Hitachi MK-96RD647-01 manual Writing Data, DatasetPut Function

Writing Data

reclen = datasetPut (datasetHandle, buf, buflen)

The datasetPut function writes one record from the buf into the dataset specified by datasetHandle. Table 6-3shows the datasetPut arguments and return values.

Table 6-3	DatasetPut Function
Item	Value	Type	Description
Argument	datasetHandl	DATASET_HAND	The datasetHandle value returned by the datasetOpen
	e	LE	function.
	buf		Buffer area for storing the write data.
		char *	Size of the buffer area. If any of the following conditions is detected,
	buflen
		long	datasetPut returns an error and does not transfer any data to the dataset:
			For fixed-length record: buflen ≠ RL of the dataset
			For variable-length record: (buflen + 4) > RL of dataset
			For variable-length record: buflen = 0 (no data entity)
Return value	reclen	long	Data entity size written into the dataset.
	-1		Error end

Figure 6-2shows the format requirements for variable-length records accessed by the datasetPut function. When the target dataset is variable-length, the datasetPut function takes the data entity from the buf, automatically adds the two-byte RL field, and writes the record into the dataset. When the data is written into the dataset, multiple records are blocked within the extent defined by the VTOC of the dataset.

Block length Record length Data entity

Record length Data entity

Record length	Record length
Block Length (≤block length defined in VTOC)

Block length format:

2 bytes	2 bytes
Block length	0x0000

	2 bytes	2 bytes
Record length format:	Record length	0x0000

Figure 6-2 Format Requirements for Writing Variable-Length Records

When the datasetPut function terminates successfully, it returns the length of the data entity written to the dataset. If the datasetPut function terminates unsuccessfully, it returns a value of -1. To get the error code information, execute the datasetGetLastError function (see section Acquiring Error Information).

6-6 Performing File Access Library (FAL) Operations

Hitachi USP V Cross-OS File Exchange User’s Guide