Q59127: Testing Math Coprocessor Instructions FLD FADD FSTP FST

Article: Q59127
Product(s): Microsoft Macro Assembler
Version(s): 5.1
Operating System(s): 
Keyword(s): 
Last Modified: 04-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), version 5.1 
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SUMMARY
=======

The following code was used to view coprocessor instructions on an 80386 machine
with an 80387 coprocessor. It is a combination of the examples on Pages 384 and
385 of "Microsoft Macro Assembler 5.1 for the MS-DOS Operating System
Programmer's Guide."

                 .model small
                 .386
                 .387
                 .stack 100h
                 .data
        m1       dd   1.0
        m2       dd   2.0
                 .code
        start    proc
                 mov ax, @data ;load address of segment
                 mov ds,  ax   ;     register
                 fld   m1      ;push m1 into st(0)
                 fld   m2      ;push m2 into st(0)
                 fadd  m1      ;add m2 to st(0)
                 fstp  m1      ;pop st(0) into m1
                 fst   m2      ;copy st(0) into m2

                 fld1          ;push 1 into st(0)
                 fldpi         ;push pi into st(0)
                 fadd          ;add st(0) and st(1)
                               ;and pop, place result in st(0)
        start    endp
                 end  start

While assembling the above code, the .386 and .387 directives must be placed
below the .model directive to generate 16-bit segments. If placed above the
.model directive, 32-bit segments will be generated and will produce erroneous
results, as 32-bit segments cannot be run under DOS.

While running the code through CodeView, the number 7 entered in the dialog box
displays a dump of the present status of the chip.

Additional query words: 5.10

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Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510
Version           : :5.1

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