Trailing-Edge
-
PDP-10 Archives
-
decuslib10-05
-
43,50337/25/tdiv.mem
There is 1 other file named tdiv.mem in the archive. Click here to see a list.
CHAPTER 1
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.1-1
741101 780302 6 Ingrid Wennerstrom
IV THE DEBUG SYSTEM
----------------
IV.1 SYSTEM DESCRIPTION
The SIMULA Language Handbook Part II, Chapter 9, contains a
description of the SIMDDT system from the user's point of view.
The main tasks of SIMDDT are:
* to produce a message stating the reason for SIMDDT invocation.
* to produce a diagnostic message when a run time error has been
found. The message contains a reference to the source line
where the error occurred.
* to respond to valid user commands and give a message for invalid
commands.
* to set, remove or display breakpoints in the user program.
* to perform breakpoint actions on reaching a breakpoint.
* to display values of variables, the entire storage pool, the
operating chain and all scheduled processes (OUTPUT, VARIABLES,
CHAIN, SCHEDULED and ALL commands).
* to change the value of a variable (INPUT command).
* to direct the output from SIMDDT to another file or terminal
than the user TTY (USE command).
* to take command input from a file or another terminal (@
command).
* to display source program lines (DISPLAY command).
* to change the viewpoint of the program (INSPECT).
* to close files on demand (CLOSE).
The SIMDDT program is self-relocating and is read from disk by
the SIMRTS routine OCLD on demand. It exists as a binary file
SIMDDn.ABS (n = version number, e.g. 4). The file is normally
read into the dynamic part of the low segment area and may be
moved by the garbage collector routine (SAGC). If SIMDDT is
invoked before the SIMULA program starts execution, however, by
a LOAD-REENTER sequence or a DEBUG command, it will be placed
before the SIMULA data area and will not be moved, neither will
it disappear if the program exits and is restarted by a START
command. The SIMDDn.ABS file is generated by execution of the
special utility program SUTABS loaded together with the REL file
produced by assembling the SIMDDT source modules.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.1-2
741101 780302 6 Ingrid Wennerstrom
The commands to SIMDDT are normally taken from the user terminal
but may be taken from a file (or terminal) specified by the @
command. Communication with the RTS is via information in the
low segment STATIC area and via accumulators at entry to SIMDDT
and to RTS routines from SIMDDT.
Output from SIMDDT is written on the user's TTY (which may be a
controlling PTY if SIMDDT is run in a subjob to e.g. BATCON).
Output can also be directed to a disk file or another TTY.
New feature starting with version 4(302): If another TTY is
used both as input (@TTYn:) and as output (USE TTYn:), no output
will appear on the controlling user TTY. This is useful if the
ordinary TTY should be undisturbed by debug info.
The LINE NUMBER TABLE generated by the compiler is used by
SIMDDT to find the core address that corresponds to a source
program line or vice versa.
One type of entry found in the line number table shows the block
structure of the program. From these entries, the corresponding
SYMBOL TABLES can be found (via the prototypes) and this enables
SIMDDT to find the proper match to an identifier given in a
command by following the block structure outwards. SIMDDT only
accepts identifiers visible from the current block. For an
OUTPUT or INPUT command, the current block is the block in which
program execution was interrupted, and for a breakpoint command
(AT ...) it is the block containing the statement referenced via
the line number.
The INSPECT command can be used to change the current block,
however, to any block reachable via the operating chain or via
reference variables.
The SYMBOL TABLES generated by the compiler contain for each
identifier its name, characteristics and the offset within its
block instance. Every object with a prototype also has a symbol
table.
The BREAKPOINT RECORD TABLE contains the information from the
user breakpoint commands and the instructions that were replaced
by breakpoint UUO's in the generated code. The breakpoint
record contains pointers to the line number table, the symbol
tables and the effective block level (copied from the
prototype). To implement the IFCHANGED form of the breakpoint
command the REF and TEXT variable addresses and values must be
kept between breakpoints. The SIMDDT work area does not contain
space for the actual text values saved. To solve the space and
relocation problems for these variables, one REF array and one
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.1-3
741101 780302 6 Ingrid Wennerstrom
TEXT array are allocated via the RTS. Old REF and TEXT pointers
are kept in those arrays, which are properly relocated by the
garbage collector, thus the referenced values will be retained
for later comparison.
The KEYWORD TABLE contains one entry for each special identifier
or operator that must be recognized by SIMDDT when scanning a
user command. The entry consists of name (SIXBIT), control bits
and a dispatch routine address for command starting kewwords.
All messages form SIMDDT are created in SIMDDT and this applies
also to most of the messages from the generated program and from
SIMRTS. Some terminating error messages and the I/O file
specification dialogue messages are not handled by SIMDDT. The
method for handling diagnostic messages is almost the same as
the method used in the compiler, see II.5.
CHAPTER 2
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-1
741101 780302 6 Ingrid Wennerstrom
IV.2 SIMDDT DECOMPOSITION
SIMDDT consists of the following components:
Source module Function
SIMDS1 entry points
SIMDS2 I/O, messages, initialization, search of the
line number table and interface to SIMRTS
routines.
SIMDS3 breakpoint table processing, output text
creation, search of symbol tables and scanning
of input.
SIMDS8 error message table start address.
SIMEDS error message tables created by SUTEDS utility.
SIMDS9 breakpoint and command processing.
SIMDS7 data area.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-2
741101 780302 6 Ingrid Wennerstrom
IV.2.1 Main flow
---------
----------- ----------- ----------- -----------
( from OCEI ) ( from OCUU ) ( from OCRE ) ( from OCUU )
----------- ----------- ----------- -----------
! ! ! !
! ! ! !
+-------------+ +-------------+ +--------------+ +--------------+
! DSINI ! ! DSINB, DSBP ! ! DSINR ! ! DSINE !
! initialise ! ! breakpoint ! ! ^C-interrupt ! ! Error in the !
! SIMDDT ! ! actions ! ! - REENTER ! ! program !
+-------------+ +-------------+ +--------------+ +--------------+
! ! ! !
! +-----+ +-----+ +-----+
! Y + break- + + SIMDDT + + termin- +
!<--------< point > < active >-+ < ating >-+
! + STOP? + + already?+ ! Y + error? + ! Y
! +-----+ +-----+ (1) +-----+ (1)
! ! N ! N ! N
! (2) ! !
