.TH ADB 1
.SH NAME
adb \- debugger
.SH SYNOPSIS
.B adb
[\fB\-w\fR] [ objfil [ corfil ] ]
.ds TW \v'.25m'\s+2~\s-2\v'-.25m'
.ds ST \v'.25m'*\v'-.25m'
.ds IM \v'.1m'=\v'-.1m'\s-2\h'-.1m'>\h'.1m'\s+2
.ds LE \(<=
.ds LT \s-2<\s+2
.ds GT \s-2>\s+2
.SH DESCRIPTION
.I adb
is a general purpose debugging program.
It may be used to examine files and to provide
a controlled environment for the execution
of UNIX programs.
.PP
.I Objfil
is normally an executable program file, preferably
containing a symbol table;
if not then the
symbolic features of
.I  adb
cannot be used although the file can still
be examined.
The default for
.I objfil
is `a.out'.
.I Corfil
is assumed to be a core image file produced after
executing
.IR objfil ;
the default for
.I corfil
is `core'.
.PP
Requests to
.I  adb
are read from the standard input and
responses are to the standard output.
If the
.B  \-w
flag is present then both
.I  objfil
and
.I corfil
are
created if necessary and
opened for reading and writing
so that files can be modified using
.IR adb .
.I Adb
ignores QUIT; INTERRUPT
causes return to the next
.I adb
command.
.PP
In general requests to
.I  adb
have the form
.PP
.if n .ti 16
.if t .ti 1.6i
[\|\fIaddress\fR\|]  [\|,
.IR count \|]
[\|\fIcommand\fR\|] [\|;\|]
.PP
If
.I address
is present then
.I  dot
is set to
.IR address .
Initially
.I dot
is set to 0.
For most commands
.I count
specifies how many times
the command will be executed.
The default
.I count
is 1.
.I Address
and
.I count
are expressions.
.SH EXPRESSIONS
.TP 7.2n
.B .
The value of
.IR dot .
.TP 7.2n
+
The value of
.I dot
incremented by the current increment.
.TP 7.2n
^
The value of
.I dot
decremented by the current increment.
.TP 7.2n
"
The last
.I address
typed.
.TP 7.2n
.I integer
A number.
The prefixes 0o and 0O (zero oh) force interpretation
in octal radix; the prefixes 0t and 0T force interpretation in
decimal radix; the prefixes 0x and 0X
or a leading sharp-sign
.RB ` # '
force interpretation in
hexadecimal radix.
Thus 0o20 = 0t16 = 0x10 = sixteen.
If no prefix appears, then the
.I default\ radix
is used; see the
.B $d
command.
The default radix is initially hexadecimal.
The hexadecimal digits are 0123456789abcdefABCDEF with the obvious
values.
Note that a hexadecimal number whose most significant
digit would otherwise be an alphabetic character must have a 0x
(or 0X) prefix (or a leading zero if the default radix is hexadecimal).
.TP 7.2n
.IB integer . fraction
A 32 bit floating point number.
.TP 7.2n
.I \'cccc\|\'
The ASCII value of up to 4 characters.
\\ may be used to escape a \'.
.TP 7.2n
.I \*(LT name
The value of
.IR name ,
which is either a variable name or a register name.
.I Adb
maintains a number of variables
(see
.SM VARIABLES\*S)
named by single letters or digits.
If
.I name
is a register name then
the value of the register is obtained from
the system header in
.IR corfil .
The register names are
those printed by the
.B $r
command.
.TP 7.2n
.I symbol
A
.I symbol
is a sequence
of upper or lower case letters, underscores or
digits, not starting with a digit.
.BR \\ " may be used to escape other characters."
The value of the
.I symbol
is taken from the symbol table
in
.IR objfil .
An initial \_ or \*(TW will be prepended to
.I symbol
if needed.
.TP
.I _ symbol
In C, the `true name' of an external symbol begins with _.
It may be necessary to utter this name to disinguish it
from internal or hidden variables of a program.
.TP 7.2n
.IB routine . name
The address of the variable
.I name
in the specified
C routine.
Both
.I routine
and
.I name
are
.IR symbols .
If
.I name
is omitted the value is the address of the
most recently activated C stack frame
corresponding to
.IR routine ;
if
.I routine
is omitted,
the active procedure
is assumed.
.TP 7.2n
.RI ( exp )
The value of the expression
.IR exp .
.LP
.SM
.B  "Monadic\ operators"
.TP 7.2n
.RI \*(ST exp
The contents of the location addressed
by
.I exp
in
.IR corfil .
.TP 7.2n
.RI @ exp
The contents of the location addressed by
.I exp
in
.IR objfil .
