Implement segalloc for minijort

minijort.c

@@ -791,6 +791,14 @@ void f_rand() {
   PUSHI(rand());
 }
 
+void f_segalloc() {
+  void far* ptr = farmalloc(0x10010UL);
+  unsigned long linearaddr = ((unsigned long)FP_SEG(ptr) << 4) +
+			     ((unsigned long)FP_OFF(ptr));
+  int segment = ((linearaddr & 0x000ffff0UL) >> 4);
+  PUSHI(segment);
+}
+
 void f_init() {
   CDEF("[", f_compileoff); f_immediate();
   CDEF("]", f_compileon);
@@ -900,6 +908,7 @@ void f_init() {
   CDEF("chdir", f_chdir);
   CDEF("memmove", f_memmove);
   CDEF("rand", f_rand);
+  CDEF("segalloc", f_segalloc);
   PCONST("$DOCREATE", f_docreate);
   PCONST("$DOVAR", f_dovar);
   PCONST("$DODEFERRED", f_dodeferred);