| Routines

07595: THE 'NEXT' COMMAND ROUTINE

The address of this routine is found in the parameter table. The 'variable in assignment' has already been determined (see CLASS_04), and it remains to change the VALUE as required.
NEXT | 07595 | BIT 1,(IY+55) | Jump to give the error report if the variable was not found (bit 1 of FLAGX set).
| 07599 | JP NZ,REPORT_2
| 07602 | LD HL,(23629) | The address of the variable is fetched from DEST and the name tested further.
| 07605 | BIT 7,(HL)
| 07607 | JR Z,REPORT_1
Next the variable's VALUE (v) and STEP (s) are manipulated by the calculator.
| 07609 | INC HL | Step past the name.
| 07610 | LD (23656),HL | Make the variable a temporary 'memory area' by setting MEM.
| 07613 | RST 40 | -
| 07614 | DEFB 224 | get_mem_0: v
| 07615 | DEFB 226 | get_mem_2: v, s
| 07616 | DEFB 15 | addition: v+s
| 07617 | DEFB 192 | st_mem_0: v+s (v is replaced by v+s in mem-0)
| 07618 | DEFB 2 | delete: -
| 07619 | DEFB 56 | end_calc: -
The result of adding the VALUE and the STEP is now tested against the LIMIT by calling NEXT_LOOP.
| 07620 | CALL NEXT_LOOP | Test the new VALUE against the LIMIT.
| 07623 | RET C | Return now if the FOR-NEXT loop has been completed.
Otherwise collect the 'looping' line number and statement.
| 07624 | LD HL,(23656) | Find the address of the low byte of the looping line number (MEM+15).
| 07627 | LD DE,15
| 07630 | ADD HL,DE
| 07631 | LD E,(HL) | Now fetch this line number.
| 07632 | INC HL
| 07633 | LD D,(HL)
| 07634 | INC HL
| 07635 | LD H,(HL) | Followed by the statement number.
| 07636 | EX DE,HL | Exchange the numbers before jumping forward to treat them as the destination line of a GO TO command.
| 07637 | JP GO_TO_2
Report 1 - NEXT without FOR.
REPORT_1 | 07640 | RST 8 | Call the error handling routine.
| 07641 | DEFB 0