WIP split of ROM loading/argument parsing from Genesis emulation code. Compiles and doesn't crash, but nothing works. Still a few too many globals as well.

1 files changed, 32 insertions, 953 deletions

diff --git a/blastem.c b/blastem.c
index 7a75123..5e3ac59 100644
--- a/blastem.c
+++ b/blastem.c
@@ -14,42 +14,23 @@
 #include "mem.h"
 #include "vdp.h"
 #include "render.h"
-#include "blastem.h"
+#include "genesis.h"
 #include "gdb_remote.h"
 #include "gst.h"
 #include "util.h"
 #include "romdb.h"
 #include "terminal.h"
 #include "arena.h"
+#include "config.h"
 
 #define BLASTEM_VERSION "0.4.1"
 
-#define MCLKS_NTSC 53693175
-#define MCLKS_PAL  53203395
-
-uint32_t MCLKS_PER_68K;
-#define MCLKS_PER_YM  7
-#define MCLKS_PER_Z80 15
-#define MCLKS_PER_PSG (MCLKS_PER_Z80*16)
-#define DEFAULT_SYNC_INTERVAL MCLKS_LINE
-#define DEFAULT_LOWPASS_CUTOFF 3390
-
-//TODO: Figure out the exact value for this
-#define LINES_NTSC 262
-#define LINES_PAL 312
-
-#define MAX_SOUND_CYCLES 100000
-
 #ifdef __ANDROID__
 #define FULLSCREEN_DEFAULT 1
 #else
 #define FULLSCREEN_DEFAULT 0
 #endif
 
-uint16_t *cart;
-uint16_t *ram;
-uint8_t z80_ram[Z80_RAM_BYTES];
-
 int headless = 0;
 int exit_after = 0;
 int z80_enabled = 1;
@@ -67,13 +48,13 @@ tern_node * config;
 #define SMD_MAGIC3 0xBB
 #define SMD_BLOCK_SIZE 0x4000
 
-int load_smd_rom(long filesize, FILE * f)
+int load_smd_rom(long filesize, FILE * f, uint16_t **buffer)
 {
 	uint8_t block[SMD_BLOCK_SIZE];
 	filesize -= SMD_HEADER_SIZE;
 	fseek(f, SMD_HEADER_SIZE, SEEK_SET);
 
-	uint16_t * dst = cart = malloc(nearest_pow2(filesize));
+	uint16_t *dst = *buffer = malloc(nearest_pow2(filesize));
 	int rom_size = filesize;
 	while (filesize > 0) {
 		fread(block, 1, SMD_BLOCK_SIZE, f);
@@ -85,15 +66,7 @@ int load_smd_rom(long filesize, FILE * f)
 	return rom_size;
 }
 
-void byteswap_rom(int filesize)
-{
-	for(unsigned short * cur = cart; cur - cart < filesize/2; ++cur)
-	{
-		*cur = (*cur >> 8) | (*cur << 8);
-	}
-}
-
-int load_rom(char * filename)
+int load_rom(char * filename, uint16_t **dst)
 {
 	uint8_t header[10];
 	FILE * f = fopen(filename, "rb");
@@ -117,742 +90,25 @@ int load_rom(char * filename)
 			if (header[2]) {
 				fatal_error("%s is a split SMD ROM which is not currently supported", filename);
 			}
-			return load_smd_rom(filesize, f);
+			return load_smd_rom(filesize, f, dst);
 		}
 	}
-	cart = malloc(nearest_pow2(filesize));
-	if (filesize != fread(cart, 1, filesize, f)) {
+	*dst = malloc(nearest_pow2(filesize));
+	if (filesize != fread(*dst, 1, filesize, f)) {
 		fatal_error("Error reading from %s\n", filename);
 	}
 	fclose(f);
 	return filesize;
 }
 
-uint16_t read_dma_value(uint32_t address)
-{
-	//addresses here are word addresses (i.e. bit 0 corresponds to A1), so no need to do multiply by 2
-	uint16_t *ptr = get_native_pointer(address*2, (void **)genesis->m68k->mem_pointers, &genesis->m68k->options->gen);
-	if (ptr) {
-		return *ptr;
-	}
-	//TODO: Figure out what happens when you try to DMA from weird adresses like IO or banked Z80 area
-	return 0;
-}
 
