re is no length limit: all characters are significant. Symbols are delimited by characters not in that set, or by the beginning of a file (since the source program must end with a newline, the end of a file is not a possible symbol delimiter). *Note Symbols::.  File: as.info, Node: Statements, Next: Constants, Prev: Symbol Intro, Up: Syntax 3.5 Statements ============== A "statement" ends at a newline character (`\n') or line separator character. (The line separator is usually `;', unless this conflicts with the comment character; see *Note Machine Dependencies::.) The newline or separator character is considered part of the preceding statement. Newlines and separators within character constants are an exception: they do not end statements. It is an error to end any statement with end-of-file: the last character of any input file should be a newline. An empty statement is allowed, and may include whitespace. It is ignored. A statement begins with zero or more labels, optionally followed by a key symbol which determines what kind of statement it is. The key symbol determines the syntax of the rest of the statement. If the symbol begins with a dot `.' then the statement is an assembler directive: typically valid for any computer. If the symbol begins with a letter the statement is an assembly language "instruction": it assembles into a machine language instruction. Different versions of `as' for different computers recognize different instructions. In fact, the same symbol may represent a different instruction in a different computer's assembly language. A label is a symbol immediately followed by a colon (`:'). Whitespace before a label or after a colon is permitted, but you may not have whitespace between a label's symbol and its colon. *Note Labels::. For HPPA targets, labels need not be immediately followed by a colon, but the definition of a label must begin in column zero. This also implies that only one label may be defined on each line. label: .directive followed by something another_label: # This is an empty statement. instruction operand_1, operand_2, ...  File: as.info, Node: Constants, Prev: Statements, Up: Syntax 3.6 Constants ============= A constant is a number, written so that its value is known by inspection, without knowing any context. Like this: .byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value. .ascii "Ring the bell\7" # A string constant. .octa 0x123456789abcdef0123456789ABCDEF0 # A bignum. .float 0f-314159265358979323846264338327\ 95028841971.693993751E-40 # - pi, a flonum. * Menu: * Characters:: Character Constants * Numbers:: Number Constants  File: as.info, Node: Characters, Next: Numbers, Up: Constants 3.6.1 Character Constants ------------------------- There are two kinds of character constants. A "character" stands for one character in one byte and its value may be used in numeric expressions. String constants (properly called string _literals_) are potentially many bytes and their values may not be used in arithmetic expressions. * Menu: * Strings:: Strings * Chars:: Characters  File: as.info, Node: Strings, Next: Chars, Up: Characters 3.6.1.1 Strings ............... A "string" is written between double-quotes. It may contain double-quotes or null characters. The way to get special characters into a string is to "escape" these characters: precede them with a backslash `\' character. For example `\\' represents one backslash: the first `\' is an escape which tells `as' to interpret the second character literally as a backslash (which prevents `as' from recognizing the second `\' as an escape character). The complete list of escapes follows. `\b' Mnemonic for backspace; for ASCII this is octal code 010. `\f' Mnemonic for FormFeed; for ASCII this is octal code 014. `\n' Mnemonic for newline; for ASCII this is octal code 012. `\r' Mnemonic for carriage-Return; for ASCII this is octal code 015. `\t' Mnemonic for horizontal Tab; for ASCII this is octal code 011. `\ DIGIT DIGIT DIGIT' An octal character code. The numeric code is 3 octal digits. For compatibility with other Unix systems, 8 and 9 are accepted as digits: for example, `\008' has the value 010, and `\009' the value 011. `\`x' HEX-DIGITS...' A hex character code. All trailing hex digits are combined. Either upper or lower case `x' works. `\\' Represents one `\' character. `\"' Represents one `"' character. Needed in strings to represent this character, because an unescaped `"' would end the string. `\ ANYTHING-ELSE' Any other character when escaped by `\' gives a warning, but assembles as if the `\' was not present. The idea is that if you used an escape sequence you clearly didn't want the literal interpretation of the following character. However `as' has no other interpretation, so `as' knows it is giving you the wrong code and warns you of the fact. Which characters are escapable, and what those escapes represent, varies widely among assemblers. The current set is what we think the BSD 4.2 assembler recognizes, and is a subset of what most C compilers recognize. If you are in doubt, do not use an escape sequence.  File: as.info, Node: Chars, Prev: Strings, Up: Characters 3.6.1.2 Characters .................. A single character may be written as a single quote immediately followed by that character. The same escapes apply to characters as to strings. So if you want to write the character backslash, you must write `'\\' where the first `\' escapes the second `\'. As you can see, the quote is an acute accent, not a grave accent. A newline immediately following an acute accent is taken as a literal character and does not count as the end of a statement. The value of a character constant in a numeric expression is the machine's byte-wide code for that character. `as' assumes your character code is ASCII: `'A' means 65, `'B' means 66, and so on.  File: as.info, Node: Numbers, Prev: Characters, Up: Constants 3.6.2 Number Constants ---------------------- `as' distinguishes three kinds of numbers according to how they are stored in the target machine. _Integers_ are numbers that would fit into an `int' in the C language. _Bignums_ are integers, but they are stored in more than 32 bits. _Flonums_ are floating point numbers, described below. * Menu: * Integers:: Integers * Bignums:: Bignums * Flonums:: Flonums  File: as.info, Node: Integers, Next: Bignums, Up: Numbers 3.6.2.1 Integers ................ A binary integer is `0b' or `0B' followed by zero or more of the binary digits `01'. An octal integer is `0' followed by zero or more of the octal digits (`01234567'). A decimal integer starts with a non-zero digit followed by zero or more digits (`0123456789'). A hexadecimal integer is `0x' or `0X' followed by one or more hexadecimal digits chosen from `0123456789abcdefABCDEF'. Integers have the usual values. To denote a negative integer, use the prefix operator `-' discussed under expressions (*note Prefix Operators: Prefix Ops.).  File: as.info, Node: Bignums, Next: Flonums, Prev: Integers, Up: Numbers 3.6.2.2 Bignums ............... A "bignum" has the same syntax and semantics as an integer except that the number (or its negative) takes more than 32 bits to represent in binary. The distinction is made because in some places integers are permitted while bignums are not.  