start packing some binary image structures

src/bin.h

@@ -2,6 +2,7 @@
 #define BIN_H_
 
 #include <blue/core/endian.h>
+#include "misc.h"
 
 #define EC3_SIGNATURE            0x45433358
 
@@ -34,7 +35,7 @@
 #define EC3_TAG_ENCRYPTED        0x00000004u
 
 /* 32K per cluster group */
-#define EC3_CLUSTERS_PER_GROUP   1635
+#define EC3_CLUSTERS_PER_GROUP   1637
 /* 1K per extent group */
 #define EC3_EXTENTS_PER_GROUP    36
 
@@ -67,6 +68,7 @@
 
 typedef uint8_t ec3_chunk_id[EC3_CHUNK_ID_SIZE];
 
+PACK(
 	struct ec3_header {
 		b_i32 h_magic;
 		b_i16 h_version;
@@ -81,8 +83,10 @@ struct ec3_header {
 		b_i16 h_encryption;
 		b_i64 h_app_magic;
 		uint8_t h_reserved[8];
-};
+	}
+);
 
+PACK(
 	struct ec3_cluster {
 		/* cluster identifier */
 		b_i32 c_id;
@@ -94,8 +98,10 @@ struct ec3_cluster {
 		b_i16 c_checksum;
 		/* flags that apply to this cluster */
 		b_i16 c_flags;
-};
+	}
+);
 
+PACK(
 	struct ec3_cluster_group {
 		/* the number of clusters that this group contains */
 		b_i16 g_nr_clusters;
@@ -105,9 +111,9 @@ struct ec3_cluster_group {
 		/* offsets to other cluster groups, relative to the start of the
 		 * cluster group table. the cluster groups form a B-tree. */
 		b_i32 g_child_offsets[EC3_CLUSTERS_PER_GROUP + 1];
-	/* pad the group out to an even 32K */
 		uint8_t g_padding[20];
-};
+	}
+);
 
 struct ec3_tag_table_entry {
 	b_i32 tag_type;

src/misc.h

@@ -0,0 +1,12 @@
+#ifndef MISC_H_
+#define MISC_H_
+
+#ifdef __GNUC__
+#define PACK( __Declaration__ ) __Declaration__ __attribute__((__packed__))
+#endif
+
+#ifdef _MSC_VER
+#define PACK( __Declaration__ ) __pragma( pack(push, 1) ) __Declaration__ __pragma( pack(pop))
+#endif
+
+#endif