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Terms, Literals, and Expressions The following example shows how to use the length attribute to move a character constant into either the high-order or low-order end of a storage field. A1 DS CL8 B2 DC CL2'AB' HIORD MVC A1(L'B2),B2 LOORD MVC A1+L'A1-L'B2(L'B2),B2 A1 names a storage field 8 bytes in length and is assigned a length attribute of 8. B2 names a character constant 2 bytes in length and is assigned a length attribute of 2. The statement named HIORD moves the contents of B2 into the first 2 bytes of A1. The term L'B2 in parentheses provides the length specification required by the instruction. The statement named LOORD moves the contents of B2 into the rightmost 2 bytes of A1. The combination of terms A1+L'A1-L'B2 adds the length of A1 to the beginning address of A1, and subtracts the length of B2 from this value. The result is the address of the seventh byte in field A1. The constant represented by B2 is moved into A1 starting at this address. L'B2 in parentheses provides the length specification in both instructions. For ease in following the preceding example, the length attributes of A1 and B2 are specified explicitly in the DS and DC statements that define them. However, keep in mind that the L'symbol term makes coding such as this possible in situations where lengths are unknown. For example: C3 DC C'This is too long a string to be worth counting' STRING MVC BUF(L'C3),C3 Other Attribute References Other attributes describe the characteristics and structure of the data you define in a program; for example, the kind of constant you specify or the number of characters you need to represent a value. These other attributes are: Count (K') Defined (D') Integer (I') Number (N') Operation code (O') Scale (S') | Type (T'); allowed only in conditional assembly. You can refer to the count (K'), defined (D'), number (N'), and operation code (O') attributes only in conditional assembly instructions and expressions. For full details, see “Data Attributes” on page 324. Literals You can use literals as operands in order to introduce data into your program. The literal is a special type of relocatable term. It behaves like a symbol in that it represents data. However, it is a special kind of term because it also is used to define the constant specified by the literal. This is convenient because: The data you enter as numbers for computation, addresses, or messages to be printed is visible in the instruction in which the literal appears. You avoid the added effort of defining constants elsewhere in your source module and then using their symbolic names in machine instruction operands. 40 HLASM V1R5 Language Reference
Terms, Literals, and Expressions The assembler assembles the data item specified in a literal into a literal pool (See “Literal Pool” on page 44). It then assembles the address of this literal data item in the pool into the object code of the instruction that contains the literal specification. Thus, the assembler saves you a programming step by storing your literal data for you. The assembler also organizes literal pools efficiently, so that the literal data is aligned on the correct boundary alignment and occupies a minimum amount of space. Literals, Constants, and Self-Defining Terms Literals, constants, and self-defining terms differ in three important ways: Where you can specify them in machine instructions, that is, whether they represent data or an address of data Whether they have relocatable or absolute values What is assembled into the object code of the machine instruction in which they appear Figure 15 on page 42 shows examples of the differences between literals, constants, and self-defining terms. Chapter 2. Coding and Structure 41
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High Level Assembler for MVS & VM &
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Note! Before using this information
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Contents Source Module . . . . . .
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Contents Ordinary USING Instruction
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Contents Sublists in Operands . . .
