ID Number: Q30601
5.10 6.00 | 6.00
MS-DOS | OS/2
Summary:
By default, the Microsoft Macro Assembler Versions 5.10 (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.