A scalar data item represents a numeric quantity that may be increased or decreased in magnitude as a single unit. Thus, an Initializer expression for a scalar data item must be coded such that it resolves to a single scalar value. See the section on Scalar-Initializer-ExpressionType for the syntax and semantics of such expressions.
The old-style allocation directives (DB, DW, DD, DF, DQ, and DT) are supported in all assembler emulation modes, but for modes other than M510, the Scalar-TypeName keywords should be used instead.
When the Scalar-TypeName keywords are used instead of the old-style allocation directives, the assembler has full knowledge of the data types of the variables being created. This allows the assembler to make more intelligent code generation decisions, and it enables the assembler to correctly describe the variable in the symbolic debugging information that it generates for the source level debugger. Scalar-TypeNames may not be used as allocation directives in the M510 mode.
To allocate an uninitialized scalar data item, use the Indeterminate-Value-Alias ($) in the Initializer field.
旼컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿟ype Name쿏ata Type 쿔nitializer Description � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏B, BYTE,쿌llocates 8-bit 쿐ach Initializer must be in the range � 쿽r SBYTE �(byte) values. 쿯rom 0 to 255 (unsigned) for a DB or � � � 쿍YTE directive, and from -128 to 127 � � � �(signed) for a SBYTE directive. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏W, WORD,쿌llocates 16-bit 쿐ach Initializer must be in the range � 쿽r SWORD �(word) values. 쿯rom 0 to 65535 (unsigned) for a DW or � � � 쿥ORD directive, and from -32768 to 32767� � � �(signed) for a SWORD directive. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏D, 쿌llocates 32-bit 쿔f the Initializer is an integer, each � 쿏WORD, or�(double-word) 쿺ust be in the range from 0 to � 쿞DWORD 퀆alues. �4,294,967,295 (unsigned) for a DD or � � � 쿏WORD directive, and from -2,147,483,648� � � 퀃o 2,147,483,647 (signed) for a SDWORD � � � 쿭irective. If the DD directive is being� � � 퀅sed, an Initializer may also resolve to� � � 쿪 32-bit Floating-Point-ExpressionType. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏F or 쿌llocates 48-bit 쿐ach Initializer typically specifies the� 쿑WORD �(6-byte far-word) 쿯ull address of a 32-bit far code or � � 퀆alues. 쿭ata label, but normal 32-bit integer � � � 퀆alues may also be used. The processor � � � 쿭oes not support 48-bit integer � � � 쿽perations, thus the assembler does � � � 퀂upport 48-bit integer precision when � � � 쿶nitializing such variables. These � � � 쿭irectives are typically only useful for� � � 쿭efining pointer variables for use on � � � �32-bit processors. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏Q or 쿌llocates 64-bit 쿍oth DQ and QWORD allow an integer � 쿜WORD �(quad-word) values. �Initializer with 64-bit (8-byte) � � � 쿾recision. If the DQ directive is being� � � 퀅sed, the Initializer field may resolve � � � 퀃o a 64-bit � � � �Floating-Point-ExpressionType. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿏T or 쿌llocates 80-bit 쿍oth DT and TBYTE allow an integer � 쿟BYTE �(10-byte) values �Initializer with 80-bit (10-byte) � � � 쿾recision. If the DT directive is being� � � 퀅sed, the Initializer field may resolve � � � 퀃o a 80-bit � � � �Floating-Point-ExpressionType. � 쳐컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿝EAL4, 쿌llocates real 쿐ach Initializer must resolve to a � 쿝EAL8, or�(floating-point) �Floating-Point-ExpressionType. The � 쿝EAL10 퀆alues of a specific쿪ssembler converts the floating-point � � 퀂ize (4 bytes, 8 쿹iteral to the IEEE format appropriate � � 쿫ytes, or 10 bytes).쿯or the type of variable being � � � 쿪llocated. � 읕컴컴컴컴좔컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴�
Examples
Here are some examples of scalar initialization:
; Allocate some integer variables uint8 BYTE 0, 255 ; min, max values for unsigned byte sint8 SBYTE -128, 127 ; min, max values for signed byte USHORT_T TYPEDEF WORD ; Define a typedef alias for WORD ushort USHORT_T 0, 0FFFFh ; and use it as allocation type name ; Some things to know about string-literal initializers char BYTE "a" ; a single BYTE value (061h) is_int WORD "ab" ; a single WORD value (06162h) this_too DWORD "abcd" ; a single DWORD value (061626364h) too_long WORD "abcd" ; error, expression too big for a word string BYTE "string", 0 ; but strings can allocate many bytes ; Integers, pointers, and old-style initializations PDWORD_T TYPEDEF PTR DWORD ; First, define a pointer type ulong DWORD 0, 0FFFFFFFFh ; min, max values for unsigned dword pulong PDWORD_T OFFSET ulong ; pointer to the ulong variable old_style DD 1.314 ; old style, floats are accepted new_int SDWORD 1.314 ; new style, error-must use integers new_real REAL4 1314 ; new style, error-must use floats ; Allocate some real numbers using decimal floating-point literals float_f REAL4 123.45 ; 4-byte IEEE real double_f REAL8 98.7654E1 ; 8-byte IEEE real longdbl_f REAL10 1000.0E-2 ;10-byte IEEE real ; The same values using hexdecimal floating-point literals float_h REAL4 42F6E666r ; 4-byte IEEE real double_h REAL8 408EDD3B645A1CACr ; 8-byte IEEE real longdbl_h REAL10 4002A000000000000000r ;10-byte IEEE real