dataframe/src/dataframe.c

/*
 * @file dataframe.c
 *
 *  @date: 31. 12. 2022
 *  @author: juraj
 *
 *  @brief Simple Data Frame
 *
 *  Structure of data frame:
 *  - starting byte (0xCC)
 *  - length of frame: count of bytes in payload. Maximum length: 254 (0xFE)h
 *  - payload
 *
 *  Supported data types:
 *  - uint8_t, int8_t
 *  - uint16_t, int16_t
 *  - uint32_t, int32_t
 *  - float
 *
 *  \code{.c}
    void main(){
		uint8_t data[128];

	    packet_create(data, 128);
		packet_add_uint8(0xAB);
		packet_add_uint16(0xABCD);
		packet_add_uint32(0x12345678);
		packet_add_float(0.265);

		int data_length = packet_commit();
    }
 * \endcode
 *
 */

#include "dataframe.h"


uint8_t *packet;
static volatile uint8_t length;
static volatile uint8_t capacity;

void packet_create(uint8_t *usr_packet, uint8_t size) {
    packet = usr_packet;
    capacity = size;
    packet[0] = HEADER_CHAR;
    packet[1] = 0;	//length of packet
    length = 2;
}


uint8_t packet_add_uint8(uint8_t d)
{
    if((length+1) >= capacity){
        return VALUE_ERR;
    }
	packet[length] = d;
	length++;
    return VALUE_OK;
}

uint8_t packet_add_uint16(uint16_t d)
{
    if((length+2) >= capacity){
        return VALUE_ERR;
    }

	packet[length++] =  (d >> 8) & 0xFF;
	packet[length++] =  d & 0xFF;

    return VALUE_OK;
}


uint8_t packet_add_uint32(uint32_t d)
{
    if((length+4) >= capacity){
        return VALUE_ERR;
    }
	packet[length++] =  (d >> 24) & 0xFF;
	packet[length++] =  (d >> 16) & 0xFF;
	packet[length++] =  (d >> 8) & 0xFF;
	packet[length++] =  d & 0xFF;
    return VALUE_OK;
}

uint8_t packet_add_int8(int8_t d)
{
    return packet_add_uint8((uint8_t)d);
}

uint8_t packet_add_int16(int16_t d)
{
    return packet_add_uint16((uint16_t)d);
}

uint8_t packet_add_int32(int32_t d)
{
    return packet_add_uint32((uint32_t)d);
}

uint8_t packet_add_float(float f)
{
    if((length+4) >= capacity){
        return VALUE_ERR;
    }

	 uint8_t *ptr;
	 ptr = (unsigned char *)&f;

	 packet[length++] = *(ptr);
	 packet[length++] = *(ptr+1);
	 packet[length++] = *(ptr+2);
	 packet[length++] = *(ptr+3);
    return VALUE_OK;

}

uint8_t packet_commit()
{
	packet[1] = length;
	return length;
}