// SPDX-FileCopyrightText: 2022-2023 Cesanta Software Limited
// SPDX-License-Identifier: MIT
//
// https://www.espressif.com/sites/default/files/documentation/esp32-c3_technical_reference_manual_en.pdf

#ifndef LED_PIN
#define LED_PIN 2  // Default LED pin
#endif

#ifndef BUTTON_PIN
#define BUTTON_PIN 9  // Default Button pin
#endif

#ifndef UART_DEBUG
#define UART_DEBUG C3_UART
#endif

#pragma once

#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define BIT(x) ((uint32_t) 1U << (x))
#define REG(x) ((volatile uint32_t *) (x))
#define SETBITS(R, CLEARMASK, SETMASK) (R) = ((R) & ~(CLEARMASK)) | (SETMASK)

#define C3_SYSTEM 0x600c0000
#define C3_SENSITIVE 0x600c1000
#define C3_INTERRUPT 0x600c2000
#define C3_EXTMEM 0x600c4000
#define C3_MMU_TABLE 0x600c5000
#define C3_AES 0x6003a000
#define C3_SHA 0x6003b000
#define C3_RSA 0x6003c000
#define C3_HMAC 0x6003e000
#define C3_DIGITAL_SIGNATURE 0x6003d000
#define C3_GDMA 0x6003f000
#define C3_ASSIST_DEBUG 0x600ce000
#define C3_DEDICATED_GPIO 0x600cf000
#define C3_WORLD_CNTL 0x600d0000
#define C3_DPORT_END 0x600d3FFC
#define C3_UART 0x60000000
#define C3_SPI1 0x60002000
#define C3_SPI0 0x60003000
#define C3_GPIO 0x60004000
#define C3_FE2 0x60005000
#define C3_FE 0x60006000
#define C3_RTCCNTL 0x60008000
#define C3_IO_MUX 0x60009000
#define C3_RTC_I2C 0x6000e000
#define C3_UART1 0x60010000
#define C3_I2C_EXT 0x60013000
#define C3_UHCI0 0x60014000
#define C3_RMT 0x60016000
#define C3_LEDC 0x60019000
#define C3_EFUSE 0x60008800
#define C3_NRX 0x6001CC00
#define C3_BB 0x6001D000
#define C3_TIMERGROUP0 0x6001F000
#define C3_TIMERGROUP1 0x60020000
#define C3_SYSTIMER 0x60023000
#define C3_SPI2 0x60024000
#define C3_SYSCON 0x60026000
#define C3_APB_CTRL 0x60026000
#define C3_TWAI 0x6002B000
#define C3_I2S0 0x6002D000
#define C3_APB_SARADC 0x60040000
#define C3_AES_XTS 0x600CC000

#define CSR_WRITE(reg, val) ({ asm volatile("csrw " #reg ", %0" ::"rK"(val)); })
#define CSR_READ(reg)                          \
  ({                                           \
    unsigned long v_;                          \
    asm volatile("csrr %0, " #reg : "=r"(v_)); \
    v_;                                        \
  })
#define CSR_SETBITS(reg, cm, sm) CSR_WRITE(reg, (CSR_READ(reg) & ~(cm)) | (sm))

struct sysreg {  // System registers. 16.4 (incomplete)
  volatile uint32_t CPU_PERI_CLK_EN, CPU_PERI_RST_EN, RESERVED0[2], PERIPH_CLK_EN0, PERIPH_CLK_EN1,
      PERIPH_RST_EN0, PERIPH_RST_EN1;
};
#define SYSREG ((struct sysreg *) C3_SYSTEM)

