THE 'NEXT' COMMAND ROUTINE
The 'variable in assignment' has already been determined (see CLASS-04,1C6C); and it remains to change the VALUE as required.

1DAB	NEXT	BIT	1,(FLAGX)	Jump to give the error report
		JP	NZ,1C2E,REPORT-2	if the variable was not found.
		LD	HL,(DEST)	The address of the variable
		BIT	7,(HL)	is fetched and the name
		JR	Z,1DD8,REPORT-1	tested further.

Next the variable's VALUE and STEP are manipulated by the calculator.

		INC	HL	Step past the name.
		LD	(MEM),HL	Make the variable a
				temporary 'memory area'.
		RST	0028,FP-CALC	-
		DEFB	+E0,get-mem-0	v
		DEFB	+E2,get-mem-2	v, s
		DEFB	+0F,addition	v+s
		DEFB	+C0,st-mem-0	v+s
		DEFB	+02,delete	-
		DEFB	+38,end-calc	-

The result of adding the VALUE and the STEP is now tested against the LIMIT by calling NEXT-LOOP.

		CALL	1DDA,NEXT-LOOP	Test the new VALUE against
				the LIMIT
		RET	C	Return now if the FOR-NEXT
				loop has been completed.

Otherwise collect the 'looping' line number and statement.

		LD	HL,(MEM)	Find the address of the
		LD	DE,+000F	low byte of the looping
		ADD	HL,DE	line number.
		LD	E,(HL)	Now fetch this line number.
		INC	HL
		LD	D,(HL)
		INC	HL
		LD	H,(HL)	Followed by the statement
				number.
		EX	DE,HL	Exchange the numbers before
		JP	1E73,GO-TO-2	jumping forward to treat them
				as the destination line of a
				GO TO command.

Report 1 - NEXT without FOR

1DD8	REPORT-1	RST	0008,ERROR-1	Call the error handling
		DEFB	+00	routine.

THE 'NEXT-LOOP SUBROUTINE
This subroutine is used to determine whether the LIMIT has been exceeded by the present VALUE. Note has to be taken of the sign of the STEP.
	The subroutine returns the carry flag set if the LIMIT is exceeded.

1DDA	NEXT-LOOP	RST	0028,FP-CALC	-
		DEFB	+E1,get-mem-1	l
		DEFB	+E0,get-mem-0	l, v
		DEFB	+E2,get-mem-2	l, v, s
		DEFB	+36,less-0	l, v,(1/0)
		DEFB	+00,jump-true	l, v,(1/0)
		DEFB	+02,to NEXT-1	l, v,(1/0)
		DEFB	+01,exchange	v, l
1DE2	NEXT-1	DEFB	+03,subtract	v-l or l-v
		DEFB	+37,greater-0	(1/0)
		DEFB	+00,jump-true	(1/0)