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Directives |
Topical Cross-reference for Directives................................. 22
Directives........................................................ 25
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ALIGN |
EVEN |
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LABEL |
ORG |
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ELSE |
ELSEIF |
ELSEIF2 |
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ENDIF |
IF |
IF2 |
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IFB/IFNB |
IFDEF/IFNDEF |
IFDIF/IFDIFI |
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IFE |
IFIDN/IFIDNI |
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.BREAK |
.CONTINUE |
.ELSE |
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.ELSEIF |
.ENDIF |
.ENDW |
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.IF |
.REPEAT |
.UNTIL/ |
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.UNTILCXZ |
.WHILE |
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.ERR |
.ERR2 |
.ERRB |
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.ERRDEF |
.ERRDIF/.ERRDIFI |
.ERRE |
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.ERRIDN/.ERRIDNI |
.ERRNB |
.ERRNDEF |
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.ERRNZ |
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ALIGN |
BYTE/SBYTE |
DWORD/SDWORD |
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EVEN |
FWORD |
LABEL |
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ORG |
QWORD |
REAL4 |
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REAL8 |
REAL10 |
TBYTE |
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WORD/SWORD |
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= |
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EQU |
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TEXTEQU |
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.CREF |
.LIST |
.LISTALL |
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.LISTIF |
.LISTMACRO |
.LISTMACROALL |
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.NOCREF |
.NOLIST |
.NOLISTIF |
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.NOLISTMACRO |
PAGE |
SUBTITLE |
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.TFCOND |
TITLE |
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ENDM |
EXITM |
GOTO |
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LOCAL |
MACRO |
PURGE |
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ASSUME |
COMMENT |
ECHO |
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END |
INCLUDE |
INCLUDELIB |
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OPTION |
POPCONTEXT |
PUSHCONTEXT |
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.RADIX |
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ENDP |
INVOKE |
PROC |
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PROTO |
USES |
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.186 |
.286 |
.286P |
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.287 |
.386 |
.386P |
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.387 |
.486 |
.486P |
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.8086 |
.8087 |
.NO87 |
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ENDM |
FOR |
FORC |
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GOTO |
REPEAT |
WHILE |
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COMM |
EXTERN |
EXTERNDEF |
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INCLUDELIB |
PUBLIC |
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.ALPHA |
ASSUME |
.DOSSEG |
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END |
ENDS |
GROUP |
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SEGMENT |
.SEQ |
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.CODE |
.CONST |
.DATA |
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.DATA? |
.DOSSEG |
.EXIT |
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.FARDATA |
.FARDATA? |
.MODEL |
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.STACK |
.STARTUP |
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CATSTR |
INSTR |
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SIZESTR |
SUBSTR |
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ENDS |
RECORD |
STRUCT |
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TYPEDEF |
UNION |
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name = expression
Assigns the numeric value of expression to name. The symbol may be redefined later.
.186
Enables assembly of instructions for the 80186 processor; disables assembly of instructions introduced with later processors. Also enables 8087 instructions.
.286
Enables assembly of nonprivileged instructions for the 80286 processor; disables assembly of instructions introduced with later processors. Also enables 80287 instructions.
.286P
Enables assembly of all instructions (including privileged) for the 80286 processor; disables assembly of instructions introduced with later processors. Also enables 80287 instructions.
.287
Enables assembly of instructions for the 80287 coprocessor; disables assembly of instructions introduced with later coprocessors.
.386
Enables assembly of nonprivileged instructions for the 80386 processor; disables assembly of instructions introduced with later processors. Also enables 80387 instructions.
.386P
Enables assembly of all instructions (including privileged) for the 80386 processor; disables assembly of instructions introduced with later processors. Also enables 80387 instructions.
.387
Enables assembly of instructions for the 80387 coprocessor.
.486
Enables assembly of nonprivileged instructions for the 80486 processor.
.486P
Enables assembly of all instructions (including privileged) for the 80486 processor.
.8086
Enables assembly of 8086 instructions (and the identical 8088 instructions); disables assembly of instructions introduced with later processors. Also enables 8087 instructions. This is the default mode for processors.
.8087
Enables assembly of 8087 instructions; disables assembly of instructions introduced with later coprocessors. This is the default mode for coprocessors.
ALIGN [[number]]
Aligns the next variable or instruction on a byte that is a multiple of number.
.ALPHA
Orders segments alphabetically.
ASSUME segregister:name [[, segregister:name]]...
ASSUME dataregister:type [[, dataregister:type]]...