.TP 7.2n
.RI \- exp
Integer negation.
.TP 7.2n
.RI \*(TW exp
Bitwise complement.
.TP 7.2n
.RI % exp
If
.I exp
is used as an address,
it is in register space;
see
.SM ADDRESSES .
.LP
.B  "Dyadic\ operators"
are left associative
and are less binding than monadic operators.
.TP 7.2n
.IR e1 + e2
Integer addition.
.TP 7.2n
.IR e1 \- e2
Integer subtraction.
.TP 7.2n
.IR e1 \*(ST e2
Integer multiplication.
.TP 7.2n
.IR e1 % e2
Integer division.
.TP 7.2n
.IR e1 & e2
Bitwise conjunction.
.TP 7.2n
.IR e1 \(bv e2
Bitwise disjunction.
.TP 7.2n
.IR e1 # e2
.I E1
rounded up to the next multiple of
.IR e2 .
.DT
.SH COMMANDS
Most commands consist of a verb followed by a modifier or list
of modifiers.
The following verbs are available.
(The commands `?' and `/' may be followed by `\*(ST';
see
.SM ADDRESSES
for further details.)
.TP .5i
.RI ? f
Locations starting at
.I address
in
.I  objfil
are printed according to the format
.IR f .
.I dot
is incremented by the sum of the increments for each format letter (q.v.).
.TP
.RI / f
Locations starting at
.I address
in
.I  corfil
are printed according to the format
.I f
and
.I dot
is incremented as for `?'.
.TP
.RI  = f
The value of
.I address
itself is printed in the
styles indicated by the format
.IR f .
(For
.B i 
format `?' is printed for the parts of the instruction that reference
subsequent words.)
.PP
A
.I format
consists of one or more characters that specify a style
of printing.
Each format character may be preceded by a decimal integer
that is a repeat count for the format character.
While stepping through a format
.I dot
is incremented
by the amount given for each format letter.
If no format is given then the last format is used.
The format letters available are as follows.
.ta 2.5n .5i
.RS
.TP
.PD 0
.BR o "	2"
Print 2 bytes in octal.
.TP
.BR O "	4"
Print 4 bytes in octal.
.TP
.BR q "	2"
Print in signed octal.
.TP
.BR Q "	4"
Print long signed octal.
.TP
.BR d "	2"
Print in decimal.
.TP
.BR D "	4"
Print long decimal.
.TP
.BR x "	2"
Print 2 bytes in hexadecimal.
.TP
.BR X "	4"
Print 4 bytes in hexadecimal.
.TP
.BR u "	2"
Print unsigned decimal.
.TP
.BR U "	4"
Print long unsigned decimal.
.TP
.BR f "	4"
Print the 32 bit value
as a floating point number.
.TP
.BR F "	8"
Print double floating point.
.TP
.BR b "	1"
Print the addressed byte in octal.
.TP
.BR c "	1"
Print the addressed character.
.TP
.BR C "	1"
Print the addressed character using
the standard escape convention where control characters
are printed as ^X and the delete character is printed as ^?.
.TP
.BI s "	n"
Print the addressed characters until a zero character
is reached.
.TP
.BI S "	n"
Print a string using 
the ^X escape convention (see \fBC\fR above).
.I n
is the length of the string including its zero terminator.
.TP
.BR Y "	4"
Print 4 bytes in date format (see
.IR ctime (3)).
.TP
.BR i "	n"
Print as VAX instructions.
.I n
is the number of bytes occupied by the instruction.
This style of printing causes variables
0, (1, ...)
to be set to the offset parts
of the first (second, ...)
operand of the instruction.
.TP
.BR a "	0"
Print the value of
.I dot
in symbolic form.
.TP
.BR p "	4"
Print the addressed value in symbolic form using
the same rules for symbol lookup as
.BR a .
.TP
.BR t "	0"
When preceded by an integer tabs to the next
appropriate tab stop.
For example,
.B 8t 
moves to the next 8-space tab stop.
.TP
.BR r "	0"
Print a space.
.TP
.BR n "	0"
Print a newline.
.tr '"
.TP
.BR '...' " 0"
Print the enclosed string.
.br
.tr ''
.TP
.B ^
.I Dot
is decremented by the current increment.
Nothing is printed.
.TP
+
.I Dot
is incremented by 1.
Nothing is printed.
.TP
\-
.I Dot
is decremented by 1.
Nothing is printed.
.RE
.PD
.TP
newline
Repeat the previous command with a
.I count
of 1.
.TP
.RB [ ?/ ] l "\fI value mask\fR"
Words starting at
.I  dot
are masked with
.I mask
and compared with
.I value
until
a match is found.
