ASM11

A two-pass absolute DOS cross-assembler for the 68HC11

Quick Reference Guide

ASM11 - Copyright © 1998-2010 by Tony Papadimitriou <tonyp@acm.org>

Last Update: February 17, 2010 for ASM11 v2.50

Command-Line Syntax and Options

ASM11 [-option [...]] [[@]filespec [...]] [>errfile]

· option(s) may appear before, in between or after filespec(s).

· option(s) specified apply to all files assembled, regardless of command line placement.

· Text file(s) containing list(s) of files to be processed may be specified by naming the text file on the command line, prefixed with a «@» character. These text files may not contain command line options.

· filespec(s) may include wildcard characters (?,*). Wildcards are not allowed in filespec(s) that are prefixed with a «@» but are allowed in filespecs inside @files.

· If the file extension for a source filespec is omitted, the extension «.ASM» is assumed (see description of the –R.ext option below).

· Assembler errors may be redirected to errfile using standard DOS output redirection syntax. This capability may be used in conjunction with, or as an alternative to the –E+ option.

· Any label can hold a value that is 32-bit long. Even though the CPU cannot understand numbers larger than 16-bit for data or addressing, the ability to have 32-bit labels allows to keep constants that are larger than 16-bit for use in later constant calculations. Decimal numbers are signed; the largest number is +/-2147483647. Hex or binary numbers are unsigned and can go up to the full 32-bit value (2^³²-1). For example, a symbol holding the crystal frequency of operation can be expressed with Hz detail to be used later to derive other constant values (such as cycle-based delays). The 32-bit capability is NOT available in the DOS version.

· The assembler will set the DOS ERRORLEVEL variable when it terminates as indicated:
0 No error, assembly of last file was successful
1 System error (hardware I/O failure, out of disk space, etc.), or -W option failure
2 Error(s) generated (or Escape pressed) during assembly of last file
3 Warning(s) generated during assembly of last file
4 Assembler was not started (help screen displayed, -W option used with success)

5 No file(s) found

Option	Default	Description
-C[±]	-C-	Label case sensitivity: + = case sensitive (See also #CASEON/#CASEOFF)
-Dlabel [:expr]		Use up to ten times to define symbols either for conditional assembly (e.g., IFDEF, IFNDEF, and IF directives) or normal use. Symbols are always uppercase (regardless of -C option). If they are not followed by a value (or expression) they assume the value zero. Expression is limited to 19 characters. Character constants should not contain spaces, and they are converted to uppercase. Cannot be saved with -W.
-E[±]	-E-	Generate *.ERR file (one for each file assembled). *.ERR files are not generated for file(s) that do not contain errors.
-EH[±]	-EH+	If –E+ is in effect, hide (do not display) error messages on screen.
-EXP[±]	-EXP-	When on, an .EXP file is created containing all symbols defined with an EXP rather than an EQU pseudo-opcode. The resulting file can then be used as an #INCLUDE file for other programs. This allows for automatic creation of include files with exported global symbols.
-Ix		Define default INCLUDE directory root. Relative path files not found relative to the main file, will be tried next relative to this directory. This switch does not affect absolute path file definitions. Affects both the INCLUDE and the IF(N)EXISTS directives.
-L[±]	-L+	Create a *.LST file (one for each file assembled).
-LC[±]	-LC+	List any conditional directives fully (the directives only, not the contents in between), even when they are False. This is the new behavior of ASM11 as of v1.81 but the option is there for those few that liked the old way.
-LS[±]	-LS-	Create a *.SYM symbol list (one for each file assembled). May be useful for debuggers that do not support the P&E map file format.
-LSx	-LSS	x may be either S (default) for simple SYM file, E for EM11/Shadow11 SYM format, or N for NoICE SYM format.
-M[±]	-M+	Create a *.MAP (one for each file assembled). *.MAP files created may be used with debuggers that support the P&E source-level map file format.
-MTx	-MTP	Specifies type of MAP file to be generated (if –M+ in effect): -MTA : Generate parsable ASCII map file -MTP : Generate P&E-style map file
-O[±]	-O+	Enables these three warnings: ‘S19 overlap’, ‘Violation of MEMORY directive’, and ‘Violation of VARIABLE directive’.
-P[±]	-P+	When on it tells the assembler to stop after Pass 1 if there were any errors. Provides for faster overall assembly process and less confusion by irrelevant side errors of Pass 2. Warnings alone never stop in Pass 1.
-Q[±]	-Q-	Specifies quiet run (no output) when redirecting to an error file. Useful for IDEs that call ASM11 and don’t want to have their display messed up. Beginning with v2.07, this option can also be used to suppress all output from #Message directives.
-Rn	-R74	Specifies maximum length of S-record files. The length count n includes all characters in an S-record, including the leading «S» and record type, but not the CR/LF line terminator. Minimum value is 12 (for one object byte per record) while maximum is 250 (120 object bytes per record).
-R.ext	-R.ASM	Specifies the default extension to assume for source files specified on the command line, which do not directly specify an extension.
-REL[±]	-REL+	Allows generation of «BRA/BSR instead of JMP/JSR» optimization warnings when enabled. (See also OPTRELON/OPTRELOFF)
-RTS[±]	-RTS-	Allows generation of «JSR followed by RTS» subroutine call optimization warnings when enabled. (See also OPTRTSON/OPTRTSOFF)
-S[±]	-S+	Generate *.S19 object file (one for each file assembled).
-SH[±]	-SH-	Include dummy «S0» record (header) in object file (only if –S+).
-SP[±]	-SP-	When enabled, the operand part of an instruction is stripped of spaces before parsing. In this case, possible comments must begin with semi-colon. (See also SPACESON/SPACESOFF)
-T[±]	-T-	Makes all errors look like Borland errors (useful to fool certain third-party IDEs).
-Tn	-T8	Specifies tab field width to use in *.LST files and object code strings. Tab characters embedded in the source file are converted to spaces in the object code strings, and in the listing file such that columns are aligned to 1 + every nth character.
-Ux		Define default OUTPUT directory. If this option is defined, all produced files will end up in this directory, regardless of where the source file is located. When this option is undefined (no path given), produced files will end up in the same directory as the primary source file. Not available in the DOS version.
-X[±]	-X+	Allow recognition of extra, non-68HC11-standard mnemonics in source files. (See also EXTRAON/EXTRAOFF)
-WRN[±]	-WRN+	Enables or disables the display of all warnings. When enabled, only warnings that aren’t disabled individually will be generated. When disabled, it overrides local warning options (such as -REL and -RTS).
-W	(none)	Write options specified earlier on the command line to the ASM11 executable. The user-specified options become the default values used by ASM11 in subsequent invocations. Filespec(s) on the command line are ignored. Assembly of source files does not take place if this option is specified.

