+/* 'start_frame' is a variable in the MON960 runtime startup routine
+ that contains the frame pointer of the 'start' routine (the routine
+ that calls 'main'). By reading its contents out of remote memory,
+ we can tell where the frame chain ends: backtraces should halt before
+ they display this frame. */
+
+int
+mon960_frame_chain_valid (CORE_ADDR chain, struct frame_info *curframe)
+{
+ struct symbol *sym;
+ struct minimal_symbol *msymbol;
+
+ /* crtmon960.o is an assembler module that is assumed to be linked
+ * first in an i80960 executable. It contains the true entry point;
+ * it performs startup up initialization and then calls 'main'.
+ *
+ * 'sf' is the name of a variable in crtmon960.o that is set
+ * during startup to the address of the first frame.
+ *
+ * 'a' is the address of that variable in 80960 memory.
+ */
+ static char sf[] = "start_frame";
+ CORE_ADDR a;
+
+
+ chain &= ~0x3f; /* Zero low 6 bits because previous frame pointers
+ contain return status info in them. */
+ if (chain == 0)
+ {
+ return 0;
+ }
+
+ sym = lookup_symbol (sf, 0, VAR_NAMESPACE, (int *) NULL,
+ (struct symtab **) NULL);
+ if (sym != 0)
+ {
+ a = SYMBOL_VALUE (sym);
+ }
+ else
+ {
+ msymbol = lookup_minimal_symbol (sf, NULL, NULL);
+ if (msymbol == NULL)
+ return 0;
+ a = SYMBOL_VALUE_ADDRESS (msymbol);
+ }
+
+ return (chain != read_memory_integer (a, 4));
+}
+
+