Added object file format spec

This is a WIP.

doc/object_format.md

@@ -0,0 +1,55 @@
+# Linker file format
+
+```C
+
+struct object_file {
+    uint64_t    magic;   // ".oo-bin"
+    uint64_t    version; // 1
+    uint64_t    architecture; // AMD64(0)
+    uint64_t    offsets_offset;
+
+    struct offsets {
+        uint64_t strings;
+        uint64_t sections;
+        uint64_t symbols;
+        uint64_t relocations;
+    } offsets;
+
+    struct string_table {
+        uint64_t size;
+        uint8_t data[static size];
+    } strings;
+
+    struct section_table {
+        uint32_t count;
+        struct section_entry {
+            uint32_t name;
+            uint64_t offset;
+            uint64_t size_on_disk;
+            uint64_t size_in_memory;
+            uint64_t flags;
+        } sections[static count];
+    } sections;
+
+    struct symbol_table {
+        uint32_t count;
+        struct symbol_entry {
+            uint32_t name;
+            uint8_t  kind;  // IMPORT(0) | EXPORT(1) | LOCAL(2)
+            uint32_t section;
+            uint64_t offset;
+        } symbols[static count];
+    } symbols;
+
+    struct relocation_table {
+        uint32_t count;
+        struct relocation_entry {
+            uint32_t section;
+            uint64_t offset;
+            uint8_t  size;
+            uint32_t symbol;
+            uint8_t  kind;  // ABSOLUTE(0) | RELATIVE(1)
+        } relocations[static count];
+    } relocations;
+};
+```