! +--------------+ +--------------+
! !Output message! ! Output error !
!<--------------------------!with interrupt! ! message !
! !address ! ! !
! +--------------+ +--------------+
! !
!<----------------------------------------------------+
!
(3)
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-3
741101 780302 6 Ingrid Wennerstrom
---------- -----------
(3) ( from START ) ( from OCSPDR )
! ---------- -----------
! ! !
! +------------+ +-------------+
! ! DSINM ! ! DSINS !
! !SIMDDT loa- ! ! Remove all !
! !ded with prg! ! breakpoints !
! +------------+ +-------------+
+------------+ ! !
! DSCM ! ---------- !
+---------->! accept user! ( to .MAIN+2 ) (1)
! ! command ! ----------
! +------------+
! !
! +--------------------------------------------------+
! ! ! ! !
! +------------+ +------------+ +------------+ +------------+
! ! DSAT ! ! DSVA ! ! DSPR ! ! DSEX !
! ! breakpoint ! ... ! VARIABLES ! ! PROCEED ! ! EXIT !
! ! settings ! ! command ! ! command ! ! command !
! +------------+ +------------+ +------------+ +------------+
! ! ! ! !
+------------------------------+ +-----+ !
Y + ENTER + !
+-------< via breakpoint> !
! + ? + !
V +-----+ !
+------------+ ! N +-----+
! Perform ! ! N + DEBUG +
! breakpoint ! !<------< mode >
! actions ! ! + ? +
+------------+ ! +-----+
! (1)-->! !
! !
------------- ------------- ------------
(EXIT to progr) (RETURN to RTS) (EXIT to OCEP)
------------- ------------- ------------
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-4
741101 780302 6 Ingrid Wennerstrom
IV.2.2 Module contents
---------------
The following list should serve as an index to the source
listing. Detailed descriptions are given there.
SIMDS1
------
DSINI Starts SIMDDT processing in debug mode. Called from the
RTS routine OCEI before starting execution of user
program code.
DSINE Starting point in SIMDDT for error processing. Called
from RTS (OCUU). Outputs the error message.
DSINEM Entry from INSPECT/START to repeat error message.
DSINB Start of breakpoint instruction processing. Called by
OCUU. Locates breakpoint and continues at DSBP.
DSINR Entry point after ^C-REENTER or CONTINUE following
program exit. Called from OCRE. Indicates interruption
point (source line) by a message.
DSINRM Entry from INSPECT/START to repeat message.
DSINC This routine is entered from a code sequence in the
static low segment area on return from certain RTS
routines which may have caused garbage collection or
detected an error (see DSCRT). Relocates the SIMDDT
stack and I/O text variables if a garbage collection was
performed since SIMDDT called the RTS routine. Writes
any error message replacing the message prefix ZYQ by
ZYD.
DSINM The whole program starts in this entry point if
SIMDDT.REL was loaded with the user main program and the
last entry point definition seen by LINK was DSINM.
This feature is mainly used for SIMDDT debugging
purposes. Exits directly to the generated program (at
.MAIN+2) with the base address of SIMDDT (DSSTAR) in ac
X1.
DSINS Removes all breakpoints. Called from the RTS routine
OCSPDR before restarting a SIMULA program that has
executed since being loaded to core. Since the low
segment will be cleared, it is not possible to keep the
breakpoints.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-5
741101 780302 6 Ingrid Wennerstrom
SIMDS2
------
DSFK Finds a keyword in the keyword table.
DSTC Converts a valid ASCII character to SIXBIT.
DSIT Inputs a command line from the TTY or a file.
DSO Several routines to create a message in the output
buffer, write the buffer on the tty or a file.
DSVO Outputs message on file and tty.
DSSCI Loads next input character in an accumulator.
DSSKB Loads next non-blank, non-tab character in an
accumulator.
DSGI Gets the next identifier or relational operator from the
input buffer.
DSIFK Finds keyword identifier in input buffer.
DSPM Creates a message and puts it in the output buffer using
the message tables generated by SUTEDS.
DSIS Initialises SIMDDT.
DSISRB Removes all breakpoints from user code.
DSOC Puts a character in the output text.
DSONL Initialises the output text pointers.
DSINL Initialises the input text pointers.
DSPL Locates an address in the line number table and puts the
string <MODULE>:<NNNNN>, <MODULE>: O<oooooo> or
O<oooooo> in the output buffer.
DSLL Locates a line number in a given line number table.
DSLO Locates an octal address in any of the line number
tables.
DSEZLN Searches the line number table for the main program to
find the line number tables for external classes and
procedures.
DSPO Puts an octal number in the output buffer.
DSTX Several routines handling the interface to the RTS text
routines TXPI, TXPR, TXGI and TXGR.
DSCRT
DSCTX Save status and call an RTS routine via a code sequence
in the low segment area. Any call from SIMDDT to a RTS
routine which may cause garbage collection or find an
error must be routed via DSCRT or DSCTX. DSCTX calls
the TXGI or the TXGR routine.
DSCLO Collection of routines that close a (specific) file
using the RTS routine IOCL.
DSBUTX Initialises the input and output text pointers and the
SIMDDT stack.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-6
741101 780302 6 Ingrid Wennerstrom
DSEXPR Closes an open display file and resets variables.
DSFSP Creates a file specification.
DSCF Creates a file object and opens the file.
DSCFAB Allocate buffers when normal method cannot be used (no
GC allowed).
DSCFLB Link buffers set up by DSCFAB.
DSRUC Finds static or dynamic link.
DSRU Calls DSRUC.
DSLPR Finds prototype or class identifier in any of the
existing line number tables.
DSCHGC Checks if a command is allowed (garbage collection may
be prohibited).
DSVAK Checks for /-ARRAY, /-TEXT, /-GC or /START:oooooo in
command.
DSIOCT Compute value of integer given in octal radix.
SIMDS3
------
DSRB Releases all linked breakpoint entries (ZBE records).
DSNB Finds the next breakpoint entry or word within the
breakpoint entry (ZBE).
DSNBC Finds the next breakpoint entry (ZBE) which contains
information from a new command.
DSFB Reserve and link one more breakpoint entry (ZBE) or
reserve the next word within the breakpoint entry.
DSPS Puts identifier from the keyword table or the symbol
table or puts MAIN or BLOCK in the output buffer.