If
.B L
is used then the match is for 4 bytes at a time instead of 2.
If no match is found then
.I dot
is unchanged; otherwise
.I dot
is set to the matched location.
If
.I mask
is omitted then \-1 is used.
.TP
.RB [ ?/ ] w "\fI value ...\fR"
Write the 2-byte
.I value
into the addressed
location.
If the command is
.BR W ,
write 4 bytes.
.TP
[\fB?/\fR]\fBm\fI b e f\fR[\fB?/\fR]
.br
New values for
.RI ( b,\ e,\ f )
in the first map entry
are recorded.
If less than three expressions are given then
the remaining map parameters are left unchanged.
The address type (instruction or data)
is unchanged in any case.
If the `?' or `/' is followed by `\*(ST' then
the second segment
of the mapping is changed.
If the list is terminated by `?' or `/' then the file
(\fIobjfil\fR or
.I corfil
respectively) is used
for subsequent requests.
(So that, for example, `/m?' will cause `/' to refer to
.IR objfil .)
.TP
.BI \*(GT name
.I Dot
is assigned to the variable or register named.
.TP
.B !
A shell is called to read the
rest of the line following `!'.
.TP
.RI $ modifier
Miscellaneous commands.
The available 
.I modifiers 
are:
.RS
.TP
.PD 0
.BI < f
Read commands from the file
.IR f .
If this command is executed in a file, further commands
in the file are not seen.
If
.I f
is omitted, the current input stream is terminated.
If a
.I count
is given, and is zero, the command will be ignored.
The value of the count will be placed in variable 9
before the first command in
.I f
is executed.
.TP
.BI << f
Similar to
.B <
except it can be used in a file of commands without
causing the file to be closed.
Variable 9
is saved during the execution of this command, and restored
when it completes.
There is a (small) finite limit to the number of
.B <<
files that can be open at once.
.br
.ns
.TP
.BI > f
Append output to the file
.IR f ,
which is created if it does not exist.
If
.I f
is omitted, output is returned to the terminal.
.TP
.B ?
Print process id, the signal which caused stopping or termination,
as well as the registers.
This is the default if
\fImodifier\fR is omitted.
.TP
.B r
Print the general registers and
the instruction addressed by
.BR pc .
.I Dot
is set to \fBpc\fR.
.TP
.B R
Like
.BR $r ,
but include boring registers
like the kernel stack pointer.
.TP
.B b
Print all breakpoints
and their associated counts and commands.
.TP
.B c
C stack backtrace.
If
.I address
is given then it is taken as the
address of the current frame (instead of
.BR fp ).
If
.B C 
is used then the names and (32 bit) values of all
parameters,
automatic
and static variables are printed for each active function.
If
.I count
is given then only the first
.I count
frames are printed.
.TP
.B d
Set the default radix to
.I address
and report the new value.
.I Address
is interpreted in the (old) current radix;
`10$d' never changes the default radix.
To make decimal the default radix, use `0t10$d'.
A radix of zero is a special case:
input with a leading zero is octal,
that with a leading sharp-sign
.RB ` # '
is hexadecimal,
other numbers are decimal;
output is hexadecimal by default;
hex and octal numbers are printed
with a leading
.B #
and
.B 0
respectively.
.TP
.B e
The names and values of
external variables are printed.
.TP
.B w
Set the page width for output to
.I address
(default 80).
.TP
.B s
Set the limit for symbol matches to
.I address
(default 255).
.TP
.B q
Exit from
.IR adb .
.TP
.B v
Print all non zero variables in the current radix.
.TP
.B m
Print the address maps.
.TP
.B k
Simulated VAX memory management:
set the system base register pointer to
.IR address .
System space addresses will hereafter be mapped
according to the system page table.
If
.I address
is zero,
mapping is turned off.
.TP
.B p
Set the PCB base pointer to
.IR address ,
which may be either the physical address of a process control block
(as found in the PCBB register)
or the system space address of a page table entry
which points to a PCB
(as found in
.IR p_addr ).
User space addresses will hereafter
be translated according to the
user page tables
pointed to by the PCB.
Kernel mapping
.RB ( $k )
must already be in effect.
If
.I address
is zero,
user mapping is turned off;
addresses less than
0x80000000
will be treated as physical addresses.
.IP
.B $k
and
.B $p
are useful for system debugging.
.PD
.RE
.TP
.BI : modifier
Manage a subprocess.
Available modifiers are:
.RS
.TP
.PD 0
.BI b c
Set breakpoint at
.IR address .
The breakpoint is executed
.IR count \-1
times before
causing a stop.
