fifo8.c

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#include "fifo8.h"


fifo8_error_t FIFO8_put(FIFO8 *target, uint8_t byte){

    //The fifo is full when the head is one position behind the tale
    if((target->head == ((target->tail-1) & target->mask))){

        return E_FIFO8_FULL;
    }

    //Add a byte than increase the position
    target->buffer[target->head] = byte;
    target->head++;

    //Wrap around if at end
    target->head = (target->head & target->mask);

    //Start dumping characters if need
    if((target->idle == 1) && (target->mode == FIFO8_AUTO)){

        FIFO8_get(target);
    }

    return E_FIFO8_NOERROR;

}

fifo8_error_t FIFO8_get(FIFO8 *target){

    //The fifo is empty when the head and tail are at the same position.
    if(target->head == target->tail){

        target->idle = 1;
        return E_FIFO8_EMPTY;
    }

    target->idle = 0;

    //Get a byte and wrap around if need
    target->out(target->buffer[target->tail]);
    target->tail++;
    target->tail = (target->tail & target->mask);

    return E_FIFO8_NOERROR;
}

fifo8_error_t FIFO8_init(FIFO8 *target, fifo8_mode_t mode, uint8_t *buffer, uint16_t size, void (*output)(uint8_t byte)){

    //First check if the size is a power of 2
    if(!(size && !(size & (size - 1)))){

        return E_FIFO8_NONBINARY;
    }

    //Check if the mode exists
    if((mode != FIFO8_AUTO) && (mode != FIFO8_TRIGGER) && (mode != FIFO8_DUMP)){

        return E_FIFO8_NOMODE;
    }

    //All good, set up inital values.
    target->buffer = buffer;
    target->head = 0;
    target->tail = 0;
    target->mask = size - 1;
    target->idle = 1;
    target->mode = mode;
    target->out = output;

    return E_FIFO8_NOERROR;
}

uint16_t FIFO8_size(FIFO8 *target){

    return (target->head - target->tail) & target->mask;
}

fifo8_error_t FIFO8_flush(FIFO8 *target){
    
    uint8_t test = 0;

    //The idle bit is used to determine if the fifo is empty
    while(!test){

        FIFO8_get(target);
        test = target->idle;
    }

    return E_FIFO8_NOERROR;
}
uint8_t FIFO8_pop(FIFO8 *target){

    uint8_t byte;
    //The fifo is empty when the head and tail are at the same position.
    if(target->head == target->tail){

        target->idle = 1;
        return E_FIFO8_EMPTY;
    }

    target->idle = 0;

    //Get a byte and wrap around if need
    byte = (target->buffer[target->tail]);
    target->tail++;
    target->tail = (target->tail & target->mask);

    return byte;

}