ISO/IEC TECHNICAL SPECIFICATION TS 18661-1 First edition 2014-07-15 Information technology Programming languages, their environments, and system software interfaces Floating point extensions for C - Part 1: Binary floating-point arithmetic Technologies de I'informationLangages de programmation, leurs environnements et interfaces du logiciel systeme Extensions a virguleflottantepourC Partie 1: Arithmétique binaire en virgule flottante Reference number ISO/IEC TS 18661-1:2014(E) ISO IEC @ISO/IEC2014 ISO/IEC TS 18661-1:2014(E) COPYRIGHTPROTECTEDDOCUMENT ISO/IEC2014 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. ISO copyright office Case postale 56. CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland @ ISO/IEC 2014 - All rights reserved y IHS under Not for Resale ISO/IEC TS 18661-1:2014(E) Contents Page Introduction. Background.. IEC 60559 floating-point standard C supportforIEC 60559. Purpose ... vii 1 Scope.. 2 Conformance 3 Normative references 4 Terms and definitions. 5 C standard conformance 5.1 Freestanding implementations 5.2 Predefined macros.. 5.3 Standard headers ... 6 Revised floating-point standard 5 7.1 Terminology... .6 7.2 Canonical representation . 8 Operation binding .. .8 9 Floating to integer conversion.... 10 Conversions between floating types and character sequences 13 10.1 Conversionswithdecimalcharactersequences 13 10.2 Conversionstocharactersequences..... 11 Constant rounding directions 12 NaN support. 13 Integer width macros . 14 Mathematics <math.h> 29 14.1 Nearest integer functions.. 29 14.1.1 Round to integer value in floating type. 29 14.1.2 Convert to integer type .... 31 14.2 The 1logb functions .. 34 14.3 Max-min magnitude functions 35 14.4 The nextup and nextdown functions 36 14.5 Functions that round result to narrower type.. 37 14.6 Comparison macros .... 40 14.7 Classification macros .. 41 14.8 Total order functions ... 43 14.9 Canonicalizefunctions. .44 14.10 NaN functions .... 45 15 The floating-point environment <fenv.h>. 47 15.1 The fesetexcept function... 47 15.2 The fetestexceptflag function 48 15.3 Control modes .... 48 16 Type-genericmath<tgmath.h .50 Bibliography 52 ii from IHS Not for Resale