File: as.info, Node: Flonums, Prev: Bignums, Up: Numbers 3.6.2.3 Flonums ............... A "flonum" represents a floating point number. The translation is indirect: a decimal floating point number from the text is converted by `as' to a generic binary floating point number of more than sufficient precision. This generic floating point number is converted to a particular computer's floating point format (or formats) by a portion of `as' specialized to that computer. A flonum is written by writing (in order) * The digit `0'. (`0' is optional on the HPPA.) * A letter, to tell `as' the rest of the number is a flonum. `e' is recommended. Case is not important. On the H8/300, Renesas / SuperH SH, and AMD 29K architectures, the letter must be one of the letters `DFPRSX' (in upper or lower case). On the ARC, the letter must be one of the letters `DFRS' (in upper or lower case). On the Intel 960 architecture, the letter must be one of the letters `DFT' (in upper or lower case). On the HPPA architecture, the letter must be `E' (upper case only). * An optional sign: either `+' or `-'. * An optional "integer part": zero or more decimal digits. * An optional "fractional part": `.' followed by zero or more decimal digits. * An optional exponent, consisting of: * An `E' or `e'. * Optional sign: either `+' or `-'. * One or more decimal digits. At least one of the integer part or the fractional part must be present. The floating point number has the usual base-10 value. `as' does all processing using integers. Flonums are computed independently of any floating point hardware in the computer running `as'.  File: as.info, Node: Sections, Next: Symbols, Prev: Syntax, Up: Top 4 Sections and Relocation ************************* * Menu: * Secs Background:: Background * Ld Sections:: Linker Sections * As Sections:: Assembler Internal Sections * Sub-Sections:: Sub-Sections * bss:: bss Section  File: as.info, Node: Secs Background, Next: Ld Sections, Up: Sections 4.1 Background ============== Roughly, a section is a range of addresses, with no gaps; all data "in" those addresses is treated the same for some particular purpose. For example there may be a "read only" section. The linker `ld' reads many object files (partial programs) and combines their contents to form a runnable program. When `as' emits an object file, the partial program is assumed to start at address 0. `ld' assigns the final addresses for the partial program, so that different partial programs do not overlap. This is actually an oversimplification, but it suffices to explain how `as' uses sections. `ld' moves blocks of bytes of your program to their run-time addresses. These blocks slide to their run-time addresses as rigid units; their length does not change and neither does the order of bytes within them. Such a rigid unit is called a _section_. Assigning run-time addresses to sections is called "relocation". It includes the task of adjusting mentions of object-file addresses so they refer to the proper run-time addresses. For the H8/300, and for the Renesas / SuperH SH, `as' pads sections if needed to ensure they end on a word (sixteen bit) boundary. An object file written by `as' has at least three sections, any of which may be empty. These are named "text", "data" and "bss" sections. When it generates COFF or ELF output, `as' can also generate whatever other named sections you specify using the `.section' directive (*note `.section': Section.). If you do not use any directives that place output in the `.text' or `.data' sections, these sections still exist, but are empty. When `as' generates SOM or ELF output for the HPPA, `as' can also generate whatever other named sections you specify using the `.space' and `.subspace' directives. See `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001) for details on the `.space' and `.subspace' assembler directives. Additionally, `as' uses different names for the standard text, data, and bss sections when generating SOM output. Program text is placed into the `$CODE$' section, data into `$DATA$', and BSS into `$BSS$'. Within the object file, the text section starts at address `0', the data section follows, and the bss section follows the data section. When generating either SOM or ELF output files on the HPPA, the text section starts at address `0', the data section at address `0x4000000', and the bss section follows the data section. To let `ld' know which data changes when the sections are relocated, and how to change that data, `as' also writes to the object file details of the relocation needed. To perform relocation `ld' must know, each time an address in the object file is mentioned: * Where in the object file is the beginning of this reference to an address? * How long (in bytes) is this reference? * Which section does the address refer to? What is the numeric value of (ADDRESS) - (START-ADDRESS OF SECTION)? * Is the reference to an address "Program-Counter relative"? In fact, every address `as' ever uses is expressed as (SECTION) + (OFFSET INTO SECTION) Further, most expressions `as' computes have this section-relative nature. (For some object formats, such as SOM for the HPPA, some expressions are symbol-relative instead.) In this manual we use the notation {SECNAME N} to mean "offset N into section SECNAME." Apart from text, data and bss sections you need to know about the "absolute" section. When `ld' mixes partial programs, addresses in the absolute section remain unchanged. For example, address `{absolute 0}' is "relocated" to run-time address 0 by `ld'. Although the linker never arranges two partial programs' data sections with overlapping addresses after linking, _by definition_ their absolute sections must overlap. Address `{absolute 239}' in one part of a program is always the same address when the program is running as address `{absolute 239}' in any other part of the program. The idea of sections is extended to the "undefined" section. Any address whose section is unknown at assembly time is by definition rendered {undefined U}--where U is filled in later. Since numbers are always defined, the only way to generate an undefined address is to mention an undefined symbol. A reference to a named common block would be such a symbol: its value is unknown at assembly time so it has section _undefined_. By analogy the word _section_ is used to describe groups of sections in the linked program. `ld' puts all partial programs' text sections in contiguous addresses in the linked program. It is customary to refer to the _text section_ of a program, meaning all the addresses of all partial programs' text sections. Likewise for data and bss sections. Some sections are manipulated by `ld'; others are invented for use of `as' and have no meaning except during assembly.  File: as.info, Node: Ld Sections, Next: As Sections, Prev: Secs Background, Up: Sections 4.2 Linker Sections =================== `ld' deals with just four kinds of sections, summarized below. *named sections* *text section* *data section* These sections hold your program. `as' and `ld' treat them as separate but equal sections. Anything you can say of one section is true of another. When the program is running, however, it is customary for the text section to be unalterable. The text section is often shared among processes: it contains instructions, constants and the like. The data section of a running program is usually alterable: for example, C variables would be stored in the data section. *bss section* This section contains zeroed bytes when your program begins running. It is used to hold uninitialized variables or common storage. The length of each partial program's bss section is important, but because it starts out containing zeroed bytes there is no need to store explicit zero bytes in the object file. The bss section was invented to eliminate those explicit zeros from object files. *absolute section* Address 0 of this section is always "relocated" to runtime address 0. This is useful if you want to refer to an address that `ld' must not change when relocating. In this sense we speak of absolute addresses being "unrelocatable": they do not change during relocation. *undefined section* This "section" is a catch-all for address references to objects not in the preceding sections. An idealized example of three relocatable sections follows. The example uses the traditional section names `.text' and `.data'. Memory addresses are on the horizontal axis. +-----+----+--+ partial program # 1: |ttttt|dddd|00| +-----+----+--+ text data bss seg. seg. seg. +---+---+---+ partial program # 2: |TTT|DDD|000| +---+---+---+ +--+---+-----+--+----+---+-----+~~ linked program: | |TTT|ttttt| |dddd|DDD|00000| +--+---+-----+--+----+---+-----+~~ addresses: 0 ...  