struct systimer {  // 10.6 (complete)
  volatile uint32_t CONF, UNIT0_OP, UNIT1_OP, UNIT0_LOAD_HI, UNIT0_LOAD_LO, UNIT1_LOAD_HI,
      UNIT1_LOAD_LO, TARGET0_HI, TARGET0_LO, TARGET1_HI, TARGET1_LO, TARGET2_HI, TARGET2_LO,
      TARGET0_CONF, TARGET1_CONF, TARGET2_CONF, UNIT0_VALUE_HI, UNIT0_VALUE_LO, UNIT1_VALUE_HI,
      UNIT1_VALUE_LO, COMP0_LOAD, COMP1_LOAD, COMP2_LOAD, UNIT0_LOAD, UNIT1_LOAD, INT_ENA, INT_RAW,
      INT_CLR, INT_ST, RESERVED0[34], DATE;
};
#define SYSTIMER ((struct systimer *) C3_SYSTIMER)

struct gpio {  // 5.14 (incomplete)
  volatile uint32_t BT_SELECT, OUT, OUT_W1TS, OUT_W1TC, RESERVED0[4], ENABLE, ENABLE_W1TS,
      ENABLE_W1TC, RESERVED1[3], STRAP, IN, RESERVED2[1], STATUS, STATUS_W1TS, STATUS_W1TC,
      RESERVED3[3], PCPU_INT, PCPU_NMI_INT,
      // TODO(cpq): complete next
      STATUS_NEXT, PIN[22], FUNC_IN[128], FUNC_OUT[22], DATE, CLOCK_GATE;
};
#define GPIO ((struct gpio *) C3_GPIO)

struct io_mux {  // 5.14 (incomplete)
  volatile uint32_t PIN_CTRL, IO[22];
};
#define IO_MUX ((struct io_mux *) C3_IO_MUX)

enum { GPIO_OUT_EN = 8, GPIO_OUT_FUNC = 341, GPIO_IN_FUNC = 85 };

// Perform `count` "NOP" operations
static inline void spin(volatile unsigned long count) {
  while (count--) asm volatile("nop");
}

static inline uint64_t systick(void) {
  SYSTIMER->UNIT0_OP = BIT(30);  // TRM 10.5
  spin(1);
  return ((uint64_t) SYSTIMER->UNIT0_VALUE_HI << 32) | SYSTIMER->UNIT0_VALUE_LO;
}

static inline uint64_t uptime_us(void) {
  return systick() >> 4;
}

static inline void delay_us(unsigned long us) {
  uint64_t until = uptime_us() + us;
  while (uptime_us() < until) spin(1);
}

static inline void delay_ms(unsigned long ms) {
  delay_us(ms * 1000);
}

static inline void wdt_disable(void) {
  REG(C3_RTCCNTL)[42] = 0x50d83aa1;  // Disable write protection
  // REG(C3_RTCCNTL)[36] &= BIT(31);    // Disable RTC WDT
  REG(C3_RTCCNTL)[36] = 0;  // Disable RTC WDT
  REG(C3_RTCCNTL)[35] = 0;  // Disable

  // bootloader_super_wdt_auto_feed()
  REG(C3_RTCCNTL)[44] = 0x8F1D312A;
  REG(C3_RTCCNTL)[43] |= BIT(31);
  REG(C3_RTCCNTL)[45] = 0;

  // REG(C3_TIMERGROUP0)[63] &= ~BIT(9);  // TIMG_REGCLK -> disable TIMG_WDT_CLK
  REG(C3_TIMERGROUP0 + 0x48)[0] = 0;  // Disable TG0 WDT
  REG(C3_TIMERGROUP1 + 0x48)[0] = 0;  // Disable TG1 WDT
}

static inline void wifi_get_mac_addr(uint8_t mac[6]) {
  uint32_t a = REG(C3_EFUSE)[17], b = REG(C3_EFUSE)[18];
  mac[0] = (b >> 8) & 255, mac[1] = b & 255, mac[2] = (uint8_t) (a >> 24) & 255;
  mac[3] = (a >> 16) & 255, mac[4] = (a >> 8) & 255, mac[5] = a & 255;
}

static inline void set_irq_handler(void (*fn)(void)) {
  CSR_WRITE(mtvec, (uintptr_t) fn);
}

static inline void soc_init(void) {
  // Init clock. TRM 6.2.4.1
  // REG(C3_SYSTEM)[2] &= ~3U;
  // REG(C3_SYSTEM)[2] |= BIT(0) | BIT(2);
  // REG(C3_SYSTEM)[22] = BIT(19) | (40U << 12) | BIT(10);
  // REG(C3_RTCCNTL)[47] = 0; // RTC_APB_FREQ_REG -> freq >> 12
  //((void (*)(int)) 0x40000588)(160);  // ets_update_cpu_frequency(160)
  wdt_disable();

