#include <stdint.h>

// a pointer to this is a null pointer, but the compiler does not
// know that because "sram" is a linker symbol from sections.lds.
extern uint32_t sram;

#define reg_spictrl (*(volatile uint32_t*)0x02000000)
#define reg_uart_clkdiv (*(volatile uint32_t*)0x02000004)
#define reg_uart_data (*(volatile uint32_t*)0x02000008)
#define reg_leds (*(volatile uint32_t*)0x03000000)

// --------------------------------------------------------

extern uint32_t flashio_worker_begin;
extern uint32_t flashio_worker_end;

void flashio(uint8_t *data, int len)
{
	uint32_t func[&flashio_worker_end - &flashio_worker_begin];

	uint32_t *src_ptr = &flashio_worker_begin;
	uint32_t *dst_ptr = func;

	while (src_ptr != &flashio_worker_end)
		*(dst_ptr++) = *(src_ptr++);

	((void(*)(uint8_t*, int))func)(data, len);
}

// --------------------------------------------------------

void putchar(char c)
{
	if (c == '\n')
		putchar('\r');
	reg_uart_data = c;
}

void print(const char *p)
{
	while (*p)
		putchar(*(p++));
}

void print_hex(uint32_t v, int digits)
{
	for (int i = 7; i >= 0; i--) {
		char c = "0123456789abcdef"[(v >> (4*i)) & 15];
		if (c == '0' && i >= digits) continue;
		putchar(c);
		digits = i;
	}
}

void print_dec(uint32_t v)
{
	if (v >= 100) {
		print(">=100");
		return;
	}

	if      (v >= 90) { putchar('9'); v -= 90; }
	else if (v >= 80) { putchar('8'); v -= 80; }
	else if (v >= 70) { putchar('7'); v -= 70; }
	else if (v >= 60) { putchar('6'); v -= 60; }
	else if (v >= 50) { putchar('5'); v -= 50; }
	else if (v >= 40) { putchar('4'); v -= 40; }
	else if (v >= 30) { putchar('3'); v -= 30; }
	else if (v >= 20) { putchar('2'); v -= 20; }
	else if (v >= 10) { putchar('1'); v -= 10; }

	if      (v >= 9) { putchar('9'); v -= 9; }
	else if (v >= 8) { putchar('8'); v -= 8; }
	else if (v >= 7) { putchar('7'); v -= 7; }
	else if (v >= 6) { putchar('6'); v -= 6; }
	else if (v >= 5) { putchar('5'); v -= 5; }
	else if (v >= 4) { putchar('4'); v -= 4; }
	else if (v >= 3) { putchar('3'); v -= 3; }
	else if (v >= 2) { putchar('2'); v -= 2; }
	else if (v >= 1) { putchar('1'); v -= 1; }
	else putchar('0');
}

char getchar_prompt(char *prompt)
{
	int32_t c = -1;

	uint32_t cycles_begin, cycles_now, cycles;
	__asm__ volatile ("rdcycle %0" : "=r"(cycles_begin));

	if (prompt)
		print(prompt);

	reg_leds = ~0;
	while (c == -1) {
		__asm__ volatile ("rdcycle %0" : "=r"(cycles_now));
		cycles = cycles_now - cycles_begin;
		if (cycles > 12000000) {
			if (prompt)
				print(prompt);
			cycles_begin = cycles_now;
			reg_leds = ~reg_leds;
		}
		c = reg_uart_data;
	}
	reg_leds = 0;
	return c;
}

char getchar()
{
	return getchar_prompt(0);
}

// --------------------------------------------------------

void cmd_read_spi_flash_id()
{
	uint8_t buffer[17] = { 0x9F, /* zeros */ };
	flashio(buffer, 17);

	for (int i = 1; i <= 16; i++) {
		putchar(' ');
		print_hex(buffer[i], 2);
	}
	putchar('\n');
}

