/* 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/>.
 *
 */
/** BusVoodoo SPI mode (code)
 *  @file busvoodoo_spi.c
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2018
 *  @note peripherals used: SPI @ref busvoodoo_spi
 */
/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdlib.h> // standard utilities
#include <string.h> // string utilities

/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/spi.h> // SPI library

/* own libraries */
#include "global.h" // board definitions
#include "print.h" // printing utilities
#include "menu.h" // menu definitions
#include "busvoodoo_global.h" // BusVoodoo definitions
#include "busvoodoo_oled.h" // OLED utilities
#include "busvoodoo_spi.h" // own definitions

/** @defgroup busvoodoo_spi SPI peripheral used for SPI communication
 *  @{
 */
#define BUSVOODOO_SPI_ID 2 /**< SPI peripheral */
/** @} */

/** mode setup stage */
static enum busvoodoo_spi_setting_t {
	BUSVOODOO_SPI_SETTING_NONE,
	BUSVOODOO_SPI_SETTING_DUPLEX,
	BUSVOODOO_SPI_SETTING_FREQUENCY,
	BUSVOODOO_SPI_SETTING_DATABITS,
	BUSVOODOO_SPI_SETTING_BITORDER,
	BUSVOODOO_SPI_SETTING_MODE,
	BUSVOODOO_SPI_SETTING_DRIVE,
	BUSVOODOO_SPI_SETTING_DONE,
} busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_NONE; /**< current mode setup stage */
/** SPI duplex mode (true = full-duplex, false = bidirectional) */
static bool busvoodoo_spi_duplex = true;
/** SPI baud rate (corresponding to baud rate control, e.g. 36MHz/(2<<br))) */
static uint8_t busvoodoo_spi_baudrate = 1;
/** SPI data frame bit width (8 or 16) */
static uint8_t busvoodoo_spi_databits = 8;
/** SPI data frame bit order (true = MSb first, false = LSb first) */
static bool busvoodoo_spi_bitorder = true;
/** SPI mode (defining clock polarity and phase) */
static uint8_t busvoodoo_spi_standard_mode = 0;
/** pin drive mode (true = push-pull, false = open-drain) */
static bool busvoodoo_spi_drive = true;
/** if embedded pull-up resistors are used */
static bool busvoodoo_spi_pullup = true;

