---
name: "unw_get_fpreg"
section: "3"
platform: "linux"
package: "libunwind"
version: "1.8.3-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/unw_get_fpreg"
---

# unw\_get\_fpreg(3)

## NAME

unw\_get\_fpreg -- get contents of floating-point register

## SYNOPSIS

\#include \<libunwind.h\>\

int unw\_get\_fpreg(unw\_cursor\_t \*cp, unw\_regnum\_t reg, unw\_fpreg\_t \*valp);\

## DESCRIPTION

The unw\_get\_fpreg() routine reads the value of floating-point  register reg in the stack frame identified by cursor cp and stores the value in the variable pointed to by valp.

The register numbering is target-dependent and described in separate  manual pages (e.g., libunwind-ia64(3libunwind) for the IA-64 target).  Furthermore, the exact set of accessible registers may depend on the  type of frame that cp is referring to. For ordinary stack  frames, it is normally possible to access only the preserved  (\`\`callee-saved'') registers and frame-related registers (such as the  stack-pointer). However, for signal frames (see  unw\_is\_signal\_frame(3libunwind)), it is usually possible to access  all registers.

Note that unw\_get\_fpreg() can only read the contents of  floating-point registers. See unw\_get\_fpreg(3libunwind) for a way to  read registers which fit in a single word.

## RETURN VALUE

On successful completion, unw\_get\_fpreg() returns 0.  Otherwise the negative value of one of the error codes below is  returned.

## THREAD AND SIGNAL SAFETY

unw\_get\_fpreg() is thread safe as well as safe to use  from a signal handler.

## ERRORS

- UNW\_EUNSPEC

   An unspecified error occurred.

- UNW\_EBADREG

   An attempt was made to read a register  that is either invalid or not accessible in the current frame.

In addition, unw\_get\_fpreg() may return any error returned by  the access\_mem(), access\_reg(), and  access\_fpreg() call-backs (see  unw\_create\_addr\_space(3libunwind)).

## SEE ALSO

libunwind(3libunwind), libunwind-ia64(3libunwind), unw\_get\_reg(3libunwind), unw\_is\_fpreg(3libunwind), unw\_is\_signal\_frame(3libunwind), unw\_set\_fpreg(3libunwind)

## AUTHOR

David Mosberger-Tang\
 Email: **dmosberger@gmail.com**\
 WWW: **http://www.nongnu.org/libunwind/**.