ISO/IEC/IEEE 60559:2011

Information technology - Microprocessor Systems - Floating-Point arithmetic

ISO/IEC/IEEE 60559:2011(E) specifies formats and methods for floating-point arithmetic in computer systems - standard and extended functions with single, double, extended, and extendable precision - and recommends formats for data interchange. Exception conditions are defined and standard handling of these conditions is specified. It provides a method for computation with floating-point numbers that will yield the same result whether the processing is done in hardware, software, or a combination of the two. The results of the computation will be identical, independent of implementation, given the same input data. Errors, and error conditions, in the mathematical processing will be reported in a consistent manner regardless of implementation. This first edition, published as ISO/IEC/IEEE 60559, replaces the second edition of IEC 60559.

General Information

• Status: Replaced
• Publication Date: 27-Jun-2011
• ICS: 35.200 - Interface and interconnection equipment
• Technical Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 08-May-2020

Relations

• Replaced By: ISO/IEC 60559:2020 - Floating-point arithmetic
• Effective Date: 05-Sep-2023

Standards Content (Sample)

ISO/IEC/IEEE 60559
Edition 1.0 2011-06
INTERNATIONAL
STANDARD
Information technology – Microprocessor Systems – Floating-Point arithmetic

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ISO/IEC/IEEE 60559
Edition 1.0 2011-06
INTERNATIONAL
STANDARD
Information technology – Microprocessor Systems – Floating-Point arithmetic

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
U
ICS 35.200 ISBN 978-2-88912-566-1

ISO/IEC/IEEE FDIS 60559:2010(E)

Contents
1. Overview .1

1.1 Scope .1

1.2 Purpose .1
1.3 Inclusions .1
1.4 Exclusions .2

1.5 Programming environment considerations .2

1.6 Word usage .2

2. Definitions, abbreviations, and acronyms .3

2.1 Definitions .3

2.2 Abbreviations and acronyms .5

3. Floating-point formats .6
3.1 Overview .6
3.2 Specification levels .7
3.3 Sets of floating-point data .7
3.4 Binary interchange format encodings .9
3.5 Decimal interchange format encodings .10
3.6 Interchange format parameters .13
3.7 Extended and extendable precisions .14
4. Attributes and rounding .15
4.1 Attribute specification .15
4.2 Dynamic modes for attributes .15
4.3 Rounding-direction attributes .16
5. Operations .17
5.1 Overview .17
5.2 Decimal exponent calculation .18
5.3 Homogeneous general-computational operations .19
5.4 formatOf general-computational operations .21
5.5 Quiet-computational operations .23
5.6 Signaling-computational operations .24
5.7 Non-computational operations .24
5.8 Details of conversions from floating-point to integer formats .26
5.9 Details of operations to round a floating-point datum to integral value .27
5.10 Details of totalOrder predicate .28
5.11 Details of comparison predicates .29
5.12 Details of conversion between floating-point data and external character sequences .30
6. Infinity, NaNs, and sign bit .34
6.1 Infinity arithmetic .34
6.2 Operations with NaNs .34
6.3 The sign bit .35

7. Default exception handling .36
7.1 Overview: exceptions and flags .36
7.2 Invalid operation .37
7.3 Division by zero .37
7.4 Overflow .37
7.5 Underflow .38
7.6 Inexact .38
8. Alternate exception handling attributes .39
8.1 Overview .39
8.2 Resuming alternate exception handling attributes .39
8.3 Immediate and delayed alternate exception handling attributes .40

Copyright © IEEE 2008. All rights reserved        i

9. Recommended operations .41

9.1 Conforming language- and implementation-defined functions .41

9.2 Recommended correctly rounded functions .42

9.3 Operations on dynamic modes for attributes .46

9.4 Reduction operations .46

10. Expression evaluation .48

10.1 Expression evaluation rules .48

10.2 Assignments, parameters, and function values .48

10.3 preferredWidth attributes for expression evaluation .49

10.4 Literal meaning and value-changing optimizations .50

11. Reproducible floating-point results .51

Annex A (informative) Bibliography .53
Annex B (informative) Program debugging support .55
Index of operations .57

ii                                                                Copyright © IEEE 2008. All rights reserved

Foreword
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