File: as.info, Node: As Sections, Next: Sub-Sections, Prev: Ld Sections, Up: Sections 4.3 Assembler Internal Sections =============================== These sections are meant only for the internal use of `as'. They have no meaning at run-time. You do not really need to know about these sections for most purposes; but they can be mentioned in `as' warning messages, so it might be helpful to have an idea of their meanings to `as'. These sections are used to permit the value of every expression in your assembly language program to be a section-relative address. ASSEMBLER-INTERNAL-LOGIC-ERROR! An internal assembler logic error has been found. This means there is a bug in the assembler. expr section The assembler stores complex expression internally as combinations of symbols. When it needs to represent an expression as a symbol, it puts it in the expr section.  File: as.info, Node: Sub-Sections, Next: bss, Prev: As Sections, Up: Sections 4.4 Sub-Sections ================ Assembled bytes conventionally fall into two sections: text and data. You may have separate groups of data in named sections that you want to end up near to each other in the object file, even though they are not contiguous in the assembler source. `as' allows you to use "subsections" for this purpose. Within each section, there can be numbered subsections with values from 0 to 8192. Objects assembled into the same subsection go into the object file together with other objects in the same subsection. For example, a compiler might want to store constants in the text section, but might not want to have them interspersed with the program being assembled. In this case, the compiler could issue a `.text 0' before each section of code being output, and a `.text 1' before each group of constants being output. Subsections are optional. If you do not use subsections, everything goes in subsection number zero. Each subsection is zero-padded up to a multiple of four bytes. (Subsections may be padded a different amount on different flavors of `as'.) Subsections appear in your object file in numeric order, lowest numbered to highest. (All this to be compatible with other people's assemblers.) The object file contains no representation of subsections; `ld' and other programs that manipulate object files see no trace of them. They just see all your text subsections as a text section, and all your data subsections as a data section. To specify which subsection you want subsequent statements assembled into, use a numeric argument to specify it, in a `.text EXPRESSION' or a `.data EXPRESSION' statement. When generating COFF output, you can also use an extra subsection argument with arbitrary named sections: `.section NAME, EXPRESSION'. When generating ELF output, you can also use the `.subsection' directive (*note SubSection::) to specify a subsection: `.subsection EXPRESSION'. EXPRESSION should be an absolute expression (*note Expressions::). If you just say `.text' then `.text 0' is assumed. Likewise `.data' means `.data 0'. Assembly begins in `text 0'. For instance: .text 0 # The default subsection is text 0 anyway. .ascii "This lives in the first text subsection. *" .text 1 .ascii "But this lives in the second text subsection." .data 0 .ascii "This lives in the data section," .ascii "in the first data subsection." .text 0 .ascii "This lives in the first text section," .ascii "immediately following the asterisk (*)." Each section has a "location counter" incremented by one for every byte assembled into that section. Because subsections are merely a convenience restricted to `as' there is no concept of a subsection location counter. There is no way to directly manipulate a location counter--but the `.align' directive changes it, and any label definition captures its current value. The location counter of the section where statements are being assembled is said to be the "active" location counter.  File: as.info, Node: bss, Prev: Sub-Sections, Up: Sections 4.5 bss Section =============== The bss section is used for local common variable storage. You may allocate address space in the bss section, but you may not dictate data to load into it before your program executes. When your program starts running, all the contents of the bss section are zeroed bytes. The `.lcomm' pseudo-op defines a symbol in the bss section; see *Note `.lcomm': Lcomm. The `.comm' pseudo-op may be used to declare a common symbol, which is another form of uninitialized symbol; see *Note `.comm': Comm. When assembling for a target which supports multiple sections, such as ELF or COFF, you may switch into the `.bss' section and define symbols as usual; see *Note `.section': Section. You may only assemble zero values into the section. Typically the section will only contain symbol definitions and `.skip' directives (*note `.skip': Skip.).  File: as.info, Node: Symbols, Next: Expressions, Prev: Sections, Up: Top 5 Symbols ********* Symbols are a central concept: the programmer uses symbols to name things, the linker uses symbols to link, and the debugger uses symbols to debug. _Warning:_ `as' does not place symbols in the object file in the same order they were declared. This may break some debuggers. * Menu: * Labels:: Labels * Setting Symbols:: Giving Symbols Other Values * Symbol Names:: Symbol Names * Dot:: The Special Dot Symbol * Symbol Attributes:: Symbol Attributes  File: as.info, Node: Labels, Next: Setting Symbols, Up: Symbols 5.1 Labels ========== A "label" is written as a symbol immediately followed by a colon `:'. The symbol then represents the current value of the active location counter, and is, for example, a suitable instruction operand. You are warned if you use the same symbol to represent two different locations: the first definition overrides any other definitions. On the HPPA, the usual form for a label need not be immediately followed by a colon, but instead must start in column zero. Only one label may be defined on a single line. To work around this, the HPPA version of `as' also provides a special directive `.label' for defining labels more flexibly.  File: as.info, Node: Setting Symbols, Next: Symbol Names, Prev: Labels, Up: Symbols 5.2 Giving Symbols Other Values =============================== A symbol can be given an arbitrary value by writing a symbol, followed by an equals sign `=', followed by an expression (*note Expressions::). This is equivalent to using the `.set' directive. *Note `.set': Set. In the same way, using a double equals sign `='`=' here represents an equivalent of the `.eqv' directive. *Note `.eqv': Eqv. Blackfin does not support symbol assignment with `='.  