// --------------------------------------------------------

uint8_t cmd_read_spi_flash_regs_print(uint32_t addr, const char *name)
{
	uint8_t buffer[6] = {0x65, addr >> 16, addr >> 8, addr, 0, 0};
	flashio(buffer, 6);

	print("0x");
	print_hex(addr, 6);
	print(" ");
	print(name);
	print(" 0x");
	print_hex(buffer[5], 2);
	print("\n");

	return buffer[5];
}

void cmd_read_spi_flash_regs()
{
	print("\n");
	uint8_t sr1v = cmd_read_spi_flash_regs_print(0x800000, "SR1V");
	uint8_t sr2v = cmd_read_spi_flash_regs_print(0x800001, "SR2V");
	uint8_t cr1v = cmd_read_spi_flash_regs_print(0x800002, "CR1V");
	uint8_t cr2v = cmd_read_spi_flash_regs_print(0x800003, "CR2V");
	uint8_t cr3v = cmd_read_spi_flash_regs_print(0x800004, "CR3V");
	uint8_t vdlp = cmd_read_spi_flash_regs_print(0x800005, "VDLP");
}

// --------------------------------------------------------

void cmd_benchmark()
{
	uint8_t data[256];
	uint32_t *words = (void*)data;

	uint32_t x32 = 314159265;

	uint32_t cycles_begin, cycles_end;
	uint32_t instns_begin, instns_end;
	__asm__ volatile ("rdcycle %0" : "=r"(cycles_begin));
	__asm__ volatile ("rdinstret %0" : "=r"(instns_begin));

	for (int i = 0; i < 20; i++)
	{
		for (int k = 0; k < 256; k++)
		{
			x32 ^= x32 << 13;
			x32 ^= x32 >> 17;
			x32 ^= x32 << 5;
			data[k] = x32;
		}

		for (int k = 0, p = 0; k < 256; k++)
		{
			if (data[k])
				data[p++] = k;
		}

		for (int k = 0, p = 0; k < 64; k++)
		{
			x32 = x32 ^ words[k];
		}
	}

	__asm__ volatile ("rdcycle %0" : "=r"(cycles_end));
	__asm__ volatile ("rdinstret %0" : "=r"(instns_end));

	print("Cycles: 0x");
	print_hex(cycles_end - cycles_begin, 8);
	putchar('\n');

	print("Instns: 0x");
	print_hex(instns_end - instns_begin, 8);
	putchar('\n');

	print("Chksum: 0x");
	print_hex(x32, 8);
	putchar('\n');
}

// --------------------------------------------------------

void main()
{
	reg_uart_clkdiv = 104;
	while (getchar_prompt("Press ENTER to continue..\n") != '\r') { /* wait */ }

	print("\n");
	print("  ____  _          ____         ____\n");
	print(" |  _ \\(_) ___ ___/ ___|  ___  / ___|\n");
	print(" | |_) | |/ __/ _ \\___ \\ / _ \\| |\n");
	print(" |  __/| | (_| (_) |__) | (_) | |___\n");
	print(" |_|   |_|\\___\\___/____/ \\___/ \\____|\n");

	while (1)
	{
		print("\n");
		print("\n");
		print("SPI State:\n");

		print("  DDR ");
		if ((reg_spictrl & (1 << 22)) != 0)
			print("ON");
		else
			print("OFF");

		print(" (latency=");
		print_dec((reg_spictrl >> 16) & 15);
		print(")\n");

		print("  QSPI ");
		if ((reg_spictrl & (1 << 21)) != 0)
			print("ON\n");
		else
			print("OFF\n");

		print("  XIP ");
		if ((reg_spictrl & (1 << 20)) != 0)
			print("ON\n");
		else
			print("OFF\n");

		print("\n");
		print("Select an action:\n");
		print("\n");
		print("   [1] Read SPI Flash ID\n");
		print("   [2] Read SPI Config Regs\n");
		print("   [3] Enable/disable DDR\n");
		print("   [4] Enable/disable QSPI\n");
		print("   [5] Enable/disable XIP\n");
		print("   [0] Run simplistic benchmark\n");
		print("\n");

		for (int rep = 10; rep > 0; rep--)
		{
			print("Command> ");
			char cmd = getchar();
			if (cmd > 32 && cmd < 127)
				putchar(cmd);
			print("\n");

			switch (cmd)
			{
			case '1':
				cmd_read_spi_flash_id();
				break;
			case '2':
				cmd_read_spi_flash_regs();
				break;
			case '3':
				reg_spictrl ^= 1 << 22;
				break;
			case '4':
				reg_spictrl ^= 1 << 21;
				break;
			case '5':
				reg_spictrl ^= 1 << 20;
				break;
			case '0':
				cmd_benchmark();
				break;
			default:
				continue;
			}

			break;
		}
	}
}