Source File Pseudo-Opcodes (Pseudo-Instructions)

Pseudo-Op	Description
DB string|expr[,...]	Define Byte(s). expr may be a constant numeric, a label reference, an expression, or a string. DB encodes a single byte in the object file at the current location counter for each expr encountered (using the LSB of the result) or one byte for each character in strings.
DS blocksize	Define Storage. The assembler’s location counter is incremented by blocksize. Forward references not allowed. No code is generated.
DW expr[,...]	Define Word(s). expr may be a constant numeric, a label or an expression. expr is always interpreted as a word (16-bit) quantity, and is stored in the object file at the current location counter, high byte followed by low byte.
END [expr]	Provided for compatibility. The END directive cannot be used to terminate assembly; ASM11 always processes the source file to the end of file. If expr is specified, the word result is encoded in the S9 record of the object file.
label EQU expr	Assigns the value of expr to label. See also EXP and SET
label EXP expr	Assigns the value of expr to label. This is similar to EQU but with the following difference: Labels defined thus will be included in the .EXP file as regular SETs. This effectively allows exporting symbols for use from other source files. It makes it possible to give only object code to others along with the produced .EXP file so that they can «link» the object to their source. Found in versions 1.84b+ but will be honored only in 1.85+
FCB string|expr[,...]	Form Constant Byte(s). Same as DB.
FCC string|expr[,...]	Form Constant Character(s). Same as DB.
FCS string|expr[,...]	Form Constant String. Similar to FCC, but it automatically adds a terminating null (0) byte to the end of the string defined (for ASCIZ strings).
FDB expr[,...]	Form Double Byte(s). Same as DW.
LONG expr[,...]	Form 32-bit long word(s). expr may be a constant numeric, a label or an expression. expr is always interpreted as a 32-bit quantity, and is stored in the object file at the current location counter in big-endian order. Not available in the DOS version.
label NEXP symbol[,expr]	Assigns the current value of symbol to label as if with EXP. Then, it increments the value of symbol by one (as if with SET) or, if the optional expression is present, by the value of that expression. Useful for defining a series of symbols based on a common starting value. Note: symbol is a single label and not an expression. See also NEXT, SETN
label NEXT symbol[,expr]	Assigns the current value of symbol to label as if with EQU. Then, it increments the value of symbol by one (as if with SET) or, if the optional expression is present, by the value of that expression. Useful for defining a series of symbols based on a common starting value. Note: symbol is a single label and not an expression. See also NEXP, SETN
ORG expr	Sets the assembler’s location counter for the active segment. Code generated after this directive will be assembled starting at the location specified by expr.
RMB blocksize	Reserve Memory Byte(s). Same as DS.
label SET expr	Assigns the value of expr to label even if label is already defined with a different value. This is similar to EQU but allows making multiple re-definitions. The value set will be used until another SET pseudo-instruction or to the end of the assembly process. Warning: Careless, or simply wrong use of this directive can lead to multiple side errors or warnings (please note this is a two-pass assembler). Using a forward SET defined symbol may lead to problems, as the value used will be the one from the last SET definition, which is not necessarily the one we want. Correct behavior is guaranteed if any symbols re-defined with SET are used only after each new re-definition, otherwise, the first reference in Pass 2 will use the value from the last re-definition in Pass 1. Example of wrong use: 1. lda #Value ;we expect 123, actual is 234 2. Value equ 123 ... 3. lda #Value ;we expect 234, actual is 123 4. Value set 234 Value in line 1 will be 234 (the last known value from Pass 1) while Value in line 3 will be 123 (most recent value in current Pass 2). Example of correct use: 1. Value equ 123 2. lda #Value ;we expect 123, actual is 123 ... 3. Value set 234 4. lda #Value ;we expect 234, actual is 234 See also EXP and EQU
label SETN symbol[,expr]	Assigns the current value of symbol to label as if with SET. Then, it increments the value of symbol by one (as if with SET) or, if the optional expression is present, by the value of that expression. Useful for (re-)defining a series of symbols based on a common starting value. Note: symbol is a single label and not an expression. See also NEXP, NEXT

Source File Processing Directives

· All processing directives must be prefixed with a $ or # character. ASM11 will recognize either character as the start of a processing directive.

· If a directive has a corresponding command-line option, the directive in the source file will override the command line directive at the point in which the source file directive is encountered.

· [text] will be trimmed of duplicate spaces. To have more than one consecutive space display, use the Alt-255 character, as many times as needed.