File: as.info, Node: Symbol Names, Next: Dot, Prev: Setting Symbols, Up: Symbols 5.3 Symbol Names ================ Symbol names begin with a letter or with one of `._'. On most machines, you can also use `$' in symbol names; exceptions are noted in *Note Machine Dependencies::. That character may be followed by any string of digits, letters, dollar signs (unless otherwise noted for a particular target machine), and underscores. Case of letters is significant: `foo' is a different symbol name than `Foo'. Each symbol has exactly one name. Each name in an assembly language program refers to exactly one symbol. You may use that symbol name any number of times in a program. Local Symbol Names ------------------ A local symbol is any symbol beginning with certain local label prefixes. By default, the local label prefix is `.L' for ELF systems or `L' for traditional a.out systems, but each target may have its own set of local label prefixes. On the HPPA local symbols begin with `L$'. Local symbols are defined and used within the assembler, but they are normally not saved in object files. Thus, they are not visible when debugging. You may use the `-L' option (*note Include Local Symbols: `-L': L.) to retain the local symbols in the object files. Local Labels ------------ Local labels help compilers and programmers use names temporarily. They create symbols which are guaranteed to be unique over the entire scope of the input source code and which can be referred to by a simple notation. To define a local label, write a label of the form `N:' (where N represents any positive integer). To refer to the most recent previous definition of that label write `Nb', using the same number as when you defined the label. To refer to the next definition of a local label, write `Nf'--the `b' stands for "backwards" and the `f' stands for "forwards". There is no restriction on how you can use these labels, and you can reuse them too. So that it is possible to repeatedly define the same local label (using the same number `N'), although you can only refer to the most recently defined local label of that number (for a backwards reference) or the next definition of a specific local label for a forward reference. It is also worth noting that the first 10 local labels (`0:'...`9:') are implemented in a slightly more efficient manner than the others. Here is an example: 1: branch 1f 2: branch 1b 1: branch 2f 2: branch 1b Which is the equivalent of: label_1: branch label_3 label_2: branch label_1 label_3: branch label_4 label_4: branch label_3 Local label names are only a notational device. They are immediately transformed into more conventional symbol names before the assembler uses them. The symbol names are stored in the symbol table, appear in error messages, and are optionally emitted to the object file. The names are constructed using these parts: `_local label prefix_' All local symbols begin with the system-specific local label prefix. Normally both `as' and `ld' forget symbols that start with the local label prefix. These labels are used for symbols you are never intended to see. If you use the `-L' option then `as' retains these symbols in the object file. If you also instruct `ld' to retain these symbols, you may use them in debugging. `NUMBER' This is the number that was used in the local label definition. So if the label is written `55:' then the number is `55'. `C-B' This unusual character is included so you do not accidentally invent a symbol of the same name. The character has ASCII value of `\002' (control-B). `_ordinal number_' This is a serial number to keep the labels distinct. The first definition of `0:' gets the number `1'. The 15th definition of `0:' gets the number `15', and so on. Likewise the first definition of `1:' gets the number `1' and its 15th definition gets `15' as well. So for example, the first `1:' may be named `.L1C-B1', and the 44th `3:' may be named `.L3C-B44'. Dollar Local Labels ------------------- `as' also supports an even more local form of local labels called dollar labels. These labels go out of scope (i.e., they become undefined) as soon as a non-local label is defined. Thus they remain valid for only a small region of the input source code. Normal local labels, by contrast, remain in scope for the entire file, or until they are redefined by another occurrence of the same local label. Dollar labels are defined in exactly the same way as ordinary local labels, except that they have a dollar sign suffix to their numeric value, e.g., `55$:'. They can also be distinguished from ordinary local labels by their transformed names which use ASCII character `\001' (control-A) as the magic character to distinguish them from ordinary labels. For example, the fifth definition of `6$' may be named `.L6C-A5'.  File: as.info, Node: Dot, Next: Symbol Attributes, Prev: Symbol Names, Up: Symbols 5.4 The Special Dot Symbol ========================== The special symbol `.' refers to the current address that `as' is assembling into. Thus, the expression `melvin: .long .' defines `melvin' to contain its own address. Assigning a value to `.' is treated the same as a `.org' directive. Thus, the expression `.=.+4' is the same as saying `.space 4'.  File: as.info, Node: Symbol Attributes, Prev: Dot, Up: Symbols 5.5 Symbol Attributes ===================== Every symbol has, as well as its name, the attributes "Value" and "Type". Depending on output format, symbols can also have auxiliary attributes. If you use a symbol without defining it, `as' assumes zero for all these attributes, and probably won't warn you. This makes the symbol an externally defined symbol, which is generally what you would want. * Menu: * Symbol Value:: Value * Symbol Type:: Type * a.out Symbols:: Symbol Attributes: `a.out' * COFF Symbols:: Symbol Attributes for COFF * SOM Symbols:: Symbol Attributes for SOM  File: as.info, Node: Symbol Value, Next: Symbol Type, Up: Symbol Attributes 5.5.1 Value ----------- The value of a symbol is (usually) 32 bits. For a symbol which labels a location in the text, data, bss or absolute sections the value is the number of addresses from the start of that section to the label. Naturally for text, data and bss sections the value of a symbol changes as `ld' changes section base addresses during linking. Absolute symbols' values do not change during linking: that is why they are called absolute. The value of an undefined symbol is treated in a special way. If it is 0 then the symbol is not defined in this assembler source file, and `ld' tries to determine its value from other files linked into the same program. You make this kind of symbol simply by mentioning a symbol name without defining it. A non-zero value represents a `.comm' common declaration. The value is how much common storage to reserve, in bytes (addresses). The symbol refers to the first address of the allocated storage.  File: as.info, Node: Symbol Type, Next: a.out Symbols, Prev: Symbol Value, Up: Symbol Attributes 5.5.2 Type ---------- The type attribute of a symbol contains relocation (section) information, any flag settings indicating that a symbol is external, and (optionally), other information for linkers and debuggers. The exact format depends on the object-code output format in use.  