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SDFI, SDFO–System Data Format I/O Routines
Word 6
The addresses of the I/O buffers when two buffers are used. If only one buffer is
used, this word must be zero, and the address of the single buffer must be put in
word 4.
Word 7 (H1)
The length in sectors of the I/O buffers used by SDFI.
Word 7 (H2)
The length in words of the image buffer into which SDFI transfers the individual SDF
images.
Word 8 (H2)
The address of the image buffer into which SDFI transfers the individual images.
Word 9 (H2)
The location in the I/O buffer of the next SDF image to be read (filled by SDFI).
Word 10
The SDF control word of the image read (filled by SDFI).
SDFI may use one or two buffers. If SDFI uses one I/O buffer, that buffer address is
stored in H2 of word 4. Word 6 must be set to zero. If SDFI uses two I/O buffers, the
buffer addresses are placed in H1 and H2 of word 6. Words 0 through 5 are the
standard I/O packet used by Executive Requests.
21.1.1.2. Packet Generation PROC
S$DFCT is a MASM procedure that generates the SDFI packet (or FCT). S$DFCT
defines the fields of the packet, initializes the packet, and displays a diagram of the
packet.
The MASM definition element SDFP$ contains the S$DFCT procedure. This element
must be included in the calling program in order to use the S$DFCT procedure. It is
included by using the following MASM directive:
$INCLUDE ‘SDFP$’
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