ASSUME register:ERROR [[, register:ERROR]]...
ASSUME [[register:]] NOTHING [[, register:NOTHING]]...
Enables error-checking for register values. After an ASSUME is put into effect, the assembler watches for changes to the values of the given registers. ERROR generates an error if the register is used. NOTHING removes register error-checking. You can combine different kinds of assumptions in one statement.
.BREAK [[.IF condition]]
Generates code to terminate a .WHILE or .REPEAT block if condition is true.
[[name]] BYTE initializer [[, initializer]] ...
Allocates and optionally initializes a byte of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
name CATSTR [[textitem1 [[, textitem2]] ...]]
Concatenates text items. Each text item can be a literal string, a constant preceded by a %, or the string returned by a macro function.
.CODE [[name]]
When used with .MODEL, indicates the start of a code segment called name (the default segment name is _TEXT for tiny, small, compact, and flat models, or module_TEXT for other models).
COMM definition [[, definition]] ...
Creates a communal variable with the attributes specified in definition. Each definition has the following form:
[[langtype]] [[NEAR | FAR]] label:type[[:count]]
The label is the name of the variable. The type can be any type specifier (BYTE, WORD, and so on) or an integer specifying the number of bytes. The count specifies the number of data objects (one is the default).
COMMENT delimiter [[text]]
[[text]]
[[text]] delimiter [[text]]
Treats all text between or on the same line as the delimiters as a comment.
.CONST
When used with .MODEL, starts a constant data segment (with segment name CONST). This segment has the read-only attribute.
.CONTINUE [[.IF condition]]
Generates code to jump to the top of a .WHILE or .REPEAT block if condition is true.
.CREF
Enables listing of symbols in the symbol portion of the symbol table and browser file.
.DATA
When used with .MODEL, starts a near data segment for initialized data (segment name _DATA).
.DATA?
When used with .MODEL, starts a near data segment for uninitialized data (segment name _BSS).
.DOSSEG
Orders the segments according to the MS-DOS segment convention: CODE first, then segments not in DGROUP, and then segments in DGROUP. The segments in DGROUP follow this order: segments not in BSS or STACK, then BSS segments, and finally STACK segments. Primarily used for ensuring CodeView support in MASM stand-alone programs. Same as DOSSEG.
DOSSEG
Identical to .DOSSEG, which is the preferred form.
DB
Can be used to define data like BYTE.
DD
Can be used to define data like DWORD.
DF
Can be used to define data like FWORD.
DQ
Can be used to define data like QWORD.
DT
Can be used to define data like TBYTE.
DW
Can be used to define data like WORD.
[[name]] DWORD initializer [[, initializer]]...
Allocates and optionally initializes a doubleword (4 bytes) of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
ECHO message
Displays message to the standard output device (by default, the screen). Same as %OUT.
.ELSE
See .IF.
ELSE
Marks the beginning of an alternate block within a conditional block. See IF.
ELSEIF
Combines ELSE and IF into one statement. See IF.
ELSEIF2
ELSEIF block evaluated on every assembly pass if OPTION:SETIF2 is TRUE.
END [[address]]
Marks the end of a module and, optionally, sets the program entry point to address.
.ENDIF
See .IF.
ENDIF
See IF.
ENDM
Terminates a macro or repeat block. See MACRO, FOR, FORC, REPEAT, or WHILE.
name ENDP
Marks the end of procedure name previously begun with PROC. See PROC.
name ENDS
Marks the end of segment, structure, or union name previously begun with SEGMENT, STRUCT, UNION, or a simplified segment directive.
.ENDW
See .WHILE.
name EQU expression
Assigns numeric value of expression to name. The name cannot be redefined later.
name EQU <text>
Assigns specified text to name. The name can be assigned a different text later. See TEXTEQU.
.ERR [[message]]
Generates an error.
.ERR2 [[message]]
.ERR block evaluated on every assembly pass if OPTION:SETIF2 is TRUE.
.ERRB <textitem> [[, message]]
Generates an error if textitem is blank.
.ERRDEF name [[, message]]
Generates an error if name is a previously defined label, variable, or symbol.
.ERRDIF[[I]] <textitem1>, <textitem2> [[, message]]
Generates an error if the text items are different. If I is given, the comparison is case insensitive.
.ERRE expression [[, message]]
Generates an error if expression is false (0).
.ERRIDN[[I]] <textitem1>, <textitem2> [[, message]]
Generates an error if the text items are identical. If I is given, the comparison is case insensitive.