Directive	Description
#CASEOFF	When #CASEOFF is in effect, all symbol references that follow are converted to uppercase internally before they are searched for or placed in the symbol table. (Debug and DEBUG are the same symbol.) Equivalent to the –C- command line option.
#CASEON	When #CASEON is in effect, symbol references are NOT internally converted to uppercase before they are searched for or placed in the symbol table. (Debug and DEBUG are two different symbols.) Equivalent to the –C+ command line option.
#CRC expr	The two CRCs (user and S19) maintained by the assembler are 16-bit each, and they are updated only during PASS2 by each produced user code/data byte that is put into the S19 file. The starting CRC value for both CRCs is zero. With this directive you can alter the user CRC value at any time (either before the very first byte of code/data to produce a different CRC for the same firmware, or several times in between to skip certain volatile sections, for example). The computed CRCs are available by accessing the internal symbols :CRC and :S19CRC The formula used for the 16-bit CRC calculation is very simple to be easily implemented even in tiny bootloaders: 16BitCRC := 16BitCRC + 16BitAddress*8BitData :S19CRC is mostly useful with the END directive (END :S19CRC) as it is not affected by the #CRC directive. An S19 loader can check the overall integrity of the S19 file. :CRC, on the other hand, is mostly useful for checking code after it has been loaded into the MCU, at each reset, for example. Please note that for both CRCs all $00 bytes do not affect the calculation while, for the user CRC only (:CRC), all $FF bytes are intentionally skipped. This allows for the CRC in an S19 file (which does not necessarily fill a contiguous block of memory) to match the CRC computed by the MCU over a complete block of memory without the MCU bootloader knowing in advance the actual addresses used within that block, provided any unused bytes are in the erased state. As a side effect, however, any $00->$FF or $FF->$00 alterations in the file cannot be detected with the user CRC.
#DATA	Activation of the DATA segment. Default starting value is $103F (the CONFIG register).
#EEPROM	Activation of the EEPROM segment. Default starting value is $B600.
#EJECT	See #PAGE
#ELSE	When used in conjunction with conditional assembly directives (#IF, #IF[N]DEF, $IF[N]Z, #IFMAIN, #IFINCLUDED, etc.), code following the #ELSE directive is assembled if the conditional it is paired with evaluates to a not-true result.
#ENDIF	Marks the end of a conditional-assembly block. Conditional assembly statements may be nested if they are properly blocked with #ENDIF directives.
#ERROR [text]	When encountered in the source, the assembler issues a error message in the same form as internally-generated errors, using the text specified, prefixed with «USER: »
#EXTRAOFF	Disables recognition of ASM11’s extended instruction set for source lines that follow this directive. Equivalent to the –X- command line option.
#EXTRAON	Enables recognition of ASM11’s extended instruction set for source lines that follow this directive. Equivalent to the –X+ command line option.
#FATAL [text]	Similar to the #ERROR directive, but generates an assembler fatal error message and terminates the assembler (possible further files in the command line supplied file list will not be processed).
#IF expr1 cond expr2	Evaluates expr1 and expr2 (which may be any valid ASM11 expression) and compares them using the specified cond conditional operator. If the condition is true, the code following the #IF operator is assembled, up to its matching #ELSE or #ENDIF directive. Cond may be any one of: < <= = >= > <> The condition is always evaluated using unsigned arithmetic. If a symbol referenced in expr1 or expr2 is not defined, the statement will always evaluate as false. At least one space must embrace cond on each side.
#IFDEF expr	Attempts to evaluate expr, and if successful, assembles the code that follows, up to the matching #ELSE or #ENDIF directive. This directive is usually used to test if a specified symbol has been defined. Symbol(s) referenced in expr must be defined before the directive for the result to evaluate true (e.g., forward references will evaluate as false). #IFDEF without an expr following will always evaluate to False.
#IFEXISTS fpath	It checks for the existence of the file specified by fpath (using the same rules as those used for #INCLUDE directives) and assembles the code that follows if the specified fpath exists.
#IFINCLUDED	Assembles the code which follows if the file containing this directive is a file used in an INCLUDE directive of a higher-level file (regardless of nesting level). See also #IFMAIN
#IFMAIN	Assembles the code that follows if the file containing this directive is the main (primary) file being assembled. See also #IFINCLUDED.
#INCLUDE fpath	INCLUDEs the specified fpath file in the assembly stream, as if the contents of the file were physically present in the source at the point where the #INCLUDE directive is encountered. Up to 100 INCLUDEs may be used and they may be nested, up to 100 levels deep (the main source file counts as one level). Relative fpath specifications are always referenced to the directory in which the main source file resides, including any relative #INCLUDE fpath references in nested include files. Note: As of version 1.46, ASM11 will only generate a standard error (not an assembly-terminating fatal error) if a file specified in a #INCLUDE directive is not found. The #IFEXISTS and #IFNEXISTS directives may be used in conjunction with #FATAL if termination of assembly is desired under such conditions.
#IFNDEF expr	Evaluates expr and assembles the code that follows if the expression could NOT be evaluated, usually as the result of a reference to an undefined symbol. This directive is the functional opposite of the #IFDEF directive.
#IFNEXISTS fpath	The opposite of #IFEXISTS; code following this directive is assembled if the specified fpath does NOT exist. As of version 1.61, the -Ix path will also be searched to determine whether a file exists or not.