Each time the breakpoint is encountered
the command
.I c
is executed.
If this command is omitted or sets
.I dot
to zero
then the breakpoint causes a stop.
.TP
.B d
Delete breakpoint at
.IR address .
.TP
.B r
Run
.I objfil
as a subprocess.
If
.I address
is given explicitly then the
program is entered at this point; otherwise
the program is entered at its standard entry point.
.I count
specifies how many breakpoints are to be
ignored before stopping.
Arguments to the subprocess may be supplied on the
same line as the command.
An argument starting with < or > causes the standard
input or output to be established for the command.
All signals are turned on on entry to the subprocess.
.TP
.BI c s
The subprocess is continued.
If
.I s
is omitted
or nonzero,
the subprocess
is sent the signal that caused it to stop;
if 0
is specified,
no signal is sent.
Breakpoints
and single-stepping
don't count as signals.
Breakpoint skipping is the same
as for
.BR r .
.TP
.BI s s
As for
.B c 
except that
the subprocess is single stepped
.I count
times.
If a signal is sent,
it is received
before the first instruction is executed.
If there is no current subprocess then
.I objfil
is run
as a subprocess as for
.BR r .
In this case no signal can be sent; the remainder of the line
is treated as arguments to the subprocess.
.TP
.B k
The current subprocess, if any, is terminated.
.PD
.RE
.SH VARIABLES
.I Adb
provides a number of variables.
Named variables are set initially by
.I  adb
but are not used subsequently.
Numbered variables are reserved for communication
as follows.
.TP
0, 1, ...
The offset parts of the first, second, ...
operands of the last instruction printed.
Meaningless if the operand was a register.
.br
.ns
.TP
9
The count on the last $< or $<< command.
.PP
On entry the following are set
from the system header in the
.IR corfil .
If
.I corfil
does not appear to be a
.B core 
file then
these values are set from
.IR objfil .
.TP
b
The base address of the data segment.
.br
.ns
.TP
d
The data segment size.
.br
.ns
.TP
e
The entry point.
.br
.ns
.TP
m
The `magic' number (0407, 0410 or 0413).
.br
.ns
.TP
s
The stack segment size.
.br
.ns
.TP
t
The text segment size.
.SH ADDRESSES
The address in a file associated with
a written address is determined by a mapping
associated with that file.
Each mapping is represented by one or more quadruples
.RI ( "t, b, e, f" ),
each mapping addresses of type
.I t
(instruction,
data,
user block)
in the range
.I b
through
.I e
to the part of the file
beginning at
address
.IR f .
An address
.I a
of type
.I t
is mapped
to a file address
by finding a quadruple
of type
.IR t ,
for which
.IR b \*(LE a < e ;
the file address
is
.IR address + f \(mi b .
As a special case,
if an instruction space address is not found,
a second search is made
for the same address in data space.
.PP
Typically,
the text segment of a program
is mapped as instruction space,
the data and bss segments
as data space.
If
.I objfil
is an
.IR a.out,
or if
.I corfil
is a core image
or process file,
maps are set accordingly.
Otherwise,
a single `data space'
map is set up,
with
.I b
and
.I f
set to zero,
and
.I e
set to a huge number;
thus the entire file can be examined
without address translation.
.PP
The
.B ?
and
.B /
commands attempt to examine
instruction and data space
respectively.
.B ?*
tries for data space
(in
.IR objfil );
.B /*
accesses instruction space
(in
.IR corfil ).
.PP
Registers in
process and core images
are a special case;
they live in a special `register' address space.
The contents of register 0
are located at address
.BR %0 ;
register 1
at
.BR %4
(registers are 4 bytes long);
and so on.
.B %
addresses
are mapped to the registers
for the `current frame,'
set by local variable references,
and reset to the outermost frame
(the `real' registers)
whenever a process runs
or a stack trace is requested.
.PP
Simulated memory management
translations
(the
.B $k
and
.B $p
commands)
are done before the mapping described above.
.PP
So that
.I adb
may be used on large files
all appropriate values are kept as signed 32 bit integers.
.SH FILES
a.out
.br
core
.br
/usr/lib/adb/*  parameter files
.SH SEE\ ALSO
pi(9.1),
sdb(1),
proc(4),
a.out(5),
core(5)
.SH DIAGNOSTICS
`Adb' when there is no current command or format.
Comments about inaccessible files, syntax errors,
abnormal termination of commands, etc.
Exit status is 0, unless last command failed or
returned nonzero status.
.SH BUGS
Either the explanation
or the implementation
of register variables
is too complex and arcane.
.PP
.B 0$d
should probably be the default.