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About this Manual This manual descr
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IBM High Level Assembler for MVS &
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| The Internet. You can access IBM
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▌C▐ The item referred to by ▌
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Miscellany The ASCII translation t
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Part 1. Assembler Language—Struct
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Language Compatibility Language Com
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Assembler Program Assembler Program
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Relationship of Assembler to Operat
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Coding Made Easier Linkage between
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Character Set Compatibility with Ea
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Assembler Language Coding Conventio
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Assembler Language Coding Conventio
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Assembler Language Coding Conventio
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Assembler Language Coding Conventio
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Assembler Language Structure Condit
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Assembler Language Structure Machin
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Assembler Language Structure Condit
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Terms, Literals, and Expressions Te
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| Chapter 3. Program Structures and
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Source Module A source module is co
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The CSECT instruction can be used a
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| in linker control statements for
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This is not only convenient, but it
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| SECT_A CSECT , Define section SEC
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| For executable sections, the loca
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Addressing | The System/390® and z
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Addressing | Parts must always be r
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Addressing Literal Pools ALPHA LR 3
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Addressing If the symbol is the nam
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Addressing External Symbol Dictiona
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Addressing 74 HLASM V1R5 Language R
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Part 2. Machine and Assembler Instr
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General Instructions Chapter 4. Mac
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Input/Output Operations For further
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Branching with Extended Mnemonic Co
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Symbolic Operation Codes variations
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Operand Entries Registers You can s
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Operand Entries “Program Structur
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Operand Entries Format │ Coded or
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Examples of Coded Machine Instructi
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Examples of Coded Machine Instructi
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Examples of Coded Machine Instructi
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Examples of Coded Machine Instructi
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Chapter 5. Assembler Instruction St
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*PROCESS Statement *PROCESS Stateme
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ACONTROL Instruction ►►──
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ACONTROL Instruction FLAG(PAGE0) in
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AINSERT Instruction character_strin
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AMODE Instruction alias_string is t
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CATTR Instruction Figure 25. AMODE/
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CATTR Instruction | statements for
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CCW1 Instruction data_count is an a
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CEJECT Instruction If symbol is an
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CNOP Instruction Figure 29 (Page 2
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COPY Instruction In the following e
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CSECT Instruction symbol in the nam
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DC Instruction ROUTINE B GAMMA DXD
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DC Instruction duplication_factor c
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DC Instruction Figure 33 (Page 2 of
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DC Instruction With EBCDIC spaces
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DC Instruction Further information
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DC Instruction | Symbols used in su
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DC Instruction The length attribute
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DC Instruction Notes: 1. Don't conf
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DC Instruction—Character Constant
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DC Instruction—Character Constant
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DC Instruction—Graphic Constant r
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DC Instruction—Fixed-Point Consta
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DC Instruction—Fixed-Point Consta
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DC Instruction—Decimal Constants
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DC Instruction—Address Constants
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DC Instruction—Address Constants
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DC Instruction—Offset Constant re
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DC Instruction—Length Constant Le
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DC Instruction—Hexadecimal Floati
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DC Instruction—Hexadecimal Floati
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DC Instruction—Hexadecimal Floati
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DC Instruction—Binary Floating-Po
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DC Instruction—Binary Floating-Po
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DROP Instruction DROP Instruction T
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DS Instruction USING DSECTA,14 ALBL
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DS Instruction The size of a storag
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DSECT Instruction DSECT Instruction
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DXD Instruction ASEMBLY2 CSECT USIN
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END Instruction change but no addit
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EQU Instruction EQU Instruction The
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EQU Instruction 5. The length attri
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EXITCTL Instruction sequence_symbol
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ISEQ Instruction must be greater th
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LOCTR Instruction A CSECT , See not
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LTORG Instruction If symbol is an o
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MNOTE Instruction When two literals
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OPSYN Instruction ,ERROR, SEV 1 An
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ORG Instruction AFTER is defined in
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ORG Instruction If you specify mult
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POP Instruction POP Instruction The
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PRINT Instruction Note: If the next
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Process Statement Process Statement
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REPRO Instruction NOPRINT instructs
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RSECT Instruction 4. AMODE or RMODE
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START Instruction START Instruction
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TITLE Instruction The name value is
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USING Instruction Only the characte
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USING Instruction Base Registers fo
