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Debugging facilities in Dec-10 Simula-67 compiler (test version)
I. Test character handling:
Whenever the special symbol occurs in the source file,
it will cause the next three characters (2 letters and 1 digit)
to be scanned, and the resulting identification is then matched
against three tables:
ZLSTT1 - a match will cause a debug switch in reg x1mask to be
set on. (used e.g. to start trace actions)
ZLSTT2 - a match will cause a switch to be set off
(e.g. stop tracing)
ZLSTT3 - a match will invoke a routine.
(used e.g. to initiate a dump)
If no match occurs, a debug symbol followed by the identification
found, will be output to file IC1, in order to be handled
later by pass 2.
So far, the following identifications have been
pass 1: LS1 start successive output of symbols found by scanner
LS0 setoff LS1
SR1 start successive output of entry/exit of
SR0 setoff SR1
SD1 start successive output of block stack entries 5 and 6,
for every execution of routines SDBEG and SDEND
SD0 setoff SD1
O11 start successive output of symbols output to IC1
O10 setoff O11
IC1 init dump of IC1 (to be printed when pass 1 is completed)
DF1 init dump of DF1 (to be printed when pass 1 is completed)
pass 2: M20 stop trace program
M21 start trace program
M22 abort with dump
M23 set SM2DB3
CG0 setoff CG1
CG1 dump expression tree before compilation
O21 output assembly list
O22 trace all fixups
II. Debug File handling:
In order to facilitate edited test output, a special debug
file is constructed, into which file any submodule can place
debug information records for later output.
Every record in the debug file starts with a control half word,
indicating the meaning of the record. This half word is divided
into six fields, each one comprising of 3 bits of information.
case 1: first field is zero.
meaning of second field: 1 = new page
2 = new line
3 = define new identifier,
in this case the control
half word is followed by
a half word containing
an index (1024-4095) and
by 4 half words containing
the identifier in sixbit
case 2: first field nonzero.
every subsequent field indicates how the following
half words of data should be output.
codes: 0 = end of record
1 = convert field to octal
2 = convert field to decimal
3 = print a symbol or an identifier.
half word contains corr index
4 = print text.
the next 2 half words contains
char in sixbit
5 = print text.
half word contains index to text table
6 = print text.
half word contains three sixbit char
7 = print text.
the next 2 half words contains
5 characters in ASCII (left adjusted)
Placing records in the debug file is accomplished by calls
to one or more of the subroutines O1DB1-O1DB7, where
the last digit indicates how many half words the record
consists of. On call to such a routine, the record
is to be placed in the system stack.
ex. record consists of control half word and 4 data half words:
/ / return address /
/ data half word 4 / not used /
/ data half word 2 / data half word 3 /
stacktop: / control half word / data half word 1 /
Each record written, starts in a position, which
is the next multiple of 20. If remaining space of
present line is not sufficient, the record is written at
the beginning of next line. One blank separates the fields
from each other.
debug file: /520000/000000/000010/
/030000/002000/SKR/#P / / /
DEBUG OUTPUT SIMULA-67 VERSION: 8
SR BPROG LS0 SKR#P
General record dump macro:
Define Record Dump (DRD)
R = record name
Fi= field name (previously defined by a call to
Define Field (DF) - macro)
DRD expands a subroutine named .R and it also
defines a macro R, which when later called, will
produce a symbolic dump of all the Fi-fields that were
specified in the call to the DRD-macro.
The dump will be octal and if the bit length, L, of a
field is not a multiple of 3, then ENTIER(L/3)+1 digits
will appear in the dump.
The fields will be dumped in the order of appearance
in the DRD-call.
The address of the record (first word) is supposed
to be in reg X1 at execution.
DRD may not be called inside a PROC/EPROC body
(but the expanded routine may of course).
ex. of use:
Output on execution:
DCZHE AT ADDRESS 400982