as.1

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th AS I 1/15/73
.sh NAME
as \*- assembler
.sh SYNOPSIS
.bd as
[
.bd \*-
] name ...
.sh DESCRIPTION
.it As
assembles the concatenation of the named files.
If the optional first argument
.bd \*-
is used,
all undefined symbols in the assembly
are treated as global.
.s3
The output of the assembly is left on the file
.bd "a.out."
It is executable if no errors occurred
during the assembly,
and if there were no unresolved external references.
.sh FILES
/lib/as2   	pass 2 of the assembler
.br
/tmp/atm[1-3]?	temporary
.br
a.out		object
.sh "SEE ALSO"
ld (I),
nm (I),
db (I),
a.out (V),
`UNIX Assembler Manual'.
.sh DIAGNOSTICS
When
an input file cannot be read, its name
followed by a question mark is typed and assembly
ceases.
When syntactic or semantic errors occur, a single-character diagnostic is typed out
together with the line number and the file name in which it
occurred.
Errors in pass 1 cause cancellation of pass 2.
The possible errors are:
.s3
.ta 3
)	Parentheses error
.br
]	Parentheses error
.br
<	String not terminated properly
.br
*	Indirection used illegally
.br
.li
\fB.\fR	Illegal assignment to `\fB.\fR'
.br
A	Error in address
.br
B	Branch instruction is odd or too remote
.br
E	Error in expression
.br
F	Error in local (`f' or `b') type symbol
.br
G	Garbage (unknown) character
.br
I	End of file inside an if
.br
M	Multiply defined symbol as label
.br
O	Word quantity assembled at odd address
.br
P	`\fB.\fR' different in pass 1 and 2
.br
R	Relocation error
.br
U	Undefined symbol
.br
X	Syntax error
.br
.sh BUGS
Symbol table overflow is not checked.
\fBx\fR errors can cause incorrect line numbers
in following diagnostics.