Record format and interface for syntax checking

Either fixed-length (numbered) or variable-length (numbered) records can be passed to syntax checkers. Figure 1 shows the format of the records that are passed.

Figure 1. Format of Records Passed to Syntax Checkers

TSO/E provides a standard interface that allows the EDIT modules to invoke any syntax checker. Figure 2 shows the EDIT modules that invoke syntax checkers, the standard interface, and the syntax checkers that TSO/E provides. The interface consists of a syntax checker parameter list that you use for writing your syntax checker.

Figure 2. Interface Between the EDIT Program and Syntax Checkers

Interface Between the EDIT Program and Syntax Checkers

The parameter list for the syntax checker points to the:

Buffer control block
Syntax checker communication area
Option word

Table 1, Table 2, and Table 3 show the contents of the buffer control block, syntax checker communication area, and option word.

Table 1. Contents of the buffer control block
Disp dec.	Disp hex.	Field name	Field size	Contents or meaning
0	0	C	1	Number of records in buffer (maximum – 127). Bit zero is set to 1 when the syntax checker has scanned all records in the buffer.
1	1	Chain	3	Address of next buffer; set to zero if this is the last buffer in chain.
4	4	Record	Variable	Line or lines of source input data to be syntax checked. Can be fixed- or variable-length, numbered or unnumbered.

Table 2. Contents of the syntax checker communication area
Disp desc.	Disp hex.	Field name	Field size	Setting	Meaning (instruction to syntax checker)
				Bits 0-3	(where n=0 or 1).
				0nnn	First entry — obtain and initialize work area. If a buffer chain is supplied, the syntax checker will set the relative line number counter to zero.
				1n 1n	Last entry — release the work area and return. Syntax checking is not performed.
				1000	Normal entry — set relative line number to counter zero. Perform syntax checking.
0	0	None	1	110n	Entry after return code 8 (error - buffer checking incomplete) — continue syntax checking.
				1001	Entry after return code 12 (complete statements have been checked, but last statement in input buffer is incomplete). If there is no more input (chain address of last buffer or buffer address is zero), syntax check the incomplete statement and return. If there is a new buffer chain, that is, more input, (chain address or buffer address is not zero), resume syntax checking at the incomplete statement.
				Bits 4-7	Reserved
1	1	None	4	xxxx	Address of work area stored by syntax checker on first entry.
4	4	None	4	xxxx	Initial entry — maximum statement size specified when the EDIT defaults for the data set type were set (if 0, checker assumes sufficient storage for largest legal statement is available). Entry after return code 4 (error detected, syntax checking complete, second-level message present), or 8 (error detected, syntax checking incomplete) — address of error message area.
8	8	None	4	xxxx	Initial entry — temporary area. Subsequent entries — address of second error message, if any.
12	C	None	4	xxxx	Temporary storage area used for GETMAIN.

Table 3. Contents of the option word
Disp desc.	Disp hex.	Field name	Field size	Setting	Meaning	Syntax checker
0	0	None	1	X'00'	FORTRAN H level	FORTRAN
				X'03'	GOFORT	FORTRAN
				X'04'	FORTRANG1	FORTRAN

				X'00'	IPLI level	IPLI
				X'01'	BASIC level	BASIC

				xxxx	Value of left source margin	PLIF
1	1	None	1	Bits 0-5	Reserved	FORTRAN

				Bit 6 = 1	FORTRAN G1/H Code and Go definition to be loaded on initial entry.	FORTRAN

				= 0	FORTRAN G1/H Code and Go definition not to be loaded on initial entry.	FORTRAN

				Bit 0 = 1	Entry from INPUT, Insert, linenum, *, CHANGE	IPLI or BASIC
				Bit 1 = 1	Entry from DELETE	IPLI or BASIC
				Bit 2 = 1	Entry from MERGE or RENUM	IPLI or BASIC
				Bit 3 = 1	Translation already complete	IPLI or BASIC
				Bit 4 = 1	Entry from RUN	IPLI or BASIC
				Bits 5-7	Reserved	IPLI or BASIC
				xxxx	Value of right source margin	PLIF
2	2	None	1	xxxx	Record length of fixed-length records; binary zero, if variable-length records.	All
3	3	None	1	Bit 0 = 0	CHAR 60	PLI or IPLI
				= 1	CHAR 48	PLI or IPLI
				Bit 1 = 0	Line-numbered data set.	All
				= 1	Data set not line-numbered.	All
				Bit 2	Reserved	All
				Bit 3 = 0	Diagnose an incomplete statement.	All
				= 1	Delayed scan – return with code of 12, if last statement in input buffer is incomplete. Immediate scan – possible incomplete statement in buffer.	All
				Bit 4 = 0	Fixed-length records.	All
				= 1	Variable-length records.	All
				Bit 5 = 0	Standard form source input.	All
				= 1	Free form source input.	All
				Bit 6 = 0
				= 1
				Bit 7 = 0	SCAN or SCAN ON specified.	All
				= 1	NOSCAN or SCAN OFF specified.	All

The syntax checkers that TSO/E provides determine the attributes of the associated data set type by referring to information that EDIT initialization sets in the option word. For your own data set types and syntax checkers, EDIT initialization does not place attribute information in the option word. You can write an exit routine for your syntax checker that fills in the option word according to information that the user provides when editing a data set. Writing an exit for syntax checkers describes how to write an exit routine.