Add actual parity calculation for the P/V flag (configurable at compi…

…le time).
redcode · Apr 6, 2024 · d9e59e8 · d9e59e8
1 parent 94b0771
commit d9e59e8
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Showing 2 changed files with 35 additions and 20 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -114,6 +114,13 @@ Enable optional notifications for any `reti` or `retn` instruction \
 executed during the interrupt mode 0 response."
 NO)
 
+option(${PROJECT_NAME}_WITH_PARITY_COMPUTATION
+"${PROJECT_NAME}: \
+Enable actual parity calculation for the P/V flag instead of using a \
+table of precomputed values (this is for benchmarks, DO NOT ENABLE in \
+production builds)."
+NO)
+
 option(${PROJECT_NAME}_WITH_Q
 "${PROJECT_NAME}: \
 Build the implementation of Q."
@@ -212,6 +219,7 @@ target_compile_definitions(
 	$<$<BOOL:${${PROJECT_NAME}_WITH_EXECUTE}>:Z80_WITH_EXECUTE>
 	$<$<BOOL:${${PROJECT_NAME}_WITH_FULL_IM0}>:Z80_WITH_FULL_IM0>
 	$<$<BOOL:${${PROJECT_NAME}_WITH_IM0_RETX_NOTIFICATIONS}>:Z80_WITH_IM0_RETX_NOTIFICATIONS>
+	$<$<BOOL:${${PROJECT_NAME}_WITH_PARITY_COMPUTATION}>:Z80_WITH_PARITY_COMPUTATION>
 	$<$<BOOL:${${PROJECT_NAME}_WITH_Q}>:Z80_WITH_Q>
 	$<$<BOOL:${${PROJECT_NAME}_WITH_SPECIAL_RESET}>:Z80_WITH_SPECIAL_RESET>
 	$<$<BOOL:${${PROJECT_NAME}_WITH_UNOFFICIAL_RETI}>:Z80_WITH_UNOFFICIAL_RETI>

diff --git a/sources/Z80.c b/sources/Z80.c
@@ -230,26 +230,33 @@ static Z_ALWAYS_INLINE void write_16b(Z80 *self, zuint16 address, zuint16 value)
 
 #define ZF_ZERO(value) (!(value) << 6)
 
-static zuint8 const pf_parity_table[256] = {
-/*	0  1  2  3  4  5  6  7	8  9  A  B  C  D  E  F */
-/* 0 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* 1 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* 2 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* 3 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* 4 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* 5 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* 6 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* 7 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* 8 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* 9 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* A */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* B */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* C */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
-/* D */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* E */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
-/* F */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4};
-
-#define PF_PARITY(value) pf_parity_table[value]
+#ifdef Z80_WITH_PARITY_COMPUTATION
+	static Z_ALWAYS_INLINE zuint8 pf_parity(zuint8 value)
+		{return (((0x9669U >> ((value ^ (value >> 4)) & 0xF)) & 1) << 2);}
+
+#	define PF_PARITY pf_parity
+#else
+	static zuint8 const pf_parity_table[256] = {
+	/*	0  1  2  3  4  5  6  7	8  9  A  B  C  D  E  F */
+	/* 0 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* 1 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* 2 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* 3 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* 4 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* 5 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* 6 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* 7 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* 8 */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* 9 */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* A */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* B */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* C */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4,
+	/* D */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* E */ 0, 4, 4, 0, 4, 0, 0, 4, 4, 0, 0, 4, 0, 4, 4, 0,
+	/* F */ 4, 0, 0, 4, 0, 4, 4, 0, 0, 4, 4, 0, 4, 0, 0, 4};
+
+#	define PF_PARITY(value) pf_parity_table[value]
+#endif
 
 /*-----------------------------------------------------------------------------.
 | `PF_OVERFLOW` computes PF according to whether signed overflow occurs in the |