Program Structure | HP UX Developer Tools guide

2	Program Structure

An assembly language program is a sequence of statements. There are three classes of statements:

•Instructions

•Pseudo-operations

•Directives

Instructions represent a single machine instruction in symbolic form. Pseudo-operations cause the Assembler to initialize or reserve one or more words of storage for data, rather than machine instructions.

Directives communicate information about the program to the Assembler, but do not generally cause the Assembler to output any machine instructions.

An assembly statement contains four ﬁelds:

•Label

•Opcode

•Operands

•Comments

Each of these ﬁelds is optional. However the operands ﬁeld cannot appear without an opcode ﬁeld.The label ﬁeld is used to associate a symbolic address with an instruction or data location, or to deﬁne a symbolic constant using the .EQU, .REG, or .MACRO directives. This ﬁeld is optional for all but a few statement types; if present, the label must begin in column one of a source program line. If a label appears on a line by itself, or with a comment only, the label is associated with the next address within the same subspace and location counter.

When the label ﬁeld begins with the pound sign (#) character, it is not treated as a label. If # is followed by white space and an integer, the Assembler's line number counter, used when reporting errors, is reset to the value of the integer. Otherwise, the line beginning with # is ignored. This feature is for the use of the C language preprocessor cpp.

The opcode ﬁeld contains either a mnemonic machine instruction, a pseudo-operation code, or the name of an Assembler directive. It must be separated from the label ﬁeld by a blank or tab. For certain machine instructions, the opcode ﬁeld can also contain completers, separated from the instruction mnemonic by commas.

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HP UX Developer Tools manual Program Structure

