Simplify start_of_data, start_of_text and related code.

* src/mem-limits.h: Remove !emacs and _LIBC conditional code.
(start_of_data): Merge into start_of_data function.
* src/sysdep.c (start_of_text): Remove.  Move simplified versions of
it in the only users: src/unexaix.c and unexec.c.
(read_input_waiting): Remove local declaration of quit_char.
(start, etext): Remove declarations.
(start_of_data): Merge with the version in mem-limits.h and move
to vm-limits.c.
* src/vm-limit.c (start_of_data): Merged and simplified version of the
code formerly in mem-limits.h and sysdep.c.
* src/unexec.c (start): New declaration, moved from sysdep.c.
(start_of_text): Simplified version of the code formerly in sysdep.c.
* unexaix.c (start_of_text): Simplified version of the code
formerly in sysdep.c.
* src/m/alpha.h (HAVE_TEXT_START): Remove.
(TEXT_START): Move ...
* src/unexalpha.c (TEXT_START): ... here.
* src/s/hpux10-20.h (TEXT_START): Remove.
* src/s/darwin.h (TEXT_START):
* src/m/mips.h (TEXT_START):
* src/m/macppc.h (HAVE_TEXT_START):
* src/m/m68k.h (TEXT_START):
* src/m/iris4d.h (TEXT_START):
* src/m/intel386.h (TEXT_START):
* src/m/ibmrs6000.h (TEXT_START):
* src/m/ia64.h (HAVE_TEXT_START):
* src/s/msdos.h (TEXT_START): Likewise.

1 files changed, 40 insertions, 0 deletions

diff --git a/src/vm-limit.c b/src/vm-limit.c
index 00b041d8ef8..cb42f78701b 100644
--- a/src/vm-limit.c
+++ b/src/vm-limit.c
@@ -244,6 +244,46 @@ check_memory_limits (void)
     (*warn_function) ("Warning: memory in use exceeds lisp pointer size");
 }
 
+#if !defined(CANNOT_DUMP) || !defined(SYSTEM_MALLOC)
+/* Some systems that cannot dump also cannot implement these.  */
+
+/*
+ *      Return the address of the start of the data segment prior to
+ *      doing an unexec.  After unexec the return value is undefined.
+ *      See crt0.c for further information and definition of data_start.
+ *
+ *      Apparently, on BSD systems this is etext at startup.  On
+ *      USG systems (swapping) this is highly mmu dependent and
+ *      is also dependent on whether or not the program is running
+ *      with shared text.  Generally there is a (possibly large)
+ *      gap between end of text and start of data with shared text.
+ *
+ */
+
+POINTER
+start_of_data (void)
+{
+#ifdef BSD_SYSTEM
+  extern char etext;
+  return (POINTER)(&etext);
+#elif defined DATA_START
+  return ((POINTER) DATA_START);
+#elif defined ORDINARY_LINK
+  /*
+   * This is a hack.  Since we're not linking crt0.c or pre_crt0.c,
+   * data_start isn't defined.  We take the address of environ, which
+   * is known to live at or near the start of the system crt0.c, and
+   * we don't sweat the handful of bytes that might lose.
+   */
+  extern char **environ;
+  return ((POINTER) &environ);
+#else
+  extern int data_start;
+  return ((POINTER) &data_start);
+#endif
+}
+#endif /* (not CANNOT_DUMP or not SYSTEM_MALLOC) */
+
 /* Enable memory usage warnings.
    START says where the end of pure storage is.
    WARNFUN specifies the function to call to issue a warning.  */