demi_sgaalloc.md

demi_sgaalloc()

Name

demi_sgaalloc - Allocates a scatter-gather array.

Synopsis

#include <demi/sga.h>
#include <demi/types.h> /* For demi_sgarray_t. */

demi_sgarray_t demi_sgaalloc(size_t size);

Description

demi_sgaalloc() allocates a scatter gather-array of size bytes and returns it.

Depending on the underlying libOS, memory is allocated from a zero-copy memory pool.

The demi_sgarray_t structure is defined as follows:

typedef struct demi_sgarray
{
    // Reserved.
    void *sga_buf;
    // Number of segments in the scatter-gather array.
    uint32_t sga_numsegs;
    // Scatter-gather array segments.
    demi_sgaseg_t segments[DEMI_SGARRAY_MAXSIZE];
    // Source address of scatter-gather array.
    struct sockaddr_in sga_addr;
} demi_sgarray_t;

The demi_sgaseg_t is defined as follows:

typedef struct demi_sgaseg
{
    // Underlying data.
    void *data_buf_ptr;
    // Size in bytes of data.
    uint32_t data_len_bytes;
} demi_sgaseg_t;

Return Value

On success, the allocated scatter-gather array is returned. On error, a null scatter-gather array is returned.

A null scatter-gather array is one that has zero segments, that is the sga_numsegs member field set to zero.

Disclaimer

Any behavior that is not documented in this manual page is unintentional and should be reported.

See Also

demi_sgafree().