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Libraries and Floating Point Support Guide

Preface The ARM C and C++ Libraries The ARM C Micro-library Floating-point Support About floating-point support The software floating-point library, fplib Calling fplib routines fplib arithmetic on numbers in a particular format fplib conversions between floats, long longs, doub fplib comparisons between floats and doubles fplib C99 functions Controlling the ARM floating-point environment Floating-point functions for compatibility with Mi C99-compatible functions for controlling the ARM f C99 rounding mode and floating-point exception mac Exception flag handling Functions for handling rounding modes Functions for saving and restoring the whole float Functions for temporarily disabling exceptions ARM floating-point compiler extensions to the C99 Writing a custom exception trap handler Example of a custom exception handler Exception trap handling by signals mathlib double and single-precision floating-point IEEE 754 arithmetic Basic data types for IEEE 754 arithmetic Single precision data type for IEEE 754 arithmetic Double precision data type for IEEE 754 arithmetic Sample single precision floating-point values for Sample double precision floating-point values for IEEE 754 arithmetic and rounding Exceptions arising from IEEE 754 floating-point ar Exception types recognized by the ARM floating-poi Using the Vector Floating-Point (VFP) support libr The C and C++ Library Functions reference Floating-point Support Functions Reference

Functions for handling rounding modes

3.3.5 Functions for handling rounding modes

The fegetround() and fesetround functions let you get and set the current rounding mode.

Note

The following functionality requires you to select a floating-point model that supports exceptions, such as --fpmode=ieee_full or --fpmode=ieee_fixed.
C99 defines these functions as follows:
int fegetround(void);
int fesetround(int round);
The fegetround() function returns the current rounding mode. The current rounding mode has a value equal to one of the C99 rounding mode macros or exceptions.
The fesetround() function sets the current rounding mode to the value provided. fesetround() returns zero for success, or nonzero if its argument is not a valid rounding mode.
Related information
Non-ConfidentialPDF file icon PDF versionARM DUI0378H
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