-uint16_t get_open_bus_value()
-{
-	return read_dma_value(genesis->m68k->last_prefetch_address/2);
-}
-
-void adjust_int_cycle(m68k_context * context, vdp_context * v_context)
-{
-	//static int old_int_cycle = CYCLE_NEVER;
-	genesis_context *gen = context->system;
-	if (context->sync_cycle - context->current_cycle > gen->max_cycles) {
-		context->sync_cycle = context->current_cycle + gen->max_cycles;
-	}
-	context->int_cycle = CYCLE_NEVER;
-	if ((context->status & 0x7) < 6) {
-		uint32_t next_vint = vdp_next_vint(v_context);
-		if (next_vint != CYCLE_NEVER) {
-			context->int_cycle = next_vint;
-			context->int_num = 6;
-		}
-		if ((context->status & 0x7) < 4) {
-			uint32_t next_hint = vdp_next_hint(v_context);
-			if (next_hint != CYCLE_NEVER) {
-				next_hint = next_hint < context->current_cycle ? context->current_cycle : next_hint;
-				if (next_hint < context->int_cycle) {
-					context->int_cycle = next_hint;
-					context->int_num = 4;
-
-				}
-			}
-		}
-	}
-	if (context->int_cycle > context->current_cycle && context->int_pending == INT_PENDING_SR_CHANGE) {
-		context->int_pending = INT_PENDING_NONE;
-	}
-	/*if (context->int_cycle != old_int_cycle) {
-		printf("int cycle changed to: %d, level: %d @ %d(%d), frame: %d, vcounter: %d, hslot: %d, mask: %d, hint_counter: %d\n", context->int_cycle, context->int_num, v_context->cycles, context->current_cycle, v_context->frame, v_context->vcounter, v_context->hslot, context->status & 0x7, v_context->hint_counter);
-		old_int_cycle = context->int_cycle;
-	}*/
-
-	context->target_cycle = context->int_cycle < context->sync_cycle ? context->int_cycle : context->sync_cycle;
-	if (context->should_return) {
-		context->target_cycle = context->current_cycle;
-	} else if (context->target_cycle < context->current_cycle) {
-		//Changes to SR can result in an interrupt cycle that's in the past
-		//This can cause issues with the implementation of STOP though
-		context->target_cycle = context->current_cycle;
-	}
-	/*printf("Cyc: %d, Trgt: %d, Int Cyc: %d, Int: %d, Mask: %X, V: %d, H: %d, HICount: %d, HReg: %d, Line: %d\n",
-		context->current_cycle, context->target_cycle, context->int_cycle, context->int_num, (context->status & 0x7),
-		v_context->regs[REG_MODE_2] & 0x20, v_context->regs[REG_MODE_1] & 0x10, v_context->hint_counter, v_context->regs[REG_HINT], v_context->cycles / MCLKS_LINE);*/
-}
 
 int break_on_sync = 0;
 char *save_state_path;
 
