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/.