DSPI Puts <IDENTIFICATION2> in the output buffer. The
information is fetched from the breakpoint entries given
in the call.
DSNI Gets a new <IDENTIFICATION> or <IDENTIFICATION2> from
the input buffer and places the information in the
breakpoint entries (ZBE).
DSSS Finds all blocks accessible via the current program
block or via a specified class and its prefix classes.
The symbol tables accessible for each block are passed
as parameters (one at a time) to a subroutine whose
address is given in the call to DSSS as a parameter.
DSSS searches the line number table and finds the symbol
tables via the prototype pointers.
DSCT Checks if a symbol table entry (ZSD) can be handled by
SIMDDT.
DSLV Locates the address of a variable with the help of the
XCB ac and the breakpoint entries (ZBE).
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-7
741101 780302 6 Ingrid Wennerstrom
DSSPV Gets system procedure value address.
DSCSQU Calls RTS routine CSQU to check a qualification.
DSNILV CAlls DSNI and DSLV to find the address of an
<IDENTIFICATION2>.
DSPV Edits the value of a variable into the output text.
DSPVS Outputs array elements or a complete block (*).
DSFA Puts the class, procedure or block identification in the
output buffer. The identification consists of name,
octal address, reactivation point or invocation address.
DSVIV Checks if a variable has its standard initial value.
DSVAR Fetches the subscript, dope vector and base address for
an array element.
DSGS Loads the next text constant character from the input
buffer.
DSGL Gets the statement identification <LINE> from the input
buffer and returns the address of the correponding line
number table entry.
DSGV Gets a <VALUE> from the input command and saves the
information in the breakpoint entry (ZBE).
DSRLB Resets all information from one breakpoint command.
DSRLBA Resets all information from one breakpoint command if an
error occurred while scanning the command.
DSRLBI Removes a breakpoint instruction from the compiled code.
DSRL Removes the information from all breakpoint commands
relating to the same breakpoint location.
DSPB Reconstructs a breakpoint command and puts it in the
output buffer.
DSLB Scans the breakpoint records (ZBR) for a match to an
input statement identification <LINE>.
DSRAF Reserves any free element in the REF array YDSREF.
DSRAT Reserves any free element in the TEXT array YDSTXT.
DSFAR Releases an element in the REF array YDSREF.
DSFAT Releases an element in the TEXT array YDSTXT.
DSFCV Loads address of a constant to an ac.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-8
741101 780302 6 Ingrid Wennerstrom
SIMDS9
------
DSBP Performs the actions specified for a breakpoint.
DSCM Outputs the prompting asterisk (*) on the terminal where
commands are input, scans the first word of the command
and dispatches control to the proper routine via the
keyword table.
DSST Sets a flag when STOP was found as the first word of the
command.
DSHE Outputs helpful text on the terminal (HELP command).
DSAT Scans the AT command, saves the information in a
breakpoint record and a set of linked breakpoint entries
(ZBR and ZBE) and substitutes a special instruction
(BREAK UUO) for the user code instruction.
DSDP Outputs the requested source program lines (DISPLAY
command).
DSOP Handles the OUTPUT command.
DSIP Handles the INPUT command.
DSRE Handles the REMOVE command; removes information for one
or all breakpoints.
DSBR Handles BREAKS command, listing all breakpoint commands
currently defined and removes a command if requested by
the uesr.
DSCL Closes all open files except SYSIN, SYSOUT or lists all
open files, letting the user decide on closing each file
separately.
DSPR Handles PROCEED command. Exits from SIMDDT via the RTS
stack if SIMDDT was entered via DSINI, DSINE or DSINR.
Interprets the user instruction and branches to the
following instruction if SIMDDT was entered at DSINB
(breakpoint entry).
DSUS Handles USE command. Calls the RTS routines IOLN, CPNE,
CSEN and IOOP to establish a USE file object and to
initialise the file.
DSCH Handles CHAIN command. Outputs operating chain starting
from the current block.
DSVA Handles VARIABLES command. The garbage collector
routine in the RTS is called unless prohibited by a /-GC
switch, by entering through DSINR or by the SWNOGC flag
being on. All variables in the storage pool are listed,
normally from the bottom of the pool, unless modified by
a /START switch.
DSPAE Outputs an array identifier, its bounds and any array
element which have values different from the default
initial value.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.2-9
741101 780302 6 Ingrid Wennerstrom
DSVA01 Outputs all variables in a block.
DSSC Handles SCHEDULED command. Uses the SUNE procedure of
the RTS to find the next scheduled process.
DSPC Handles INSPECT command. Changes current block pointer.
DSAL Handles ALL command. Invokes DSCH, DSVA, DSSC.
DSEX Handles EXIT command. In error mode, exit is via the
SIMRTS stack, in debug mode exit is to OCEP for program
termination.
DSNOPR Handles NOPROCEED command. Inhibits use of the PROCEED
command. This allows more SIMDDT actions at the expense
of not being able to continue.
DSGET Handles @ command. Opens a file for input (using the
RTS routines for file handling) and sets the YDSITTY
switch off to indicate command input from a file (which
may represent a disk file or another TTY).
DSNOTI Handles unimplemented commands.
DSTERM
DSIE Entered after a termination error detected within
SIMDDT. Outputs message and branches to OCEP to
terminate the program.
CHAPTER 3
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-1
741101 780302 6 Ingrid Wennerstrom
IV.3 LOW SEGMENT ORGANISATION
ACCUMULATORS +---------------+ GENERATED PROGRAM
------------ !---------------! -----------------
! ZLN, ZSM, ZSD ! Constant records generated by the
! ZPR, ZMP ! compiler, referenced by SIMDDT,
: - - - - - - - : see I.5
XLOW -------> !---------------!
! Global variab-! STATIC LOW SEGMENT AREA
! les (STATIC) ! -----------------------
XPDP -------> !...............! Used by RTS and SIMDDT,
! RTS stack ! relocated by garbage collector
: - - - - - - - :
XDBAS ------> :---------------: DYNAMIC LOW SEGMENT AREA
:---------------: ------------------------
! ZDN ! SIMDDn.ABS (approx. 6.5K)
XDZBR ------> !---------------!
! ZBR ! SIMDDT data area:
!---------------! Breakpoint record and
! ZBE ! entries
:---------------:
XDSTK ------> :---------------:
! SIMDDT stack !