/** setup SPI mode
 *  @param[out] prefix terminal prompt prefix
 *  @param[in] line terminal prompt line to configure mode
 *  @return if setup is complete
 */
static bool busvoodoo_spi_setup(char** prefix, const char* line)
{
	bool complete = false; // is the setup complete
	if (NULL==line) { // first call
		busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_NONE; // re-start configuration
	}
	switch (busvoodoo_spi_setting) {
		case BUSVOODOO_SPI_SETTING_NONE:
			busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DUPLEX;
			printf("1) full-duplex\n");
			printf("2) bidirectional\n");
			snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "duplex mode (1,2) [%c]", busvoodoo_spi_duplex ? '1' : '2');
			*prefix = busvoodoo_global_string; // ask for setting
			break;
		case BUSVOODOO_SPI_SETTING_DUPLEX:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_FREQUENCY; // go to next setting
			} else if (1==strlen(line)) { // setting provided
				uint8_t duplex = atoi(line); // parse setting
				if (1==duplex || 2==duplex) { // check setting
					busvoodoo_spi_duplex = (1==duplex); // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_FREQUENCY; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_FREQUENCY==busvoodoo_spi_setting) { // if next setting
				// SPI2 used APB1 as PCLK, which has a maximum frequency of 36 MHz
				for (uint8_t div=0; div<8; div++) {
					printf("%u) %u kHz\n", div+1, 36000/(2<<div)); // print possible frequencies
				}
				snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "frequency (1-9) [%u]", busvoodoo_spi_baudrate+1);
				*prefix = busvoodoo_global_string; // display next setting
			}
			break;
		case BUSVOODOO_SPI_SETTING_FREQUENCY:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DATABITS; // go to next setting
			} else if (1==strlen(line)) { // setting provided
				uint8_t baudrate = atoi(line); // parse setting
				if (baudrate>0 && baudrate<=9) { // check setting
					busvoodoo_spi_baudrate = baudrate-1; // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DATABITS; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_DATABITS==busvoodoo_spi_setting) { // if next setting
				snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "data frame width in bits (8,16) [%u]", busvoodoo_spi_databits); // prepare next setting
				*prefix = busvoodoo_global_string; // display next setting
			}
			break;
		case BUSVOODOO_SPI_SETTING_DATABITS:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_BITORDER; // go to next setting
			} else if (1==strlen(line) || 2==strlen(line)) { // setting provided
				uint8_t databits = atoi(line); // parse setting
				if (8==databits || 16==databits) { // check setting
					busvoodoo_spi_databits = databits; // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_BITORDER; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_BITORDER==busvoodoo_spi_setting) { // if next setting
				printf("1) most significant bit first\n");
				printf("2) least significant bit first\n");
				snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "data frame bit order (1,2) [%c]", busvoodoo_spi_bitorder ? '1' : '2'); // prepare next setting
				*prefix = busvoodoo_global_string; // display next setting
			}
			break;
		case BUSVOODOO_SPI_SETTING_BITORDER:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_MODE; // go to next setting
			} else if (1==strlen(line)) { // setting provided
				uint8_t bitorder = atoi(line); // parse setting
				if (1==bitorder || 2==bitorder) { // check setting
					busvoodoo_spi_bitorder = (1==bitorder); // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_MODE; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_MODE==busvoodoo_spi_setting) { // if next setting
				printf("1) mode 0 (clock polarity: idle low, clock phase: sample data on rising edge)\n");
				printf("2) mode 1 (clock polarity: idle low, clock phase: sample data on falling edge)\n");
				printf("3) mode 2 (clock polarity: idle high, clock phase: sample data on falling edge)\n");
				printf("4) mode 3 (clock polarity: idle high, clock phase: sample data on rising edge)\n");
				snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "mode (1,2,3,4) [%u]", busvoodoo_spi_standard_mode+1); // prepare next setting
				*prefix = busvoodoo_global_string; // display next setting
			}
			break;
		case BUSVOODOO_SPI_SETTING_MODE:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DRIVE; // go to next setting
			} else if (1==strlen(line)) { // setting provided
				uint8_t mode = atoi(line); // parse setting
				if (mode>=1 && mode<=4) {
					busvoodoo_spi_standard_mode = mode-1; // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DRIVE; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_DRIVE==busvoodoo_spi_setting) { // if next setting
				printf("1) push-pull (3.3V)\n");
				printf("2) open-drain, with embedded pull-up resistors (2kO)\n");
				printf("3) open-drain, with external pull-up resistors\n");
				snprintf(busvoodoo_global_string, LENGTH(busvoodoo_global_string), "drive mode (1,2,3) [%c]", busvoodoo_spi_drive ? '1' : (busvoodoo_spi_pullup ? '2' : '3')); // show drive mode
				*prefix = busvoodoo_global_string; // display next setting
			}
			break;
		case BUSVOODOO_SPI_SETTING_DRIVE:
