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SDFI, SDFO–System Data Format I/O Routines
Word 7 (H1)
The length in sectors of the I/O buffer used by SDFO.
Word 7 (H2)
The length in words of the SDF image transferred from the image buffer (filled by
SDFO).
Word 8 (H2)
The address of the image buffer containing the SDF image that SDFO writes out.
Word 9 (H2)
The location in the buffer that SDFO places the next image to be written out (filled
by SDFO).
Word 10
The SDF control word of the image that SDFO writes out.
SDFO may use one or two buffers. If SDFO uses one output buffer, that buffer address
is stored in H2 of word 4. Word 6 must be set to zero.
If SDFO uses two buffers, the buffer addresses are placed in H1 and H2 of word 6. H2
of word 4 must be set to zero.
SDF Image Control Word Formats
The calling program must place an ICW in word 10 for each SDF data record or control
record written out.
SDFO does not automatically generate 051 continuation control records. These are
generally found only in symbiont generated print files.
The general format of the ICW for an SDF data record is as follows:
image length (words) variable information
0 1 11 12 35
The general format of the ICW for an SDF control record is as follows:
control code image length variable information
0 5 6 11 12 35
The ICW for SDF control records always has bit 0 set.
SDF is described in the Data Structures Programming Reference Manual.
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