#IFNZ expr	Evaluates expr and assembles the code that follows if the expression evaluates to a non-zero value. #IFNZ always evaluates to false if expr references undefined or forward-defined symbols.
#IFZ expr	Evaluates expr and assembles the code that follows if the expression is equal to zero. #IFZ always evaluates to false if expr references undefined or forward-defined symbols.
#LIST	See #LISTON
#LISTOFF	Turns off generation of source and object data in the *.LST file for all lines which follow this directive. Useful for excluding the contents of #INCLUDE files in the *.LST file. This directive is not shown in the *.LST file.
#LISTON	Enables generation of source and object data in the *.LST file for the source code following this directive. Has no effect if list file generation is disabled (-L- command line option in effect). This directive is not shown in the *.LST file if the listing was turned off just prior to it.
#MAPOFF	Suppresses generation of source-line information in the *.MAP file for the code following this directive. Symbols which are defined following this directive are still included in the *.MAP file.
#MAPON	Enables generation of source-line information in the *.MAP file for the code following this directive. #MAPON is the default state when assembly is started when map file generation is enabled (-M+ command line option).
#MEMORY addr1 [addr2]	Maps a memory location (or range, if addr2 is also supplied) of object code and/or data areas as valid. Use multiple directives to specify additional ranges. Any code or data that falls outside the given range(s) will produce a warning (if the -O option is enabled) for each violating byte. Very useful for segmented memory devices, etc. Addr1 and addr2 may be specified in any order. The range defined will always be between the smaller and the higher values. See also #VARIABLE
#MESSAGE [text]	Displays text on screen during the first pass of assembly when this directive is encountered in the source. Messages are not written to the error file. They are meant to inform the user of options used or conditional paths taken.
#NOLIST	See #LISTOFF
#NOWARN	Turns warnings off. Equivalent to the –WRN- command line option. See also #WARN
#OPTRELOFF	Disable «BRA/BSR instead of JMP/JSR» optimization warnings. Equivalent to the –REL- command line option.
#OPTRELON	Enable warning generation when an absolute branch or subroutine call (JMP or JSR) is encountered that could be successfully implemented using the relative form of the same instruction (BRA or BSR). This option is on by default. Equivalent to the –REL+ command line option.
#OPTRTSOFF	Disable RTS-after-JSR/BSR optimization warning (default). Equivalent to the –RTS- command line option.
#OPTRTSON	Enable warning generation when a subroutine call (JSR or BSR) is immediately followed by a RTS. This option is off by default. Command-line option -RTS+ does the same thing.
#S19FLUSH	Forces the immediate termination of an S-record line when encountered, rather than waiting for the record to reach the size specified by the –Rn command line directive. This directive may be used to make identification of the end of code blocks easier when viewing the *.S19 file.
#PAGE	Outputs a Form Feed (ASCII 12) character followed by a Carriage Return (ASCII 13) in the *.LST file just before displaying the line that contains this directive.
#PUSH	Pushes on an internal stack the current segment and the current settings of the following options: MAPx, LISTx, CASEx, EXTRAx, SPACESx, OPTRELx, OPTRTSx, WARN, NOWARN, and TABSIZE. Useful in included files that want to change any of these options without affecting parent/sibling files. See also #PULL
#PULL	Pulls from an internal stack the last pushed segment and settings of the following options: MAPx, LISTx, CASEx, EXTRAx, SPACESx, OPTRELx, OPTRTSx, WARN, NOWARN, and TABSIZE. Useful in included files that want to change any of these options without affecting parent/sibling files. You can use PULL even if haven’t used PUSH; no action will take place. See also #PUSH
#RAM	Activation of the RAM segment. Default starting value is $0000.
#ROM	Activation of the ROM segment. Default starting value is $D000. This is the default segment if none is specified.
#SEGn	Activation of the SEGn segment (n is a number from 0 through 9). Default starting value for all ten segments is $0000.
#TABSIZE n	Specifies the field width of tab stops used in the source file. Proper use of this directive ensures that the *.LST files generated by ASM11 are formatted in the same way as your source files appear in your text editor. This directive overrides the setting of the –Tn command line option at the point in the source file(s) in which it is encountered.
#VARIABLE addr1 [addr2]	Maps a location (or range, if addr2 is also supplied) of variable allocation area (normally in RAM) as valid. Use multiple directives to specify additional ranges. Any RMB or DS definitions that fall (fully or partially) outside the given range(s) will produce a warning (if the -O option is enabled) for each such definition. Addr1 and addr2 may be specified in any order. The range defined will always be between the smaller and the higher values. See also #MEMORY
#VECTORS	Activation of the VECTORS segment. Default starting value is $FFD6.
#WARN	Turns warnings on. Equivalent to the -WRN+ command line option. See also #NOWARN
#WARNING [text]	Similar to the #ERROR directive, but generates an assembler warning message instead of an error message.
#XRAM	Activation of the XRAM segment. Default starting value is $2000.
#XROM	Activation of the XROM segment. Default starting value is $8000.
#UNDEF symbol[,symbol]*	Undefines one or more symbols. If a symbol is not currently defined, a warning will be issued (to protect from possible typing errors). Careless, or simply wrong use of this directive can lead to multiple side errors or warnings (please note this is a two-pass assembler). If you simply want to redefine the value of a symbol, prefer using the SET pseudo-op, rather than #UNDEF followed by another symbol definition. #UNDEF can be used, for example, to completely remove unrelated or conflicting conditionals.

