Move assembly into the arch directory

Rakefile

@@ -324,14 +324,19 @@ def relative_from_tmp(path)
   Pathname.new(path).relative_path_from(TMP).each_filename
 end
 
+def architecture_instruction_set(architecture)
+  architecture.gsub /[[:digit:]]+$/, ''
+end
+
 CLEAN.include(TMP + 'riscv32')
 directory(TMP + 'riscv32')
 
 rule '.s.o' => ->(match) {
   architecture, *path_components = relative_from_tmp(match).to_a
   path_components[-1] = path_components.last.ext('')
+  instruction_set = architecture_instruction_set architecture
 
-  [File.join(path_components), TMP + architecture]
+  [File.join('arch', instruction_set, path_components), TMP + architecture]
 } do |t|
   options = BuildTarget.new relative_from_tmp(t.name).first
   compiler = options.rootfs + "bin/#{options.target}-gcc"
@@ -356,9 +361,15 @@ rule '.elna.o' => ->(match) {
 end
 
 rule 'kernel.elf' => ->(match) {
-  architecture_tmp = TMP + relative_from_tmp(match).first
+  architecture = relative_from_tmp(match).first
+  instruction_set = architecture_instruction_set architecture
 
-  FileList['*.s', '*.elna'].map { |source| (architecture_tmp + source).to_path + '.o' } << 'kernel.ld'
+  arch_objects = FileList["arch/#{instruction_set}/*.s"]
+    .map { |source| Pathname.new(source).relative_path_from("arch/#{instruction_set}").sub_ext('.s.o') }
+    .map { |source| TMP + architecture + source }
+    .map(&:to_path)
+
+  arch_objects + FileList['*.elna'].map { |source| (TMP + architecture + source).to_path + '.o' } << 'kernel.ld'
 } do |t|
   options = BuildTarget.new relative_from_tmp(t.name).first
   compiler = options.rootfs + "bin/#{options.target}-gcc"