NOT should be a bitwise negation, not logic

hjaremko · Jan 6, 2022 · 651507b · 651507b
1 parent c6808d3
commit 651507b
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Showing 4 changed files with 8 additions and 4 deletions.
diff --git a/README.md b/README.md
@@ -52,7 +52,7 @@ $ ./von-neumann -rmf example/array_sum.vnm
 * **`DIV  `**, code: `1001`, operation: `AC = AC / OR`
 * **`AND  `**, code: `1010`, operation: `AC = AC & OR`
 * **`OR   `**, code: `1011`, operation: `AC = AC | OR`
-* **`NOT  `**, code: `1100`, operation: `AC = !OR`
+* **`NOT  `**, code: `1100`, operation: `AC = ~OR`
 * **`CMP  `**, code: `1101`, operation: `AC == OR => AC = -1`,`AC != OR => AC = 0`
 * **`SHZ  `**, code: `1110`, operation: `OR < 0 => AC >> |OR|`, `OR > 0 => AC << |OR|`
 * **`SHC  `**, code: `1111`, circular shift left or right, depending on the sign of the operand

diff --git a/include/machine.hpp b/include/machine.hpp
@@ -65,7 +65,7 @@ class machine
         [ & ]() { accumulator = accumulator / operand_reg; },
         [ & ]() { accumulator = accumulator & operand_reg; },
         [ & ]() { accumulator = accumulator | operand_reg; },
-        [ & ]() { accumulator = !operand_reg; },
+        [ & ]() { accumulator = ~operand_reg; },
         [ & ]() {
             accumulator = *accumulator == *operand_reg
                               ? static_cast<word::type>( -1 )

diff --git a/include/word.hpp b/include/word.hpp
@@ -157,6 +157,11 @@ class word
         return tmp;
     }
 
+    constexpr auto operator~() const -> word
+    {
+        return word( get() ^ 0xFFFF );
+    }
+
 private:
     type word_ { 0 };
     bool is_instruction_ { false }; // not sure if necessary

diff --git a/test/word_test.cpp b/test/word_test.cpp
@@ -186,8 +186,7 @@ TEST_CASE( "word operators test", "[word]" )
 
     SECTION( "negation" )
     {
-        auto w { word::type { 0b0100'0100'0010'1110u } };
-        REQUIRE( *( !word { w } ) == !w );
+        REQUIRE( *( ~word { lhs } ) == word::type { 0b1111'1111'0000'0101u } );
     }
 
     SECTION( "increment" )