o cleanup

tools/bsnes/chip/bsx/bsx_flash.cpp

@@ -0,0 +1,113 @@
+#ifdef BSX_CPP
+
+void BSXFlash::init() {}
+void BSXFlash::enable() {}
+
+void BSXFlash::power() {
+  reset();
+}
+
+void BSXFlash::reset() {
+  regs.command   = 0;
+  regs.write_old = 0x00;
+  regs.write_new = 0x00;
+
+  regs.flash_enable = false;
+  regs.read_enable  = false;
+  regs.write_enable = false;
+}
+
+unsigned BSXFlash::size() const {
+  return memory::bscram.size();
+}
+
+uint8 BSXFlash::read(unsigned addr) {
+  if(addr == 0x0002) {
+    if(regs.flash_enable) return 0x80;
+  }
+
+  if(addr == 0x5555) {
+    if(regs.flash_enable) return 0x80;
+  }
+
+  if(regs.read_enable && addr >= 0xff00 && addr <= 0xff13) {
+    //read flash cartridge vendor information
+    switch(addr - 0xff00) {
+      case 0x00: return 0x4d;
+      case 0x01: return 0x00;
+      case 0x02: return 0x50;
+      case 0x03: return 0x00;
+      case 0x04: return 0x00;
+      case 0x05: return 0x00;
+      case 0x06: return 0x2a;  //0x2a = 8mbit, 0x2b = 16mbit (not known to exist, though BIOS recognizes ID)
+      case 0x07: return 0x00;
+      default:   return 0x00;
+    }
+  }
+
+  return memory::bscram.read(addr);
+}
+
+void BSXFlash::write(unsigned addr, uint8 data) {
+  //there exist both read-only and read-write BS-X flash cartridges ...
+  //unfortunately, the vendor info is not stored inside memory dumps
+  //of BS-X flashcarts, so it is impossible to determine whether a
+  //given flashcart is writeable.
+  //however, it has been observed that LoROM-mapped BS-X carts always
+  //use read-write flashcarts, and HiROM-mapped BS-X carts always use
+  //read-only flashcarts.
+  //below is an unfortunately necessary workaround to this problem.
+  if(cartridge.mapper() == Cartridge::BSCHiROM) return;
+
+  if((addr & 0xff0000) == 0) {
+    regs.write_old = regs.write_new;
+    regs.write_new = data;
+
+    if(regs.write_enable && regs.write_old == regs.write_new) {
+      return memory::bscram.write(addr, data);
+    }
+  } else {
+    if(regs.write_enable) {
+      return memory::bscram.write(addr, data);
+    }
+  }
+
+  if(addr == 0x0000) {
+    regs.command <<= 8;
+    regs.command  |= data;
+
+    if((regs.command & 0xffff) == 0x38d0) {
+      regs.flash_enable = true;
+      regs.read_enable  = true;
+    }
+  }
+
+  if(addr == 0x2aaa) {
+    regs.command <<= 8;
+    regs.command  |= data;
+  }
+
+  if(addr == 0x5555) {
+    regs.command <<= 8;
+    regs.command  |= data;
+
+    if((regs.command & 0xffffff) == 0xaa5570) {
+      regs.write_enable = false;
+    }
+
+    if((regs.command & 0xffffff) == 0xaa55a0) {
+      regs.write_old = 0x00;
+      regs.write_new = 0x00;
+      regs.flash_enable = true;
+      regs.write_enable = true;
+    }
+
+    if((regs.command & 0xffffff) == 0xaa55f0) {
+      regs.flash_enable = false;
+      regs.read_enable  = false;
+      regs.write_enable = false;
+    }
+  }
+}
+
+#endif