Appendix B

BNF Grammar

This appendix provides a complete description of symbols, operators, and directives for MASM 6.1. It uses the Backus-Naur Form (BNF) for grammar notation. You can use BNF grammar to determine the exact syntax for any language component and find all available options for any MASM command.

BNF definitions consist of “nonterminals” and “terminals.” Nonterminals are placeholders within a BNF definition, defined elsewhere in the BNF grammar. Terminals are endpoints in a BNF definition, consisting of MASM 6.1 keywords. In this Appendix, all nonterminals appear in italics type and all terminals appear in bold type.

BNF Conventions

The conventions use different font attributes for different items in the BNF. The symbols and formats are as follows:

Attribute	Description
nonterminal	Italic type indicates nonterminals.
RESERVED	Terminals in boldface type are literal reserved words and symbols that must be entered as shown. Characters in this context are always case insensitive.
[[ ]]	Objects enclosed in double brackets ([[ ]]) are optional. The brackets do not actually appear in the source code.
|	A vertical bar indicates a choice between the items on each side of the bar.
.8086	Underlined items indicate the default option if one is given.
default typeface	Characters in the set described or listed can be used as terminals in MASM statements.

How to Use the BNF Grammar

To illustrate the use of the BNF, Figure B.1 diagrams the definition of the TYPEDEF directive, starting with the nonterminal typedefDir.

The entries under each horizontal brace in Figure B.1 are terminals (such as NEAR16, NEAR32, FAR16, and FAR32) or nonterminals (such as qualifier, qualifiedType, distance, and protoSpec) that can be further defined. Each italicized nonterminal in the typedefDir definition is also an entry in the BNF. Three vertical dots indicate a branching definition for a nonterminal that, for the sake of simplicity, this figure does not illustrate.

The BNF grammar allows recursive definitions. For example, the grammar uses qualifiedType as a possible definition for qualifiedType, which is also a component of the definition for qualifier.

Figure B.1 BNF Definition of the TYPEDEF Directive

Nonterminal	Definition
;;	endOfLine | comment
=Dir	id = immExpr ;;
addOp	+ | -
aExpr	term | aExpr && term

Nonterminal	Definition
altId	id
arbitraryText	charList
asmInstruction	mnemonic [[ exprList ]]
assumeDir	ASSUME assumeList ;; | ASSUME NOTHING ;;
assumeList	assumeRegister | assumeList , assumeRegister
assumeReg	register : assumeVal
assumeRegister	assumeSegReg | assumeReg
assumeSegReg	segmentRegister : assumeSegVal
assumeSegVal	frameExpr | NOTHING | ERROR
assumeVal	qualifiedType | NOTHING | ERROR
bcdConst	[[ sign ]] decNumber
binaryOp	== | != | >= | <= | > | < | &
bitDef	bitFieldId : bitFieldSize [[ = constExpr ]]
bitDefList	bitDef | bitDefList , [[ ;; ]] bitDef
bitFieldId	id
bitFieldSize	constExpr
blockStatements	directiveList | .CONTINUE [[ .IF cExpr ]] | .BREAK [[ .IF cExpr ]]
bool	TRUE | FALSE
byteRegister	AL | AH | BL | BH | CL | CH | DL | DH
cExpr	aExpr | cExpr || aExpr
character	Any character with ordinal in the range 0–255 except linefeed (10)
charList	character | charList character
className	string
commDecl	[[ nearfar ]] [[ langType ]] id : commType [[ : constExpr ]]
commDir	COMM commList ;;
comment	; text ;;

Nonterminal	Definition
commentDir	COMMENT delimiter text text delimiter text ;;
commList	commDecl | commList , commDecl
commType	type | constExpr
constant	digits [[ radixOverride ]]
constExpr	expr
contextDir	PUSHCONTEXT contextItemList ;; | POPCONTEXT contextItemList ;;
contextItem	ASSUMES | RADIX | LISTING | CPU | ALL
contextItemList	contextItem | contextItemList , contextItem
controlBlock	whileBlock | repeatBlock
controlDir	controlIf | controlBlock
controlElseif	.ELSEIF cExpr ;; directiveList [[ controlElseif ]]
controlIf	.IF cExpr ;; directiveList [[ controlElseif ]] [[ .ELSE ;; directiveList ]] .ENDIF ;;
coprocessor	.8087 | .287 | .387 | .NO87
crefDir	crefOption ;;
crefOption	.CREF | .XCREF [[ idList ]] | .NOCREF [[ idList ]]
cxzExpr	expr | ! expr | expr == expr | expr != expr
dataDecl	DB | DW | DD | DF | DQ | DT | dataType | typeId
dataDir	[[ id ]] dataItem ;;

Nonterminal	Definition
dataItem	dataDecl scalarInstList | structTag structInstList | typeId structInstList | unionTag structInstList | recordTag recordInstList
dataType	BYTE | SBYTE | WORD | SWORD | DWORD | SDWORD | FWORD | QWORD | TBYTE | REAL4 | REAL8 | REAL10
decdigit	0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
decNumber	decdigit | decNumber decdigit
delimiter	Any character except whiteSpaceCharacter
digits	decdigit | digits decdigit | digits hexdigit
directive	generalDir | segmentDef
directiveList	directive | directiveList directive
distance	nearfar | NEAR16 | NEAR32 | FAR16 | FAR32
e01	e01 orOp e02 | e02
e02	e02 AND e03 | e03
e03	NOT e04 | e04
e04	e04 relOp e05 | e05
e05	e05 addOp e06 | e06
e06	e06 mulOp e07 | e06 shiftOp e07 | e07
e07	e07 addOp e08 | e08
e08	HIGH e09 | LOW e09 | HIGHWORD e09 | LOWWORD e09 | e09

Nonterminal	Definition
e09	OFFSET e10 | SEG e10 | LROFFSET e10 | TYPE e10 | THIS e10 | e09 PTR e10 | e09 : e10 | e10
e10	e10 . e11 | e10 [[ expr ]] | e11
e11	( expr ) | [[ expr ]] | WIDTH id | MASK id | SIZE sizeArg | SIZEOF sizeArg | LENGTH id | LENGTHOF id | recordConst | string | constant | type | id | $ | segmentRegister | register |