Q30601: Real-Number Data in IEEE Format

Article: Q30601
Product(s): Microsoft Macro Assembler
Version(s): 5.1,6.0
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), versions 5.1, 6.0 
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SUMMARY
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By default, the Microsoft Macro Assembler Versions 5.1 (MASM) and later assemble
real-number data in IEEE format. The previous versions of the assemblers used
the Microsoft binary format by default.

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

The following is the IEEE format for encoding 4- and 8-byte real numbers:

  Short Real Number
    31      23      15      7       0
   _________________________________
  |_|_______|_______|_______|_______|
  ^ ^       ^                       ^
  | |       |                       |
  | Exponent|                       |
  |         |Mantissa ------------->|
  |Sign

The parts of the real numbers are described below:

1. Sign (0 for positive or 1 for negative) is in the upper bit of the first
  byte.

2. Exponent is in the next bits in sequence (8 bits for a short real number or
  11 bits for a long real number).

3. All except the first-set bit of Mantissa are in the remaining bits of the
  variable (13 bits for short real numbers, and 52 bits for long real numbers).
  Because the first significant bit is known to be set, it does not need to be
  stored.

Additional query words: kbinf 5.10 6.00

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Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM600
Version           : :5.1,6.0

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