!---------------!
! ZTE (ZDSZTE) ! TEXT record for I/O
!---------------!
!input text buf !
!---------------!
!output text buf!
!---------------!
!input text str.!
!---------------!
! ZAR (ZDSTXT) ! TEXT array used by SIMDDT
!---------------!
! ZAR (ZDSREF) ! REF array used by SIMDDT
:---------------:
: :
XCB --------> :---------------:
! ZBI ! Current block instance
:---------------:
: :
+---------------+
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-2
741101 780302 6 Ingrid Wennerstrom
IV.3.1 Static low segment area
-----------------------
This is the communication area for the RTS. It is also used for
interface between SIMDDT and the RTS. When SIMDDT is active,
the XLOW ac always points to the STATIC area.
IV.3.2 SIMDDn.ABS
----------
The SIMDDT code is read from the disk file SIMDDn.ABS. n =
SIMULA system version number, e.g. the version 4 SIMDDT file is
called SIMDD4.ABS. Earlier versions were called SIMDDT.ABS
regardless of version. The data in the file has the form of two
dynamic records, one ZYS record and a ZTE (TEXT) record,
referenced as ZDSZTE.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-3
741101 780302 6 Ingrid Wennerstrom
IV.3.2.1 Keyword Table (ZKW)
-------------------
+---------------------------------------+
!ZKW!ZKW!ZKW!ZKWTYP!ZKWCOD! ZKWADR !
!LNE!DBG!ERR! ! ! !
!---------------------------------------!
! ZKWNM1 !
!---------------------------------------!
! ZKWNM2 !
!---------------------------------------!
! ! ! !
!---------------------------------------!
! !
!- - - - - - - - - - - - - - - - - - - -!
: :
: :
!---------------------------------------!
! ! ! !
!---------------------------------------!
! !
!---------------------------------------!
: :
:- - - - - - - - - - - - - - - - - - - -:
class ZKW; comment
----- -------
This class describes the format of the keyword
table. Each keyword entry occupies two or three
words in the table. Every keyword used in a
SIMDDT command has an entry in this table.
Entries also exist for the comparison
(relational) operators >, >=, ..., \=, == and
=/=. All entries starting with the same
character form a group. Within this group the
entries are sorted on the length of the name;
boolean ZKWLNE; comment
------- -------
<0:0> This flag is set when the second word, ZKWNM2,
of the name is present;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-4
741101 780302 6 Ingrid Wennerstrom
boolean ZKWDBG; comment
------- -------
<1:1> This flag is set when the keyword is allowed in
a debug mode command;
boolean ZKWERR; comment
------- -------
<2:2> This flag is set when the keyword is allowed in
an error mode command;
integer ZKWTYP; comment
------- -------
<3:5> This field gives the type of keyword.
The different types are:
start of command
inside command
used in relations
after / in INSPECT;
integer ZKWCOD; comment
------- -------
<6:17> The accumulator XDBAS is placed in this field if
ZKWTYP is start of command.
This field gives the type of a relational
operator or the type of a constant;
integer ZKWADR; comment
------- -------
<18:35> This field gives the relative address of a
command routine if ZKWTYP is start of command.
For a relational operator it gives the
instruction to be used and for a constant
(FALSE, NONE, NOTEXT or TRUE) it gives the
value;
integer ZKWNM1; comment
------- -------
<0:35> This field gives the six initial characters of
the keyword (sixbit code);
integer ZKWNM2; comment
------- -------
<0:35> This field gives the last six characters of a
keyword longer than 6 characters. Only present
if ZKWLNE is set;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-5
741101 780302 6 Ingrid Wennerstrom
IV.3.2.2 Error tables YE3DL, YE3D, YE3M and YE3MI
These tables are described in section II.C.3. The combined size
is roughly 0.8 K words.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-6
741101 780302 6 Ingrid Wennerstrom
IV.3.2.3 Breakpoint record ZBR
+-------------------------------------------------+
! ZDN !
!-------------------------------------------------!
+----! ZBRZBE [0] ! 0 !
! +-------------------------------------------------+
! ! ZBRZBE [1] ! ZBRZLN [1] !
! +-------------------------------------------------+
! ! ZBRINS [1] !
! +-------------------------------------------------+
! ! ZBRZBE [2] ! ZBRZLN [2] !----+
! !-------------------------------------------------! !
! ! ZBRINS [2] ! !
! +-------------------------------------------------+ !
! : : !
! : : !
! +-------------------------------------------------+ !
! +--! ZBRZBE [QBRN] ! ZBRZLN [QBRN] ! !
! ! +-------------------------------------------------+ !
! ! ! ZBRINS [QBRN] ! !
! ! !-------------------------------------------------! !
! +->! First ZBE for first breakpoint line !--+ !
! !-------------------------------------------------! ! !
! +--! Second ZBE for first breakpoint line !<-+ !
! ! !-------------------------------------------------! !
! +->! Last ZBE for first breakpoint line ! !
! !-------------------------------------------------! !
! ! First ZBE for second breakpoint line !<---+
! +-------------------------------------------------+
! : :
! : :
! +-------------------------------------------------+
+--->! First free ZBE !--+
!-------------------------------------------------! !
+--: :<-+
! +-------------------------------------------------+
+->! Last free ZBE !
+-------------------------------------------------+
! !
!-------------------------------------------------!
! !
! Work area for SIMDDT !
! !
+-------------------------------------------------+
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-7
741101 780302 6 Ingrid Wennerstrom
ZDN class ZBR; comment
----- -------
This class describes the format of the
breakpoint record. It is used for storage of
information from breakpoint commands. The last
part of the ZBR record is used as a work area.
