add preliminary implementation of the unofficial opcodes

1 files changed, 57 insertions, 34 deletions

diff --git a/cpu.c b/cpu.c
index e3bb7d5..039337f 100644
--- a/cpu.c
+++ b/cpu.c
@@ -128,8 +128,8 @@ opcode_mem(enum addressing_mode mode)
                 break;
         case AM_REL:
                 val = arg + regs.pc;
-                if ((regs.pc + 1) & 0xFF00 != val & 0xFF00)
-                        page_crossed = true;
+                if (((regs.pc + 1) & 0xFF00) != (val & 0xFF00))
+                        val -= 0x0100;
                 break;
         case AM_IMM:
         case AM_ABS:
@@ -703,133 +703,158 @@ TYA(uint16_t arg)
 void
 AAC(uint16_t arg)
 {
-        NOP(0);
+        AND(arg);
+
+        regs.status.carry = regs.status.negative;
 }
 
 void
-AAX(uint16_t arg)
+SAX(uint16_t arg)
 {
-        NOP(0);
+        uint8_t tmp = regs.x & regs.a;
+        memwrite(arg, tmp);
 }
 
 void
 ARR(uint16_t arg)
 {
-        NOP(0);
+        uint8_t tmp = arg & regs.a;
+
+        AND(arg);
+        ROR_acc(0);
+
+        if ((tmp & (1 << 5)) != 0 && (tmp & (1 << 6)) != 0)
+                SEC(0), CLV(0);
+        else if ((tmp & (1 << 5)) == 0 && (tmp & (1 << 6)) == 0)
+                CLC(0), CLV(0);
+        else if ((tmp & (1 << 5)) != 0)
+                CLC(0), regs.status.overflow = 1;
+        else if ((tmp & (1 << 6)) != 0)
+                SEC(0), regs.status.overflow = 1;
 }
 
 void
 ASR(uint16_t arg)
 {
-        NOP(0);
+        AND(arg);
+        LSR_acc(0);
 }
 
 void
 ATX(uint16_t arg)
 {
-        NOP(0);
+        AND(arg);
+        TAX(0);
 }
 
 void
 AXA(uint16_t arg)
 {
-        NOP(0);
+        uint8_t tmp = regs.x & regs.a & 7;
+        memwrite(arg, tmp);
 }
 
 void
 AXS(uint16_t arg)
 {
-        NOP(0);
+        regs.x &= regs.a;
+        regs.x -= arg;
+
+        regs.status.carry = arg <= regs.x;
+        STATUS_UPDATE_NZ(regs.x);
 }
 
 void
 DCP(uint16_t arg)
 {
-        NOP(0);
-}
+        uint8_t tmp = peek(arg) - 1;
+        memwrite(arg, tmp);
 
-void
-DOP(uint16_t arg)
-{
-        NOP(0);
+        regs.status.carry = tmp <= regs.a;
+        STATUS_UPDATE_NZ(tmp);
 }
 
 void
 ISC(uint16_t arg)
 {
-        NOP(0);
+        INC(arg);
+        SBC(peek(arg));
 }
 
 void
 KIL(uint16_t arg)
 {
+        /* TODO: figure out how to stop interpret(), I guess with global bool */
         NOP(0);
 }
 
 void
 LAR(uint16_t arg)
 {
-        NOP(0);
+        regs.a = regs.x = regs.sp = regs.a & regs.sp;
+
+        STATUS_UPDATE_NZ(regs.a);
 }
 
 void
 LAX(uint16_t arg)
 {
-        NOP(0);
+        LDA(arg);
+        LDX(arg);
 }
 
 void
 RLA(uint16_t arg)
 {
-        NOP(0);
+        ROL(arg);
+        AND(arg);
 }
 
 void
 RRA(uint16_t arg)
 {
-        NOP(0);
+        ROR(arg);
+        ADC(peek(arg));
 }
 
 void
 SLO(uint16_t arg)
 {
-        NOP(0);
+        ASL(arg);
+        ORA(arg);
 }
 
 void
 SRE(uint16_t arg)
 {
-        NOP(0);
+        LSR(arg);
+        EOR(arg);
 }
 
 void
 SXA(uint16_t arg)
 {
-        NOP(0);
+        memwrite(arg, regs.x & ((arg & 0xFF00) + 1));
 }
 
 void
 SYA(uint16_t arg)
 {
-        NOP(0);
-}
-
-void
-TOP(uint16_t arg)
-{
-        NOP(0);
+        memwrite(arg, regs.x & ((arg & 0xFF00) + 1));
 }
 
 void
 XAA(uint16_t arg)
 {
+        /* TODO: apparently the exact operation is unknown */
         NOP(0);
 }
 
 void
 XAS(uint16_t arg)
 {
-        NOP(0);
+        regs.sp = regs.a & regs.x;
+        memwrite(arg, regs.sp & ((arg & 0xFF00) + 1));
 }
 
 static void
@@ -877,8 +902,6 @@ interpret(void)
                         printf("$%02X,Y", arg);
                         break;
                 case AM_REL:
-                        printf("$%04X", regs.pc + arg);
-                        break;
                 case AM_ABS:
                         printf("$%04X", arg);
                         break;