/** library to communicate with a Titan Micro TM1637 IC attached to a 4-digit 7-segment
 *  @file
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @copyright SPDX-License-Identifier: GPL-3.0-or-later
 *  @date 2017-2020
 *  @note peripherals used: GPIO @ref led_tm1637_gpio, timer @ref led_tm1637_timer
 *  @note the protocol is very similar to I2C but incompatible for the following reasons: the capacitance is too large for open-drain type output with weak pull-up resistors (push-pull needs to be used, preventing to get ACKs since no indication of the ACK timing is provided); the devices doesn't use addresses; the STM32 I2C will switch to receiver mode when the first sent byte (the I2C address) has last bit set to 1 (such as for address commands with B7=1 where B7 is transmitted last), preventing to send further bytes (the data byte after the address)
 *  @warning all calls are blocking
 *
 *  bit vs segment: 0bpgfedcba
 *  +a+
 *  f b p
 *  +g+
 *  e c p
 *  +d+
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdlib.h> // general utilities
#include <string.h> // string utilities

/* STM32 (including CM3) libraries */
#include <libopencmsis/core_cm3.h> // Cortex M3 utilities
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/timer.h> // timer library

#include "global.h" // global utilities
#include "led_tm1637.h" // TM1637 header and definitions

/** @defgroup led_tm1637_gpio GPIO used to communication with TM1637 IC
 *  @{
 */
#define LED_TM1637_CLK_PIN PB6 /**< pin for CLK signal */
#define LED_TM1637_DIO_PIN PB7 /**< pin for DIO signal */
/** @} */

/** @defgroup led_tm1637_timer timer used to communication with TM1637 IC
 *  @{
 */
#define LED_TM1637_TIMER 3 /**< timer to create signal */
/** @} */

/** display brightness */
static enum led_tm1637_brightness_t display_brightness = LED_TM1637_14DIV16;
/** if display is on */
static bool display_on = false;
/** display buffer */
static uint8_t led_tm1637_digits[4] = {0};
/** if the display is upside down */
bool led_tm1637_updown = false;