			if (NULL==line || 0==strlen(line)) { // use default setting
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DONE; // go to next setting
			} else if (1==strlen(line)) { // setting provided
				uint8_t drive = atoi(line); // parse setting
				if (1==drive || 2==drive || 3==drive) { // check setting
					busvoodoo_spi_drive = (1==drive); // remember setting
					busvoodoo_spi_pullup = (2==drive); // remember setting
					busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_DONE; // go to next setting
				}
			}
			if (BUSVOODOO_SPI_SETTING_DONE==busvoodoo_spi_setting) { // we have all settings, configure SPI
				rcc_periph_clock_enable(RCC_AFIO); // enable clock for SPI alternate function
				rcc_periph_clock_enable(RCC_SPI(BUSVOODOO_SPI_ID)); // enable clock for SPI peripheral
				spi_reset(SPI(BUSVOODOO_SPI_ID)); // clear SPI values to default
				spi_set_baudrate_prescaler(SPI(BUSVOODOO_SPI_ID), busvoodoo_spi_baudrate); // set baud rate (i.e. frequency)
				spi_set_standard_mode(SPI(BUSVOODOO_SPI_ID), busvoodoo_spi_standard_mode); // set SPI mode
				if (8==busvoodoo_spi_databits) { // set data frame bit width
					spi_set_dff_8bit(SPI(BUSVOODOO_SPI_ID)); // set to 8 bits
				} else {
					spi_set_dff_16bit(SPI(BUSVOODOO_SPI_ID)); // set to 16 bits
				}
				if (busvoodoo_spi_bitorder) { // set bit order
					spi_send_msb_first(SPI(BUSVOODOO_SPI_ID)); // MSb-first
				} else {
					spi_send_lsb_first(SPI(BUSVOODOO_SPI_ID)); // LSb-first
				}
				rcc_periph_clock_enable(RCC_SPI_MOSI_PORT(BUSVOODOO_SPI_ID)); // enable clock for GPIO peripheral for MOSI signal
				if (busvoodoo_spi_drive) {
					gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set MOSI as output
				} else {
					gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set MOSI as output
				}
				if (busvoodoo_spi_duplex) {
					spi_set_full_duplex_mode(SPI(BUSVOODOO_SPI_ID)); // set full duplex mode
					rcc_periph_clock_enable(RCC_SPI_MISO_PORT(BUSVOODOO_SPI_ID)); // enable clock for GPIO peripheral for MISO signal
					if (busvoodoo_spi_drive) {
						gpio_set_mode(SPI_MISO_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_MISO_PIN(BUSVOODOO_SPI_ID)); // set MISO as input
					} else {
						gpio_set_mode(SPI_MISO_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_MISO_PIN(BUSVOODOO_SPI_ID)); // set MISO as input
					}
				} else {
					spi_set_bidirectional_mode(SPI(BUSVOODOO_SPI_ID)); // set bidirectional mode
				}
				rcc_periph_clock_enable(RCC_SPI_SCK_PORT(BUSVOODOO_SPI_ID)); // enable clock for GPIO peripheral for SCK signal
				if (busvoodoo_spi_drive) {
					gpio_set_mode(SPI_SCK_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_SCK_PIN(BUSVOODOO_SPI_ID)); // set SCK as output
				} else {
					gpio_set_mode(SPI_SCK_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, SPI_SCK_PIN(BUSVOODOO_SPI_ID)); // set SCK as output
				}
				spi_enable_software_slave_management(SPI(BUSVOODOO_SPI_ID)); // control SS by software
				spi_set_nss_high(SPI(BUSVOODOO_SPI_ID)); // set NSS high (internally) so we can output
				rcc_periph_clock_enable(RCC_SPI_NSS_PORT(BUSVOODOO_SPI_ID)); // enable clock for GPIO peripheral for SS signal
				gpio_set(SPI_NSS_PORT(BUSVOODOO_SPI_ID), SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // de-select slave (on high)
				if (busvoodoo_spi_drive) {
					gpio_set_mode(SPI_NSS_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // set NSS as output
				} else {
					gpio_set_mode(SPI_NSS_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // set NSS as output
				}
				spi_set_master_mode(SPI(BUSVOODOO_SPI_ID)); // set master mode
				spi_enable(SPI(BUSVOODOO_SPI_ID)); // enable SPI
				if (!busvoodoo_spi_drive && busvoodoo_spi_pullup) {
					busvoodoo_embedded_pullup(true); // set embedded pull-ups
					printf("use LV to set pull-up voltage\n");
				}
				busvoodoo_led_blue_off(); // disable blue LED because there is no activity
				busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_NONE; // restart settings next time
				*prefix = "SPI"; // display mode
				busvoodoo_oled_text_left(*prefix); // set mode title on OLED display
				const char* pinout_io[10] =  {"GND", "5V", "3V3", "LV", NULL, NULL, "MISO", "SCK", "MOSI", "SS"}; // SPI mode pinout
				if (!busvoodoo_spi_duplex) {
					pinout_io[6] = NULL; // MISO is not used
					pinout_io[8] = "MOSIMISO"; // MOSI is also used as MISO
				}
				for (uint8_t i=0; i<LENGTH(pinout_io) && i<LENGTH(busvoodoo_global_pinout_io); i++) {
					busvoodoo_global_pinout_io[i] = pinout_io[i]; // set pin names
				}
				if (busvoodoo_full) {
					const char* pinout_rscan[5] = {"HV", NULL, NULL, NULL, NULL}; // HiZ mode RS/CAN pinout
					for (uint8_t i=0; i<LENGTH(pinout_rscan) && i<LENGTH(busvoodoo_global_pinout_rscan); i++) {
						busvoodoo_global_pinout_rscan[i] = pinout_rscan[i]; // set pin names
					}
				}
				busvoodoo_oled_text_pinout(pinout_io, true); // set pinout on display
				busvoodoo_oled_update(); // update display to show text and pinout
				complete = true; // configuration is complete
			}
			break;
		default: // unknown case
			busvoodoo_spi_setting = BUSVOODOO_SPI_SETTING_NONE; // restart settings next time
			break;
	}
	return complete;
}

