thumb push/pop registers

src/crab/thumb/push_pop_registers.cr

@@ -0,0 +1,33 @@
+module THUMB
+  def thumb_push_pop_registers(instr : Word) : Nil
+    pop = bit?(instr, 11)
+    pclr = bit?(instr, 8)
+    list = bits(instr, 0..8)
+    address = @r[13]
+    if pop
+      8.times do |idx|
+        if bit?(list, idx)
+          @r[idx] = @gba.bus.read_word(address)
+          address &+= 4
+        end
+      end
+      if pclr
+        @r[15] = @gba.bus.read_word(address)
+        address &+= 4
+        clear_pipeline
+      end
+    else
+      if pclr
+        @gba.bus[address] = @r[14]
+        address &-= 4
+      end
+      7.downto(0).each do |idx|
+        if bit?(list, idx)
+          @gba.bus[address] = @r[idx]
+          address &-= 4
+        end
+      end
+    end
+    @r[13] = address
+  end
+end

src/crab/thumb/thumb.cr

@@ -17,7 +17,7 @@ module THUMB
       elsif idx & 0b11110000 == 0b11000000
         lut[idx] = ->thumb_multiple_load_store(Word)
       elsif idx & 0b11110110 == 0b10110100
-        # push/pop registers
+        lut[idx] = ->thumb_push_pop_registers(Word)
       elsif idx & 0b11111111 == 0b10110000
         # add offset to stack pointer
       elsif idx & 0b11110000 == 0b10100000