buffers?

buffers.h

/**
 * @brief Buffer segment
 */
typedef struct rd_segment_s {
        TAILQ_ENTRY(rd_segment_s)  seg_link; /*<< rbuf_segments Link */
        char  *seg_p;                /**< Backing-store memory */
        size_t seg_of;               /**< Current relative write-position
                                      *   (length of payload in this segment) */
        size_t seg_size;             /**< Allocated size of seg_p */
        size_t seg_absof;            /**< Absolute offset of this segment's
                                      *   beginning in the grand rd_buf_t */
        void (*seg_free) (void *p);  /**< Optional free function for seg_p */
        int    seg_flags;            /**< Segment flags */
#define RD_SEGMENT_F_RDONLY   0x1    /**< Read-only segment */
#define RD_SEGMENT_F_FREE     0x2    /**< Free segment on destroy,
                                      *   e.g, not a fixed segment. */
} rd_segment_t;




TAILQ_HEAD(rd_segment_head,rd_segment_s);

/**
 * @brief Buffer, containing a list of segments.
 */
typedef struct rd_buf_s {
        struct rd_segment_head rbuf_segments; /**< TAILQ list of segments */
        size_t            rbuf_segment_cnt;   /**< Number of segments */

        rd_segment_t     *rbuf_wpos;          /**< Current write position seg */

        size_t            rbuf_len;           /**< Current (written) length */
        size_t            rbuf_size;          /**< Total allocated size of
                                               *   all segments. */

        rd_segment_t     *rbuf_fixed_segs;    /**< Pre-allocated segments */
        size_t            rbuf_fixed_seg_cnt; /**< Pre-allocated segment count*/
        size_t            rbuf_fixed_seg_usecnt; /**< Number of used
                                                  *   pre-allocated segments. */
} rd_buf_t;




/**
 * @name Buffer read operations
 * @{
 */

/**
 * @brief Buffer read position, pointing to a segment and the relative
 *        offset within that segment.
 *
 * @warning A read buffer position will not be valid/safe after the buffer or
 *          segments have been modified by a buf write / update / seek.
 */
typedef struct rd_buf_pos_s {
        const rd_buf_t *buf;   /**< Pointer to buffer */
        rd_segment_t   *seg;   /**< Current read position segment */
        size_t          rof;   /**< Relative read offset in segment */
} rd_buf_pos_t;


typedef struct rd_buf_slice_s {
        const rd_buf_t *buf;   /**< Pointer to buffer */
        rd_segment_t   *seg;   /**< Current read position segment */
        size_t          rof;   /**< Relative read offset in segment */
        size_t          size;  /**< Remaining slice size, will be reduced as
                                *   the reader progresses. */
} rd_buf_slice_t;