Note: [text] in directives and all strings may contain expressions enclosed in curly brackets, e.g. {expr}. The expression may not contain spaces (regardless of the –SP option state, or #SPACESON directive. An optional format modifier (case-insensitive) within parentheses after the expression can force the display in the specified format. (D) for default/decimal, (H) for hex, (S) for signed decimal, (1) thru (4) (or, thru (9) for the 32-bit versions) for the corresponding number of decimal places after division by 10ⁿ where n is a number from 1 to 4 (or 9), and (X) for eXpanded. If no format modifier is used, (D) is assumed. Some examples using this feature:

ROM EQU $F000

#Message ROM is at {ROM}

will display:

ROM is at 61440

Adding a format modifier will have the following effect:

#Message ROM is at {ROM(x)}

will display:

ROM is at 61440 [$F000]

#Message ROM is at {ROM(d)}

will display:

ROM is at 61440

#Message ROM is at {ROM(h)}

will display:

ROM is at $F000

#Message ROM is at {ROM(s)}

will display:

ROM is at -4096

It can also be used in strings, like so:

VERSION equ 101 ;Firmware version as x.xx

MsgVersion fcs ‘Firmware v{VERSION(2)}’,LF

is equivalent to

MsgVersion fcs ‘Firmware v1.01’,LF

but it will automatically adjust the MsgVersion string each time the symbol VERSION changes value. No need to re-adjust all relevant messages manually.

An expression that cannot be evaluated (due to forward references or undefined symbols) will display as three question marks (???) in directives, but no error or warning message will be issued. When used in strings, however, errors will be displayed as usual.

To prevent an expression evaluation in directives, enclose the [text] that contains the curly brackets within quotes.

To prevent an expression evaluation in strings, break the string into two so that both curly brackets are not part of the same string, e.g.:

instead of fcc ‘{Hello}’ which tries to evaluate the symbol Hello use: fcc ‘{‘,’Hello}’.

Internally defined symbols

Some special internal symbols are defined by the assembler. All such symbols begin with a colon (:) character. Currently, the following internal symbols are defined:

:YEAR returns the year at assembly time (e.g., 2010) Hint: Use :YEAR\100 for two-digit year.

:MONTH returns the month at assembly time (e.g., 2)

:DATE returns the date at assembly time (e.g., 17)

:CRC returns the current value of the running user CRC

:S19CRC returns the current value of the running S19 CRC.

:CYCLES returns the current value of the cycles counter.

Notes about :cycles:

§ The cycles counter is reset to zero as soon as it is accessed. To count cycles for a section of code, you must access :cycles twice, once before the code section to reset its value to zero (if not already zero from a previous access to :cycles), and once right after the code section to get the accumulated cycles. Hint: You can use the END directive to reset :cycles without assigning the unwanted value to any label, or if you simply want to display the current cycles in the listing file.

§ Because of the auto-reset on access, if you need to use the same value in more than one place at a time (e.g., code and #MESSAGE directive), you must assign it to a label first, then use the label.

§ The obvious advantage is that if you alter code as in the example loop below (e.g., by adding conditional early escape code inside the loop), it will still be timed correctly without requiring a manual adjustment of the delay constant.

§ Example use of :cycles that automatically calculates the appropriate delay constant:

end :cycles ; reset counter

Delay10ms pshx

ldx #10*BUS_KHZ-?extracycles/?loopcycles

?extracycles equ :cycles ; grab counter (and reset)

?Delay.Loop dex

bne ?Delay.Loop

?loopcycles equ :cycles ; grab counter (and reset)

pulx

rts

?extracycles set ?extracycles+:cycles

(SET instead of EQU allows re-using symbols, so you can use it to accumulate related cycles.)
Example assembly code for calculating user CRC

;*******************************************************************************

; Purpose: Calculate the same user CRC as that produced by ASM11

; Input : X -> First byte of block

; : Y -> Last byte of block

; : D = Initial/Previous CRC

; Output : D = updated CRC

; Note(s): Call repeatedly for different address ranges, if skipping sections

; Call : ldd #CRC

; : ldx #StartAddress

; : ldy #EndAddress

; : jsr GetAsmCRC

? set 0

?StartAddress next ?,2

?EndAddress next ?,2

?CRC next ?,2

GetAsmCRC pshx

pshy

pshd ;CRC

pshy ;ending address

pshx ;starting address

tsy ;Y -> stack frame

?GetAsmCRC.Loop cmpx ?EndAddress,y

bhi ?GetAsmCRC.Exit

sta COPRST ;in case of many iterations

lda ,x

beq ?GetAsmCRC.Next

cmpa #$FF

beq ?GetAsmCRC.Next

ldb ?StartAddress+1,y

mul ;low address with data byte

addd ?CRC,y

std ?CRC,y

lda ,x

ldb ?StartAddress,y

mul ;high address with data byte

addb ?CRC,y

stb ?CRC,y

?GetAsmCRC.Next inx

stx ?StartAddress,y

bra ?GetAsmCRC.Loop

?GetAsmCRC.Exit pulx

puly

puld

puly

pulx

rts

Example coding for skipping CRC calculation for volatile sections

?crc set :crc ;use SET, not EQU

;CODE/DATA TO SKIP FROM CRC CALCULATION HERE

#CRC ?crc

Expression Operators and Other Special Characters

Recognized by Asm11

· Expressions are evaluated in the order they are written (left to right).
All operators have equal precedence.

· Avoid inserting spaces between values and operators (unless using -SP+ switch and semicolon beginning comments).