File: as.info, Node: a.out Symbols, Next: COFF Symbols, Prev: Symbol Type, Up: Symbol Attributes 5.5.3 Symbol Attributes: `a.out' -------------------------------- * Menu: * Symbol Desc:: Descriptor * Symbol Other:: Other  File: as.info, Node: Symbol Desc, Next: Symbol Other, Up: a.out Symbols 5.5.3.1 Descriptor .................. This is an arbitrary 16-bit value. You may establish a symbol's descriptor value by using a `.desc' statement (*note `.desc': Desc.). A descriptor value means nothing to `as'.  File: as.info, Node: Symbol Other, Prev: Symbol Desc, Up: a.out Symbols 5.5.3.2 Other ............. This is an arbitrary 8-bit value. It means nothing to `as'.  File: as.info, Node: COFF Symbols, Next: SOM Symbols, Prev: a.out Symbols, Up: Symbol Attributes 5.5.4 Symbol Attributes for COFF -------------------------------- The COFF format supports a multitude of auxiliary symbol attributes; like the primary symbol attributes, they are set between `.def' and `.endef' directives. 5.5.4.1 Primary Attributes .......................... The symbol name is set with `.def'; the value and type, respectively, with `.val' and `.type'. 5.5.4.2 Auxiliary Attributes ............................ The `as' directives `.dim', `.line', `.scl', `.size', `.tag', and `.weak' can generate auxiliary symbol table information for COFF.  File: as.info, Node: SOM Symbols, Prev: COFF Symbols, Up: Symbol Attributes 5.5.5 Symbol Attributes for SOM ------------------------------- The SOM format for the HPPA supports a multitude of symbol attributes set with the `.EXPORT' and `.IMPORT' directives. The attributes are described in `HP9000 Series 800 Assembly Language Reference Manual' (HP 92432-90001) under the `IMPORT' and `EXPORT' assembler directive documentation.  File: as.info, Node: Expressions, Next: Pseudo Ops, Prev: Symbols, Up: Top 6 Expressions ************* An "expression" specifies an address or numeric value. Whitespace may precede and/or follow an expression. The result of an expression must be an absolute number, or else an offset into a particular section. If an expression is not absolute, and there is not enough information when `as' sees the expression to know its section, a second pass over the source program might be necessary to interpret the expression--but the second pass is currently not implemented. `as' aborts with an error message in this situation. * Menu: * Empty Exprs:: Empty Expressions * Integer Exprs:: Integer Expressions  File: as.info, Node: Empty Exprs, Next: Integer Exprs, Up: Expressions 6.1 Empty Expressions ===================== An empty expression has no value: it is just whitespace or null. Wherever an absolute expression is required, you may omit the expression, and `as' assumes a value of (absolute) 0. This is compatible with other assemblers.  File: as.info, Node: Integer Exprs, Prev: Empty Exprs, Up: Expressions 6.2 Integer Expressions ======================= An "integer expression" is one or more _arguments_ delimited by _operators_. * Menu: * Arguments:: Arguments * Operators:: Operators * Prefix Ops:: Prefix Operators * Infix Ops:: Infix Operators  File: as.info, Node: Arguments, Next: Operators, Up: Integer Exprs 6.2.1 Arguments --------------- "Arguments" are symbols, numbers or subexpressions. In other contexts arguments are sometimes called "arithmetic operands". In this manual, to avoid confusing them with the "instruction operands" of the machine language, we use the term "argument" to refer to parts of expressions only, reserving the word "operand" to refer only to machine instruction operands. Symbols are evaluated to yield {SECTION NNN} where SECTION is one of text, data, bss, absolute, or undefined. NNN is a signed, 2's complement 32 bit integer. Numbers are usually integers. A number can be a flonum or bignum. In this case, you are warned that only the low order 32 bits are used, and `as' pretends these 32 bits are an integer. You may write integer-manipulating instructions that act on exotic constants, compatible with other assemblers. Subexpressions are a left parenthesis `(' followed by an integer expression, followed by a right parenthesis `)'; or a prefix operator followed by an argument.  File: as.info, Node: Operators, Next: Prefix Ops, Prev: Arguments, Up: Integer Exprs 6.2.2 Operators --------------- "Operators" are arithmetic functions, like `+' or `%'. Prefix operators are followed by an argument. Infix operators appear between their arguments. Operators may be preceded and/or followed by whitespace.  File: as.info, Node: Prefix Ops, Next: Infix Ops, Prev: Operators, Up: Integer Exprs 6.2.3 Prefix Operator --------------------- `as' has the following "prefix operators". They each take one argument, which must be absolute. `-' "Negation". Two's complement negation. `~' "Complementation". Bitwise not.  File: as.info, Node: Infix Ops, Prev: Prefix Ops, Up: Integer Exprs 6.2.4 Infix Operators --------------------- "Infix operators" take two arguments, one on either side. Operators have precedence, but operations with equal precedence are performed left to right. Apart from `+' or `-', both arguments must be absolute, and the result is absolute. 1. Highest Precedence `*' "Multiplication". `/' "Division". Truncation is the same as the C operator `/' `%' "Remainder". `<<' "Shift Left". Same as the C operator `<<'. `>>' "Shift Right". Same as the C operator `>>'. 2. Intermediate precedence `|' "Bitwise Inclusive Or". `&' "Bitwise And". `^' "Bitwise Exclusive Or". `!' "Bitwise Or Not". 3. Low Precedence `+' "Addition". If either argument is absolute, the result has the section of the other argument. You may not add together arguments from different sections. `-' "Subtraction". If the right argument is absolute, the result has the section of the left argument. If both arguments are in the same section, the result is absolute. You may not subtract arguments from different sections. `==' "Is Equal To" `<>' `!=' "Is Not Equal To" `<' "Is Less Than" `>' "Is Greater Than" `>=' "Is Greater Than Or Equal To" `<=' "Is Less Than Or Equal To" The comparison operators can be used as infix operators. A true results has a value of -1 whereas a false result has a value of 0. Note, these operators perform signed comparisons. 4. Lowest Precedence `&&' "Logical And". `||' "Logical Or". These two logical operations can be used to combine the results of sub expressions. Note, unlike the comparison operators a true result returns a value of 1 but a false results does still return 0. Also note that the logical or operator has a slightly lower precedence than logical and. In short, it's only meaningful to add or subtract the _offsets_ in an address; you can only have a defined section in one of the two arguments.  