From 7983009e0655547bf85fd47430c6fbcc2dbdda40 Mon Sep 17 00:00:00 2001
From: uz <uz@b7a2c559-68d2-44c3-8de9-860c34a00d81>
Date: Mon, 31 Aug 2009 15:11:32 +0000
Subject: [PATCH] Improved code for bit fields.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4097 b7a2c559-68d2-44c3-8de9-860c34a00d81
---
 src/cc65/loadexpr.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/cc65/loadexpr.c b/src/cc65/loadexpr.c
index 8e7f83b76..fd09a4d7f 100644
--- a/src/cc65/loadexpr.c
+++ b/src/cc65/loadexpr.c
@@ -95,8 +95,16 @@ void LoadExpr (unsigned Flags, struct ExprDesc* Expr)
 {
     if (ED_IsLVal (Expr)) {
 
-       	/* Dereferenced lvalue */
-       	Flags |= TypeOf (Expr->Type);
+       	/* Dereferenced lvalue. If this is a bit field its type is unsigned.
+         * But if the field is completely contained in the lower byte, we will
+         * throw away the high byte anyway and may therefore load just the
+         * low byte.
+         */
+        if (ED_IsBitField (Expr) && Expr->BitOffs + Expr->BitWidth <= CHAR_BITS) {
+            Flags |= CF_CHAR | CF_UNSIGNED;
+        } else {
+            Flags |= TypeOf (Expr->Type);
+        }
      	if (ED_NeedsTest (Expr)) {
      	    Flags |= CF_TEST;
      	}