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Q40872: Some Coprocessor Assembler Instructions Are Not Emulated

Article: Q40872
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 S_C H_Fortran H_MASM SR# S890111-171 | mspl13_basic
Last Modified: 1-FEB-1990

Microsoft Macro Assembler Version 5.10 does not come with routines to
emulate a math coprocessor.

Page 382 of the "Microsoft Macro Assembler 5.1: Programmer's Guide"
states that to emulate math-coprocessor instructions, you must link
with a Microsoft high-level language that supports floating-point
emulation of the coprocessor. You would write the assembler procedure
using coprocessor instructions, then assemble with the /E option, and
finally link it with the high-level language modules.

However, only a subset of coprocessor instructions are emulated by the
Microsoft high-level languages.

If you link your Microsoft higher-level language to an assembler
routine that invokes an instruction that is NOT emulated by the
higher-level language, then the program gives a run-time error (or
possibly hangs, or gives incorrect results) when run on a machine that
has no coprocessor.

This information applies to the following products:

1.  Microsoft BASIC Compiler Versions 6.00 and 6.00b

2.  Microsoft BASIC Professional Development System (PDS) Version 7.00

3.  Microsoft QuickBASIC Version 4.50

4.  Microsoft C Compiler Version 5.10

5.  Microsoft FORTRAN Compiler Version 4.10

Below is a list of the coprocessor (8087 or 80287) instructions that
are not emulated by Microsoft high-level languages:

   FBLD    - packed decimal load
   FBSTP   - packed decimal store and pop
   FCOS    - cosine function
   FDECSTP - decrement stack pointer
   FINCSTP - increment stack pointer
   FINIT   - initialize processor
   FLDENV  - load environment
   FNOP    - No operation
   FPREM1  - partial remainder
   FRSTOR  - restore saved state
   FSAVE   - save state
   FSETPM  - set protected mode
   FSIN    - only sine function
   FSINCOS - sine and cosine function
   FSTENV  - store environment
   FUCOM   - unordered comparison
   FUCOMP  - unordered comparison and pop
   FUCOMPP - unordered comparison and double pop
   FXTRACT - extract exponent and significant

Also, some of the No-Wait forms of instructions are not emulated, such
as FNSTENV and FNINIT.

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