File: as.info, Node: Pseudo Ops, Next: Object Attributes, Prev: Expressions, Up: Top 7 Assembler Directives ********************** All assembler directives have names that begin with a period (`.'). The rest of the name is letters, usually in lower case. This chapter discusses directives that are available regardless of the target machine configuration for the GNU assembler. Some machine configurations provide additional directives. *Note Machine Dependencies::. * Menu: * Abort:: `.abort' * ABORT (COFF):: `.ABORT' * Align:: `.align ABS-EXPR , ABS-EXPR' * Altmacro:: `.altmacro' * Ascii:: `.ascii "STRING"'... * Asciz:: `.asciz "STRING"'... * Balign:: `.balign ABS-EXPR , ABS-EXPR' * Byte:: `.byte EXPRESSIONS' * CFI directives:: `.cfi_startproc [simple]', `.cfi_endproc', etc. * Comm:: `.comm SYMBOL , LENGTH ' * Data:: `.data SUBSECTION' * Def:: `.def NAME' * Desc:: `.desc SYMBOL, ABS-EXPRESSION' * Dim:: `.dim' * Double:: `.double FLONUMS' * Eject:: `.eject' * Else:: `.else' * Elseif:: `.elseif' * End:: `.end' * Endef:: `.endef' * Endfunc:: `.endfunc' * Endif:: `.endif' * Equ:: `.equ SYMBOL, EXPRESSION' * Equiv:: `.equiv SYMBOL, EXPRESSION' * Eqv:: `.eqv SYMBOL, EXPRESSION' * Err:: `.err' * Error:: `.error STRING' * Exitm:: `.exitm' * Extern:: `.extern' * Fail:: `.fail' * File:: `.file' * Fill:: `.fill REPEAT , SIZE , VALUE' * Float:: `.float FLONUMS' * Func:: `.func' * Global:: `.global SYMBOL', `.globl SYMBOL' * Gnu_attribute:: `.gnu_attribute TAG,VALUE' * Hidden:: `.hidden NAMES' * hword:: `.hword EXPRESSIONS' * Ident:: `.ident' * If:: `.if ABSOLUTE EXPRESSION' * Incbin:: `.incbin "FILE"[,SKIP[,COUNT]]' * Include:: `.include "FILE"' * Int:: `.int EXPRESSIONS' * Internal:: `.internal NAMES' * Irp:: `.irp SYMBOL,VALUES'... * Irpc:: `.irpc SYMBOL,VALUES'... * Lcomm:: `.lcomm SYMBOL , LENGTH' * Lflags:: `.lflags' * Line:: `.line LINE-NUMBER' * Linkonce:: `.linkonce [TYPE]' * List:: `.list' * Ln:: `.ln LINE-NUMBER' * Loc:: `.loc FILENO LINENO' * Loc_mark_labels:: `.loc_mark_labels ENABLE' * Local:: `.local NAMES' * Long:: `.long EXPRESSIONS' * Macro:: `.macro NAME ARGS'... * MRI:: `.mri VAL' * Noaltmacro:: `.noaltmacro' * Nolist:: `.nolist' * Octa:: `.octa BIGNUMS' * Org:: `.org NEW-LC, FILL' * P2align:: `.p2align ABS-EXPR, ABS-EXPR, ABS-EXPR' * PopSection:: `.popsection' * Previous:: `.previous' * Print:: `.print STRING' * Protected:: `.protected NAMES' * Psize:: `.psize LINES, COLUMNS' * Purgem:: `.purgem NAME' * PushSection:: `.pushsection NAME' * Quad:: `.quad BIGNUMS' * Reloc:: `.reloc OFFSET, RELOC_NAME[, EXPRESSION]' * Rept:: `.rept COUNT' * Sbttl:: `.sbttl "SUBHEADING"' * Scl:: `.scl CLASS' * Section:: `.section NAME[, FLAGS]' * Set:: `.set SYMBOL, EXPRESSION' * Short:: `.short EXPRESSIONS' * Single:: `.single FLONUMS' * Size:: `.size [NAME , EXPRESSION]' * Skip:: `.skip SIZE , FILL' * Sleb128:: `.sleb128 EXPRESSIONS' * Space:: `.space SIZE , FILL' * Stab:: `.stabd, .stabn, .stabs' * String:: `.string "STR"', `.string8 "STR"', `.string16 "STR"', `.string32 "STR"', `.string64 "STR"' * Struct:: `.struct EXPRESSION' * SubSection:: `.subsection' * Symver:: `.symver NAME,NAME2@NODENAME' * Tag:: `.tag STRUCTNAME' * Text:: `.text SUBSECTION' * Title:: `.title "HEADING"' * Type:: `.type ' * Uleb128:: `.uleb128 EXPRESSIONS' * Val:: `.val ADDR' * Version:: `.version "STRING"' * VTableEntry:: `.vtable_entry TABLE, OFFSET' * VTableInherit:: `.vtable_inherit CHILD, PARENT' * Warning:: `.warning STRING' * Weak:: `.weak NAMES' * Weakref:: `.weakref ALIAS, SYMBOL' * Word:: `.word EXPRESSIONS' * Deprecated:: Deprecated Directives  File: as.info, Node: Abort, Next: ABORT (COFF), Up: Pseudo Ops 7.1 `.abort' ============ This directive stops the assembly immediately. It is for compatibility with other assemblers. The original idea was that the assembly language source would be piped into the assembler. If the sender of the source quit, it could use this directive tells `as' to quit also. One day `.abort' will not be supported.  File: as.info, Node: ABORT (COFF), Next: Align, Prev: Abort, Up: Pseudo Ops 7.2 `.ABORT' (COFF) =================== When producing COFF output, `as' accepts this directive as a synonym for `.abort'.  File: as.info, Node: Align, Next: Altmacro, Prev: ABORT (COFF), Up: Pseudo Ops 7.3 `.align ABS-EXPR, ABS-EXPR, ABS-EXPR' ========================================= Pad the location counter (in the current subsection) to a particular storage boundary. The first expression (which must be absolute) is the alignment required, as described below. The second expression (also absolute) gives the fill value to be stored in the padding bytes. It (and the comma) may be omitted. If it is omitted, the padding bytes are normally zero. However, on some systems, if the section is marked as containing code and the fill value is omitted, the space is filled with no-op instructions. The third expression is also absolute, and is also optional. If it is present, it is the maximum number of bytes that should be skipped by this alignment directive. If doing the alignment would require skipping more bytes than the specified maximum, then the alignment is not done at all. You can omit the fill value (the second argument) entirely by simply using two commas after the required alignment; this can be useful if you want the alignment to be filled with no-op instructions when appropriate. The way the required alignment is specified varies from system to system. For the arc, hppa, i386 using ELF, i860, iq2000, m68k, or32, s390, sparc, tic4x, tic80 and xtensa, the first expression is the alignment request in bytes. For example `.align 8' advances the location counter until it is a multiple of 8. If the location counter is already a multiple of 8, no change is needed. For the tic54x, the first expression is the alignment request in words. For other systems, including ppc, i386 using a.out format, arm and strongarm, it is the number of low-order zero bits the location counter must have after advancement. For example `.align 3' advances the location counter until it a multiple of 8. If the location counter is already a multiple of 8, no change is needed. This inconsistency is due to the different behaviors of the various native assemblers for these systems which GAS must emulate. GAS also provides `.balign' and `.p2align' directives, described later, which have a consistent behavior across all architectures (but are specific to GAS).  File: as.info, Node: Altmacro, Next: Ascii, Prev: Align, Up: Pseudo Ops 7.4 `.altmacro' =============== Enable alternate macro mode, enabling: `LOCAL NAME [ , ... ]' One additional directive, `LOCAL', is available. It is used to generate a string replacement for each of the NAME arguments, and replace any instances of NAME in each macro expansion. The replacement string is unique in the assembly, and different for each separate macro expansion. `LOCAL' allows you to write macros that define symbols, without fear of conflict between separate macro expansions. `String delimiters' You can write strings delimited in these other ways besides `"STRING"': `'STRING'' You can delimit strings with single-quote characters. `' You can delimit strings with matching angle brackets. `single-character string escape' To include any single character literally in a string (even if the character would otherwise have some special meaning), you can prefix the character with `!' (an exclamation mark). For example, you can write `<4.3 !> 5.4!!>' to get the literal text `4.3 > 5.4!'. `Expression results as strings' You can write `%EXPR' to evaluate the expression EXPR and use the result as a string.  File: as.info, Node: Ascii, Next: Asciz, Prev: Altmacro, Up: Pseudo Ops 7.5 `.ascii "STRING"'... ======================== `.ascii' expects zero or more string literals (*note Strings::) separated by commas. It assembles each string (with no automatic trailing zero byte) into consecutive addresses.  File: as.info, Node: Asciz, Next: Balign, Prev: Ascii, Up: Pseudo Ops 7.6 `.asciz "STRING"'... ======================== `.asciz' is just like `.ascii', but each string is followed by a zero byte. The "z" in `.asciz' stands for "zero".  