Q45146

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Q45146: DOCERR: Some Coprocessor Instructions Not Emulated

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Article: Q45146
Product(s): Microsoft Macro Assembler
Version(s): 5.0,5.1,5.1a,6.0,6.0a,6.0b,6.1,6.11a,6.1a
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 5.0, 5.1, 5.1a, 6.0, 6.0a, 6.0b, 6.1, 6.1a, 6.11a 
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SUMMARY
=======

The /E option of the Microsoft Macro Assembler (MASM) 5.0 and 5.1 directs the
assembler to generate data and code as it is expected by coprocessor emulator
libraries. The /FPi option and the OPTION EMULATOR directive provide the same
functionality, starting with MASM version 6.0.

The emulator libraries are available with the high-level languages like C, BASIC,
FORTRAN, and Pascal. However, the emulator libraries do not support all
coprocessor instructions. The following error message will result when an
unsupported coprocessor instruction is executed:

  run-time error M6107: MATH - floating-point error: unemulated

MORE INFORMATION
================

The following is the list of unemulated coprocessor instructions in MASM 5.1:

  FBLD                    FSAVE
  FBSTP                   FSETPM
  FCOS                    FSIN
  FDECSTP                 FSINCOS
  FINCSTP                 FSTENV
  FINIT                   FUCOM
  FLDENV                  FUCOMP
  FNOP                    FUCOMPP
  FPREM1                  FXTRACT
  FRSTOR

The following is the list of unemulated coprocessor instructions in MASM 6.0 as
indicated on page 161 of the "Microsoft Macro Assembler Programmer's Guide":

  FCOS                    FSAVE32
  FDECSTP                 FSETPM
  FINCSTP                 FSIN
  FPREM1                  FSINCOS
  FRSTOR                  FUCOM
  FRSTOR16                FUCOMP
  FRSTOR32                FUCOMPP
  FSAVE                   FXTRACT
  FSAVE16

However, this list is not complete. When tested with the run-time libraries from
Microsoft C/C++ 7.0, the following instructions also result in the M6107 error

  FBLD                    FLDENV
  FBSTP                   FNOP
  FINIT                   FSTENV

In addition, a few of the names are incorrect

  FRSTOR16   should be    FRSTORW
  FRSTOR32   should be    FRSTORD
  FSAVE16    should be    FSAVEW
  FSAVE32    should be    FSAVED

The following stand-alone assembler sample reproduces the M6107 error for the
instruction FBLD. Note that the C run-time code must be brought in. In this
case, the small model emulator library (slibce) is used.

Sample Code
-----------

  ; Assemble options needed: /Cx /link slibce

  OPTION EMULATOR
  .MODEL small, C
  PUBLIC main

  .DATA
  packbcd TBYTE 0

  .CODE
  main:
     fbld packbcd
  END

Additional query words: 5.00 5.10 5.10a 6.00 6.00a 6.00b 6.10 6.10a

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM32bit611a kbMASM510 kbMASM600 kbMASM610 kbMASM610a kbMASM500 kbMASM600a kbMASM510a kbMASM600b
Version           : :5.0,5.1,5.1a,6.0,6.0a,6.0b,6.1,6.11a,6.1a

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