[gnumeric] Styles: make hash better.

[Morten Welinder <mortenw src gnome org>]

commit 2bf3bc8685cd4163c96b4d7eb0bafacb00fc82b4
Author: Morten Welinder <terra gnome org>
Date:   Fri May 11 11:15:25 2012 -0400

    Styles: make hash better.

 ChangeLog    |    6 ++++
 src/mstyle.c |   89 ++++++++++++++++++++++++++++------------------------------
 2 files changed, 49 insertions(+), 46 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index bca40ea..9ec6f2f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-05-11  Morten Welinder  <terra gnome org>
+
+	* src/mstyle.c (gnm_style_update): Make hashing half-way decent.
+	Avoid clash between two styles where one is bold and the other is
+	italic.
+
 2012-05-10  Morten Welinder  <terra gnome org>
 
 	* src/workbook.c (workbook_dispose): Dispose of views early.
diff --git a/src/mstyle.c b/src/mstyle.c
index ebf02d3..92f8342 100644
--- a/src/mstyle.c
+++ b/src/mstyle.c
@@ -148,10 +148,15 @@ clear_conditional_merges (GnmStyle *style)
 	}
 }
 
+#define MIX(H) do {				\
+  H *= G_GUINT64_CONSTANT(123456789012345);	\
+  H ^= (H >> 31);				\
+} while (0)
+
 static void
 gnm_style_update (GnmStyle *style)
 {
-	guint32 hash = 0;
+	guint64 hash = 0;
 	int i;
 
 	g_return_if_fail (style->changed);
@@ -164,99 +169,89 @@ gnm_style_update (GnmStyle *style)
 
 	if (style->color.back && !style->color.back->is_auto)
 		hash ^= GPOINTER_TO_UINT (style->color.back);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	if (style->color.pattern && !style->color.pattern->is_auto)
 		hash ^= GPOINTER_TO_UINT (style->color.pattern);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	if (style->color.font && !style->color.font->is_auto)
 		hash ^= GPOINTER_TO_UINT (style->color.font);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	for (i = MSTYLE_BORDER_TOP; i <= MSTYLE_BORDER_DIAGONAL; i++) {
 		hash ^= GPOINTER_TO_UINT (style->borders[i - MSTYLE_BORDER_TOP]);
-		hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+		MIX (hash);
 	}
 
 	hash ^= style->pattern;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= GPOINTER_TO_UINT (style->font_detail.name);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
-	if (style->font_detail.bold) {
-		hash ^= 0x1379;
-		hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
-	}
+	if (style->font_detail.bold) hash ^= 1;
+	MIX (hash);
 
-	if (style->font_detail.italic) {
-		hash ^= 0x1379;
-		hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
-	}
+	if (style->font_detail.italic) hash ^= 1;
+	MIX (hash);
 
 	hash ^= style->font_detail.underline;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
-	if (style->font_detail.strikethrough)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->font_detail.strikethrough) hash ^= 1;
+	MIX (hash);
 
 	hash ^= ((int)(style->font_detail.size * 97));
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= GPOINTER_TO_UINT (style->format);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= style->h_align;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= style->v_align;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= style->indent;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= style->rotation;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= style->text_dir;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
-	if (style->wrap_text)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->wrap_text) hash ^= 1;
+	MIX (hash);
 
-	if (style->shrink_to_fit)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->shrink_to_fit) hash ^= 1;
+	MIX (hash);
 
-	if (style->contents_locked)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->contents_locked) hash ^= 1;
+	MIX (hash);
 
-	if (style->contents_hidden)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->contents_hidden) hash ^= 1;
+	MIX (hash);
 
-	style->hash_key_xl = hash;
+	style->hash_key_xl = (guint32)hash;
 
 	/* From here on, fields are not in MS XL */
 
-	if (style->validation)
-		hash ^= 0x1379;
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	if (style->validation != NULL) hash ^= 1;
+	MIX (hash);
 
 	hash ^= GPOINTER_TO_UINT (style->hlink);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= GPOINTER_TO_UINT (style->input_msg);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
 	hash ^= GPOINTER_TO_UINT (style->conditions);
-	hash = (hash << 7) ^ (hash >> (sizeof (hash) * 8 - 7));
+	MIX (hash);
 
-	style->hash_key = hash;
+	style->hash_key = (guint32)hash;
 
 	if (G_UNLIKELY (style->set == 0)) {
 		/*
@@ -269,6 +264,8 @@ gnm_style_update (GnmStyle *style)
 	}
 }
 
+#undef MIX
+
 guint
 gnm_style_hash_XL (gconstpointer style)
 {