AS31 Documentation
This document is an adaptation of the original AS31 man
page written by Ken Stauffer (University of Calgary),
stauffer@cpsc.ucalgary.ca, who is of course the original
author of AS31. All of the little changes made here
at OSU are reflected in this documentation (I hope).
Usage
as31 [-Fformat] [-Aarg] [-l] infile.asm
as31 [-Fformat] [-Aarg] [-l] infile
AS31 assembles infile.asm into
one of several different output formats. The output will be in a
file called infile.obj. The .asm extension is required.
Command Line Options
The options must appear before the input file name. Both options
are optional. The text of each flag must appear on the same
argument as the flag. For example, "-Fod" is a valid argument,
but "-F od" is not.
- -Fformat
- This options specifies the output format
that is to be used. Currently the only options available for
this are:
- hex
- This format is the Intel HEX format which is expected
by a number of EPROM programmers and the
PAULMON debugger. For
use with some programmers, the output file's extension may have
to be changed to .HEX to be recognized by the programmer. No -A
option is used. This format should be the default if no -F
option is used.
- tdr
- This format generates an ascii file of hex digits formatted in
such a way that they can be read by tdr's debugger. An
argument can be specified (See -A option) which will pass a
format specific string to the format generator. In this case, the
argument string represents an offset to add to the location
counter. This offset is specified in decimal and defaults to
64*1024 (0x10000). To specify an offset of 100, you would need
"-Ftdr -A100" when invoking the assembler.
- byte
- This format is simply an address and a byte on each line, in
ascii. No -A option is used.
- od
- This format is similar to the output from od(1). The format
consists of an address followed by sixteen hexadecimal bytes,
followed by the ASCII equivalant. No -A option is used.
- srec2, srec3, srec4
- The srecord generator is capable of generating output with any
one of 2, 3, or 4 byte addresses. The -A option can be used to
set the base address offset and the default here is 0x0000 (unlike
tdr).
NOTE: This assembler allows for the output formats to be
expanded to include many different output formats. See the file
emitter.c for details.
- -Aarg
- This option
specifies a format specific string which is passed to the format
generator. Both format "tdr" and the srecord formats use this
option.
- -l
- This option tells the assembler to also generate a
listing file. A listing will be placed in the file infile.lst.
Where 'infile' is the file that is being assembled. This option
may appear anywhere before infile.asm. The option must occur
isolated on the command line. The listing file shows the
assembler generated code in hex, and up to 60 characters are
retained from the source file.
- -cgi
-
This option instructs the
assembler to supress the listing, output the object code to
stdout, and DELETE the original assembly source file.
This is
intended to be used with a cgi script which builds a custom
configured temporary copy of an assembly source. This option
should not normally be used.
|
Instructions
The AS31 assembler supports all of the standard 8051 family
instructions. Please refer to this
Instruction Set Reference
sheet.
Directives
AS31 includes the following assembler directives:
- .ORG expr
- Start
assembling at the address specified by the expression expr. An
error occurs if the assembler starts assembling over an address
space that has previously been assembled into.
- .EQU symbol, expr
- Set symbol to the value of expr. The value for expr must be known
during the first pass, when the line containing the .EQU is
encountered.
- .DB expr, expr, ...
- .BYTE expr, expr, ...
- Assemble the bytes specified by the expression into memory. A
string may also be specified with this directive.
- .WORD expr, expr, ...
- Assemble the words specified by the expression into memory. The
byte ordering used, is that used by the 8031.
- .FLAG symbol1, symbol.[0-7]
- Sets symbol1 to the bit address specified by the symbol.[0-7]
expression, where [0-7] denotes a character between 0 and 7. The
resulting bit address is checked to see if it is a valid bit
address.
- .END
- This directive is ignored.
- .SKIP expr
- Adds the value of expr to the location counter. Used to reserve a
block of uninitialized data. Expr should be in bytes.
Language Lexical Details
All characters following a semi-colon are ignored until a newline
is encountered.
All numbers default to decimal, unless the number starts with one
of the following:
- 0x or 0X
- This indicates a hexadecimal number. ie. 0x00ff
- 0b or 0B
- This indicates a binary number. (1's and 0's). ie. 0b1100110010
- 0
- This indicates an octal number. ie. 0377
All numbers default to
decimal, unless the number ends with one of the following
characters:
- b or B
- This indicates a binary number. Unless 0x was used
above. ie. 1010101b
- h or H
- This always indicates a hex number. However
if the first character is not numeric, then either 0x or 0
must be specified. This avoids confusing the assembler into
thinking a hex number is a symbol. For example: 0ffh, 0xffh,
0XffH, 20h, 0x20 and 020h are means to specify a valid hexdigit,
but the following are not: ffh, 0ff.
- d or D
- This forces a number to
decimal. Unless 0X was used. ie. 129d This causes the number to
be interpreted as octal. ie. 377o
A character constant can be entered as 'c' where c is some
character. \b, \n, \r, \t, \' \0 are also valid. A character
constant can be used anywhere that an integer value can.
A string is entered as a set of characters enclosed in double
quotes "". A string is only valid with the .BYTE directive. \b,
\n, \r, \t, \" are also valid escapes. However \0 is not.
Instructions, directives, and the symbols: R0, R1, R2, R3, R4,
R5, R6, R7, A, AB, and C can be entered in upper or lower case
without assembler confusion. These words however cannot be
defined as a user symbol. User symbols are also case insensitive.
A symbol can be any alpha numerical character plus the underscore
('_').
Expressions are accepted in most places where a value or a symbol
is needed. An expression consists of the following operators. All
operators evaulate to integer objects (higher precedence operators
listed first):
- -
- Unary minus
- &
- Bit-wise AND.
- |
- Bit-Wise OR.
- *
- Integer multiplication.
- \
- Integer division
- %
- Integer modulus
- +
- Integer addition.
- -
- Integer subtraction.
- <<
- Left bitwise shift
- >>
- Right bitwise shift
In addition to these operators,
a special symbol '*' may be used to represent the current
location counter.
Examples
.org 0
start: mov P3, #0xff ; use alternate fns on P3
; leds on P1 are inverted.
setb F0 ; climbing up
mov A, #0x01 ; initial bit
write: cpl A ; write it
mov P1, A
cpl A
acall delay
jb F0, climbup ; climbing which way?
climbdn: rr A ; down - shift right
jnb ACC.0, write ; back for more
setb F0
ajmp write
climbup: rl A ; up - shift left
jnb ACC.7, write ; back for more
clr F0
ajmp write
.end ; this directive ignored.
AS31, An Intel 8031/8051 assembler, Ken Stauffer (University of Calgary)
Minor changes and HTML markup, Paul Stoffregen
http://www.pjrc.com/tech/8051/tools/as31-doc.html
Last updated: November 28, 2003
Status: HTML version adapted from original AS31 man page
Suggestions, comments, criticisms??
<paul@pjrc.com>
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