Contents

92432-90012 June HP 9000 Computers Restricted Rights Legend Legal NoticesHanover Street Palo Alto, California Contents Assembler Directives and Pseudo-Operations Contents Contents Contents Contents Pseudo-Instruction Set Assembling Your Program Programming Examples Diagnostic MessagesIndex Printing History PrefaceEdition Date Software Version Related Documentation Audience This Manual Typographical Conventions Summary of Technical Changes for HP-UX Assembler Features Assembly Language Assembler Features Chapter Summary of Changes for PA-RISCSummary of Changes for PA-RISC 2.0W Wide Mode, 64-bit Summary of Changes for PA-RISC Summary of Changes for PA-RISC 2.0W Wide Mode, 64-bit Program Structure Label Opcode Operands Comments Program Structure Symbols and Constants Symbols and Constants Integer Constants Signed Unsigned Registers and Register Mnemonics Registers and Register Mnemonics Registers by using an L or R sufﬁx General Registers Single-Precision Floating-Point Registers Space Registers Double-Precision Floating-Point RegistersControl Registers Synonyms Register Synonyms Description Register Procedure Calling Conventions Operator Operation ExpressionsExpressions Standard Arithmetic Operators Legal Combinations For Relocatable Terms Operation Result Available Field Selectors Meaning Field Meaning Selector Multiple of 2048 allows a three-instruction sequence Parenthesized Subexpressions Operands and Completers Operands and Completers Addi Deﬁning New Instructions With Macros Macro ProcessingMacro Processing Contains general register 19, or binary 10011. These Spaces HP-UX Architecture Conventions Spaces Memory Layout on HP-UX Sr4 Sr5 Sr6 Attributes SubspacesSubspaces Standard Subspaces and Sort Keys DirectivesSpace Subspace Sort Key Use Sections in 64-bit Mode Sections in 64-bit Mode $INIT$ Location Counters Location Counters Compiler Conventions Compiler Conventions Compiler Conventions Global Symbol Usage Mfctl Shared Libraries Assembly ListingShared Libraries Assembly Listing Assembler Directives IntroductionDirective Function Requests common storage for a speciﬁed number Bytes Pseudo-Operations Directive Function Reserves 16 bits a half word of storage Example Align DirectiveSyntax Parameters Discussion Allow DirectiveAllow Directive To the .LEVEL speciﬁed for the ﬁle Block and .BLOCKZ Pseudo-Operations Block and .BLOCKZ Pseudo-Operations Space $TEXT$ Subspa $CODE$ Block Byte Pseudo-Operation Byte Pseudo-OperationByte initvalue , initvalue Call Directive Call DirectiveCall argumentdescription argumentdescription Second word in the argument list Form of argument-description is Arg=location Where arg canReturn value for a procedure ﬁrst word in the argument list LIT Align Word Procend Export Callinfo Directive Callinfo DirectiveCallinfo parameter , parameter Register ENTRYSR= Unwound It restores the RP value when it encounters a .LEAVE Callinfo Directive Stack Frames Re-enter code subspace Label Labels the location of the reserved storage Comm DirectiveComm Directive Label .COMM numbytes Copyright Directive Copyright DirectiveCompany-name Proc Callinfo Enter Double Pseudo-Operation Integer .fraction E powerFraction E power Double Pseudo-Operation Dword Pseudo-Operation Dword Pseudo-OperationDword initvalue , initvalue END Directive END Directive Endm Directive Endm Directive Enter and .LEAVE Pseudo-Operations Enter and .LEAVE Pseudo-Operations Space $TEXT$ Entry and .EXIT Directives Entry and .EXIT Directives Value Symbolicname .EQU valueEQU Directive EQU Directive Export Directive Export Directive Argument Export proc,ENTRY,ARGW0=GR Float Pseudo-Operation Float Pseudo-Operation Half Pseudo-Operation Half Pseudo-OperationHalf initvalue , initvalue Import Directive Import Directive NOP END Labelid Names the label identiﬁer Label DirectiveLabel Directive Label labelid Level Directive Level Directive Level Directive Listoff and .LISTON Directives Listoff and .LISTON Directives Liston Code Space $TEXT$ SPNUM=0,SORT=0 Subspa $CODE$ Locct Directive Locct Directive Macro Directive Macro DirectiveLabel .MACRO formalparameter,formalparameter Examples 100 Origin Directive Origin DirectiveChapter 101 Proc and .PROCEND Directives Proc and .PROCEND Directives102 Chapter 103 Label User-deﬁned register name REG DirectiveREG Directive Label .REG typedregister Shlibversion Directive Shlibversion DirectiveChapter 105 Space Directive Space Directive106 Chapter 107 Spnum Pseudo-Operation Spnum Pseudo-Operation108 String and .STRINGZ Pseudo-Operations String and .STRINGZ Pseudo-OperationsChapter 109 110 Chapter 111 Subspa DirectiveSubspa Directive Name An identiﬁer that names the current subspace 112 Chapter 113 Version Directive Version Directive114 Chapter 115 Word Pseudo-OperationWord Pseudo-Operation Word initvalue , initvalue Predeﬁned Subspace Directives Directive Space Name Default ParametersProgramming Aids Programming Aids Chapter 117 Shortdata Programming Aids 118 119 Pseudo-Instruction Set 120 Cond Description Compare and Branch Conditions Comb and ComibChapter 121 122 Add and Branch Conditions Addb and Addib Description 123 Invoking the Assembler 124 Using the as CommandUsing the as Command Assemble code for the architecture Level ﬁlenameChapter 125 126 WnumberTables, see HP-UX Linker and Libraries Online User Guide Wa, ,as-argument as-argument Using the cc CommandUsing the cc Command Passing Arguments to the Assembler 128 Cpp Preprocessor 129 Programming Examples Binary Search for Highest Bit Position Binary Search for Highest Bit Position130 Chapter 131 Copying a String Copying a String132 Chapter 133 Dividing a Double-Word Dividend Dividing a Double-Word Dividend134 Chapter 135 Programming Examples 136 Demonstrating the Procedure Calling ConventionDemonstrating the Procedure Calling Convention Program Listing Chapter 137 Assembly Program Listing 138 Output of the cc -S CommandAssembly Program Listing From the C Compiler Output of the cc -S Command Chapter 139 Output of the cc -S Command 140 141 142 Option operand Chapter 143 144 Reserve Use a general register Wrong register type usedChapter 145 Use a control register Use a space register146 Chapter 147 148 Chapter 149 150 Chapter 151 152 Used to invoke the assembler Chapter 153 Error Messages Error Messages154 Chapter 155 156 Chapter 157 158 1030 10271028 1029 1034 10311032 1033 1038 10351036 1037 162 Chapter 163 1057 10541055 1056 Chapter 165 166 Chapter 167 168 1082 Format keyword=value1080 1081 170 Chapter 171 10881089 1090 1096 10911094 1095 1100 10971098 1099 1104 11011102 1103 Chapter 175 1105 Panic Messages Panic Messages176 2008 20052006 2007 User Warning Messages User Warning Messages178 7006 70037004 7005 180 Chapter 181 182 7201 Limit Error MessagesLimit Error Messages 7200 184 72027203 7204 Chapter 185 Diagnostic Messages 186 Branching Error Messages Branching Error MessagesChapter 187 188 Chapter 189 190 Chapter 191 192 7835 78277828 7834 194 78367837 Expr Index 195 Index Numerics 196 Copyright Index 197 HP C/HP-UX,49 198 Mfctl Index 199 Double 200 See also memory Index 201 202