com32: add a common zero-register structure

When we don't have any registers to pass, it's convenient to be able
to share a common all-zero structure.

diff --git a/com32/include/com32.h b/com32/include/com32.h
index f1df2d6..264f609 100644 (file)
--- a/com32/include/com32.h
+++ b/com32/include/com32.h
@@ -82,6 +82,7 @@ extern struct com32_sys_args {
 void __intcall(uint8_t __i, const com32sys_t *__sr, com32sys_t *__dr);
 void __farcall(uint16_t __es, uint16_t __eo,
               const com32sys_t *__sr, com32sys_t *__dr);
+extern const com32sys_t __com32_zero_regs;
 
 /*
  * These functions convert between linear pointers in the range