implement a handful more illegal instructions (6502)

README.md

@@ -13,7 +13,7 @@ Properties of this simulator:
 - simulates various hardware components (bus, cpu, memory, i/o controllers)
 - IRQ and NMI
 - instruction cycle times are simulated (however the *internal* cpu behavior is not cycle-exact for simplicity reasons)
-- has all 6502 and 65c02 instructions, including many of the 'illegal' 6502 instructions (goal is 100% eventually)
+- simulates all 6502 and 65c02 instructions, including many of the 'illegal' 6502 instructions
 - correct BCD mode for adc/sbc instructions on both cpu types
 - passes several extensive unit test suites that verify instruction and cpu flags behavior
 - simple debugging machine monitor, which basic disassembler and assembler functions

src/main/kotlin/razorvine/ksim65/Cpu6502.kt

@@ -1416,10 +1416,11 @@ sealed class Cpu6502Core : BusComponent() {
     // or https://github.com/quietust/nintendulator/blob/master/src/CPU.cpp (search for LogBadOps)
     // or https://github.com/stardot/b-em/blob/master/src/6502.c
     // or https://github.com/wpmed92/MedNES/blob/master/NES/6502.cpp
-    // TODO: some of the instructions below may be implemented incorrectly / are not finished yet
+
+    // NOTE: some instructions below may be unimplemented due to cpu quirkyness
 
     private fun iAhx(): Boolean {
-        val addrHi = 0xff   // TODO get the correct byte from the instruction (=last byte read)
+        val addrHi = (fetchedAddress shr 8) and 0xff
         val value = regA and regX and (addrHi+1)
         write(fetchedAddress, value)
         return false
@@ -1506,13 +1507,13 @@ sealed class Cpu6502Core : BusComponent() {
     }
 
     private fun iShx(): Boolean {
-        val addrHi = 0xff   // TODO get the correct byte from the instruction (=last byte read)
+        val addrHi = (fetchedAddress shr 8) and 0xff
         write(fetchedAddress, regX and (addrHi+1))
         return false
     }
 
     private fun iShy(): Boolean {
-        val addrHi = 0xff   // TODO get the correct byte from the instruction (=last byte read)
+        val addrHi = (fetchedAddress shr 8) and 0xff
         write(fetchedAddress, regY and (addrHi+1))
         return false
     }
@@ -1531,7 +1532,7 @@ sealed class Cpu6502Core : BusComponent() {
 
     private fun iTas(): Boolean {
         regSP = regA and regX
-        val addrHi = 0xff   // TODO get the correct byte from the instruction (=last byte read)
+        val addrHi = (fetchedAddress shr 8) and 0xff
         write(fetchedAddress, regSP and addrHi)
         return false
     }

src/main/resources/version.properties

@@ -1 +1 @@
-version=1.21
+version=1.22

src/test/kotlin/Test6502TestSuiteIllegalInstructions.kt

@@ -283,60 +283,56 @@ class Test6502TestSuiteIllegalInstructions: FunctionalTestsBase() {
     @Test
     @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testAlrb() {
-        runTest("alrb") // TODO fix?
+        runTest("alrb")
     }
 
     @Test
     @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testAneb() {
-        runTest("aneb") // TODO fix?
+        runTest("aneb")
     }
 
     @Test
     @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testArrb() {
-        runTest("arrb") // TODO fix?
+        runTest("arrb")
     }
 
     @Test
     @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testLxab() {
-        runTest("lxab")         // TODO fix something?
+        runTest("lxab")
     }
 
     @Test
     @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testSbxb() {
-        runTest("sbxb") // TODO fix?
+        runTest("sbxb")
     }
 
     @Test
-    @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testShaay() {
-        runTest("shaay")    // TODO fix?
+        runTest("shaay")
     }
 
     @Test
-    @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testShaiy() {
-        runTest("shaiy")    // TODO fix?
+        runTest("shaiy")
     }
 
     @Test
-    @Disabled("this illegal instruction is probably not implemented correctly yet")
+    @Disabled("this instruction has quirky behavior that varies between machines")
     fun testShsay() {
-        runTest("shsay")    // TODO fix?
+        runTest("shsay")
     }
 
     @Test
-    @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testShxay() {
-        runTest("shxay")    // TODO fix?
+        runTest("shxay")
     }
 
     @Test
-    @Disabled("this illegal instruction is probably not implemented correctly yet")
     fun testShyax() {
-        runTest("shyax")    // TODO fix?
+        runTest("shyax")
     }
 }