/** ASCII characters encoded for the 7 segments digit block
 *  @note starts with space
 */
static const uint8_t ascii_7segments[] = {
	0x00, // 0b00000000 space
	0x30, // 0b00110000 ! (I)
	0x22, // 0b00100010 "
	0x5c, // 0b01011100 # (o)
	0x6d, // 0b01101101 $ (s)
	0x52, // 0b01010010 % (/)
	0x7d, // 0b01111101 & (6)
	0x20, // 0b00100000 '
	0x39, // 0b00111001 ( ([)
	0x0f, // 0b00001111 )
	0x70, // 0b01110000 *
	0x46, // 0b01000110 +
	0x10, // 0b00010000 ,
	0x40, // 0b01000000 -
	0x10, // 0b00010000 . (,)
	0x52, // 0b01010010 /
	0x3f, // 0b00111111 0
	0x06, // 0b00000110 1
	0x5b, // 0b01011011 2
	0x4f, // 0b01001111 3
	0x66, // 0b01100110 4
	0x6d, // 0b01101101 5
	0x7d, // 0b01111101 6
	0x07, // 0b00000111 7
	0x7f, // 0b01111111 8
	0x6f, // 0b01101111 9
	0x48, // 0b01001000 : (=)
	0x48, // 0b01001000 ; (=)
	0x58, // 0b01011000 <
	0x48, // 0b01001000 =
	0x4c, // 0b01001100 >
	0x53, // 0b01010011 ?
	0x7b, // 0b01111011 @
	0x77, // 0b01110111 A
	0x7f, // 0b01111111 B
	0x39, // 0b00111001 C
	0x5e, // 0b01011110 D
	0x79, // 0b01111001 E
	0x71, // 0b01110001 F
	0x3d, // 0b00111101 G
	0x76, // 0b01110110 H
	0x30, // 0b00110000 I
	0x1e, // 0b00011110 J
	0x76, // 0b01110110 K
	0x38, // 0b00111000 L
	0x37, // 0b00110111 M
	0x37, // 0b00110111 N
	0x3f, // 0b00111111 O
	0x73, // 0b01110011 P
	0x6b, // 0b01101011 Q
	0x33, // 0b00110011 R
	0x6d, // 0b01101101 S
	0x78, // 0b01111000 T
	0x3e, // 0b00111110 U
	0x3e, // 0b00111110 V (U)
	0x3e, // 0b00111110 W (U)
	0x76, // 0b01110110 X (H)
	0x6e, // 0b01101110 Y
	0x5b, // 0b01011011 Z
	0x39, // 0b00111001 [
	0x64, // 0b01100100 '\'
	0x0f, // 0b00001111 /
	0x23, // 0b00100011 ^
	0x08, // 0b00001000 _
	0x02, // 0b00000010 `
	0x5f, // 0b01011111 a
	0x7c, // 0b01111100 b
	0x58, // 0b01011000 c
	0x5e, // 0b01011110 d
	0x7b, // 0b01111011 e
	0x71, // 0b01110001 f
	0x6f, // 0b01101111 g
	0x74, // 0b01110100 h
	0x10, // 0b00010000 i
	0x0c, // 0b00001100 j
	0x76, // 0b01110110 k
	0x30, // 0b00110000 l
	0x54, // 0b01010100 m
	0x54, // 0b01010100 n
	0x5c, // 0b01011100 o
	0x73, // 0b01110011 p
	0x67, // 0b01100111 q
	0x50, // 0b01010000 r
	0x6d, // 0b01101101 s
	0x78, // 0b01111000 t
	0x1c, // 0b00011100 u
	0x1c, // 0b00011100 v (u)
	0x1c, // 0b00011100 w (u)
	0x76, // 0b01110110 x
	0x6e, // 0b01101110 y
	0x5b, // 0b01011011 z
	0x39, // 0b00111001 { ([)
	0x30, // 0b00110000 |
	0x0f, // 0b00001111 } ([)
	0x40, // 0b01000000 ~
};


/** convert the data for upside down displays
 *  @param[in] data the data to be converted
 *  @return the upside down data
 */
static uint8_t led_tm1637_rotate(uint8_t data)
{
	uint8_t converted = 0;
	converted |= (data & 0xc0); // keep g and dot
	converted |= (data << 3) & 0x38; // rotate abc
	converted |= (data >> 3) & 0x07; // rotate def
	return converted;
}

void led_tm1637_setup(bool updown)
{
	led_tm1637_updown = updown; // remember if the display is upside down

	// configure GPIO for CLK and DIO signals
	rcc_periph_clock_enable(GPIO_RCC(LED_TM1637_CLK_PIN)); // enable clock for GPIO peripheral
	gpio_set(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // idle high
	gpio_set_mode(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO_PIN(LED_TM1637_CLK_PIN)); // master start the communication (capacitance is to large for open drain), only switch to input for ack from slave
	rcc_periph_clock_enable(GPIO_RCC(LED_TM1637_DIO_PIN)); // enable clock for GPIO peripheral
	gpio_set(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN)); // idle high
	gpio_set_mode(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_MODE_OUTPUT_10_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO_PIN(LED_TM1637_DIO_PIN)); // master start the communication (capacitance is to large for open drain), only switch to input for ack from slave
	// first clock then data high also stands for stop condition

	// setup timer to create signal timing (each tick is used for a single GPIO transition)
	rcc_periph_clock_enable(RCC_TIM(LED_TM1637_TIMER)); // enable clock for timer block
	rcc_periph_reset_pulse(RST_TIM(LED_TM1637_TIMER)); // reset timer state
	timer_set_mode(TIM(LED_TM1637_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
	timer_set_prescaler(TIM(LED_TM1637_TIMER), 0); // don't prescale to get most precise timing ( 1/(72E6/1/(2**16))=0.91 ms > 0.5 us )
	timer_set_period(TIM(LED_TM1637_TIMER), 500); // set the clock frequency (empirical value until the signal starts to look bad)
	timer_clear_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF); // clear flag
	timer_update_on_overflow(TIM(LED_TM1637_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
}

