while(1) potato_wfi();

				break;
			}
			default:
				potato_disable_irq(irq);
				break;
		}
	}
}

int main(void)
{
	// Configure GPIOs:
	gpio_initialize(&gpio0, (volatile void *) PLATFORM_GPIO_BASE);
	gpio_set_direction(&gpio0, 0xf00);	// Set LEDs to output, buttons and switches to input
	gpio_set_output(&gpio0, 0x100);		// Turn LED0 on.

	// Configure the UART:
	uart_initialize(&uart0, (volatile void *) PLATFORM_UART0_BASE);
	uart_set_divisor(&uart0, uart_baud2divisor(115200, PLATFORM_SYSCLK_FREQ));
	uart_tx_string(&uart0, "--- SHA256 Benchmark Application ---\r\n\n");

	// Set up timer0 at 1 Hz:
	timer_initialize(&timer0, (volatile void *) PLATFORM_TIMER0_BASE);
	timer_reset(&timer0);
	timer_set_compare(&timer0, PLATFORM_SYSCLK_FREQ);
	timer_start(&timer0);

	// Set up timer1 at 4 Hz:
	timer_initialize(&timer1, (volatile void *) PLATFORM_TIMER1_BASE);
	timer_reset(&timer1);
	timer_set_compare(&timer1, PLATFORM_SYSCLK_FREQ >> 2);
	timer_start(&timer1);

	// Set up the interconnect error module for detecting invalid bus accesses:
	icerror_initialize(&icerror0, (volatile void *) PLATFORM_ICERROR_BASE);
	icerror_reset(&icerror0);

	// Enable interrupts:
	potato_enable_irq(PLATFORM_IRQ_TIMER0);
	potato_enable_irq(PLATFORM_IRQ_TIMER1);
	potato_enable_irq(PLATFORM_IRQ_BUS_ERROR);
	potato_enable_interrupts();

	struct sha256_context context;

	// Prepare a block for hashing:
	uint32_t block[16];
	uint8_t * block_ptr = (uint8_t *) block;
	block_ptr[0] = 'a';
	block_ptr[1] = 'b';
	block_ptr[2] = 'c';
	sha256_pad_le_block(block_ptr, 3, 3);

	// Repeatedly hash the same data over and over again:
	while(true)
	{
		uint8_t hash[32];

		sha256_reset(&context);
		sha256_hash_block(&context, block);
		sha256_get_hash(&context, hash);

		potato_disable_interrupts();
		if(reset_counter)
		{
			hashes_per_second = 1;
			reset_counter = false;
		} else
			++hashes_per_second;
		potato_enable_interrupts();
	}

	return 0;
}

static void int2string(int n, char * s)
{
	bool first = true;

	if(n == 0)
	{
		s[0] = '0';
		s[1] =  0;
		return;
	}

	if(n & (1u << 31))
	{
		n = ~n + 1;
		*(s++) = '-';
	}

	for(int i = 1000000000; i > 0; i /= 10)
	{
		if(n / i == 0 && !first)
			*(s++) = '0';
		else if(n / i != 0)
		{
			*(s++) = '0' + n / i;
			n %= i;
			first = false;
		}
	}
	*s = 0;
}

static void int2hex32(uint32_t n, char * s)
{
	static const char * hex_digits = "0123456789abcdef";

	int index = 0;
	for(int i = 28; i >= 0; i -= 4)
		s[index++] = hex_digits[(n >> (32 - i)) & 0xf];
	s[index] = 0;
}