File: as.info, Node: Balign, Next: Byte, Prev: Asciz, Up: Pseudo Ops 7.7 `.balign[wl] ABS-EXPR, ABS-EXPR, ABS-EXPR' ============================================== Pad the location counter (in the current subsection) to a particular storage boundary. The first expression (which must be absolute) is the alignment request in bytes. For example `.balign 8' advances the location counter until it is a multiple of 8. If the location counter is already a multiple of 8, no change is needed. The second expression (also absolute) gives the fill value to be stored in the padding bytes. It (and the comma) may be omitted. If it is omitted, the padding bytes are normally zero. However, on some systems, if the section is marked as containing code and the fill value is omitted, the space is filled with no-op instructions. The third expression is also absolute, and is also optional. If it is present, it is the maximum number of bytes that should be skipped by this alignment directive. If doing the alignment would require skipping more bytes than the specified maximum, then the alignment is not done at all. You can omit the fill value (the second argument) entirely by simply using two commas after the required alignment; this can be useful if you want the alignment to be filled with no-op instructions when appropriate. The `.balignw' and `.balignl' directives are variants of the `.balign' directive. The `.balignw' directive treats the fill pattern as a two byte word value. The `.balignl' directives treats the fill pattern as a four byte longword value. For example, `.balignw 4,0x368d' will align to a multiple of 4. If it skips two bytes, they will be filled in with the value 0x368d (the exact placement of the bytes depends upon the endianness of the processor). If it skips 1 or 3 bytes, the fill value is undefined.  File: as.info, Node: Byte, Next: CFI directives, Prev: Balign, Up: Pseudo Ops 7.8 `.byte EXPRESSIONS' ======================= `.byte' expects zero or more expressions, separated by commas. Each expression is assembled into the next byte.  File: as.info, Node: CFI directives, Next: Comm, Prev: Byte, Up: Pseudo Ops 7.9 `.cfi_sections SECTION_LIST' ================================ `.cfi_sections' may be used to specify whether CFI directives should emit `.eh_frame' section and/or `.debug_frame' section. If SECTION_LIST is `.eh_frame', `.eh_frame' is emitted, if SECTION_LIST is `.debug_frame', `.debug_frame' is emitted. To emit both use `.eh_frame, .debug_frame'. The default if this directive is not used is `.cfi_sections .eh_frame'. 7.10 `.cfi_startproc [simple]' ============================== `.cfi_startproc' is used at the beginning of each function that should have an entry in `.eh_frame'. It initializes some internal data structures. Don't forget to close the function by `.cfi_endproc'. Unless `.cfi_startproc' is used along with parameter `simple' it also emits some architecture dependent initial CFI instructions. 7.11 `.cfi_endproc' =================== `.cfi_endproc' is used at the end of a function where it closes its unwind entry previously opened by `.cfi_startproc', and emits it to `.eh_frame'. 7.12 `.cfi_personality ENCODING [, EXP]' ======================================== `.cfi_personality' defines personality routine and its encoding. ENCODING must be a constant determining how the personality should be encoded. If it is 255 (`DW_EH_PE_omit'), second argument is not present, otherwise second argument should be a constant or a symbol name. When using indirect encodings, the symbol provided should be the location where personality can be loaded from, not the personality routine itself. The default after `.cfi_startproc' is `.cfi_personality 0xff', no personality routine. 7.13 `.cfi_lsda ENCODING [, EXP]' ================================= `.cfi_lsda' defines LSDA and its encoding. ENCODING must be a constant determining how the LSDA should be encoded. If it is 255 (`DW_EH_PE_omit'), second argument is not present, otherwise second argument should be a constant or a symbol name. The default after `.cfi_startproc' is `.cfi_lsda 0xff', no LSDA. 7.14 `.cfi_def_cfa REGISTER, OFFSET' ==================================== `.cfi_def_cfa' defines a rule for computing CFA as: take address from REGISTER and add OFFSET to it. 7.15 `.cfi_def_cfa_register REGISTER' ===================================== `.cfi_def_cfa_register' modifies a rule for computing CFA. From now on REGISTER will be used instead of the old one. Offset remains the same. 7.16 `.cfi_def_cfa_offset OFFSET' ================================= `.cfi_def_cfa_offset' modifies a rule for computing CFA. Register remains the same, but OFFSET is new. Note that it is the absolute offset that will be added to a defined register to compute CFA address. 7.17 `.cfi_adjust_cfa_offset OFFSET' ==================================== Same as `.cfi_def_cfa_offset' but OFFSET is a relative value that is added/substracted from the previous offset. 7.18 `.cfi_offset REGISTER, OFFSET' =================================== Previous value of REGISTER is saved at offset OFFSET from CFA. 7.19 `.cfi_rel_offset REGISTER, OFFSET' ======================================= Previous value of REGISTER is saved at offset OFFSET from the current CFA register. This is transformed to `.cfi_offset' using the known displacement of the CFA register from the CFA. This is often easier to use, because the number will match the code it's annotating. 7.20 `.cfi_register REGISTER1, REGISTER2' ========================================= Previous value of REGISTER1 is saved in register REGISTER2. 7.21 `.cfi_restore REGISTER' ============================ `.cfi_restore' says that the rule for REGISTER is now the same as it was at the beginning of the function, after all initial instruction added by `.cfi_startproc' were executed. 7.22 `.cfi_undefined REGISTER' ============================== From now on the previous value of REGISTER can't be restored anymore. 7.23 `.cfi_same_value REGISTER' =============================== Current value of REGISTER is the same like in the previous frame, i.e. no restoration needed. 7.24 `.cfi_remember_state', =========================== First save all current rules for all registers by `.cfi_remember_state', then totally screw them up by subsequent `.cfi_*' directives and when everything is hopelessly bad, use `.cfi_restore_state' to restore the previous saved state. 7.25 `.cfi_return_column REGISTER' ================================== Change return column REGISTER, i.e. the return address is either directly in REGISTER or can be accessed by rules for REGISTER. 7.26 `.cfi_signal_frame' ======================== Mark current function as signal trampoline. 7.27 `.cfi_window_save' ======================= SPARC register window has been saved. 7.28 `.cfi_escape' EXPRESSION[, ...] ==================================== Allows the user to add arbitrary bytes to the unwind info. One might use this to add OS-specific CFI opcodes, or generic CFI opcodes that GAS does not yet support. 7.29 `.cfi_val_encoded_addr REGISTER, ENCODING, LABEL' ====================================================== The current value of REGISTER is LABEL. The value of LABEL will be encoded in the output file according to ENCODING; see the description of `.cfi_personality' for details on this encoding. The usefulness of equating a register to a fixed label is probably limited to the return address register. Here, it can be useful to mark a code segment that has only one return address which is reached by a direct branch and no copy of the return address exists in memory or another register.  