xcore: handle details for some special tricky instructions
diff --git a/include/xcore.h b/include/xcore.h
index 5bc6770..a2133d4 100644
--- a/include/xcore.h
+++ b/include/xcore.h
@@ -71,7 +71,21 @@
 	XCORE_REG_R10,
 	XCORE_REG_R11,
 
-	XCORE_REG_MAX,
+	//> pseudo registers
+	XCORE_REG_PC,	// pc
+
+	// internal thread registers
+	// see The-XMOS-XS1-Architecture(X7879A).pdf
+	XCORE_REG_SCP,	// save pc
+	XCORE_REG_SSR,	// save status
+	XCORE_REG_ET,	// exception type
+	XCORE_REG_ED,	// exception data
+	XCORE_REG_SED,	// save exception data
+	XCORE_REG_KEP,	// kernel entry pointer
+	XCORE_REG_KSP,	// kernel stack pointer
+	XCORE_REG_ID,	// thread ID
+
+	XCORE_REG_MAX,	// <-- mark the end of the list of registers
 } xcore_reg;
 
 //> XCore instruction