Operator	Description
+	Addition
-	Subtraction When used as a unary operator, the 2’s complement of the value to the right is returned.
*	Multiplication Can also be used to represent the current location counter.
/	Integer Division (ignores remainder)
\	Modulus (remainder of integer division)
=	‘Equal to’ comparison for the $IF directive.
<>	‘Not equal to’ comparison for the $IF directive.
>=	‘Greater than or equal to’ comparison for the $IF directive.
>	Shift right – operand to the left is shifted right by the count to the right. Also used to specify extended addressing mode. ‘Greater than’ comparison for the $IF directive.
<=	‘Less than or equal to’ comparison for the $IF directive.
<	Shift left – operand to the left is shifted left by the count to the right. Also used to specify direct addressing mode. ‘Less than’ comparison for the $IF directive.
&	Bitwise AND
|	Bitwise OR
^	Bitwise XOR (exclusive OR)
~	Swap high and low bytes (unary): ~$1234 = $3412 Useful for converting word values from big-endian to little-endian or the inverse.
[[	Extract low 16 bits (unary): [[$123456 = $3456
]]	Extract high 16 bits (unary): ]]$123456 = $0012
[	Extract low 8 bits (unary): [$1234 = $34
]	Extract high 8 bits (unary): ]$1234 = $12
$	Interpret numeric constant that follows as a hexadecimal number. Can also be used to represent the current location counter.
%	Interpret numeric constant that follows as a binary number
¢ ` ²	Any one of these characters (single, back, or double-quote) may be used to enclose a string or character entity. The character used at the start of the string must be used to end it.
#	Specifies immediate addressing mode
@	Specifies direct addressing mode (same as «<»)

ASM11 Extended Instruction Set

The instructions listed below are not actually new instructions, rather, internal macros that generate one or more 68HC11 CPU instructions. These instructions are only recognized if the extended instruction set option is enabled (-X+ command line option or #EXTRAON processing directive).

Mnemonic/Syntax	Description
AIX #word	Add Immediate X the 16-bit value #word (signed or unsigned). Equivalent to XGDX / ADDD #word / XGDX
AIY #word	Add Immediate Y the 16-bit value #word (signed or unsigned). Equivalent to XGDY / ADDD #word / XGDY
LDA operand	Same as: LDAA operand
LDB operand	Same as: LDAB operand
STA operand	Same as: STAA operand
STB operand	Same as: STAB operand
ORA operand	Same as: ORAA operand
ORB operand	Same as: ORAB operand
PSHD	Push D: PSHB / PSHA
PULD	Pull D: PULA / PULB
CMPD operand	Same as: CPD operand
CMPX operand	Same as: CPX operand
CMPY operand	Same as: CPY operand
CLRD	Clear D: CLRA / CLRB
CLRX	Clear X: LDX #0
CLRY	Clear Y: LDY #0
COMD	1’s Complement D: COMA / COMB
NEGD	2’s Complement D: COMA / COMB / ADDD #1
XGAB	Exchange A and B: PSHA / TBA / PULB
ROLD	Rotate Left D: ROLB / ROLA
RORD	Rotate Right D: RORA / RORB
INCD	Increment D: ADDD #1
INCX	Increment X: INX
INCY	Increment Y: INY
DECD	Decrement D: SUBD #1
DECX	Decrement X: DEX
DECY	Decrement Y: DEY
LBRA addr16	Long relative branch: (22 bytes/69 cycles) Warning! Generates considerable code, use with care
LBSR addr16	Long relative subroutine call: (32 bytes/92 cycles) Warning! Generates considerable code, use with care
GETX #word	Get #word bytes of stack storage pointed to by X for temporary use. Equivalent to TSX / XGDX / SUBD #word / XGDX / TXS
GETY #word	Get #word bytes of stack storage pointed to by Y for temporary use. Equivalent to TSY / XGDY / SUBD #word / XGDY / TYS
GIVEX #word	Give (back) #word bytes of stack storage pointed to by X. Equivalent to TSX / XGDX / ADDD #word / XGDX / TXS
GIVEY #word	Give (back) #word bytes of stack storage pointed to by Y. Equivalent to TSY / XGDY / ADDD #word / XGDY / TYS
JCC addr16	Jump equivalent to BCC (BCS $+5 followed by JMP addr16)
JCS addr16	Jump equivalent to BCS (BCC $+5 followed by JMP addr16)
JEQ addr16	Jump equivalent to BEQ (BNE $+5 followed by JMP addr16)
JGE addr16	Jump equivalent to BGE (BLT $+5 followed by JMP addr16)
JGT addr16	Jump equivalent to BGT (BLE $+5 followed by JMP addr16)
JHI addr16	Jump equivalent to BHI (BLS $+5 followed by JMP addr16)
JHS addr16	Jump equivalent to BHS (BLO $+5 followed by JMP addr16)
JLE addr16	Jump equivalent to BLE (BGT $+5 followed by JMP addr16)
JLO addr16	Jump equivalent to BLO (BHS $+5 followed by JMP addr16)
JLS addr16	Jump equivalent to BLS (BHI $+5 followed by JMP addr16)
JLT addr16	Jump equivalent to BLT (BGE $+5 followed by JMP addr16)
JMI addr16	Jump equivalent to BMI (BPL $+5 followed by JMP addr16)
JNE addr16	Jump equivalent to BNE (BEQ $+5 followed by JMP addr16)
JPL addr16	Jump equivalent to BPL (BMI $+5 followed by JMP addr16)
JVC addr16	Jump equivalent to BVC (BVS $+5 followed by JMP addr16)
JVS addr16	Jump equivalent to BVS (BVC $+5 followed by JMP addr16)
CLS	Clear S flag: PSHA / TPA / ANDA #$7F / TAP / PULA
CLX	Clear X flag: PSHA / TPA / ANDA #$BF / TAP / PULA
PULL	Same as: PULD / PULX / PULY
PUSH	Same as: PSHY / PSHX / PSHD
SES	Set S flag: PSHA / TPA / ORAA #$80 / TAP / PULA
SEX	Sign extend B to A: CLRA / TSTB / BPL ? / COMA / ?
WAIT	Enter WAIT mode: CLI / WAI
OS byteval	Operating system call: SWI / DB byteval
OSW wordval	Operating system call: SWI / DW wordval
XGXY	Exchange X and Y: XGDX / XGDY / XGDX

ASM11-generated Error and Warning Messages

This section provides the lists of error and warning messages.

