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SAR$ READ
CONTROL_RECORD_WORD_LENGTH
PLUS Attribute: 6-bit integer
The length in words of the control record read.
CONTROL_RECORD_CHAR_TYPE
PLUS Attribute: 6-bit status
The character set type of the control record, if applicable to this control record
type (see the CHARACTER_TYPE field).
If a data record was read, SDF_IMAGE_CONTROL_WORD has two subfields that
are overlaid on SDF_IMAGE_CONTROL_WORD.
DATA_RECORD_WORD_LENGTH
PLUS Attribute: 12-bit integer
The length in words of the data record read.
DATA_RECORD_CHAR_TYPE
PLUS Attribute: 6-bit status
The character set type of the data record, if applicable to this input file type (see the
CHARACTER_TYPE field).
See the Data Structures Programming Reference Manual on SDF image control words.
17.1.2. Buffers and Tables for PLUS READ Procedures
The SAR$ READ function requires that an input (I/O) buffer, an image buffer, a text
buffer, an attribute table, and a select list be supplied by the calling program.
• Input buffer
The input buffer is used to read from mass storage files. The calling program never
needs to access the input buffer, but it must provide it to SAR$. If the calling
program is using both the READ and WRITE functions of SAR$, then it cannot use
the same I/O buffer for both functions. The calling program must provide a separate
input and output buffer for each function.
• Image buffer
The image buffer is used to extract individual images from the input buffer. This
buffer is necessary because images can contain information other than characters,
such as attributes and ACD formats. The calling program never needs to access the
image buffer, but it must provide it to SAR$. The calling program using the READ
and WRITE functions can use the same image buffer for both functions.
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