Memory Access Primitives

The following interfaces provide a mechanism for transferring between 8 bits and 64 bits of data. The get interfaces use a repeat count (rep_cnt) to indicate the number of data items of a given size the process will read from successive locations. The locations begin at byte offset offset in the imported segment. The data is written to successive locations that begin at datap. The put interfaces use a repeat count (rep_cnt). The count indicates the number of data items the process will read from successive locations. The locations begin at datap. The data is then written to the imported segment at successive locations. The locations begin at the byte offset specified by the offset argument.

These interfaces also provide byte swapping in case the source and destination have incompatible endian characteristics.

Function Prototypes:

int rsm_memseg_import_get8(rsm_memseg_import_handle_t im_memseg, off_t offset, uint8_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_get16(rsm_memseg_import_handle_t im_memseg, off_t offset, uint16_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_get32(rsm_memseg_import_handle_t im_memseg, off_t offset, uint32_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_get64(rsm_memseg_import_handle_t im_memseg, off_t offset, uint64_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_put8(rsm_memseg_import_handle_t im_memseg, off_t offset, uint8_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_put16(rsm_memseg_import_handle_t im_memseg, off_t offset, uint16_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_put32(rsm_memseg_import_handle_t im_memseg, off_t offset, uint32_t *datap, ulong_t rep_cnt);
int rsm_memseg_import_put64(rsm_memseg_import_handle_t im_memseg, off_t offset, uint64_t *datap, ulong_t rep_cnt);

The following interfaces are intended for data transfers that are larger than the ones supported by the segment access operations.

Segment Put

int rsm_memseg_import_put(rsm_memseg_import_handle_t im_memseg, off_t offset, void *src_addr, size_t length);

This function copies data from local memory, specified by the src_addr and length, to the corresponding imported segment locations specified by the handle and offset.

Segment Get

int rsm_memseg_import_get(rsm_memseg_import_handle_t im_memseg, off_t offset, void *dst_addr, size_t length);

This function is similar to rsm_memseg_import_put(), but data flows from the imported segment into local regions defined by the dest_vec argument

The put and get routines write or read the specified quantity of data from the byte offset location specified by the argument offset. The routines begin at the base of the segment. The offset must align at the appropriate boundary. For example, rsm_memseg_import_get64() requires that offset and datap align at a double-word boundary, while rsm_memseg_import_put32() requires an offset that is aligned at a word boundary.

By default, the barrier mode attribute of a segment is implicit. Implicit barrier mode means that the caller assumes the data transfer has completed or has failed upon return from the operation. Because the default barrier mode is implicit, the application must initialize the barrier. The application initializes the barrier by using the rsm_memseg_import_init_barrier() function before calling put or get routines when using the default mode. To use the explicit operation mode, the caller must use a barrier operation to force the completion of a transfer. After forcing the completion of the transfer, the caller must determine if any errors have occurred as a result of the forced completion.

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Note –

An import segment can be partially mapped by passing an offset in the rsm_memseg_import_map() routine. If the import segment is partially mapped, the offset argument in the put or get routines is from the base of the segment. The user must make sure that the correct byte offset is passed to put and get routines.

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Return Values: Returns 0 if successful. Returns an error value otherwise.

RSMERR_BAD_SEG_HNDL

Invalid segment handle

RSMERR_BAD_ADDR

Bad address

RSMERR_BAD_MEM_ALIGNMENT

Invalid memory alignment

RSMERR_BAD_OFFSET

Invalid offset

RSMERR_BAD_LENGTH

Invalid length

RSMERR_PERM_DENIED

Permission denied

RSMERR_BARRIER_UNINITIALIZED

Barrier not initialized

RSMERR_BARRIER_FAILURE

I/O completion error

RSMERR_CONN_ABORTED

Connection aborted

RSMERR_INSUFFICIENT_RESOURCES

Insufficient resources