From: Alan Cox <alan@linux.intel.com>
Date: Sun, 11 Feb 2018 21:31:00 +0000 (+0000)
Subject: 6502: optimise the top byte check to avoid a shift
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=f156c03b620867134fbb3fb592bf2331b40f76e0;p=FUZIX.git

6502: optimise the top byte check to avoid a shift
---

diff --git a/Kernel/cpu-6502/cpu.h b/Kernel/cpu-6502/cpu.h
index 9c3ce28d..aa104865 100644
--- a/Kernel/cpu-6502/cpu.h
+++ b/Kernel/cpu-6502/cpu.h
@@ -65,3 +65,7 @@ typedef union {            /* this structure is endian dependent */
 
 /* cc65 really wants register tags on struct pointers used repeatedly */
 #define regptr	register
+
+/* CC65 is bright enough to partly optimise this but not fully so do it
+   by hand */
+#define HIBYTE32(x)	(((uint8_t *)&(x))[3])