I coded a ring buffer for my Arduino to buffer data from either the SPI or TWI ports. In the .h file I used a pointer for the buffer:

typedef uint8_t *ring_buffer_t;
typedef uint8_t ring_count_t;
typedef uint8_t ring_index_t;
typedef uint8_t ring_size_t;

typedef struct ring_t 
{
    ring_buffer_t buffer;
    ring_count_t  count;
    ring_index_t  head;
    ring_index_t  tail;
    ring_size_t   size;
}rint_t;

int ring_init(ring_t *r, ring_buffer_t buffer, ring_size_t size);

// other function prototypes to add and remove from the ring buffer

There is more code to handle adding and removing from the buffer, but I am simplifying here. Then in my .c file I have:

#include<string.h>

void ring_init(ring_t *r, ring_buffer_t buffer, ring_size_t size)
{
    r->buffer = buffer;
    r->size   = size;
    r->head   = 0;
    r->tail   = 0;
    r->count  = 0;

    // clear out the buffer memset cheaper by 12 bytes rather than for loop
    memset((void *)r->buffer, 0, r->size);
}

Then somewhere in code where the ring buffer is going to be used:

In SPI.h ...
#define MAX_BUFFER_SIZE 32
ring_t  rx_ring;
uint8_t spi_rx_buffer[MAX_BUFFER_SIZE];

#define MAX_BUFFER_SIZE 32
ring_t  tx_ring;
uint8_t spi_tx_buffer[MAX_BUFFER_SIZE];


In SPI.c ...
void spi_init( ... )
{
    ring_init(&rx_ring, spi_rx_buffer, MAX_BUFFER_SIZE);
    ring_init(&tx_ring, spi_tx_buffer, MAX_BUFFER_SIZE);

    // initialize other spi parameters
}

Are there any issues with my code that are obvious that I am not seeing? I ask because I ran the code and it works, but I feel I am doing something wrong. I can code in C and remember something about malloc() for dynamic memory allocation, just not sure if what I am doing qualifies. Or should this work creating a buffer of some defined size?

Thanks for any help or ideas.

EDIT: 07/27/2014 Added code to try and make what I am trying to do clear. Let me know, thanks.