/** write to SPI
 *  @param[in] value value to write
 */
static void busvoodoo_spi_write(uint16_t value)
{
	if (8==busvoodoo_spi_databits) {
		printf("write: 0x%02x\n", (uint8_t)value);
	} else {
		printf("write: 0x%04x\n", value);
	}
	busvoodoo_led_blue_pulse(BUSVOODOO_LED_PULSE); // pulse blue LED to show we are writing
	while (!(SPI_SR(SPI(BUSVOODOO_SPI_ID))&SPI_SR_TXE)); // wait until Tx is empty
	(void)SPI_DR(SPI(BUSVOODOO_SPI_ID)); // clear RXNE flag by reading previously received data
	spi_send(SPI(BUSVOODOO_SPI_ID), value); // send data
	if (busvoodoo_spi_duplex) {
		busvoodoo_led_blue_pulse(BUSVOODOO_LED_PULSE); // pulse blue LED to show we read data
		value = spi_read(SPI(BUSVOODOO_SPI_ID)); // read data
		if (8==busvoodoo_spi_databits) {
			printf("read: 0x%02x\n", (uint8_t)value);
		} else {
			printf("read: 0x%04x\n", value);
		}
	}
}

/** read from SPI
 */
static void busvoodoo_spi_read(void)
{
	if (busvoodoo_spi_duplex) { // in full duplex mode
		 busvoodoo_spi_write(0xffff); // send any value in order to read
	} else { // unidirectional mode
		busvoodoo_led_blue_pulse(BUSVOODOO_LED_PULSE); // pulse blue LED to show we are reading
		gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set MOSI as input
		while (!(SPI_SR(SPI(BUSVOODOO_SPI_ID))&SPI_SR_TXE)); // wait until Tx is empty
		(void)SPI_DR(SPI(BUSVOODOO_SPI_ID)); // clear RXNE flag by reading previously received data
		spi_send(SPI(BUSVOODOO_SPI_ID), 0xffff); // send any value
		uint16_t value = spi_read(SPI(BUSVOODOO_SPI_ID)); // read data back
		if (8==busvoodoo_spi_databits) {
			printf("read: 0x%02x\n", (uint8_t)value);
		} else {
			printf("read: 0x%04x\n", value);
		}
		if (busvoodoo_spi_drive) {
			gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_PUSHPULL, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set MOSI as output
		} else {
			gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set MOSI as output
		}
	}
}