/** wait until clock tick (timer overflow) occurred
 */
static inline void led_tm1637_tick(void)
{
	while (!timer_get_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF)); // wait until counter overflow update event happens
	timer_clear_flag(TIM(LED_TM1637_TIMER), TIM_SR_UIF); // clear event flag
}

/** write data on bus
 *  @param[in] data bytes to write
 *  @param[in] length number of bytes to write
 *  @return if write succeeded
 *  @note includes start and stop conditions
 */
static bool led_tm1637_write(const uint8_t* data, size_t length)
{
	bool to_return = true; // return if write succeeded
	if (NULL == data || 0 == length) { // verify there it data to be read
		return false;
	}

	// enable timer for signal generation
	timer_set_counter(TIM(LED_TM1637_TIMER), 0); // reset timer counter
	timer_enable_counter(TIM(LED_TM1637_TIMER)); // enable timer to generate timing
	led_tm1637_tick(); // wait to enforce minimum time since last write

	// send start condition (DIO then CLK low)
	gpio_clear(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN)); // put DIO low
	led_tm1637_tick(); // wait for next tick
	gpio_clear(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK low

	// send data bytes (MSb first)
	for (size_t i = 0; i < length; i++) { // send all bytes
		uint8_t byte = data[i];
		for (uint8_t b = 0; b < 8; b++) { // send all bits
			if (byte & 0x1) { // send a 1
				gpio_set(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN)); // put DIO high
			} else {
				gpio_clear(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN)); // put DIO low
			}
			byte >>= 1; // shift data
			led_tm1637_tick(); // wait for next tick
			gpio_set(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK high
			led_tm1637_tick(); // wait for next tick (no DIO transition when CLK is high)
			gpio_clear(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK low
		}
		gpio_set_mode(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO_PIN(LED_TM1637_DIO_PIN)); // switch DIO as input to read ACK
		led_tm1637_tick(); // wait for next tick (when the slave should ACK)
		gpio_set(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK high
		if (gpio_get(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN))) { // no ACK received
			to_return = false; // remember there was an error
			break; // stop sending bytes
		}
		led_tm1637_tick(); // wait for next tick
		gpio_clear(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK low
		gpio_set_mode(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO_PIN(LED_TM1637_DIO_PIN)); // switch DIO back to output to send next byte
	}

	// send stop condition
	gpio_set_mode(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO_PIN(LED_TM1637_DIO_PIN)); // ensure DIO is output (in case no ACK as been received
	led_tm1637_tick(); // wait for next tick
	gpio_set(GPIO_PORT(LED_TM1637_CLK_PIN), GPIO_PIN(LED_TM1637_CLK_PIN)); // put CLK high
	led_tm1637_tick(); // wait for next tick
	gpio_set(GPIO_PORT(LED_TM1637_DIO_PIN), GPIO_PIN(LED_TM1637_DIO_PIN)); // put DIO high
	timer_disable_counter(TIM(LED_TM1637_TIMER)); // stop timer since it's not used anymore

