--- generator/hdr/registers.h	2020/03/04 04:46:28	1.1
+++ generator/hdr/registers.h	2020/03/04 04:46:49	1.1.1.2
@@ -1,3 +1,8 @@
+/* These registers must be registers that are preserved over function calls
+   in C.  What I mean by this is that if we're using these registers and we
+   call a C function, then when that C function returns these registers are
+   still what they were before we made the call. */
+
 #ifdef PROCESSOR_ARM
      register uint32 reg68k_pc asm ("r7");
      register uint32 *reg68k_regs asm ("r8");