Implement ROR (absolute, X).

hainesr · Oct 24, 2020 · 43394ba · 43394ba
1 parent b7e6e0a
commit 43394ba
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diff --git a/lib/mos6502/cpu_instructions.rb b/lib/mos6502/cpu_instructions.rb
@@ -261,6 +261,12 @@ def instructions
           @status.interupt_disable = true
         },
 
+        # ROR (absolute, X)
+        0x7e => lambda {
+          address = absolute(@x)
+          @memory.set(address, ror(@memory.get(address)))
+        },
+
         # STA (indexed indirect)
         0x81 => lambda {
           @memory.set(indexed_indirect, @a)

diff --git a/test/cpu_instructions_test.rb b/test/cpu_instructions_test.rb
@@ -564,6 +564,18 @@ def test_0x76
     assert_equal([0x3f], @cpu.dump_memory(0x2c, 1))
   end
 
+  def test_0x7e
+    @cpu.load!([0xa9, 0x7f, 0xa2, 0x10, 0x9d, 0x0f, 0x70, 0x7e, 0x0f, 0x70])
+    @cpu.step
+    @cpu.step
+    @cpu.step
+    @cpu.step
+    assert(@cpu.carry?)
+    refute(@cpu.negative?)
+    refute(@cpu.zero?)
+    assert_equal([0x3f], @cpu.dump_memory(0x701f, 1))
+  end
+
   def test_0x81
     @cpu.load!(
       [