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/**
 * a simple Fifo
 * @file fifo.c
 * @author Pascal Schnurr
*/

#include "fifo.h"

//--------------------------------------------------------------
void fifo_init (fifo_t * fifo, uint8_t * buffer, uint16_t size)
{
        fifo->size = size;
        fifo->buffer = buffer;
        fifo->head = 0;
        fifo->count = 0;
}

//--------------------------------------------------------------
bool fifo_is_empty (const fifo_t * fifo)
{
        return (fifo->count == 0);
}

//--------------------------------------------------------------
bool fifo_is_full (const fifo_t * fifo)
{
        return (fifo->size - fifo->count == 0);
}

//--------------------------------------------------------------
bool fifo_read (fifo_t * fifo, char *data)
{
        if (fifo_is_empty (fifo))
                return false;

        uint8_t *head = fifo->buffer + fifo->head;

        *data = (char) * head;

        fifo->head = ( (fifo->head + 1) % fifo->size);

        fifo->count--;

        return true;
}

//--------------------------------------------------------------
bool fifo_write (fifo_t * fifo, const char data)
{
        if (fifo_is_full (fifo))
                return false;

        uint8_t *end = fifo->buffer + ( (fifo->head + fifo->count) % fifo->size);

        *end = (uint8_t) data;

        fifo->count++;

        return true;
}

//--------------------------------------------------------------
bool fifo_clear (fifo_t * fifo)
{
        fifo->count = 0;
        fifo->head = 0;
        return true;
}

//--------------------------------------------------------------
static bool fifo_cmp_pgm_at (fifo_t * fifo, const prog_char * pgm, const uint16_t index)
{
        uint16_t i;
        uint8_t fifo_byte;
        uint8_t pgm_byte;

        for (i = 0; pgm_read_byte (pgm + i) != 0; i++)
        {
                if (fifo->count <= (i + index))
                        return false;

                pgm_byte = pgm_read_byte (pgm + i);

                fifo_byte = * (fifo->buffer + ( (fifo->head + i + index) % fifo->size));

                if (fifo_byte != pgm_byte)
                        return false;
        }

        // We found the string, lets move the pointer
        fifo->head = ( (fifo->head + i + index) % fifo->size);

        fifo->count -= (i + index);

        return true;
}

//--------------------------------------------------------------
bool fifo_cmp_pgm (fifo_t * fifo, const prog_char * pgm)
{
        return fifo_cmp_pgm_at (fifo, pgm, 0);
}

//--------------------------------------------------------------
bool fifo_strstr_pgm (fifo_t * fifo, const prog_char * pgm)
{
        for (uint16_t i = 0; i < fifo->count; i++)
        {
                if (fifo_cmp_pgm_at (fifo, pgm, i))
                        return true;
        }

        return false;
}