/** exit SPI mode
 */
static void busvoodoo_spi_exit(void)
{
	spi_reset(SPI(BUSVOODOO_SPI_ID)); // clear SPI values to default
	spi_disable(SPI(BUSVOODOO_SPI_ID)); // disable SPI
	rcc_periph_clock_disable(RCC_SPI(BUSVOODOO_SPI_ID)); // disable domain clock
	gpio_set_mode(SPI_SCK_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_SCK_PIN(BUSVOODOO_SPI_ID)); // set pin back to floating input
	gpio_set_mode(SPI_NSS_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // set pin back to floating input
	gpio_set_mode(SPI_MISO_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_MISO_PIN(BUSVOODOO_SPI_ID)); // set pin back to floating input
	gpio_set_mode(SPI_MOSI_PORT(BUSVOODOO_SPI_ID), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, SPI_MOSI_PIN(BUSVOODOO_SPI_ID)); // set pin back to floating input
	busvoodoo_embedded_pullup(false); // disable embedded pull-ups
}

/** perform SPI action
 *  @param[in] action action to perform
 *  @param[in] repetition how many times to perform the action
 *  @param[in] perform the action (true) or just check it (false)
 *  @return true if the action has been performed, false if it is malformed
 */
static bool busvoodoo_spi_action(const char* action, uint32_t repetition, bool perform)
{
	uint32_t length = strlen(action); // remember length since it will be used a number of times
	if (NULL==action || 0==length) { // there is nothing to do
		return true;
	}

	if (1==length && 'r'==action[0]) { // read data
		if (!perform) {
			return true;
		}
		for (uint32_t i=0; i<repetition; i++) {
			busvoodoo_spi_read(); // read from SPI
		}
	} else if (1==length && '['==action[0]) { // select slave
		if (!perform) {
			return true;
		}
		printf("select slave\n");
		while (SPI_SR(SPI(BUSVOODOO_SPI_ID))&SPI_SR_BSY); // wait until not busy
		gpio_clear(SPI_NSS_PORT(BUSVOODOO_SPI_ID), SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // select slave (on low)
	} else if (1==length && ']'==action[0]) { // deselect slave
		if (!perform) {
			return true;
		}
		printf("de-select slave\n");
		while (SPI_SR(SPI(BUSVOODOO_SPI_ID))&SPI_SR_BSY); // wait until not busy
		gpio_set(SPI_NSS_PORT(BUSVOODOO_SPI_ID), SPI_NSS_PIN(BUSVOODOO_SPI_ID)); // de-select slave (on high)
	} else if (1==length && 'u'==action[0]) { // sleep us
		if (!perform) {
			return true;
		}
		printf("wait for %u us\n", repetition);
		sleep_us(repetition); // sleep
	} else if (1==length && 'm'==action[0]) { // sleep ms
		if (!perform) {
			return true;
		}
		printf("wait for %u ms\n", repetition);
		sleep_ms(repetition); // sleep
	} else if ('0'==action[0]) { // send digit
		if (1==length) { // just send 0
			if (!perform) {
				return true;
			}
			for (uint32_t i=0; i<repetition; i++) {
				busvoodoo_spi_write(0); // write to SPI
			}
		} else if ('x'==action[1] || 'b'==action[1]) { // send hex/binary
			return busvoodoo_spi_action(action+1, repetition, perform); // just retry without leading 0
		} else if (action[1]>='0' && action[1]<='9') { // send decimal
			return busvoodoo_spi_action(action+1, repetition, perform); // just retry without leading 0
		} else { // malformed action
			return false;
		}
	} else if ('x'==action[0] && length>1) { // send hexadecimal value
		for (uint32_t i=1; i<length; i++) { // check string
			if (!((action[i]>='0' && action[i]<='9') || (action[i]>='a' && action[i]<='f') || (action[i]>='A' && action[i]<='F'))) { // check for hexadecimal character
				return false; // not an hexadecimal string
			}
		}
		if (!perform) {
			return true;
		}
		uint32_t value = strtol(&action[1], NULL, 16); // get hex value
		for (uint32_t i=0; i<repetition; i++) {
			busvoodoo_spi_write(value); // write to SPI
		}
	} else if ('b'==action[0] && length>1) { // send binary value
		for (uint32_t i=1; i<length; i++) { // check string
			if (action[i]<'0' || action[i]>'1') { // check for binary character
				return false; // not a binary string
			}
		}
		if (!perform) {
			return true;
		}
		uint32_t value = strtol(&action[1], NULL, 2); // get binary value
		for (uint32_t i=0; i<repetition; i++) {
			busvoodoo_spi_write(value); // write to SPI
		}
	} else if (action[0]>='1' && action[0]<='9') { // send decimal value
		for (uint32_t i=1; i<length; i++) { // check string
			if (action[i]<'0' || action[i]>'9') { // check for decimal character
				return false; // not a decimal string
			}
		}
		if (!perform) {
			return true;
		}
		uint32_t value = strtol(&action[0], NULL, 10); // get decimal value
		for (uint32_t i=0; i<repetition; i++) {
			busvoodoo_spi_write(value); // write to SPI
		}
	} else if (length>=2 && ('"'==action[0] || '\''==action[0]) && (action[length-1]==action[0])) { // send ASCII character
		if (!perform) {
			return true;
		}
		for (uint32_t r=0; r<repetition; r++) {
			for (uint32_t i=1; i<length-1; i++) { // go through string
				busvoodoo_spi_write(action[i]); // write to SPI
			}
		}
	} else { // malformed action
		return false;
	}
	return true; // all went well
}