#if 0
  // Configure system clock timer, TRM 8.3.1, 8.9
  REG(C3_TIMERGROUP0)[1] = REG(C3_TIMERGROUP0)[2] = 0UL;  // Reset LO and HI
  REG(C3_TIMERGROUP0)[8] = 0;                             // Trigger reload
  REG(C3_TIMERGROUP0)[0] = (83U << 13) | BIT(12) | BIT(29) | BIT(30) | BIT(31);
#endif
}

// API GPIO

static inline void gpio_output_enable(int pin, bool enable) {
  GPIO->ENABLE &= ~BIT(pin);
  GPIO->ENABLE |= (enable ? 1U : 0U) << pin;
  // SETBITS(GPIO->ENABLE, BIT(pin), (enable ? BIT(pin) : 0U));
}

static inline void gpio_output(int pin) {
  REG(C3_GPIO)[GPIO_OUT_FUNC + pin] = BIT(9) | 128;  // Simple out, TRM 5.5.3
  gpio_output_enable(pin, 1);
}

static inline void gpio_write(int pin, bool value) {
  GPIO->OUT &= ~BIT(pin);                 // Clear first
  GPIO->OUT |= (value ? 1U : 0U) << pin;  // Then set
}

static inline void gpio_toggle(int pin) {
  GPIO->OUT ^= BIT(pin);
}

static inline void gpio_input(int pin) {
  gpio_output_enable(pin, 0);         // Disable output
  IO_MUX->IO[pin] = BIT(9) | BIT(8);  // Enable pull-up
}

static inline bool gpio_read(int pin) {
  return GPIO->IN & BIT(pin) ? 1 : 0;
}

// API SPI

struct spi {
  int miso, mosi, clk, cs;  // Pins
  int spin;                 // Number of NOP spins for bitbanging
};

static inline void spi_begin(struct spi *spi) {
  gpio_write(spi->cs, 0);
}

static inline void spi_end(struct spi *spi) {
  gpio_write(spi->cs, 1);
}

static inline bool spi_init(struct spi *spi) {
  if (spi->miso < 0 || spi->mosi < 0 || spi->clk < 0) return false;
  gpio_input(spi->miso);
  gpio_output(spi->mosi);
  gpio_output(spi->clk);
  if (spi->cs >= 0) {
    gpio_output(spi->cs);
    gpio_write(spi->cs, 1);
  }
  return true;
}

// Send a byte, and return a received byte
static inline unsigned char spi_txn(struct spi *spi, unsigned char tx) {
  unsigned count = spi->spin <= 0 ? 9 : (unsigned) spi->spin;
  unsigned char rx = 0;
  for (int i = 0; i < 8; i++) {
    gpio_write(spi->mosi, tx & 0x80);   // Set mosi
    spin(count);                        // Wait half cycle
    gpio_write(spi->clk, 1);            // Clock high
    rx = (unsigned char) (rx << 1);     // "rx <<= 1" gives warning??
    if (gpio_read(spi->miso)) rx |= 1;  // Read miso
    spin(count);                        // Wait half cycle
    gpio_write(spi->clk, 0);            // Clock low
    tx = (unsigned char) (tx << 1);     // Again, avoid warning
  }
  return rx;  // Return the received byte
}

// API WS2812
static inline void ws2812_show(int pin, const uint8_t *buf, size_t len) {
  unsigned long delays[2] = {2, 6};
  for (size_t i = 0; i < len; i++) {
    for (uint8_t mask = 0x80; mask; mask >>= 1) {
      int i1 = buf[i] & mask ? 1 : 0, i2 = i1 ^ 1;  // This takes some cycles
      gpio_write(pin, 1);
      spin(delays[i1]);
      gpio_write(pin, 0);
      spin(delays[i2]);
    }
  }
}

static inline void clock_init(void) {
}

static inline uint32_t clock_sys_freq(void) {
  return 160000000U;
}

static inline bool uart_init(uint32_t uart, int baud) {
  (void) uart, (void) baud;
  return false;
}

