NAME

       unw_get_reg -- get register contents

SYNOPSIS

       #include <libunwind.h>

       int unw_get_reg(unw_cursor_t *cp, unw_regnum_t reg, unw_word_t *valp);

DESCRIPTION

       The  unw_get_reg() routine reads the value of register reg in the stack frame identified by cursor cp and
       stores the value in the word pointed to by valp.

       The  register  numbering  is  target-dependent  and   described   in   separate   manual   pages   (e.g.,
       libunwind-ia64(3)  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(3)), it is usually possible to access
       all registers.

       Note that unw_get_reg() can only read the contents of registers whose values fit in a  single  word.  See
       unw_get_fpreg(3) for a way to read registers which do not fit this constraint.

RETURN VALUE

       On  successful  completion,  unw_get_reg()  returns  0.   Otherwise  the  negative  value  of  one of the
       error-codes below is returned.

THREAD AND SIGNAL SAFETY

       unw_get_reg() 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_reg()  may  return  any  error  returned  by  the  access_mem(), access_reg(), and
       access_fpreg() call-backs (see unw_create_addr_space(3)).

SEE ALSO

       libunwind(3), libunwind-ia64(3), unw_get_fpreg(3), unw_is_signal_frame(3), unw_set_reg(3)

AUTHOR

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

Programming Library                              16 August 2007                                   UNW_GET_REG(3)