File: as.info, Node: Comm, Next: Data, Prev: CFI directives, Up: Pseudo Ops 7.30 `.comm SYMBOL , LENGTH ' ============================= `.comm' declares a common symbol named SYMBOL. When linking, a common symbol in one object file may be merged with a defined or common symbol of the same name in another object file. If `ld' does not see a definition for the symbol-just one or more common symbols-then it will allocate LENGTH bytes of uninitialized memory. LENGTH must be an absolute expression. If `ld' sees multiple common symbols with the same name, and they do not all have the same size, it will allocate space using the largest size. When using ELF or (as a GNU extension) PE, the `.comm' directive takes an optional third argument. This is the desired alignment of the symbol, specified for ELF as a byte boundary (for example, an alignment of 16 means that the least significant 4 bits of the address should be zero), and for PE as a power of two (for example, an alignment of 5 means aligned to a 32-byte boundary). The alignment must be an absolute expression, and it must be a power of two. If `ld' allocates uninitialized memory for the common symbol, it will use the alignment when placing the symbol. If no alignment is specified, `as' will set the alignment to the largest power of two less than or equal to the size of the symbol, up to a maximum of 16 on ELF, or the default section alignment of 4 on PE(1). The syntax for `.comm' differs slightly on the HPPA. The syntax is `SYMBOL .comm, LENGTH'; SYMBOL is optional. ---------- Footnotes ---------- (1) This is not the same as the executable image file alignment controlled by `ld''s `--section-alignment' option; image file sections in PE are aligned to multiples of 4096, which is far too large an alignment for ordinary variables. It is rather the default alignment for (non-debug) sections within object (`*.o') files, which are less strictly aligned.  File: as.info, Node: Data, Next: Def, Prev: Comm, Up: Pseudo Ops 7.31 `.data SUBSECTION' ======================= `.data' tells `as' to assemble the following statements onto the end of the data subsection numbered SUBSECTION (which is an absolute expression). If SUBSECTION is omitted, it defaults to zero.  File: as.info, Node: Def, Next: Desc, Prev: Data, Up: Pseudo Ops 7.32 `.def NAME' ================ Begin defining debugging information for a symbol NAME; the definition extends until the `.endef' directive is encountered.  File: as.info, Node: Desc, Next: Dim, Prev: Def, Up: Pseudo Ops 7.33 `.desc SYMBOL, ABS-EXPRESSION' =================================== This directive sets the descriptor of the symbol (*note Symbol Attributes::) to the low 16 bits of an absolute expression. The `.desc' directive is not available when `as' is configured for COFF output; it is only for `a.out' or `b.out' object format. For the sake of compatibility, `as' accepts it, but produces no output, when configured for COFF.  File: as.info, Node: Dim, Next: Double, Prev: Desc, Up: Pseudo Ops 7.34 `.dim' =========== This directive is generated by compilers to include auxiliary debugging information in the symbol table. It is only permitted inside `.def'/`.endef' pairs.  File: as.info, Node: Double, Next: Eject, Prev: Dim, Up: Pseudo Ops 7.35 `.double FLONUMS' ====================== `.double' expects zero or more flonums, separated by commas. It assembles floating point numbers. The exact kind of floating point numbers emitted depends on how `as' is configured. *Note Machine Dependencies::.  File: as.info, Node: Eject, Next: Else, Prev: Double, Up: Pseudo Ops 7.36 `.eject' ============= Force a page break at this point, when generating assembly listings.  File: as.info, Node: Else, Next: Elseif, Prev: Eject, Up: Pseudo Ops 7.37 `.else' ============ `.else' is part of the `as' support for conditional assembly; see *Note `.if': If. It marks the beginning of a section of code to be assembled if the condition for the preceding `.if' was false.  File: as.info, Node: Elseif, Next: End, Prev: Else, Up: Pseudo Ops 7.38 `.elseif' ============== `.elseif' is part of the `as' support for conditional assembly; see *Note `.if': If. It is shorthand for beginning a new `.if' block that would otherwise fill the entire `.else' section.  File: as.info, Node: End, Next: Endef, Prev: Elseif, Up: Pseudo Ops 7.39 `.end' =========== `.end' marks the end of the assembly file. `as' does not process anything in the file past the `.end' directive.  File: as.info, Node: Endef, Next: Endfunc, Prev: End, Up: Pseudo Ops 7.40 `.endef' ============= This directive flags the end of a symbol definition begun with `.def'.  File: as.info, Node: Endfunc, Next: Endif, Prev: Endef, Up: Pseudo Ops 7.41 `.endfunc' =============== `.endfunc' marks the end of a function specified with `.func'.  File: as.info, Node: Endif, Next: Equ, Prev: Endfunc, Up: Pseudo Ops 7.42 `.endif' ============= `.endif' is part of the `as' support for conditional assembly; it marks the end of a block of code that is only assembled conditionally. *Note `.if': If.  File: as.info, Node: Equ, Next: Equiv, Prev: Endif, Up: Pseudo Ops 7.43 `.equ SYMBOL, EXPRESSION' ============================== This directive sets the value of SYMBOL to EXPRESSION. It is synonymous with `.set'; see *Note `.set': Set. The syntax for `equ' on the HPPA is `SYMBOL .equ EXPRESSION'. The syntax for `equ' on the Z80 is `SYMBOL equ EXPRESSION'. On the Z80 it is an eror if SYMBOL is already defined, but the symbol is not protected from later redefinition. Compare *Note Equiv::.  File: as.info, Node: Equiv, Next: Eqv, Prev: Equ, Up: Pseudo Ops 7.44 `.equiv SYMBOL, EXPRESSION' ================================ The `.equiv' directive is like `.equ' and `.set', except that the assembler will signal an error if SYMBOL is already defined. Note a symbol which has been referenced but not actually defined is considered to be undefined. Except for the contents of the error message, this is roughly equivalent to .ifdef SYM .err .endif .equ SYM,VAL plus it protects the symbol from later redefinition.  File: as.info, Node: Eqv, Next: Err, Prev: Equiv, Up: Pseudo Ops 7.45 `.eqv SYMBOL, EXPRESSION' ============================== The `.eqv' directive is like `.equiv', but no attempt is made to evaluate the expression or any part of it immediately. Instead each time the resulting symbol is used in an expression, a snapshot of its current value is taken.  File: as.info, Node: Err, Next: Error, Prev: Eqv, Up: Pseudo Ops 7.46 `.err' =========== If `as' assembles a `.err' directive, it will print an error message and, unless the `-Z' option was used, it will not generate an object file. This can be used to signal an error in conditionally compiled code.  File: as.info, Node: Error, Next: Exitm, Prev: Err, Up: Pseudo Ops 7.47 `.error "STRING"' ====================== Similarly to `.err', this directive emits an error, but you can specify a string that will be emitted as the error message. If you don't specify the message, it defaults to `".error directive invoked in source file"'. *Note Error and Warning Messages: Errors. .error "This code has not been assembled and tested."  File: as.info, Node: Exitm, Next: Extern, Prev: Error, Up: Pseudo Ops 7.48 `.exitm' ============= Exit early from the current macro definition. *Note Macro::.  File: as.info, Node: Extern, Next: Fail, Prev: Exitm, Up: Pseudo Ops 7.49 `.extern' ============== `.extern' is accepted in the source program--for compatibility with other assemblers--but it is ignored. `as' treats all undefined symbols as external.  File: as.info, Node: Fail, Next: File, Prev: Extern, Up: Pseudo Ops 7.50 `.fail EXPRESSION' ======================= Generates an error or a warning. If the value of the EXPRESSION is 500 or more, `as' will print a warning message. If the value is less