// t: expiration time, prd: period, now: current time. Return true if expired
static inline bool timer_expired(volatile uint64_t *t, uint64_t prd, uint64_t now) {
  if (now + prd < *t) *t = 0;                    // Time wrapped? Reset timer
  if (*t == 0) *t = now + prd;                   // Firt poll? Set expiration
  if (*t > now) return false;                    // Not expired yet, return
  *t = (now - *t) > prd ? now + prd : *t + prd;  // Next expiration time
  return true;                                   // Expired, return true
}

struct irq_data {
  void (*fn)(void *);   // User-defined handler function
  void *arg;            // User-defined handler function param
  void (*clr)(void *);  // Interrupt clearance function
  void *clr_arg;        // Interrupt clearance function param
};

extern struct irq_data g_irq_data[32];
extern int cpu_alloc_interrupt(uint8_t prio /* 1..15 */);

static inline void gpio_clear_interrupt(void *param) {
  uint16_t pin = (uint16_t) (uintptr_t) param;
  GPIO->STATUS &= ~BIT(pin);
  //printf("clearing pin %d irq\n", pin);
}

static inline void gpio_set_irq_handler(uint16_t pin, void (*fn)(void *), void *arg) {
  int no = cpu_alloc_interrupt(1);
  g_irq_data[no].fn = fn;
  g_irq_data[no].arg = arg;
  g_irq_data[no].clr = gpio_clear_interrupt;
  g_irq_data[no].clr_arg = (void *) (uintptr_t) pin;
  REG(C3_INTERRUPT)[0xf8 / 4] |= BIT(16);  // Enable CPU IRQ
  REG(C3_GPIO)
  [0x74 / 4 + pin] |= (3U << 7) | BIT(13);      // Enable intr, any edge
  REG(C3_INTERRUPT)[0x40 / 4] = (uint32_t) no;  // LAST: Map GPIO IRQ to CPU
}

extern void uart_tx_one_char(uint8_t);

#define NIBBLE(c) ((c) < 10 ? (c) + '0' : (c) + 'W')
#define PUTCHAR(c) uart_tx_one_char(c)
static inline void hexdump(const void *buf, size_t len) {
  const uint8_t *p = (const uint8_t *) buf;
  char ascii[16];
  size_t i, j, n = 0;
  for (i = 0; i < len; i++) {
    if ((i % 16) == 0) {
      // Print buffered ascii chars
      if (i > 0) {
        PUTCHAR(' '), PUTCHAR(' ');
        for (j = 0; j < sizeof(ascii); j++) PUTCHAR(ascii[j]);
        PUTCHAR('\n'), n = 0;
      }
      // Print hex address, then \t
      PUTCHAR(NIBBLE((i >> 12) & 15)), PUTCHAR(NIBBLE((i >> 8) & 15));
      PUTCHAR(NIBBLE((i >> 4) & 15)), PUTCHAR('0');
      PUTCHAR(' '), PUTCHAR(' '), PUTCHAR(' ');
    }
    PUTCHAR(NIBBLE(p[i] >> 4)), PUTCHAR(NIBBLE(p[i] & 15));
    PUTCHAR(' ');  // Space after hex number
    if (p[i] >= ' ' && p[i] <= '~') {
      ascii[n++] = (char) p[i];  // Printable
    } else {
      ascii[n++] = '.';  // Non-printable
    }
  }
  if (n > 0) {
    while (n < 16) PUTCHAR(' '), PUTCHAR(' '), PUTCHAR(' '), ascii[n++] = ' ';
    PUTCHAR(' '), PUTCHAR(' ');
    for (j = 0; j < sizeof(ascii); j++) PUTCHAR(ascii[j]);
  }
  PUTCHAR('\n');
}