Since the record is placed inside the dynamic
record for the first part of SIMDDn.ABS, the
garbage collector is not aware of it. The
accumulator XDZBR addresses this record and it
would be possible to move all other parts of
SIMDDn.ABS to the high segment keeping the data
area (ZBR record) in the low segment;
ref (ZBE) array ZBRZBE[0:QBRN]; comment
--- ----- -------
<0:17> The first entry in this array points to the
first free breakpoint entry ZBE. All free ZBE's
are then linked together. The maximum number of
different line numbers for all active
breakpoints is QBRN. The ZBRZBE field points to
the first ZBE used for a set of breakpoints with
the same line number. The line number is
specified via the ZBRZLN field. The pointer is
zero for unused entries. The address ZBRZBE is
relative to the start of the ZBR record;
ref (ZLN) array ZBRZLN[0:QBRN]; comment
--- ----- -------
<18:35> The array elements point to line number table
entries defining the corresponding breakpoint
line numbers. An unused entry has a zero value;
integer array ZBRINS[0:QBRN]; comment
------- ----- -------
<0:35> The array elements contain the instructions from
generated code replaced by breakpoint
instructions. These entries are valid only when
the corresponding ZBRZBE element is non-zero;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-8
741101 780302 6 Ingrid Wennerstrom
IV.3.2.4 Breakpoint entry ZBE
AT line
+----------------------------------------------------+
! ZBEZBE !STO!STB!ZBETYP! !
!----------------------------------------------------!
! ZBESTR !
+----------------------------------------------------!
! ZBENIN ! ZBENVA !
+----------------------------------------------------!
! not used !
+----------------------------------------------------!
AT line list
+----------------------------------------------------+
! ZBEZBE !STO!STB!ZBETYP! !
!----------------------------------------------------!
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
!- - - - - - - - - - - - - - - - - - - - - - - - - - !
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
+----------------------------------------------------!
! ZBEVSU !
+----------------------------------------------------!
AT line IFCHANGED list
+----------------------------------------------------+
! ZBEZBE !STO!STB!ZBETYP! !
!----------------------------------------------------!
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
+----------------------------------------------------!
! ZBEVAL !
+----------------------------------------------------!
! ZBEVAL !
+----------------------------------------------------+
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-9
741101 780302 6 Ingrid Wennerstrom
AT line IF relation
+----------------------------------------------------+
! ZBEZBE !STO!STB!ZBETYP! !
!----------------------------------------------------!
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
+----------------------------------------------------!
! ZBEROP ! ZBETCI !
+----------------------------------------------------!
! ZBEVAL !
+----------------------------------------------------!
Continuation entry
+----------------------------------------------------+
! ZBEZBE !STO!STB!ZBETYP! !
!----------------------------------------------------!
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
+----------------------------------------------------!
! !IDL!IDD!EBL!SUN! ! ZBEZSD !
+----------------------------------------------------!
! ZBEVAL !
+----------------------------------------------------!
class ZBE; comment
----- -------
This class describes the format of the
breakpoint entry that is placed in the
breakpoint record. The length is QZBEL (4 at
present) words. Each new breakpoint command
causes a number of ZBE records to be reserved.
These contain information describing the
breakpoint command and the breakpoint action.
ZBE entries are also used when processing INPUT
and OUTPUT commands but in this case they are
released at exit from the command routine;
ref(ZBE)ZBEZBE; comment
--- -------
<0:17> This field points to the next ZBE entry for the
same line, or contains zero to mark the end of
the chain. The address is relative to the start
of the breakpoint record;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-10
741101 780302 6 Ingrid Wennerstrom
boolean ZBESTO; comment
------- -------
<18:18> This flag is set when STOP was specified in the
command;
boolean ZBESTB; comment
------- -------
<19:19> This flag is set when a text string was present
in the command;
integer ZBETYP; comment
------- -------
<20:23> This field gives the type of the ZBE entry and
it can assume one of the following meanings and
codes:
AT QBEAT
AT list QBEATL
AT IFCHANGED list QBEATC
AT IF relation QBEATR
continuation QBECON
;
integer ZBESTR; comment
------- -------
<0:35> This field is only present if the ZBESTB flag is
set. It contains the first 5 characters of the
string. This entry may exist for all but
continuation type ZBE entries;
integer ZBENIN; comment
------- -------
<0:17> This field is only present if type is QBEAT. It
gives the initial value of the counter n
(default = 1);
integer ZBENVA; comment
------- -------
<18:35> This field gives the current value of the
counter n. The breakpoint action is carried out
when n is zero;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-11
741101 780302 6 Ingrid Wennerstrom
ref(ZSD)ZBEZSD; comment
--- -------
<18:35> One word in ZBE is reserved for each identifier
present in the breakpoint commands. This field
points to the ZSD entry that represents the
identifier;
boolean ZBEIDL; comment
------- -------
<0:0> This flag is set when there are more
identifications left in a list;
boolean ZBEIDD; comment
------- -------
<2:2> This flag is set when a dot was placed after the
identifier. Note that subscripts may also be
present;
integer ZBEEBL; comment
------- -------
<3:9> This integer gives the effective block level,
copied from the prototype record for the symbol
table containing the identifier;
integer ZBESUN; comment
------- -------
<10:13> This integer gives the number of subscripts that
were placed after the identifier;
integer ZBEVSU; comment
------- -------
<0:35> This integer gives the value of a subscript;
integer ZBEVAL; comment
------- -------
<0:35> This field gives the value of a constant or a
variable. If the type is LONG REAL or TEXT, two
words are used. The value of a variable or
constant is saved for arithmetic, boolean or
character types. For TEXT the value NOTEXT may
be saved, also the subscript to an element of
the ZDSTXT array. For REF, NONE may be saved,
also the array subscript in ZDSREF and a
prototype address for a variable in an object
relation. The ZBEVAL field is used in a QBEATC
type entry to save the last value of the
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-12
741101 780302 6 Ingrid Wennerstrom
variable and it is used in a QBEATR entry to
hold the value of any constant given in the
command. ZBEVAL is also used in an INPUT
command;
ref(ZKW)ZBEROP; comment
--- -------
<0:17> This field is present only if the type is
QBEATR. It points to the relation operator
entry in the keyword table;
boolean ZBETCI; comment
------- -------
<18:18> This flag is set if a constant follows the
relational operator, implying that the next
field is ZBEVAL. Otherwise an identification
follows;
boolean ZBETHI; comment
------- -------
<1:1> This flag is set when THIS is used instead of an
identifier. The ZBEZSD entry points at the
class prototype;
boolean ZBEQUA; comment
------- -------
<14:14> This flag is set when QUA is used after the
reference variable. The class prototype is
placed in the entry following the normal
identification entries;
boolean ZBESTA; comment
------- -------
<15:15> This flag is set when a * is used instead of an
identifier;
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.3-13
741101 780302 6 Ingrid Wennerstrom
IV.3.2.5 SIMDDT stack
This is a conventional stack used to hold return addresses from
subroutines and as save area for accumulators for accummulators
and other quantities. It is addressed via the XDSTK ac, which
is set up for overflow detection by an interrupt. Underflow is
caught by a few addresses to an error routine at the stack
bottom.
