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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).
       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)