// Define a BREAKPOINT macro that will send the current process a
// SIGTRAP, causing a drop into the debugger if you're running under
// one. If this is not an i386, then this macro will drop you into the
// debugger deep inside a libc function and you'll have to single-step
// out (si).
#ifdef __i386__
#  define BREAKPOINT do { \
            int pid = getpid(); \
            int signum = SIGTRAP; \
            int trapnum = SYS_kill; \
            asm("int $0x80" : : "b"(pid), "c"(signum), "a"(trapnum)); \
} while(0)
#else
#  define BREAKPOINT kill(getpid(), SIGTRAP)
#endif