.ERRNB <textitem> [[, message]]
Generates an error if textitem is not blank.
.ERRNDEF name [[, message]]
Generates an error if name has not been defined.
.ERRNZ expression [[, message]]
Generates an error if expression is true (nonzero).
EVEN
Aligns the next variable or instruction on an even byte.
.EXIT [[expression]]
Generates termination code. Returns optional expression to shell.
EXITM [[textitem]]
Terminates expansion of the current repeat or macro block and begins assembly of the next statement outside the block. In a macro function, textitem is the value returned.
EXTERN [[langtype]] name [[(altid)]] :type [[, [[langtype]] name [[(altid)]] :type]]...
Defines one or more external variables, labels, or symbols called name whose type is type. The type can be ABS, which imports name as a constant. Same as EXTRN.
EXTERNDEF [[langtype]] name:type [[, [[langtype]] name:type]]...
Defines one or more external variables, labels, or symbols called name whose type is type. If name is defined in the module, it is treated as PUBLIC. If name is referenced in the module, it is treated as EXTERN. If name is not referenced, it is ignored. The type can be ABS, which imports name as a constant. Normally used in include files.
EXTRN
See EXTERN.
.FARDATA [[name]]
When used with .MODEL, starts a far data segment for initialized data (segment name FAR_DATA or name).
.FARDATA? [[name]]
When used with .MODEL, starts a far data segment for uninitialized data (segment name FAR_BSS or name).
FOR parameter [[:REQ | :=default]] , <argument [[, argument]]...>
statements
ENDM
Marks a block that will be repeated once for each argument, with the current argument replacing parameter on each repetition. Same as IRP.
FORC
parameter, <string> statements
ENDM
Marks a block that will be repeated once for each character in string, with the current character replacing parameter on each repetition. Same as IRPC.
[[name]] FWORD initializer [[, initializer]]...
Allocates and optionally initializes 6 bytes of storage for each initializer. Also can be used as a type specifier anywhere a type is legal.
GOTO macrolabel
Transfers assembly to the line marked :macrolabel. GOTO is permitted only inside MACRO, FOR, FORC, REPEAT, and WHILE blocks. The label must be the only directive on the line and must be preceded by a leading colon.
name GROUP segment [[, segment]]...
Add the specified segments to the group called name.
.IF condition1
statements
[[.ELSEIF condition2
statements]]
[[.ELSE
statements]]
.ENDIF
Generates code that tests condition1 (for example, AX > 7) and executes the statements if that condition is true. If an .ELSE follows, its statements are executed if the original condition was false. Note that the conditions are evaluated at run time.
IF expression1
ifstatements
[[ELSEIF expression2
elseifstatements]]
[[ELSE
elsestatements]]
ENDIF
Grants assembly of ifstatements if expression1 is true (nonzero) or elseifstatements if expression1 is false (0) and expression2 is true. The following directives may be substituted for ELSEIF: ELSEIFB,
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ELSEIFDEF, ELSEIFDIF, ELSEIFDIFI, ELSEIFE, ELSEIFIDN, ELSEIFIDNI, ELSEIFNB, and ELSEIFNDEF. Optionally, assembles elsestatements if the previous expression is false. Note that the expressions are evaluated at assembly time.
IF2 expression
IF block is evaluated on every assembly pass if OPTION:SETIF2 is TRUE. See IF for complete syntax.
IFB textitem
Grants assembly if textitem is blank. See IF for complete syntax.
IFDEF name
Grants assembly if name is a previously defined label, variable, or symbol. See IF for complete syntax.
IFDIF[[I]] textitem1, textitem2
Grants assembly if the text items are different. If I is given, the comparison is case insensitive. See IF for complete syntax.
IFE expression
Grants assembly if expression is false (0). See IF for complete syntax.
IFIDN[[I]] textitem1, textitem2
Grants assembly if the text items are identical. If I is given, the comparison is case insensitive. See IF for complete syntax.
IFNB textitem
Grants assembly if textitem is not blank. See IF for complete syntax.
IFNDEF name
Grants assembly if name has not been defined. See IF for complete syntax.
INCLUDE filename
Inserts source code from the source file given by filename into the current source file during assembly. The filename must be enclosed in angle brackets if it includes a backslash, semicolon, greater-than symbol, less-than symbol, single quotation mark, or double quotation mark.
