Refactor:Add comments and #defines for relative attribute values.

3 files changed, 26 insertions, 17 deletions

diff --git a/navit/attr.c b/navit/attr.c
index 187299c5d..a4e38f09e 100644
--- a/navit/attr.c
+++ b/navit/attr.c
@@ -249,17 +249,15 @@ attr_new_from_text(const char *name, const char *value)
 					ret->u.num=0;
 				}
 			}
-			/* Absolute values are from -0x40000000 - 0x40000000, with 0x0 being 0 (who would have thought that?)
-				 Relative values are from 0x40000001 - 0x80000000, with 0x60000000 being 0 */
 			if (value_is_relative) {
-				if ((ret->u.num > 0x20000000) || (ret->u.num < -0x1FFFFFFF)) {
-					dbg(lvl_error, "Relative possibly-relative attribute with invalid value %li\n", ret->u.num);
+				if ((ret->u.num > ATTR_REL_MAXREL) || (ret->u.num < ATTR_REL_MINREL)) {
+					dbg(lvl_error, "Relative possibly-relative attribute with value out of range: %li\n", ret->u.num);
 				}
 
-				ret->u.num += 0x60000000;
+				ret->u.num += ATTR_REL_RELSHIFT;
 			} else {
-				if ((ret->u.num > 0x40000000) || (ret->u.num < -0x40000000)) {
-					dbg(lvl_error, "Non-relative possibly-relative attribute with invalid value %li\n", ret->u.num);
+				if ((ret->u.num > ATTR_REL_MAXABS) || (ret->u.num < ATTR_REL_MINABS)) {
+					dbg(lvl_error, "Non-relative possibly-relative attribute with value out of range: %li\n", ret->u.num);
 				}
 			}
 			break;
diff --git a/navit/attr.h b/navit/attr.h
index 6835f6ef2..27b37be60 100644
--- a/navit/attr.h
+++ b/navit/attr.h
@@ -97,9 +97,24 @@ enum attr_format {
 #define AF_DG_EXPLOSIVE		(1<<2)
 #define AF_DG_FLAMMABLE		(1<<3)
 
-/* Values for attributes that could carry relative values */
-#define ATTR_REL_MAXABS			0x40000000
-#define ATTR_REL_RELSHIFT		0x60000000
+/*
+ * Values for attributes that could carry relative values.
+ * Some attributes allow both absolute and relative values. The value for these
+ * attributes is stored as an int. Absolute values are stored as-is, relative
+ * values are stored shifted by adding ATTR_REL_RELSHIFT.
+ */
+/** Minimum value for an absolute attribute value. */
+#define ATTR_REL_MINABS		-0x40000000
+/** Maximum value for an absolute attribute value. */
+#define ATTR_REL_MAXABS		0x40000000
+/** Minimum value for an relative attribute value (without value shift). */
+#define ATTR_REL_MINREL		-0x1FFFFFFF
+/** Maximum value for an relative attribute value (without value shift). */
+#define ATTR_REL_MAXREL		0x20000000
+/**
+ * Value shift for relative values. This value is added to an attribute values to indicate
+ * a relative value. */
+#define ATTR_REL_RELSHIFT	0x60000000
 
 /** Indicates whether a position is valid **/
 enum attr_position_valid {
diff --git a/navit/attr_def.h b/navit/attr_def.h
index 85c9fe908..2b945226c 100644
--- a/navit/attr_def.h
+++ b/navit/attr_def.h
@@ -195,13 +195,9 @@ ATTR(turn_around_penalty2)
 ATTR(autozoom_max)
 ATTR(nav_status)
 ATTR2(0x00027500,type_rel_abs_begin)
-/* These attributes are int that can either hold relative		*
- * or absolute values. A relative value is indicated by 		*
- * adding 0x60000000.											*
- *																*
- * The range of valid absolute values is -0x40000000 to			*
- * 0x40000000, the range of relative values is from				*
- * -0x20000000 to 0x20000000.									*/
+/* These attributes are int that can either hold relative or absolute values. See the
+ * documentation of ATTR_REL_RELSHIFT for details.
+ */
 ATTR(h)
 ATTR(w)
 ATTR(x)