CC78K4 Datasheet, PDF (44/523 Pages) NEC – CC78K4 Ver.2.30 or Later, C Compiler Language

CHAPTER 2 CONSTRUCTS OF C LANGUAGE
• Infinity expression
When exponent = FFH and mantissa = 0, ±∞ is expressed as follows.
(Value of sign)
(–1)
*∞
• Unnormalized value
When exponent = 0 and mantissa ≠ 0, the unnormalized value is expressed as follows.
(Value of sign)
–126
(–1)
* (Value of mantissa) *2
Remark
The mantissa value here is a number less than 1, so bit
positions 22 to 0 of the mantissa express as is the 1st to
23rd decimal places.
• Not-a-number (NaN) expression
When exponent = FFH and mantissa ≠ 0, NaN is expressed, regardless of the sign.
• Operation result rounding
Numerical values are rounded down to the nearest even number. If the operation result cannot be
expressed in the above floating-point format, round to the nearest expressible number.
If there are two values that can express the differential of the prerounded value, round to an even
number (a number whose lowest binary bit is 0).
• Operation exceptions
There are five types of operation exceptions, as shown below.
Table 2-5. List of Operation Exceptions
Exception
Underflow
Inexact
Overflow
Zero division
Operation impossible
Return Value
Unnormalized number
±0
±∞
±∞
Not-a-number (NaN)
Calling the matherr function causes a warning to appear when an exception occurs.
(2) Character types
The character data types include the following three types.
• char
• signed char
• unsigned char
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User’s Manual U15556EJ1V0UM