FIX: MATHERRQQ: Access Violation on C8ARG1 and C16ARG1

MS-DOS      | WINDOWS NT

The information in this article applies to:

• Microsoft FORTRAN PowerStation for MS-DOS, versions 1.0 and 1.0a
• Microsoft FORTRAN PowerStation 32 for Windows NT, version 1.0

SYMPTOMS

In Windows NT, Dr. Watson reports an access violation when parts of MATHERRQQ's INFO record are passed to other routines. The problem occurs when passing MTH$E_INFO members: C8ARG1, C8ARG2, C16ARG1, or C16ARG2.

In MS-DOS (Windows, version 3.1), the error message is:

   DOSXMSF : fatal error DX1020: unhandled exception:
             General Protection Fault.

RESOLUTION

Do not pass C8ARG1, C8ARG2, C16ARG1, or C16ARG2 directly to another routine. Assign the value to a temporary variable and pass the variable instead.

STATUS

Microsoft has confirmed this to be a bug in the products listed at the beginning of this article. This problem was corrected in Microsoft FORTRAN PowerStation 32, version 4.0.

MORE INFORMATION

To reproduce the problem, compile and run the sample code below.

To use the program without error, comment out the four lines that print C8ARG1, C8ARG2, C16ARG1, and C16ARG2.

Sample Code

c compile options needed: none

      include 'flib.fi'
      implicit none
      include 'flib.fd'
      complex a,b,c
      call LCWRQQ(#133F)
      a=(233.75875785857,145.8498498998989)
      b=(345.84984984900,298.849849849989)
      c=a**b
      write(*,*)'****** successful completion ******'
      end

      SUBROUTINE MATHERRQQ(name, length, info, retcode)
      INCLUDE 'FLIB.FD'
      INTEGER*2 length
      CHARACTER name(length)
      RECORD / MTH$E_INFO / info
      INTEGER*2 retcode
      PRINT *, 'Entered MATHERRQQ'
      PRINT *, 'Failing function: ', name, '      Length: ', length
      PRINT *, 'Error Type: ', info.errcode

      SELECT CASE (info.errcode)
      CASE (MTH$E_OVERFLOW)
         PRINT *, 'OVERFLOW'
      CASE DEFAULT
         PRINT *, 'UNKNOWN'
      END SELECT

      SELECT CASE (info.ftype)
      CASE (TY$CMPLX8)
         PRINT *, 'Type: COMPLEX*8'
         PRINT *, 'Argument1: ', info.c8arg1
         PRINT *, 'Argument2: ', info.c8arg2
         info.c8res = 0.0
         retcode = 1
      CASE (TY$CMPLX16)
         PRINT *, 'Type: COMPLEX*16'

         PRINT *, 'Argument1: ', info.c16arg1
         PRINT *, 'Argument2: ', info.c16arg2
         info.c16res = 0.0
         retcode = 1
      END SELECT
      END