IV.3.2.6 SIMDDT work area
This contains the internal SIMDDT variables and also some
instructions used by the PROCEED command routine DSPR. These
instructions are relocated by SIMDDT and cannot be
write-protected.
IV.3.2.7 ZDSZTE, text record
This record is used as a buffer area for the I/O texts. The
first 3 elements in the YDSTXT text array contain text variables
which point to three subtexts of ZDSZTE, each QDSION (135)
characters long. The buffers have the subtext form to
facilitate communication with the RTS text routines.
IV.3.3 ZAR records: ZDSTXT and ZDSREF
-------------------------------
During initialisation, SIMDDT requests two arrays from the run
time system, one text array and one ref array. Any variable
saved in those arrays is relocated by the garbage collector if
the referenced data has been moved.
CHAPTER 4
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.4-1
741101 780302 6 Ingrid Wennerstrom
IV.4 FILE DESCRIPTIONS
IV.4.1 SIMDDT input file
-----------------
IV.4.1.1 TTY input
The user TTY (which may be simulated by a PTY via a controlling
program) is normally used for all input to SIMDDT. The INCHWL
monitor call is used to read user commands into the ZDSZTE
record. The YDSIPO variable contains a byte pointer to the
buffer and the first element in the ZDSTXT array holds a text
variable which points to the proper subtext of the ZDSZTE
record.
IV.4.1.2 Input file specified in @ command
The command routine DSGET handles the @ command. The i/o
routines in the RTS are used for all processing of files other
than the user TTY. The DSIT routine calls the IOIG routine to
read an input line. The file is closed in the DSEX routine and
if end of file is found. From version 4(302), it is possible to
direct all SIMDDT i/o to another terminal, including the *
prompter, if the USE and @ commands specify a tty device other
than the controlling TTY.
IV.4.2 SIMDDT output files
-------------------
IV.4.2.1 TTY output
The user TTY (simulated by a PTY when the job is controlled by
another job, e.g. in batch) is normally used for all SIMDDT
output. The output text is edited in the ZDSZTE text record.
The variable YDSOPO contains a byte pointer into the buffer and
the second element of the ZDSTXT array holds a subtext pointer
to the buffer. The OUTSTR monitor call is used to output a
string to the TTY.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.4-2
741101 780302 6 Ingrid Wennerstrom
IV.4.2.2 SYSOUT file
The SYSOUT file is used for SIMDDT error mode output if SYSOUT
is not directed to the user TTY. The DSINE routine outputs the
last image created on the SYSOUT file before the error occurred.
DSINE also replaces the current image pointer for SYSOUT with a
pointer to the output buffer in ZDSZTE. Subsequently SYSOUT is
treated like a file specified in a USE command.
IV.4.2.3 Output file specified in a USE command
The DSUS command routine handles the USE command. The RTS i/o
routines are used for all processing of a file which is not the
user TTY. Only one USE file can exist. Any existing USE file
is closed when a new USE command is given. The DSEX routine
also closes the USE file. The DSO set of routines call the IOOG
(IOBO) RTS routine to output a line from the ZDSZTE record to
the file. Some output to the USE file is copied to the
controlling TTY, unless (from version 4(302)) the USE file is
another terminal.
IV.4.3 DISPLAY file
------------
The (source) file implied by the DISPLAY command is read and
output. The RTS I/O routines are used. The display file is
closed on exit from SIMDDT.
The name of the main source program is taken from a GETTAB entry
and the name of an external source module is assumed to be the
class or procedure name. The extension is assumed to be .SIM.
IV.4.4 Help file
---------
The help file HLP:SIMDDT.HLP is read and output. The RTS i/o
routines are used.
CHAPTER 5
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.5-1
741101 780302 6 Ingrid Wennerstrom
IV.5 DIAGNOSTIC HANDLING
IV.5.1 Introduction
------------
SIMDDT outputs diagnostic messages for all errors detected
inside SIMDDT and for most of the errors detected by the RTS.
The possible error messages are listed in the SIMULA Language
Handbook part II, appendix D. A utility program, SUTEDS (see
V.5), is used to create message tables from the RUNOFF input
file for the handbook. The SIMDDT routine DSPM reconstructs the
message and puts it in the output text buffer.
IV.5.2 SIMDDT invoked from the RTS routine OCUU
----------------------------------------
When the RTS detects an error, the error number and the user
code address corresponding to the error are stored in the static
low segment area and SIMDDT is started at its entry point DSINE.
A flag is stored with the error number determining if further
processing is possible and which input is needed if any. The
diagnostic handling in the RTS is described in III.5. If the
error was found in an RTS routine called from SIMDDT, further
processing is normally possible.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.5-2
741101 780302 6 Ingrid Wennerstrom
IV.5.3 Main flow of the DSINE routine
------------------------------
---------------------
(Enter DSINE from OCUU)
---------------------
!
------ ------ TTY/SYSOUT---+
+ SIMDDT + Yes + SIMDDT + No ! ? ERROR ! ------------
< active >----><initialised >-->! WHILE INI- !-->(Exit to OCEP)
+ ? + + ? + ! TIATING .. ! ------------
------ ------ +------------+
No !<------+ ! Yes
+------------+ ! ------ TTY/SYSOUT---+
! Set SIMDDT ! ! + RTS + Yes !ZYDnnn ! ------------
! error mode ! ! <called from >-->!message !-->(Return via )
! ! ! + SIMDDT?+ !ZYQ->ZYD ! (SIMDDT stack)
+------------+ ! ------ +------------+ ------------
! ! ! No
+------------+ ! ------ TTY/SYSOUT---+
! Find ! ! + SIMDDT + Yes !? ERROR ! ------------
! <LINE> of ! ! < in error >-->!WHILE PROCES!-->(Exit to OCEP)
! error ! ! + mode ? + !SING ERROR ! ------------
+------------+ ! ------ +------------+
! ! ! No
TTY/SYSOUT---+ ! +------------+
! ? ERROR IN ! ! ! Indicate !
! JOB AT ! +---! replacement!