Errors inform the user about problems that prevent the assembler from producing usable code. If there is even a single error during assembly, no files will be created (except for the ERR file, if one was requested).

Warnings inform the user about problems that do not prevent the assembler from producing usable code but the code produced may not be what was intended, or it may be inefficient. A program that has warnings may be totally correct and run as expected.

Errors and warnings that begin with ‘USER:’ are generated by #ERROR and #WARNING directives, respectively. The source code author decides their meaning and importance.

In the lists below, what’s enclosed in angle brackets (< and >) is a ‘variable’ part of the message. That is, it is different depending on the source line to which the error or warning refers.

The order the messages appear below is random. Some messages have similar meanings; they simply result from different checks of the assembler.

E R R O R S

1. Invalid binary number

The string following the % sign is not made up of zeros and/or ones.

2. Binary number is longer than 16 bits

A binary number may have no more than sixteen significant digits. Leading zeros are ignored.

3. "<SYMBOL>" not yet defined, forward refs not allowed

RMB and DS directives may not refer to forward defined symbols. You must define the symbol(s) used in advance.

4. Bad <MODE> instruction/operand "<OPCODE> <OPERAND>

The instruction and operand addressing mode combination is not a valid one, or you have turned the -X option (EXTRAx directive) off. For example, TST #4 will show «Bad IMMEDIATE instruction/operand "TST 4"» because although TST is a valid instruction, it does not have an immediate addressing mode option.

5. Could not close MAP file

For some reason, the MAP file could not be closed. Possibly some disk problems (check available space, etc.) If you can’t figure out what’s wrong and still must assemble, turn off the MAP with the -M- option.

6. Could not close SYM file

For some reason, the SYM file could not be closed. Possibly some disk problems (check available space, etc.) If you can’t figure out what’s wrong and still must assemble, turn off the SYM with the -S- option.

7. Could not create MAP file <FILEPATH>

For some reason, the MAP file could not be created. Possibly some disk problems (check available space, etc.) If a MAP file of the same name already exists it probably has a read-only attribute or is somehow locked by the system.

8. Could not create SYM file <FILEPATH>

For some reason, the SYM file could not be created. Possibly some disk problems (check available space, etc.) If a SYM file of the same name already exists it probably has a read-only attribute or is somehow locked by the system.

9. Expression error

Something is wrong with the attempted expression, or an expression is altogether missing.

10.Invalid argument for DB directive

The value or expression supplied is not correct.

11.Invalid argument for EQU/EXP directive

The value or expression supplied is not correct.

12.Invalid first argument

The first value or expression supplied is not correct.

13.Invalid second argument

The second value or expression supplied is not correct.

14.Missing value between commas

Two or more commas without a value in between.

15.Possibly duplicate symbol "<SYMBOL>"

The symbol shown has already been defined. The word ‘possibly’ suggests that a symbol may have been truncated to 19 characters, and thus not appear duplicate to the user, only to the assembler. It also suggests that the original may have been written for case-sensitive assembly but you turned the option off.

16.Repeater value is invalid

The repeater value (the :n part of the opcode) is a positive integer number.

17.Symbol "<SYMBOL>" contains invalid character(s)

The symbol shown contains characters that are used in special ways and, therefore, cannot be part of a symbol because they will cause ambiguities. For example, a quote within a symbol is not allowed.

18.Undefined symbol "<SYMBOL>" or bad number

The string shown is either a symbol that hasn’t been defined at all, or it is a number that has some error, for example: $ABCH and $FFFFF are not valid hex numbers. The first contains an invalid character while the second is greater than 16 significant bits ($FFFF).

19.USER: <USER TEXT>

This is a user generated error via the #ERROR directive.

20.Comma not expected

A comma was found in an unexpected position within the operand. Possibly using more arguments than required.

21.Syntax error

Some symbol is confusing the assembler. For example, FCB #$FF will give a syntax error because the # indicates immediate addressing mode which makes no sense for an FCB directive (the correct is FCB $FF).

22.Empty string not allowed

An empty string (two quotes next to each other) is not allowed because there is no value that can be generated from it.

23.Could not open include file <FILEPATH>

The [path and] file shown could not be located or opened. If the file exists, it may be locked by some other program (under Windows, the file could be loaded in an editor).

24.ELSE without previous Ifxxx

An #ELSE directive was encountered that does not match any unmatched #IF directive.

25.ENDIF without previous Ifxxx

An #ENDIF directive was encountered that does not match any unmatched #IF directive.

26.Forward references not allowed

The #MEMORY/#VARIABLE and other directives do not accept forward references.

27.Incomplete argument for Bit Instruction (commas?)

BSET, BCLR, BRSET, and BRCLR require commas between each part of the operand. You have either left the commas out or forgotten to supply all the parts of the operand. Assembling code written for Mot’s AS11 will produce a lot of these.

28.Invalid expression(s) and/or comparator

The expression or comparator used in the #IF directive is incorrect.

29.Missing branch address

BRSET and BRCLR require a target address for branching to but one was not supplied. The branch target is the last part of the operand and it can be any valid expression.

30.Missing INCLUDE filename

An #INCLUDE directive was supplied without any [path and] filename.

31.Missing required first address

A #MEMORY/#VARIABLE directive was encountered without any value or expression.

