Floating-Point Math Instructions - Omron CJ - REFERENCE MANUAL 02-2010 Reference Manual

Floating-point Math Instructions

Floating-point Math Instructions
The Floating-point Math Instructions convert data and perform floating-point arithmetic operations.
Data Format
Floating-point data expresses real numbers using a sign, exponent, and mantissa. When data is
expressed in floating-point format, the following formula applies.
Real number = (–1)
s: Sign
e: Exponent
f: Mantissa
The floating-point data format conforms to the IEEE754 standards. Data is expressed in 32 bits, as
follows:
Data
s: sign
e: exponent
f: mantissa
Number of Digits
The number of effective digits for floating-point data is seven digits for decimal.
Floating-point Data
The following data can be expressed by floating-point data:
• –
• –3.402823 10
• 0
• 1.175494 10
• +
• Not a number (NaN)
–
Special Numbers
The formats for NaN,
• NaN*:e = 255, f
• + :e = 255, f = 0, s= 0
• – :e = 255, f = 0, s= 1
• 0: e = 0
* NaN (not a number) is not a valid floating-point number. Executing floating-point calculation instructions will not
result in NaN.
CS/CJ/NSJ Series Instructions Reference Manual (W474)
s e–127
2 (1.f)
Sign Exponent
s e
31 30 23 22
No. of bits
1 0: positive; 1: negative
8 The exponent (e) value ranges from 0 to 255. The actual exponent is the
value remaining after 127 is subtracted from e, resulting in a range of
–127 to 128. "e=0" and "e=255" express special numbers.
23 The mantissa portion of binary floating-point data fits the formal 2.0 > 1.f 1.0.
38
value –1.175494
–38
value 3.402823
–38
–1.175494 10
38
–3.402823 10 – 1
, and 0 are as follows:
0
Mantissa
f
Contents
–38
10
38
10
1.175494 10
0 1
3.402823
3. Instructions
0
–38
38 +
10
3
465