To the .LEVEL speciﬁed for the ﬁle | HP UX Developer Tools guide

Assembler Directives and Pseudo-Operations

.ALLOW Directive

	When using the .ALLOW directive, a run-time check must be inserted
	into the assembly source code. This run-time check should insure that
	the code is executing on a PA-RISC processor that supports the feature
	or features being used after the .ALLOW directive. See the example below.
	An .ALLOW directive without a parameter signals the end of the region
	that the previous .ALLOW directive was controlling. Control is returned
	to the .LEVEL speciﬁed for the ﬁle.
	The .ALLOW and .LEVEL directives replace the +DA and +DS
NOTE	The .ALLOW and .LEVEL directives replace the +DA and +DS
	command-line compiler options.

Example

The following example shows how to set a range of memory to 0. In PA-RISC 1.1 architecture, use the stw instruction. In PA-RISC 2.0 architecture, use the more efﬁcient std instruction.

.LEVEL 1.1

;This object file will be marked as a PA 1.1 object file

;Check what version of PA Architecture we are linked for addil LR'_SYSTEM_ID-$global$,%dp

ldw RR'_SYSTEM_ID-$global$(%r1),%r5

ldi CPU_PA_RISC1_1,%r4 combt,<,n %r4,%r5,$00000002

;1.1 specific code

$00000001

addib,< 1,%r23,$00000001 stw,ma %r0,4(%r31)

b,n $00000003

;2.0 specific code $00000002

.ALLOW 2.0

addib,< 2,%r23,$00000002 std,ma %r0,8(%r31)

.ALLOW

$00000003

;General code

Chapter 4

59

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HP UX Developer Tools manual To the .LEVEL speciﬁed for the ﬁle

Contents

92432-90012 June HP 9000 Computers Hanover Street Palo Alto, California Legal NoticesRestricted Rights Legend Contents Assembler Directives and Pseudo-Operations Contents Contents Contents Contents Pseudo-Instruction Set Assembling Your Program Index Diagnostic MessagesProgramming Examples Edition Date Software Version PrefacePrinting History 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 Control Registers Synonyms Double-Precision Floating-Point RegistersSpace Registers 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 Macro Processing Macro ProcessingDeﬁning New Instructions With Macros Contains general register 19, or binary 10011. These Spaces HP-UX Architecture Conventions Spaces Memory Layout on HP-UX Sr4 Sr5 Sr6 Subspaces SubspacesAttributes Space Subspace Sort Key Use DirectivesStandard Subspaces and Sort Keys 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 Directive Function IntroductionAssembler Directives Requests common storage for a speciﬁed number Bytes Pseudo-Operations Directive Function Reserves 16 bits a half word of storage Example Align DirectiveSyntax Parameters Allow Directive Allow DirectiveDiscussion To the .LEVEL speciﬁed for the ﬁle Block and .BLOCKZ Pseudo-Operations Block and .BLOCKZ Pseudo-Operations Space $TEXT$ Subspa $CODE$ Block Byte initvalue , initvalue Byte Pseudo-OperationByte Pseudo-Operation Call argumentdescription argumentdescription Call DirectiveCall Directive 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 parameter , parameter Callinfo DirectiveCallinfo Directive 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 Company-name Copyright DirectiveCopyright Directive Proc Callinfo Enter Double Pseudo-Operation Integer .fraction E powerFraction E power Double Pseudo-Operation Dword initvalue , initvalue Dword Pseudo-OperationDword Pseudo-Operation 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 initvalue , initvalue Half Pseudo-OperationHalf Pseudo-Operation 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 Label .MACRO formalparameter,formalparameter Macro DirectiveMacro Directive Examples 100 Chapter 101 Origin DirectiveOrigin Directive 102 Proc and .PROCEND DirectivesProc and .PROCEND Directives Chapter 103 Label User-deﬁned register name REG DirectiveREG Directive Label .REG typedregister Chapter 105 Shlibversion DirectiveShlibversion Directive 106 Space DirectiveSpace Directive Chapter 107 108 Spnum Pseudo-OperationSpnum Pseudo-Operation Chapter 109 String and .STRINGZ Pseudo-OperationsString and .STRINGZ Pseudo-Operations 110 Chapter 111 Subspa DirectiveSubspa Directive Name An identiﬁer that names the current subspace 112 Chapter 113 114 Version DirectiveVersion Directive 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 Chapter 121 Compare and Branch Conditions Comb and ComibCond Description 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 Chapter 125 ﬁlenameLevel 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 130 Binary Search for Highest Bit PositionBinary Search for Highest Bit Position Chapter 131 132 Copying a StringCopying a String Chapter 133 134 Dividing a Double-Word DividendDividing a Double-Word Dividend 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 Chapter 145 Wrong register type usedUse a general register 146 Use a space registerUse a control register Chapter 147 148 Chapter 149 150 Chapter 151 152 Used to invoke the assembler Chapter 153 154 Error MessagesError Messages 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 176 Panic MessagesPanic Messages 2008 20052006 2007 178 User Warning MessagesUser Warning Messages 7006 70037004 7005 180 Chapter 181 182 7201 Limit Error MessagesLimit Error Messages 7200 184 72027203 7204 Chapter 185 Diagnostic Messages 186 Chapter 187 Branching Error MessagesBranching Error Messages 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