INCLUDELIB libraryname
Informs the linker that the current module should be linked with libraryname. The libraryname must be enclosed in angle brackets if it includes a backslash, semicolon, greater-than symbol, less-than symbol, single quotation mark, or double quotation mark.
name INSTR [[position,]] textitem1, textitem2
Finds the first occurrence of textitem2 in textitem1. The starting position is optional. Each text item can be a literal string, a constant preceded by a %, or the string returned by a macro function.
INVOKE expression [[, arguments]]
Calls the procedure at the address given by expression, passing the arguments on the stack or in registers according to the standard calling conventions of the language type. Each argument passed to the procedure may be an expression, a register pair, or an address expression (an expression preceded by ADDR).
IRP
See FOR.
IRPC
See FORC.
name LABEL type
Creates a new label by assigning the current location-counter value and the given type to name.
name LABEL [[NEAR | FAR | PROC]] PTR [[type]]
Creates a new label by assigning the current location-counter value and the given type to name.
.LALL
See .LISTMACROALL.
.LFCOND
See .LISTIF.
.LIST
Starts listing of statements. This is the default.
.LISTALL
Starts listing of all statements. Equivalent to the combination of .LIST, .LISTIF, and .LISTMACROALL.
.LISTIF
Starts listing of statements in false conditional blocks. Same as .LFCOND.
.LISTMACRO
Starts listing of macro expansion statements that generate code or data. This is the default. Same as .XALL.
.LISTMACROALL
Starts listing of all statements in macros. Same as .LALL.
LOCAL localname [[, localname]]...
Within a macro, LOCAL defines labels that are unique to each instance of the macro.
LOCAL label [[ [count ] ]] [[:type]] [[, label [[ [count] ]] [[type]]]]...
Within a procedure definition (PROC), LOCAL creates stack-based variables that exist for the duration of the procedure. The label may be a simple variable or an array containing count elements.
name MACRO [[parameter [[:REQ | :=default | :VARARG]]]]...
statements
ENDM [[value]]
Marks a macro block called name and establishes parameter placeholders for arguments passed when the macro is called. A macro function returns value to the calling statement.
.MODEL memorymodel [[, langtype]] [[, stackoption]]
Initializes the program memory model. The memorymodel can be TINY, SMALL, COMPACT, MEDIUM, LARGE, HUGE, or FLAT. The langtype can be C, BASIC, FORTRAN, PASCAL, SYSCALL, or STDCALL. The stackoption can be NEARSTACK or FARSTACK.
NAME modulename
Ignored.
.NO87
Disallows assembly of all floating-point instructions.
.NOCREF [[name[[, name]]...]]
Suppresses listing of symbols in the symbol table and browser file. If names are specified, only the given names are suppressed. Same as .XCREF.
.NOLIST
Suppresses program listing. Same as .XLIST.
.NOLISTIF
Suppresses listing of conditional blocks whose condition evaluates to false (0). This is the default. Same as .SFCOND.
.NOLISTMACRO
Suppresses listing of macro expansions. Same as .SALL.
OPTION optionlist
Enables and disables features of the assembler. Available options include CASEMAP, DOTNAME, NODOTNAME, EMULATOR, NOEMULATOR, EPILOGUE, EXPR16, EXPR32, LANGUAGE, LJMP, NOLJMP, M510, NOM510, NOKEYWORD, NOSIGNEXTEND, OFFSET, OLDMACROS, NOOLDMACROS, OLDSTRUCTS, NOOLDSTRUCTS, PROC, PROLOGUE, READONLY, NOREADONLY, SCOPED, NOSCOPED, SEGMENT, and SETIF2.
ORG expression
Sets the location counter to expression.
%OUT
See ECHO.
PAGE [[[[length]], width]]
Sets line length and character width of the program listing. If no arguments are given, generates a page break.
PAGE +
Increments the section number and resets the page number to 1.
POPCONTEXT context
Restores part or all of the current context (saved by the PUSHCONTEXT directive). The context can be ASSUMES, RADIX, LISTING, CPU, or ALL.
label PROC [[distance]] [[langtype]] [[visibility]] [[<prologuearg>]]
[[USES reglist]] [[, parameter [[:tag]]]]...
statements
label ENDP
Marks start and end of a procedure block called label. The statements in the block can be called with the CALL instruction or INVOKE directive.
label PROTO [[distance]] [[langtype]] [[, [[parameter]]:tag]]...
Prototypes a function.
PUBLIC [[langtype]] name [[, [[langtype]] name]]...
Makes each variable, label, or absolute symbol specified as name available to all other modules in the program.
