1 files changed, 43 insertions(+), 28 deletions(-)

M emulator/main.c

@@ 23,8 23,9 @@
 #define THROTTLE_TICKS		40000
 
 /* Determines the bank for MVP/MVN-block I/O access */
-
 #define BLOCK_IO_BANK		0xFD
+#define EMU_IO_BASE			0x00FE00
+#define EMU_IO_LIMIT		0x00FEFF
 
 static uint32_t cpu_inst_count;
 static uint32_t most_recent_insn;


@@ 344,6 345,31 @@ static void io_write(uint32_t addr, uint8_t value)
 	CPU_abort();
 }
 
+static bool
+addressing_emulator_io(uint32_t addr) {
+	return (addr >= EMU_IO_BASE && addr <= EMU_IO_LIMIT);
+}
+
+static bool
+addressing_ram(uint32_t addr) {
+	return addr < sizeof(ram);
+}
+
+static bool
+addressing_z80_io(uint32_t addr) {
+	return (addr >= 0xFF0000 && addr <= 0xFFFFFF);
+}
+
+static bool
+addressing_video_ram(uint32_t addr) {
+	return (addr >> 16) == 0xFE;
+}
+
+static bool
+addressing_block_io_bank(uint32_t addr) {
+	return (addr >> 16) == BLOCK_IO_BANK;
+}
+
 uint8_t MEM_readMem(uint32_t addr, uint32_t unused_timestamp, uint32_t emul_flags)
 {
 	addr &= 0xFFFFFF;	// bug in lib65816; sometimes $FF000000 <= addr <= $FFFFFFFF!  Why?


@@ 353,13 379,9 @@ uint8_t MEM_readMem(uint32_t addr, uint32_t unused_timestamp, uint32_t emul_flag
 		cpu_inst_count++;
 	}
 
-	if ((addr >> 16) == BLOCK_IO_BANK)
-		addr = 0xFE00 + dma;
-
-	if ((addr >> 16) == 0xFE)
-		return video_read_ram(addr);
-
-	if(addr >= 0xFF0000 && addr <= 0xFFFFFF) { // Z80 I/O space
+	if(addressing_block_io_bank(addr)) addr = EMU_IO_BASE + dma;
+	if(addressing_video_ram(addr)) return video_read_ram(addr);
+	if(addressing_z80_io(addr)) {
 		int ioaddr = addr & 0xFF;
 		switch(ioaddr) {
 		case 0: case 1:


@@ 369,32 391,27 @@ uint8_t MEM_readMem(uint32_t addr, uint32_t unused_timestamp, uint32_t emul_flag
 			return 0xFF;
 		}
 	}
-
-	if (addr >= 0xFE00 && addr < 0xFF00) {
+	if(addressing_emulator_io(addr)) {
 		/* Don't cause I/O when using debug trace read */
 		if (g_debug)
 			return 0xFF;
 		else
 			return io_read(addr);
-	} else if (addr < sizeof(ram))
-		return ram[addr];
-	else {
-		if (!g_debug) {
-			fprintf(stderr, "Invalid mem read %x (at K:PC $%06lX)\n", addr, most_recent_insn);
-		}
-		CPU_abort();
-		return 0xFF;
 	}
+	if(addressing_ram(addr)) return ram[addr];
+
+	if (!g_debug) {
+		fprintf(stderr, "Invalid mem read %x (at K:PC $%06lX)\n", addr, most_recent_insn);
+	}
+	CPU_abort();
+	return 0xFF;
 }
 
 void MEM_writeMem(uint32_t addr, uint8_t value, uint32_t unused_timestamp)
 {
-	if ((addr >> 16) == BLOCK_IO_BANK)
-		addr = 0xFE00 + dma;
-
-	if ((addr >> 16) == 0xFE)
-		video_write_ram(addr, value);
-	else if (addr >= 0xFF0000 && addr <= 0xFFFFFF) { // Z80 I/O space
+	if(addressing_block_io_bank(addr)) addr = EMU_IO_BASE + dma;
+	else if(addressing_video_ram(addr)) video_write_ram(addr, value);
+	else if(addressing_z80_io(addr)) {
 		int ioaddr = addr & 0xFF;
 		switch(ioaddr) {
 		case 0: case 1:


@@ 406,10 423,8 @@ void MEM_writeMem(uint32_t addr, uint8_t value, uint32_t unused_timestamp)
 			break;
 		}
 	}
-	else if (addr >= 0xFE00 && addr < 0xFF00)
-		io_write(addr, value);
-	else if (addr < sizeof(ram))
-		ram[addr] = value;
+	else if(addressing_emulator_io(addr)) io_write(addr, value);
+	else if(addressing_ram(addr)) ram[addr] = value;
 	else {
 	  fprintf(stderr, "Invalid mem write %X := %02X (at K:PC $%06lX)\n", addr, value, most_recent_insn);
 		CPU_abort();