UNW_GET_REG(3)						       Programming Library						    UNW_GET_REG(3)

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).  Further-
       more,  the exact set of accessible registers may depend on the type of frame that cp is referring to. For ordinary stack frames, it is nor-
       mally 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_cre-
       ate_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)