bcx partially implemented

core/broadway.cpp

@@ -36,6 +36,9 @@ void broadway::execute(ircolib::u32 instr, mem &mem) {
     case 15: // addis rd, ra, simm
         addis(instr);
         break;
+    case 16: // bcx BO, BI, target
+        bcx(instr);
+        break;
     case 18: // bx  target
         bx(instr);
         break;

core/broadway.hpp

@@ -28,6 +28,7 @@ struct broadway {
     void addi(ircolib::u32);
     void ori(ircolib::u32);
     void bx(ircolib::u32);
+    void bcx(ircolib::u32);
     void move_spr(ircolib::u32);
     void stwu(ircolib::u32, mem &);
     void sth(ircolib::u32, mem &);

core/broadway/instructions.cpp

@@ -27,14 +27,54 @@ void broadway::bx(ircolib::u32 instr) {
     const bool link = instr & 1;
     const bool absolute = instr & 2;
 
-    ircolib::s32 LI = (ircolib::s32(instr << 6) >> 6) & 0x03FFFFFC;
+    ircolib::s32 li = (ircolib::s32(instr << 6) >> 6) & 0xFFFFFFFC;
     if (!absolute)
-        LI += pc - 4;
+        li += pc - 4;
 
     if (link)
         lr = pc;
 
-    pc = LI;
+    pc = li;
+}
+
+void broadway::bcx(ircolib::u32 instr) {
+    const bool link = instr & 1;
+    const bool absolute = instr & 2;
+
+    ircolib::s32 bd = (ircolib::s32(instr << 16) >> 16) & 0xFFFFFFFC;
+    if (!absolute)
+        bd += pc - 4;
+
+    if (!ircolib::is_bit_set<ircolib::u32, 25>(instr))
+        ircolib::panic("broadway::bcx unimplemented variants with bit 25 == 0");
+
+    if (ircolib::is_bit_set<ircolib::u32, 23>(instr)) { // always
+        if (link)
+            lr = pc;
+
+        pc = bd;
+        return;
+    }
+
+    if (ircolib::is_bit_set<ircolib::u32, 22>(instr)) { // --ctr == 0
+        if (--ctr != 0)
+            return;
+
+        if (link)
+            lr = pc;
+
+        pc = bd;
+        return;
+    }
+
+    // --ctr != 0
+    if (--ctr == 0)
+        return;
+
+    if (link)
+        lr = pc;
+
+    pc = bd;
 }
 
 void broadway::move_spr(ircolib::u32 instr) {