SDL-1.2: added Watcom i386 inline asm for SDL_Swap64()

From 5dfe5127e52dbd78ec8dee59762fe0786ae40641 Mon Sep 17 00:00:00 2001
From: Ozkan Sezer <[EMAIL REDACTED]>
Date: Tue, 23 Feb 2021 17:37:10 +0300
Subject: [PATCH] added Watcom i386 inline asm for SDL_Swap64()

---
 include/SDL_endian.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/SDL_endian.h b/include/SDL_endian.h
index 48ae0eea..48f7860d 100644
--- a/include/SDL_endian.h
+++ b/include/SDL_endian.h
@@ -195,6 +195,14 @@ static __inline__ Uint64 SDL_Swap64(Uint64 x)
 	__asm__("bswapq %0" : "=r" (x) : "0" (x));
 	return x;
 }
+#elif defined(__WATCOMC__) && defined(__386__)
+extern _inline Uint64 SDL_Swap64(Uint64);
+#pragma aux SDL_Swap64 = \
+	"bswap eax"     \
+	"bswap edx"     \
+	"xchg eax,edx"  \
+	parm [eax edx]  \
+	modify [eax edx];
 #else
 static __inline__ Uint64 SDL_Swap64(Uint64 x)
 {