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171E: THE 'STREAM DATA' SUBROUTINE
Used by the routines at CLOSE and OPEN.
This subroutine returns in the BC register pair the stream data for a given stream.
Input
Output
BC Offset from the stream data table (STRMS)
HL Address of the offset in the stream data table
STR_DATA 171E CALL FIND_INT1 The given stream number is taken off the calculator stack.
1721 CP $10 Give an error if the stream number is greater than +0F.
1723 JR C,STR_DATA1
This entry point is used by the routines at OPEN and CAT_ETC.
Report O - Invalid stream.
REPORT_O_2 1725 RST $08 Call the error handling routine.
1726 DEFB $17
Continue with valid stream numbers.
STR_DATA1 1727 ADD A,$03 Range now +03 to +12.
1729 RLCA And now +06 to +24.
172A LD HL,$5C10 The base address of the stream data area.
172D LD C,A Move the stream code to the BC register pair.
172E LD B,$00
1730 ADD HL,BC Index into the data area and fetch the the two data bytes into the BC register pair.
1731 LD C,(HL)
1732 INC HL
1733 LD B,(HL)
1734 DEC HL Make the pointer address the first of the data bytes before returning.
1735 RET
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