// command handlers

/** command to perform actions
 *  @param[in] argument actions to perform
 */
static void busvoodoo_spi_command_actions(void* argument)
{
	if (NULL==argument || 0==strlen(argument)) {
		printf("available actions (separated by space or ,):\n");
		printf("[/]\tselect/deselect slave\n");
		printf("0\twrite decimal value\n");
		printf("0x0\twrite hexadecimal value\n");
		printf("0b0\twrite binary value\n");
		printf("\"a\"/'a'\twrite ASCII characters\n");
		printf("r\tread value\n");
		printf("u/m\twait 1 us/ms\n");
		printf(":n\trepeat action n times\n");
		return;
	}
	// copy argument since it will be modified
	char* copy = calloc(strlen(argument)+1, sizeof(char));
	if (!copy) {
		while (true);
	}
	strncpy(copy, argument, strlen(argument)+1);
	// verify and perform actions
	if (!busvoodoo_global_actions(copy, false, &busvoodoo_spi_action)) { // verify actions
		printf("malformed action(s)\n");
	} else { // action are ok
		busvoodoo_global_actions(argument, true, &busvoodoo_spi_action); // perform action
	}
	free(copy); // release memory
}

/** SPI menu commands */
static const struct menu_command_t busvoodoo_spi_commands[] = {
	{
		.shortcut = 'a',
		.name = "action",
		.command_description = "perform protocol actions",
		.argument = MENU_ARGUMENT_STRING,
		.argument_description = "[actions]",
		.command_handler = &busvoodoo_spi_command_actions,
	},
};

const struct busvoodoo_mode_t busvoodoo_spi_mode = {
	.name = "spi",
	.description = "Serial Peripheral Interface",
	.full_only = false,
	.setup = &busvoodoo_spi_setup,
	.commands = busvoodoo_spi_commands,
	.commands_nb = LENGTH(busvoodoo_spi_commands),
	.exit = &busvoodoo_spi_exit,
};