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USING Instruction If register 0 is
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USING Instruction A variable symbo
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USING Instruction In this MVC instr
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USING Instruction Range of a Depend
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XATTR Instruction external_symbol i
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XATTR Instruction 234 HLASM V1R5 La
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Introduction to Macro Language Chap
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Introduction to Macro Language The
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Introduction to Macro Language Macr
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MACRO and MEND Statements The assem
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Prototype Statement Macros that are
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Model Statements generated from tha
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Model Statements ▌5▐ ▌6▐
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Model Statements Notes: 1. You can
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Positional Parameters Symbolic para
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Processing Statements Processing St
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AREAD Instruction Assign Local Time
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COPY Instruction sequence_symbol is
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System Variable Symbols System Vari
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&SYSADATA_MEMBER System Variable Sy
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&SYSCLOCK System Variable Symbol &S
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&SYSECT System Variable Symbol depe
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&SYSIN_MEMBER System Variable Symbo
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&SYSJOB System Variable Symbol &SYS
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&SYSLIN_DSN System Variable Symbol
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&SYSLIST System Variable Symbol The
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&SYSLOC System Variable Symbol To
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&SYSOPT_DBCS System Variable Symbol
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&SYSPARM System Variable Symbol Not
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&SYSPUNCH_MEMBER System Variable Sy
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&SYSSTEP System Variable Symbol Not
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&SYSTERM_DSN System Variable Symbol
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&SYSTIME System Variable Symbol Not
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Macro Instruction Format sequence_s
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Macro Instruction Format Operand En
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Macro Instruction Format When you n
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Sublists in Operands the order in w
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Sublists in Operands &SYSLIST( n,m)
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Values in Operands Notes: 1. Spaces
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Values in Operands Parentheses In m
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Levels of Macro Call Nesting System
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SET Symbols SET Symbol Specificatio
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Data Attributes this example indica
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Data Attributes variable_symbol is
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Data Attributes The value of an att
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Data Attributes The following attri
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Data Attributes The scale attribute
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Data Attributes Number Attribute (N
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Data Attributes The operation code
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Lookahead MACRO &NAME MOVE &TO,&FRO
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Open Code Sequence Symbols The cond
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GBLA, GBLB, and GBLC Instructions G
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SETA Instruction expression is an a
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SETA Instruction | The logical-exp
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SETA Instruction | Figure 99 (Page
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SETA Instruction | The result of C2
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SETA Instruction NOT Format: Logica
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SETA Instruction | X2A Name Operati
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SETA Instruction In evaluating the
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SETB Instruction Any expression tha
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SETB Instruction ┌─────
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SETB Instruction | ISDEC | Format:
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SETB Instruction The two comparands
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SETC Instruction Notes: 1. The asse
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Figure 103. Substring Notation in C
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Loc Object Code Addr1 Addr2 Stmt So
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| B2C('111111') has value '3' | B2C
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| Output: D2B('decstring') converts
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SIGNED Format: Logical-expression,
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| X2D('') has value '+' | X2D('91')
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Concatenation of strings containing
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MACRO &NAME MOVE &TO,&FROM LCLC &PR
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SETAF Instruction Alternative State
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Branching Branching You can control
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AGO Instruction The extended AIF in
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ACTR Instruction AGOB—Synonym of
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ANOP Instruction statement processe
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MHELP Instruction MHELP B'10000000'
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400 HLASM V1R5 Language Reference
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Assembler Instructions and Statemen
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Assembler Instructions and Statemen
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Assembler Instructions and Statemen
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Summary of Constants Figure 113. Su
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Macro and Conditional Assembly Lang
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Macro and Conditional Assembly Lang
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Macro and Conditional Assembly Lang
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Macro and Conditional Assembly Lang
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Macro and Conditional Assembly Lang
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Macro and Conditional Assembly Lang
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Standard Character Set Code Table H
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Standard Character Set Code Table H
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Trademarks AIX BookMaster CICS DFSM
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Bibliography SMP/E Reference, SC28-
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Index A2C (SETC built-in function)
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Index B B-type binary constant 141
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Index conditional assembly instruct
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Index elements of conditional assem
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Index instructions (continued) asse
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Index machine instruction statement
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Index operands (continued) compatib
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Index relative addressing 67 reloca
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Index sublists compatibility with A
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Index variable symbols (continued)
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Readers' Comments High Level Assemb
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IBM® Program Number: 5696-234 Prin
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