Routines
Prev: 02230 Up: Map Next: 02416
02348: THE 'MERGE A LINE OR A VARIABLE' SUBROUTINE
Used by the routine at ME_CONTRL.
Input
DE Destination address of the new line/variable
HL Address of the new line/variable to MERGE
F Carry flag: MERGE a BASIC line (reset) or a variable (set)
F Zero flag: add (reset) or replace (set) the line/variable
Output
DE Address of the next line/variable in the existing program
HL Address of the next new line/variable to MERGE
ME_ENTER 02348 JR NZ,ME_ENT_1 Jump if handling an 'addition'.
02350 EX AF,AF' Save the flags.
02351 LD (23647),HL Save the 'new' pointer (in X-PTR) whilst the 'old' line or variable is reclaimed.
02354 EX DE,HL
02355 CALL NEXT_ONE
02358 CALL RECLAIM_2
02361 EX DE,HL
02362 LD HL,(23647)
02365 EX AF,AF' Restore the flags.
The new entry can now be made.
ME_ENT_1 02366 EX AF,AF' Save the flags.
02367 PUSH DE Make a copy of the 'destination' pointer.
02368 CALL NEXT_ONE Find the length of the 'new' variable/line.
02371 LD (23647),HL Save the pointer to the 'new' variable/line (in X-PTR).
02374 LD HL,(23635) Fetch PROG - to avoid corruption.
02377 EX (SP),HL Save PROG on the stack and fetch the 'new' pointer.
02378 PUSH BC Save the length.
02379 EX AF,AF' Retrieve the flags.
02380 JR C,ME_ENT_2 Jump forward if adding a new variable.
02382 DEC HL A new line is added before the 'destination' location.
02383 CALL MAKE_ROOM Make the room for the new line.
02386 INC HL
02387 JR ME_ENT_3 Jump forward.
ME_ENT_2 02389 CALL MAKE_ROOM Make the room for the new variable.
ME_ENT_3 02392 INC HL Point to the first new location.
02393 POP BC Retrieve the length.
02394 POP DE Retrieve PROG and store it in its correct place.
02395 LD (23635),DE
02399 LD DE,(23647) Also fetch the 'new' pointer (from X-PTR).
02403 PUSH BC Again save the length and the 'new' pointer.
02404 PUSH DE
02405 EX DE,HL Switch the pointers and copy the 'new' variable/line into the room made for it.
02406 LDIR
The 'new' variable/line has now to be removed from the work space.
02408 POP HL Fetch the 'new' pointer.
02409 POP BC Fetch the length.
02410 PUSH DE Save the 'old' pointer. (Points to the location after the 'added' variable/line.)
02411 CALL RECLAIM_2 Remove the variable/line from the work space.
02414 POP DE Return with the 'old' pointer in the DE register pair.
02415 RET
Prev: 02230 Up: Map Next: 02416