From a39bdaf6dca8ef640a2928a863993a11691fdf57 Mon Sep 17 00:00:00 2001
From: Bernard Blackham <dagobah@ucc.asn.au>
Date: Mon, 11 Aug 2003 16:51:25 +0000
Subject: [PATCH] bset & bclr had optimisation bugs with gcc

---
 ROM2/asm.h | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/ROM2/asm.h b/ROM2/asm.h
index 14e01ed..2c07ac8 100644
--- a/ROM2/asm.h
+++ b/ROM2/asm.h
@@ -7,24 +7,31 @@
  * always be an immediate value. Using "g" makes the compiler be quiet, but 
  * the assembler should fail if the value is not an immediate.
  */
-extern inline void bset(void* addr, u8 mask) {
-	asm volatile (
-		"ldx %0\n"
-		"bset 00,x,%1"
-		:                          /* outputs */
-		: "p" (addr), "g" (mask)   /* inputs */
-		: "x"                      /* altered registers */
-		);
+extern inline void bset(const void* addr, const u8 mask) {
+	/* The assembly breaks when gcc tries to optimise consecutive calls to
+	 * bset/bclr on the same memory address. Sigh. Either turn off optimisation
+	 * (-O1 without -Os works), or we do it the dumb way.
+	 */
+	*(u8*)addr |= mask;
+	// asm volatile (
+	// 	"ldx %0\n"
+	// 	"bset 00,x,%1" 
+	// 	:                          /* outputs */
+	// 	: "p" (addr), "g" (mask)   /* inputs */
+	// 	: "x"                      /* altered registers */
+	// 	);
 }
 
-extern inline void bclr(void* addr, u8 mask) {
-	asm volatile (
-		"ldx %0\n"
-		"bclr 00,x,%1"
-		:                          /* outputs */
-		: "p" (addr), "g" (mask)   /* inputs */
-		: "x"                      /* altered registers */
-		);
+extern inline void bclr(const void* addr, const u8 mask) {
+	/* same issue as above */
+	*(u8*)addr &= ~mask;
+	// asm volatile (
+	// 	"ldx %0\n"
+	// 	"bclr 00,x,%1"
+	// 	:                          /* outputs */
+	// 	: "p" (addr), "g" (mask)   /* inputs */
+	// 	: "x"                      /* altered registers */
+	// 	);
 }
 
 #endif /* _ASM_H_ */
-- 
2.20.1