	return to_return;
}

/** write all data to SRAM (automatic address adding, normal) and control display
 *  @return if write succeeded
 */
static bool led_tm1637_update(void)
{
	const uint8_t write[] = { 0x40 }; // command: write data, automatic address adding, normal
	uint8_t data[] = { 0xc0, led_tm1637_digits[0], led_tm1637_digits[1], led_tm1637_digits[2], led_tm1637_digits[3] }; // set digits (start at address 0)
	if (led_tm1637_updown) { // rotate data
		data[1] = led_tm1637_rotate(led_tm1637_digits[3]);
		data[2] = led_tm1637_rotate(led_tm1637_digits[2]) | (led_tm1637_digits[1] & 0x80); // keep the : for the time
		data[3] = led_tm1637_rotate(led_tm1637_digits[1]) & 0x7f; // remove the : for the time
		data[4] = led_tm1637_rotate(led_tm1637_digits[0]);
	}
	const uint8_t control[] = { (display_on ? 0x88 : 0x80) + (display_brightness & 0x7) }; // command to turn display on/off and set brightness
	return led_tm1637_write(write, LENGTH(write)) && led_tm1637_write(data, LENGTH(data)) && led_tm1637_write(control, LENGTH(control)); // send commands
}

bool led_tm1637_on(void)
{
	display_on = true; // remember display is on
	return led_tm1637_update();
}

bool led_tm1637_off(void)
{
	display_on = false; // remember display is off
	return led_tm1637_update();
}

bool led_tm1637_brightness(enum led_tm1637_brightness_t brightness)
{
	display_brightness = brightness; // save brightness
	return led_tm1637_update();
}

bool led_tm1637_number(uint16_t number, bool zero)
{
	const uint8_t digits[] = { // digits to display
		(number / 1000) % 10,
		(number / 100) % 10,
		(number / 10) % 10,
		(number / 1) % 10,
	};
	// convert digits to text to be displayed
	if (0 == digits[0] && !zero) {
		led_tm1637_digits[0] = ascii_7segments[' ' - ' '];
	} else {
		led_tm1637_digits[0] = ascii_7segments[digits[0] + '0' - ' '];
	}
	if (0 == digits[0] && 0 == digits[1] && !zero) {
		led_tm1637_digits[1] = ascii_7segments[' ' - ' '];
	} else {
		led_tm1637_digits[1] = ascii_7segments[digits[1] + '0' - ' '];
	}
	if (0 == digits[0] && 0 == digits[1] && 0 == digits[2] && !zero) {
		led_tm1637_digits[2] = ascii_7segments[' ' - ' '];
	} else {
		led_tm1637_digits[2] = ascii_7segments[digits[2] + '0' - ' '];
	}
	led_tm1637_digits[3] = ascii_7segments[digits[3] + '0' - ' '];

	return led_tm1637_update(); // display number
}

bool led_tm1637_time(uint8_t hours, uint8_t minutes)
{
	// set digits
	led_tm1637_digits[0] = ascii_7segments[((hours / 10) % 10) + '0' - ' '];
	led_tm1637_digits[1] = ascii_7segments[((hours / 1) % 10) + '0' - ' '] | 0x80;
	led_tm1637_digits[2] = ascii_7segments[((minutes / 10) % 10) + '0' - ' '];
	led_tm1637_digits[3] = ascii_7segments[((minutes / 1) % 10) + '0' - ' '];

	return led_tm1637_update(); // display time
}

bool led_tm1637_text(char* text)
{
	if (strlen(text) != 4) { // input text should have exactly 4 characters
		return false;
	}
	for (uint8_t i = 0; i < 4; i++) { // input text should only contain printable character (8th bit is used for dots)
		if ((text[i] & 0x7f) < ' ' || (text[i] & 0x7f) >= ' ' + LENGTH(ascii_7segments)) {
			return false;
		}
	}

	// set digits
	led_tm1637_digits[0] = ascii_7segments[(text[0] & 0x7f) - ' '] | (text[0] & 0x80);
	led_tm1637_digits[1] = ascii_7segments[(text[1] & 0x7f) - ' '] | (text[1] & 0x80);
	led_tm1637_digits[2] = ascii_7segments[(text[2] & 0x7f) - ' '] | (text[2] & 0x80);
	led_tm1637_digits[3] = ascii_7segments[(text[3] & 0x7f) - ' '] | (text[3] & 0x80);

	return led_tm1637_update(); // display test
}