32.Repeater value out of range (1-32767)

The repeater value (the :n part of the opcode) must be from 1 to 32767.

33.Required string delimiter not found

You have supplied only one quote to a string, or the string is inappropriately separated from the previous or next operand. For example: ’ABC’CR lacks a comma between the quote and the CR symbol. So, the found string ACB’CR is invalid.

34.Symbol "<SYMBOL>" does not start with A..Z, . or _

All symbols must start with one of the above characters. (Local symbols start with a ?)

35.Symbol "<SYMBOL>" is reserved for indexing modes

You have used a symbol named X or Y. These names are not allowed because they cause ambiguities with the X and Y registers in the various indexed mode instructions.

36.Too many include files. Maximum allowed is 99

The maximum number of INCLUDE files is 99 (regardless of nesting level). You have gone over this number. Possible solution: Combine related files together as required. Keep in mind that although the assembler allows this many files to be included, a lot of programs cannot handle these many files in the MAP files.

37.Division by zero

The expression used contains a division by zero after the / operator.

38.MOD division by zero

The expression used contains a division by zero after the \ operator.

39."<SYMBOL>" is too far back [<VALUE>], use jumps

The target of a branch instruction is too far back by as many bytes as shown. Either get it closer to the target, or use a jump instead. Some instructions, like BRCLR or BRSET do not have an equivalent jump so you must use an intermediate ‘jump hook’ instead.

40."<SYMBOL>" is too far forward [<VALUE>], use jumps

The target of a branch instruction is too far forward by as many bytes as shown. Either get it closer to the target, or use a jump instead. Some instructions, like BRCLR or BRSET do not have an equivalent jump so you must use an intermediate ‘jump hook’ instead, i.e., branch to a nearby JMP instruction that jumps to the desired destination.

41.Invalid argument for DW or FDB directive

The value or expression supplied is not correct.

42.Invalid argument for ORG directive

The value or expression supplied is not correct.

43.Invalid argument for RMB or DS directive

The value or expression supplied is not correct.

44.Invalid argument for END directive

The value or expression supplied is not correct.

W A R N I N G S

1. Direct mode wasn't used (forward reference?)

Automatic Direct Mode detection requires that any symbol(s) used be defined in advance. You should either define the referenced symbol(s) earlier in your code, or use the Direct Mode Override (<) to force the assembler to use Direct Addressing Mode.

2. Label on left side of END line ignored

The END directive does not take a label. If one is used it will be ignored (it will not be defined).

3. Label on left side of ORG line ignored

The ORG directive does not take a label. If one is used it will be ignored (it will not be defined).

4. Trailing comma ignored

A multiple-parameter pseudo-instruction was used (such as FCB and DW) and a comma was found at the end of the parameter list. This may indicate both commas and spaces separate the list. You must either remove the spaces or assemble with #SPACESON (or the -SP+ option).

5. Violation of MEMORY directive at address $<VALUE>

6. Violation of VARIABLE directive at/near $<VALUE>

ASM11 has produced code and/or data that falls outside any address ranges defined via the #MEMORY or #VARIABLE directive, respectively. You must either add more #MEMORY/#VARIABLE directives to cover the offending range or move your code/data elsewhere (using appropriate segment and/or ORG statements).

7. EQU/EXPs require a label, ignoring line

An EQU (or EXP) by definition is meant to assign a value to a symbol but no symbol name was supplied. Using a repeater value in an EQU will also produce this warning for each repetition of the statement except the first one. You should NOT use repeaters with EQU.

8. Forward references are always FALSE

Conditional directives other than #IFDEF and #IFNDEF produce this warning if the symbol(s) referenced have not yet been defined. In this case, the conditional evaluates to false, and if there is an #ELSE part, it is taken.

9. String is too long, only first 8 or 16 bits used

8-bit and 16-bit instructions (such as LDA and LDD) cannot accept a constant string value of more than 8 or 16 bits, accordingly. The longer string encountered is truncated to the first two characters before being used. If an 8-bit operand is expected, you will also get a warning about using a 16-bit value with an 8-bit operand.

10.S19 overlap at address $<VALUE>

The code/data of the shown line overlaps an already occupied memory location at the address shown. The warning appears at code/data that causes the first and consequent overlaps but the problem could be with the original code/data that occupied this address. The assembler has no way of knowing your intentions!

11.Instruction TEST is only valid in SPECIAL TEST MODE

The instruction TEST is only defined when running the 68HC11 in special test mode. This warning is generated just in case you meant to say TST and typed TEST by mistake.

12.Extra operand found ignored

In a BCLR/BSET you have supplied a branch address. Depending on what you intended to do, either change the instruction to BRCLR/BRSET or remove the last operand.

13.No ending string delimiter found

The last string quote is missing. ASM11 did its best to produce a value for you but it may not be the one you wanted. For example: «LDA #’a» will produce this warning but the value used will be correct, while «LDA #’a ;comment» will produce a wrong value (the space after the a because the string ‘a ’ is a 16-bit value downsize to an 8-bit value, you will get a warning about this also).

14.Operand is larger than 16 bits, using low 16-bits

The operand is greater than 16 bits but the instruction can only accept a 16-bit operand. The lower word was used.

15.Operand is larger than 8 bits, using low 8-bits

The operand is greater than 8 bits but the instruction can only accept an 8-bit operand. The lower byte was used.

16.Possible memory wraparound at address $<VALUE> (<DEC VALUE>)

It seems like you have reached the end of memory ($FFFF) and caused the Program Counter to wrap around to zero. In some situations this may be intentional. Using RMB 2 (rather than FDB or