From 50fd96bbabe91ad115ad324cd0aa2a19382905c1 Mon Sep 17 00:00:00 2001
From: Stefan <stefan.haubenthal@gmail.com>
Date: Thu, 7 Feb 2019 12:19:49 +0100
Subject: [PATCH] Fixed 65C02 timing.

---
 src/sim65/6502.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/sim65/6502.c b/src/sim65/6502.c
index bfbfbd78c..683937ed7 100644
--- a/src/sim65/6502.c
+++ b/src/sim65/6502.c
@@ -37,8 +37,6 @@
    BBRx, BBSx, RMBx, SMBx, WAI, and STP are unsupported
  * BCD flag handling equals 6502 (unchecked if bug is simulated or wrong for
    6502)
- * one cycle win for fetch-modify-write instructions ignored
-   (e.g., ROL abs,x takes only 6 cycles if no page break occurs)
 */
 
 #include "memory.h"
@@ -629,6 +627,8 @@ static void OPC_6502_1E (void)
     unsigned Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr) << 1;
     MemWriteByte (Addr, (unsigned char) Val);
     TEST_ZF (Val & 0xFF);
@@ -898,6 +898,8 @@ static void OPC_6502_3E (void)
     unsigned Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr);
     ROL (Val);
     MemWriteByte (Addr, Val);
@@ -1132,6 +1134,8 @@ static void OPC_6502_5E (void)
     unsigned char Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr);
     SET_CF (Val & 0x01);
     Val >>= 1;
@@ -1462,6 +1466,8 @@ static void OPC_6502_7E (void)
     unsigned Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr);
     ROR (Val);
     MemWriteByte (Addr, Val);
@@ -2341,6 +2347,8 @@ static void OPC_6502_DE (void)
     unsigned char Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr) - 1;
     MemWriteByte (Addr, Val);
     TEST_ZF (Val);
@@ -2648,6 +2656,8 @@ static void OPC_6502_FE (void)
     unsigned char Val;
     Cycles = 7;
     Addr = MemReadWord (Regs.PC+1) + Regs.XR;
+    if (CPU != CPU_6502 && !PAGE_CROSS (Addr, Regs.XR))
+        --Cycles;
     Val = MemReadByte (Addr) + 1;
     MemWriteByte (Addr, Val);
     TEST_ZF (Val);