Prev: 1736 Up: Map Next: 177A
175D: THE 'OPEN-2' SUBROUTINE
Used by the routine at OPEN.
The appropriate stream data bytes for the channel that is associated with the stream being opened are found.
OPEN_2 175D PUSH HL Save HL.
175E CALL STK_FETCH Fetch the parameters of the channel code.
1761 LD A,B Give an error if the expression supplied is a null expression, e.g. OPEN #5,"".
1762 OR C
1763 JR NZ,OPEN_3
This entry point is used by the routine at OPEN_P.
Report F - Invalid file name.
REPORT_F 1765 RST $08 Call the error handling routine.
1766 DEFB $0E
Continue if no error occurred.
OPEN_3 1767 PUSH BC The length of the expression is saved.
1768 LD A,(DE) Fetch the first character.
1769 AND $DF Convert lower case codes to upper case ones.
176B LD C,A Move code to the C register.
176C LD HL,$177A The base address of the OPEN stream look-up table.
176F CALL INDEXER Index into this table and locate the required offset.
1772 JR NC,REPORT_F Jump back if not found.
1774 LD C,(HL) Pass the offset to the BC register pair.
1775 LD B,$00
1777 ADD HL,BC Make HL point to the start of the appropriate subroutine.
1778 POP BC Fetch the length of the expression before jumping to the subroutine.
1779 JP (HL)
Prev: 1736 Up: Map Next: 177A