! <LINE> ! ! ZYQ->ZYD !
+------------+ +------------+
!
TTY/SYSOUT---+
! ZYQnnn !
! message !
! !
+------------+
!
------------
(Exit to DSCM)
------------
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.5-3
741101 780302 6 Ingrid Wennerstrom
IV.5.4 SIMDDT internal errors
----------------------
The SIMDDT routine DSOEM is called when an error is detected
while scanning an input command or while processing a breakpoint
action. DSOEM outputs the input command up to the last scanned
character (if relevant) and the ZYDnnn message. The rest of the
command is ignored and the command action is usually not
performed. E.g. the command "INPUT i:=1 xxx" will give the
messages:
INPUT i:= 1 x
ZYD603 END OF INPUT EXPECTED
The command "STOP AT 3,ab" gives:
STOP AT 3,a
ZYD605 INVALID LOOP COUNTER
After the first command, the value of i is 1, but no breakpoint
is set at line 3 after the second command.
The DSTERM routine is called when an unexpected error is
detected in SIMDDT. The ZYD675 message is output and program
execution aborted via the RTS routine OCEP.
IV.5.5 Addition of a new message to SIMDDT or SIMRTS
---------------------------------------------
- Insert the new message in the RUNOFF input file containing
appendix D (SLH2C.RNO or SIMLH2.RNM). The assembly time
constants QZYQLN, QZYDFN, QZYDLN and QMSUPN must be changed if
the message cannot be placed in a free slot in the existing
intervals. The SUTEDS program must be accordingly modified.
- Execute the SUTEDS program to create a new SIMEDS.MAC file.
Note that the input file (see above) is assumed to be
DSK:SIMLH2.RNO. The RUNOFF input file must thus be temporarily
renamed or copied to a file with the expected name.
- Insert the code for the error message in the RTS or the SIMDDT
routine or insert code generation statements in pass 2 of the
compiler if the error message will be detected by compiled code.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.5-4
741101 780302 6 Ingrid Wennerstrom
- Reassemble SIMDDT to create the SIMDDT.REL file.
- Reassemble and link any changed RTS or compiled module.
- EXECUTE SIMDDT.REL,SUTABS.MAC to create the SIMDDn.ABS file.
CHAPTER 6
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.6-1
741101 780302 6 Ingrid Wennerstrom
IV.6 SIMDDT INTERFACE
IV.6.1 Monitor interface
-----------------
The monitor commands INCHWL and OUTSTR are used to communicate
with the user TTY. All other i/o is performed via the i/o
routines in the RTS. The RTS also handles traps and UUO
processing.
The job data locations .JBSA, .JBFF, .JBUUO and .JBOPS are read
by SIMDDT but not changed.
IV.6.2 Interface with generated code
-----------------------------
The address of the line number table for the main program is
placed in the static low segment area by the OCIN routine. The
ZLN table contains addresses to generated instructions which may
be replaced by a breakpoint instruction. The ZSM, ZSD, ZPR and
ZMP records are referenced by SIMDDT.
If SIMDDT.REL was linked with the main program, the start
address .MAIN of the main program is used by SIMDDT, see DSINM.
IV.6.3 SIMRTS interface
----------------
IV.6.3.1 Entries to SIMDDT from SIMRTS
The entry points DSINI, DSINB, DSINR, DSINE and DSINS of SIMDDT
are used by SIMRTS, see IV.2.1. These entries are placed at
fixed offsets from the start of SIMDDT. If necessary, the
SIMDDn.ABS file will be read into the dynamic low segment area
from disk. SIMDDT.REL may also be linked with the main program,
usually for SIMDDT debugging purposes.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.6-2
741101 780302 6 Ingrid Wennerstrom
IV.6.3.2 SIMRTS routines used from SIMDDT
--------------------------------
SIMDDT calls a SIMRTS routine according to the standard
interface for that routine. No special code is placed in SIMRTS
routines to check for a call from SIMDDT. If a routine may
cause garbage collection or find an error, the call is placed in
the static low segment area YDSINC. The return address must not
point into SIMDDT since it may be moved by the garbage collector
before the routine returns. The eventual return to SIMDDT
enters at DSINC. This routine relocates the return address kept
in the SIMDDT stack. The following RTS routines are called from
SIMDDT:
Name Explanation
---- -----------
-+
IOLN !
IOOP !
IOOG ! I/O related routines called
IOIG ! via DSCRTU and YDSINC(XLOW)
IOOB !
IOCL !
CPNE !
CSEN !
-+
CSQU Qualification check called directly from DSCSQU.
CSNA Allocates array, called directly from DSIS.
SUNE Finds next event, called directly from DSSC. The
variable YSUNE(XLOW) contains the address of the YSUNE
routine if Simulation is active.
SAGC Performs a garbage collection. The call is initiated
from the DSVA routine if the flag SWNOGC is off. The
SIMDDT routine DSCRTS and the YDSINC(XLOW) area are used
to invoke SAGC.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.6-3
741101 780302 6 Ingrid Wennerstrom
--+
TXVA Text value assignment !
TXRE Text relation ! Called directly from
TXST Strip text ! the SIMDDT routine
TXPI Put integer in text !
TXPR Put real number in text !
--+
--+
TXGI Get integer from text ! Called from
TXGR Get real from text ! DSCTX
--+
--+
TXBL Create blank text ! Called via DSCRTS
TXCY Create text copy ! and YDSINC(XLOW)
--+
IV.6.4 Global variables
----------------
A part of the static low segment area is used for SIMDDT
variables that do not need relocation after garbage collection.
The variables YSDBCOM, YDSBSAV, YDSINC, YDSZLN are used
internally in SIMDDT. The variables YDSEAD, YDSENR, YDSZLA,
YDSNOG and YDSCAD are used by SIMRTS to pass information to
SIMDDT. The RTS routines check the variable YDSWIT to find out
if SIMDDT is active. The size of SIMDDT is defined by QDSLG.
YDSIGS is the start of a save area for the byte pointer to the
break character found by INIMAGE (IOIG). IOIG saves the value
for SIMDDT use.
The flag word YDSCLOSE is tested and set by the OCEP RTS routine
and by SIMDDT. It is used to control file closing at end of
execution.
