/*
 * crc_calc.c
 *
 * Created: 2/15/2022 3:38:31 PM
 *  Author: david
 */ 

#include "main.h"

__attribute__((__aligned__(512)))
crccu_dscr_type_t crc_dscr;

uint8_t crc8(uint8_t initcrc, const uint8_t* input_data, uint32_t len) {
	uint32_t i;
	uint8_t j;
	const uint8_t* l_input;
	
	l_input = input_data;
	for(i = 0; i < len; i++) {
		initcrc ^= *l_input;
		l_input++;
		
		for(j = 0; j < 8; j++) {
			if(initcrc & 0x80) {
				initcrc = (initcrc << 1) ^ CRC8POLY;
			} else {
				initcrc = (initcrc << 1);
			}
		}
	}
	
	return initcrc;
}

uint32_t crc32(uint32_t initcrc, const uint8_t* input_data, uint32_t len) {
	uint32_t i;
	uint8_t j;
	const uint8_t* l_input;
	
	initcrc = ~initcrc; // Invert input
	
	 l_input = input_data;
	for(i = 0; i < len; i++) {
		initcrc ^= (((uint32_t)(*l_input)) << 24);
		l_input++;
		
		for(j = 0; j < 8; j++) {
			if(initcrc & 0x80000000) {
				initcrc = (initcrc << 1) ^ CRC32POLY;
				} else {
				initcrc = (initcrc << 1);
			}
		}
	}
	
	return ~initcrc; // And invert output
}

static bool _runcrchw(void) {
	uint32_t ul_starttime;
	// Track duration
	ul_starttime = board_millis();

	// Start the CRC calculation 
	CRCCU->CRCCU_DMA_EN = 0x01; // Enable DMA transfer (starts calculation)

	// Wait for calculation ready 
	while(((CRCCU->CRCCU_DMA_SR) & 0x01) != 0) {
		if(board_millis() > ul_starttime + MAX_CRC_TIME) {
			// Stop transfer
			CRCCU->CRCCU_DMA_DIS = 0x01;
			// return bad value
			return false;
		}
	}
	return true;
}

uint32_t crc32_hw(const uint8_t* input_data, uint32_t len) {
	uint32_t done_so_far = 0;
	// Uses internal hardware CRC calculator unit to perform faster CRC
	
	// Enable clock to CRC unit
	PMC->PMC_PCER1 = (1 << (ID_CRCCU-32));
	
	// Reset CRC
	CRCCU->CRCCU_CR = CRCCU_CR_RESET;

	memset((void *)&crc_dscr, 0, sizeof(crccu_dscr_type_t));

	while(len > done_so_far) {

		crc_dscr.ul_tr_addr = (uint32_t) input_data + done_so_far;

		// Transfer width: byte, interrupt enable
		if((len - done_so_far) > 0xFFF8) {
			crc_dscr.ul_tr_ctrl = 0xFFF8;
			done_so_far += 0xFFF8;
		} else {
			crc_dscr.ul_tr_ctrl = len - done_so_far;
			done_so_far = len;
		}
		
		// Configure the CRCCU descriptor 
		CRCCU->CRCCU_DSCR = (uint32_t)(&crc_dscr);

		// Configure CRCCU mode 
		CRCCU->CRCCU_MR = 0x01; // Enable, polynomial is CCITT802.3 (0x04C11DB7), MSB first

		// Run CRC on this block
		if(_runcrchw() == false) {
			return 0;
		}
	}

	// Get CRC value
	return CRCCU->CRCCU_SR;
	
}