Altera Nios II User Manual page 21

Chapter 2: Processor Architecture
Arithmetic Logic Unit
Floating-Point Instructions
The Nios II architecture supports single precision floating-point instructions with two
components:
■ Floating Point Hardware 2—This component supports floating-point instructions as
specified by the IEEE Std 754-2008 but with simplified, non-standard rounding
modes. The basic set of floating-point custom instructions includes single
precision floating-point addition, subtraction, multiplication, division, square root,
integer to float conversion, float to integer conversion, minimum, maximum,
negate, absolute, and comparisons.
Floating Point Hardware—This component supports floating-point instructions as
■
specified by the IEEE Std 754-1985. The basic set of floating-point custom
instructions includes single precision floating-point addition, subtraction, and
multiplication. Floating-point division is available as an extension to the basic
instruction set.
These floating-point instructions are implemented as custom instructions. The
Hardware Conformance table below lists a detailed description of the conformance to
the IEEE standards.
f
For more information about using floating-point custom instructions in software,
refer to the
Table 2–2. Hardware Conformance with IEEE 754-1985 and IEEE 754-2008 Floating-Point Standard (Part 1 of 2)
Feature
Addition/subtraction Implemented
Multiplication
Division
Square root
Integer to float/float
Operations
to integer
Minimum/maximum
Negate/absolute
Comparisons
Single
Precision
Double
Invalid operation
Division by zero
Exception
Overflow
conditions
Inexact
Underflow
February 2014 Altera Corporation
Nios II Custom Instruction User
Floating-Point Hardware
Implementation with IEEE 754-1985
Implemented
Optional
Not implemented, this operation is
implemented in software.
Not implemented, this operation is
implemented in software.
Not implemented, this operation is
implemented in software.
Not implemented, this operation is
implemented in software.
Not implemented, this operation is
implemented in software.
Implemented
Not implemented. Double precision
operations are implemented in software.
Result is Not a Number (NaN)
Result is ±infinity
Result is ±infinity
Result is a normal number
Result is ±0
Guide.
Floating-Point Hardware 2
Implementation with IEEE 754-2008
Implemented
Implemented
Implemented
Implemented
Implemented
Implemented
Implemented
Implemented
Implemented
Not implemented. Double precision
operations are implemented in software.
Result is Not a Number (NaN)
Result is ±infinity
Result is ±infinity
Result is a normal number
Result is ±0
Nios II Processor Reference Handbook
2–5