PURGE macroname [[, macroname]]...
Deletes the specified macros from memory.
PUSHCONTEXT context
Saves part or all of the current context: segment register assumes, radix value, listing and cref flags, or processor/coprocessor values. The context can be ASSUMES, RADIX, LISTING, CPU, or ALL.
[[name]] QWORD initializer [[, initializer]]...
Allocates and optionally initializes 8 bytes of storage for each initializer. Also can be used as a type specifier anywhere a type is legal.
.RADIX expression
Sets the default radix, in the range 2 to 16, to the value of expression.
name REAL4 initializer [[, initializer]]...
Allocates and optionally initializes a single-precision (4-byte) floating-point number for each initializer.
name REAL8 initializer [[, initializer]]...
Allocates and optionally initializes a double-precision (8-byte) floating-point number for each initializer.
name REAL10 initializer [[, initializer]]...
Allocates and optionally initializes a 10-byte floating-point number for each initializer.
recordname RECORD fieldname:width [[= expression]]
[[, fieldname:width [[= expression]]]]...
Declares a record type consisting of the specified fields. The fieldname names the field, width specifies the number of bits, and expression gives its initial value.
.REPEAT
statements
.UNTIL condition
Generates code that repeats execution of the block of statements until condition becomes true. .UNTILCXZ, which becomes true when CX is zero, may be substituted for .UNTIL. The condition is optional with .UNTILCXZ.
REPEAT expression
statements
ENDM
Marks a block that is to be repeated expression times. Same as REPT.
REPT
See REPEAT.
.SALL
See .NOLISTMACRO.
name SBYTE initializer [[, initializer]]...
Allocates and optionally initializes a signed byte of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
name SDWORD initializer [[, initializer]]...
Allocates and optionally initializes a signed doubleword (4 bytes) of storage for each initializer. Also can be used as a type specifier anywhere a type is legal.
name SEGMENT [[READONLY]] [[align]] [[combine]] [[use]] [['class']]
statements
name ENDS
Defines a program segment called name having segment attributes align (BYTE, WORD, DWORD, PARA, PAGE), combine (PUBLIC, STACK, COMMON, MEMORY, AT address, PRIVATE), use (USE16, USE32, FLAT), and class.
.SEQ
Orders segments sequentially (the default order).
.SFCOND
See .NOLISTIF.
name SIZESTR textitem
Finds the size of a text item.
.STACK [[size]]
When used with .MODEL, defines a stack segment (with segment name STACK). The optional size specifies the number of bytes for the stack (default 1,024). The .STACK directive automatically closes the stack statement.
.STARTUP
Generates program start-up code.
STRUC
See STRUCT.
name STRUCT [[alignment]] [[, NONUNIQUE]]
fielddeclarations
name ENDS
Declares a structure type having the specified fielddeclarations. Each field must be a valid data definition. Same as STRUC.
STRUC
name SUBSTR textitem, position [[, length]]
Returns a substring of textitem, starting at position. The textitem can be a literal string, a constant preceded by a %, or the string returned by a macro function.
SUBTITLE text
Defines the listing subtitle. Same as SUBTTL.
SUBTTL
See SUBTITLE.
name SWORD initializer [[, initializer]]...
Allocates and optionally initializes a signed word (2 bytes) of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
[[name]] TBYTE initializer [[, initializer]]...
Allocates and optionally initializes 10 bytes of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
name TEXTEQU [[textitem]]
Assigns textitem to name. The textitem can be a literal string, a constant preceded by a %, or the string returned by a macro function.
.TFCOND
Toggles listing of false conditional blocks.
TITLE text
Defines the program listing title.
name TYPEDEF type
Defines a new type called name, which is equivalent to type.
name UNION [[alignment]] [[, NONUNIQUE]]
fielddeclarations
[[name]] ENDS
Declares a union of one or more data types. The fielddeclarations must be valid data definitions. Omit the ENDS name label on nested UNION definitions.
.UNTIL
See .REPEAT.
.UNTILCXZ
See .REPEAT.
.WHILE condition
statements
.ENDW
Generates code that executes the block of statements while condition remains true.
WHILE expression
statements
ENDM
Repeats assembly of block statements as long as expression remains true.
[[name]] WORD initializer [[, initializer]]...
Allocates and optionally initializes a word (2 bytes) of storage for each initializer. Can also be used as a type specifier anywhere a type is legal.
.XALL
See .LISTMACRO.
.XCREF
See .NOCREF.
.XLIST
See .NOLIST.