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Q39190: BC /A or CodeView Finds Run-Time Error Segment:Offset Address

Article: Q39190
Product(s): See article
Version(s): 6.00 6.00b 7.00 | 6.00 6.00b 7.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | B_QuickBas | mspl13_basic
Last Modified: 26-FEB-1990

The following information applies to Microsoft BASIC Compiler Versions
6.00 and 6.00b for MS-DOS and MS OS/2, to Microsoft BASIC Professional
Development System (PDS) Version 7.00 for MS-DOS and MS OS/2, and to
QuickBASIC Versions 4.00, 4.00b, and 4.50 for MS-DOS.

When a run-time error message is displayed with a segment and offset
address, the address is in hexadecimal notation. For example, "error
in module [name] at 5517:0059" means a code segment address of 5517
hexadecimal and a code offset address of 0059 hexadecimal.

To find out where this address corresponds to a statement in your
program, you can compile your program with the BC /A option and
generate a .LST file. The .LST file lists the code offsets along with
the BASIC statements and their translation into assembly-language
code. You can use the module name and code offset from the run-time
error message to find the error line in that module's .LST file. (The
segment address from the error message is not needed to find the error
line in the .LST file).

You can also use the run-time error's segment:offset address in the
Microsoft CodeView debugger to see which BASIC code caused the
run-time error.

The BC /A option requires the file to be saved in Text format. (If you
save the source file in Fast Load and Save format, BC /A gives the
compiler error "Cannot generate listing for BASIC binary source
files.")

Page 196 of the "Microsoft CodeView and Utilities: Software
Development Tools for MS-DOS" manual states that you can use "V" to
view an address in the segment:offset format. To view the source code
executed at an address, type the following in CodeView:

   V &H5517:&H0059

Note: QuickBASIC Versions 4.00, 4.00b, and 4.50 are not sold with the
CodeView debugger. The CodeView debugger comes with Microsoft BASIC
Compiler Version 6.00 or 6.00b, Microsoft BASIC PDS Version 7.00, or
with Microsoft Macro Assembler Versions 5.00 and 5.10, but is not sold
separately.

The following is an example of finding the statement in error in a
BASIC program based upon the code offset given in the run-time error
message. The BASIC .EXE program below generates a "File Not Found"
error at a specific address. Note that the error occurred at an offset
(0057) right after a call to B$OPEN. This is a clue that the error
occurred with the open routine.

The following is a code example to be compiled with the BC /A option:

   CLS
   PRINT "This is a test of the /a option"
   OPEN "NONEXIST.DAT" FOR INPUT AS #1

This program generates the following output:

   This is a test of the /a option

   File not found in module TEST     at address 5CCD:0057

The .LST file generated with BC /A is as follows:
                                                           PAGE   1
                                                          28 Dec 88
                                                           09:35:26
Offset  Data    Source Line      Microsoft (R) QuickBASIC

 0030   0006    CLS
 0030   0006    PRINT "This is a test of the /a option"
 0030   0006    OPEN "NONEXIST.DAT" FOR INPUT AS #1
 0030   0006
 0030   0006
 0030    **            I00002: mov   ax,0FFFFh
 0033    **                    push  ax
 0034    **                    call  B$SCLS
 0039    **                    mov   ax,offset <const>
 003C    **                    push  ax
 003D    **                    call  B$PESD
 0042    **                    mov   ax,offset <const>
 0045    **                    push  ax
 0046    **                    mov   ax,0001h
 0049    **                    push  ax
 004A    **                    mov   ax,0FFFFh
 004D    **                    push  ax
 004E    **                    mov   ax,0001h
 0051    **                    push  ax
 0052    **                    call  B$OPEN      <<-- offending line
 0057    **                    call  B$CENP
 005C   0006

43613 Bytes Available
43308 Bytes Free

    0 Warning Error(s)
    0 Severe  Error(s)

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