Another part of the static low segment area contains global
SIMDDT variables that must be relocated by the garbage
collector. The existence of pointers in this area also prevents
the corresponding records from being removed as garbage. The
variables in this area are: YDSIAC, YDSBAS, YDSTXT, YDSREF,
YDSUFO, YDSSIOT, YDSCFO, YDSDFO, YDSSXCB, YDSRXCB and YDSIFO.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.6-4
741101 780302 6 Ingrid Wennerstrom
SIMDDT references the garbage collector variables YSABOT, YSATOP
and YSAGCN.
SIMDDT references the simulation variables YSULEV and YSUNE.
SIMDDT also references the SYSOUT pointer YSYSOUT, the FORTRAN
interface variable YFOXCB and the SIMRTS accumulator save area
YUUOAC.
CHAPTER 7
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.7-1
741101 780302 6 Ingrid Wennerstrom
IV.7 COMMON MACRO PARAMETER FILES
The SIMDDT modules refer to the universal files (.UNV) SIMMAC,
SIMMCR, SIMRPA.
The $$RELO macro and the assembly variable $$BAS used in certain
SIMMAC macro definitions are redefined in SIMDS1.MAC. Thus the
instructions generated from conditional macros and field
definitions will not contain any relocatable addresses. SIMDDT
code is accessed via fixed offsets, indexed by XDBAS, which will
always contain the base address of SIMDDT while executing within
SIMDDT.
The SIMRPA macro file contains definitions for the SIMDDT
variables which are placed in the static low segment area. The
variable names all start with "YDS".
CHAPTER 8
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.8-1
741101 780302 6 Ingrid Wennerstrom
IV.8 TESTING
IV.8.1 Compiler switches
-----------------
When compiling a SIMULA program used to test SIMDDT, the
compiler switches D, I, L and Y should be set.
IV.8.2 Testing with DDT
----------------
The DDT program has been heavily used to test SIMDDT. Appendix
H.9 of the SIMULA Handbook part II describes how to use DDT
together with SIMDDT.
To keep the SIMDDT symbol tables used by DDT in core, SIMDDT
must be loaded as a REL file with the SIMULA program REL
file(s). The following command can be used:
DEBUG/DDT usermainprogram.SIM,SIMDDT.REL[path]/REL
The name of the loaded program will be SIMDDT - may be changed
with a SAVE command specifying another name.
It is often convenient to set a DDT breakpoint in DSCM, the
routine which reads a SIMDDT command.
The line number table of the main program starts at the location
.MAINL.
The contents of some special ac's during SIMDDT execution are:
Accumulator Explanation
----------- -----------
XPDP SIMRTS stack pointer.
XLOW Pointer to static low segment area for global
variables.
XCB Current block, never changed by SIMDDT.
XDBAS Base register for SIMDDT code.
XDSTK SIMDDT stack pointer.
XDZBR Pointer to SIMDDT data area.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.8-2
741101 780302 6 Ingrid Wennerstrom
XDINT Pointer to input text variable. Output text
variable is at 2(XDINT).
XDSWIT SIMDDT status switches.
XDZBE Pointer to last referenced ZBE entry. Useful
after a set breakpoint command.
The global variable YDSBCOM(XLOW) holds the address of the
instruction following the instruction replaced by a BREAK UUO.
The local variable YDSCZBR has the current breakpoint number.
The address of the ZBR entry for the current breakpoint is found
from the expression 3+(XDZBR)+(YDSCZBR), where () implies
"contents".
CHAPTER 9
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.9-1
741101 780302 6 Ingrid Wennerstrom
IV.9 SAMPLE PROGRAM
The program DEMDDT.SIM listed in appendix H.9 of the SIMULA
Language Handbook part II can be used together with DDT to find
out how SIMDDT works.
The following figure shows the contents of the ZBR and ZBE
records after the set breakpoint command:
*AT 39 IFCHANGED refpc.lrpc
See SIMDDT EXAMPLE, TRACING in the handbook.
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.9-2
741101 780302 6 Ingrid Wennerstrom
ZBR : :
: :
!----------------------------------------!
! 0 ! 0 !
!----------------------------------------!
! 0 !
!----------------------------------------!
+---! 63 ! 4510 ! AT 39 IFCHANGED
! !----------------------------------------! refpc.lrpc
! ! MOVEI 1, 4532 ! Instruction saved
! !----------------------------------------!
!+--! 57 ! ! AT 28 IF ipc = 4
!! !----------------------------------------!
!! ! !
!! !----------------------------------------!
!!+-! 53 ! ! AT 8 fip1
!!! !----------------------------------------!
!!! ! !
!!! !----------------------------------------!
ZBE !!+>! 0 ! !
!! !----------------------------------------!
!! ! !
!! ! !
!! !----------------------------------------!
!+->! 0 ! !
! !----------------------------------------!
! ! !
! ! !
! !----------------------------------------!
+-->! 67 ! 0 2 0 0 0 0 !
+--!----------------------------------------!
! ! 1 0 1 4 0 0 ! 4563 !
! !----------------------------------------!
! ! 0 0 0 2 0 0 ! 4544 !
! !----------------------------------------!
! ! 0 ! Saved value of lrpc
! !========================================! (word 1)
+->! 0 ! 0 !
!----------------------------------------!
XDZBE-->! 0 ! Saved value of lrpc
!----------------------------------------! (word 2)
! not used !
!----------------------------------------!
! not used !
!----------------------------------------!
: :
SIMULA FOR DEC SYSTEM 10 TD, SIMDDT IV.9-3
741101 780302 6 Ingrid Wennerstrom
ZSD entry for refpc
!----------------------------------------!
4563 ! 0 0 0 7 0 1 ! 6 !
!----------------------------------------!
! R ! E ! F ! P ! C ! !
!----------------------------------------!
! ! 4367 ! CLASS pc prototype
!----------------------------------------!
: ZSD entry for lrpc :
: :
!----------------------------------------!
4544 ! 0 0 0 3 0 1 ! 5 !
!----------------------------------------!
: :
: :
: ZLN entry for line 39 :
!----------------------------------------!
4510 ! 47 ! 4246 !
!----------------------------------------!
: :
Breakpoint instruction which replaces
the MOVEI 1,4532 instruction in code
+----------------------------------------+
4246 ! 0 1 7 0 0 0 ! 42 ! 42 is offset into
+----------------------------------------+ the ZBR record
Figure IV.9 Snapshot of core after set breakpoint instruction.