-//#define DO_DEBUG_PRINT
-#ifdef DO_DEBUG_PRINT
-#define dprintf printf
-#define dputs puts
-#else
-#define dprintf
-#define dputs
-#endif
-
-#define Z80_VINT_DURATION 128
-
-void z80_next_int_pulse(z80_context * z_context)
-{
-		genesis_context * gen = z_context->system;
-	z_context->int_pulse_start = vdp_next_vint_z80(gen->vdp);
-	z_context->int_pulse_end = z_context->int_pulse_start + Z80_VINT_DURATION * MCLKS_PER_Z80;
-			}
-
-void sync_z80(z80_context * z_context, uint32_t mclks)
-{
-#ifndef NO_Z80
-	if (z80_enabled) {
-		z80_run(z_context, mclks);
-	} else
-#endif
-	{
-		z_context->current_cycle = mclks;
-	}
-}
-
-void sync_sound(genesis_context * gen, uint32_t target)
-{
-	//printf("YM | Cycle: %d, bpos: %d, PSG | Cycle: %d, bpos: %d\n", gen->ym->current_cycle, gen->ym->buffer_pos, gen->psg->cycles, gen->psg->buffer_pos * 2);
-	while (target > gen->psg->cycles && target - gen->psg->cycles > MAX_SOUND_CYCLES) {
-		uint32_t cur_target = gen->psg->cycles + MAX_SOUND_CYCLES;
-		//printf("Running PSG to cycle %d\n", cur_target);
-		psg_run(gen->psg, cur_target);
-		//printf("Running YM-2612 to cycle %d\n", cur_target);
-		ym_run(gen->ym, cur_target);
-	}
-	psg_run(gen->psg, target);
-	ym_run(gen->ym, target);
-
-	//printf("Target: %d, YM bufferpos: %d, PSG bufferpos: %d\n", target, gen->ym->buffer_pos, gen->psg->buffer_pos * 2);
-}
-
-uint32_t last_frame_num;
-
-//My refresh emulation isn't currently good enough and causes more problems than it solves
-#ifdef REFRESH_EMULATION
-#define REFRESH_INTERVAL 128
-#define REFRESH_DELAY 2
-uint32_t last_sync_cycle;
-uint32_t refresh_counter;
-#endif
-
-m68k_context * sync_components(m68k_context * context, uint32_t address)
-{
-	genesis_context * gen = context->system;
-	vdp_context * v_context = gen->vdp;
-	z80_context * z_context = gen->z80;
-#ifdef REFRESH_EMULATION
-	//lame estimation of refresh cycle delay
-	if (!gen->bus_busy) {
-		refresh_counter += context->current_cycle - last_sync_cycle;
-		context->current_cycle += REFRESH_DELAY * MCLKS_PER_68K * (refresh_counter / (MCLKS_PER_68K * REFRESH_INTERVAL));
-		refresh_counter = refresh_counter % (MCLKS_PER_68K * REFRESH_INTERVAL);
-	}
-#endif
-
-	uint32_t mclks = context->current_cycle;
-	sync_z80(z_context, mclks);
-	sync_sound(gen, mclks);
-	vdp_run_context(v_context, mclks);
-	if (v_context->frame != last_frame_num) {
-		//printf("reached frame end %d | MCLK Cycles: %d, Target: %d, VDP cycles: %d, vcounter: %d, hslot: %d\n", last_frame_num, mclks, gen->frame_end, v_context->cycles, v_context->vcounter, v_context->hslot);
-		last_frame_num = v_context->frame;
-
-		if(exit_after){
-			--exit_after;
-			if (!exit_after) {
-				exit(0);
-			}
-		}
-
-		vdp_adjust_cycles(v_context, mclks);
-		io_adjust_cycles(gen->ports, context->current_cycle, mclks);
-		io_adjust_cycles(gen->ports+1, context->current_cycle, mclks);
-		io_adjust_cycles(gen->ports+2, context->current_cycle, mclks);
-		context->current_cycle -= mclks;
-		z80_adjust_cycles(z_context, mclks);
-		gen->ym->current_cycle -= mclks;
-		gen->psg->cycles -= mclks;
-		if (gen->ym->write_cycle != CYCLE_NEVER) {
-			gen->ym->write_cycle = gen->ym->write_cycle >= mclks ? gen->ym->write_cycle - mclks : 0;
-		}
-	}
-	gen->frame_end = vdp_cycles_to_frame_end(v_context);
-	context->sync_cycle = gen->frame_end;
-	//printf("Set sync cycle to: %d @ %d, vcounter: %d, hslot: %d\n", context->sync_cycle, context->current_cycle, v_context->vcounter, v_context->hslot);
-	if (context->int_ack) {
-		//printf("acknowledging %d @ %d:%d, vcounter: %d, hslot: %d\n", context->int_ack, context->current_cycle, v_context->cycles, v_context->vcounter, v_context->hslot);
-		vdp_int_ack(v_context);
-		context->int_ack = 0;
-	}
-	if (!address && (break_on_sync || gen->save_state)) {
-		context->sync_cycle = context->current_cycle + 1;
-	}
-	adjust_int_cycle(context, v_context);
-	if (address) {
-		if (break_on_sync) {
-			break_on_sync = 0;
-			debugger(context, address);
-		}
-		if (gen->save_state && (z_context->pc || (!z_context->reset && !z_context->busreq))) {
-			uint8_t slot = gen->save_state - 1;
-			gen->save_state = 0;
-			//advance Z80 core to the start of an instruction
-			while (!z_context->pc)
-			{
-				sync_z80(z_context, z_context->current_cycle + MCLKS_PER_Z80);
-			}
-			char *save_path;
-			if (slot == QUICK_SAVE_SLOT) {
-				save_path = save_state_path;
-			} else {
-				char slotname[] = "slot_0.gst";
-				slotname[5] = '0' + slot;
-				char const *parts[] = {gen->save_dir, PATH_SEP, slotname};
-				save_path = alloc_concat_m(3, parts);
-			}
-			save_gst(gen, save_path, address);
-			printf("Saved state to %s\n", save_path);
-			if (slot != QUICK_SAVE_SLOT) {
-				free(save_path);
-			}
-		} else if(gen->save_state) {
-			context->sync_cycle = context->current_cycle + 1;
-		}
-	}
-#ifdef REFRESH_EMULATION
-	last_sync_cycle = context->current_cycle;
-#endif
-	return context;
-}
-
-m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_t value)
-{
-	if (vdp_port & 0x2700E0) {
-		fatal_error("machine freeze due to write to address %X\n", 0xC00000 | vdp_port);
-	}
-	vdp_port &= 0x1F;
-	//printf("vdp_port write: %X, value: %X, cycle: %d\n", vdp_port, value, context->current_cycle);
-	sync_components(context, 0);
-	genesis_context * gen = context->system;
-	vdp_context *v_context = gen->vdp;
-	if (vdp_port < 0x10) {
-		int blocked;
-		uint32_t before_cycle = v_context->cycles;
-		if (vdp_port < 4) {
-
-			while (vdp_data_port_write(v_context, value) < 0) {
-				while(v_context->flags & FLAG_DMA_RUN) {
-					vdp_run_dma_done(v_context, gen->frame_end);
-					if (v_context->cycles >= gen->frame_end) {
-						uint32_t cycle_diff = v_context->cycles - context->current_cycle;
-						uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K;
-						if (m68k_cycle_diff < cycle_diff) {
-							m68k_cycle_diff += MCLKS_PER_68K;
-						}
-						context->current_cycle += m68k_cycle_diff;
-						gen->bus_busy = 1;
-						sync_components(context, 0);
-						gen->bus_busy = 0;
-					}
-				}
-				//context->current_cycle = v_context->cycles;
-			}
-		} else if(vdp_port < 8) {
-			blocked = vdp_control_port_write(v_context, value);
-			if (blocked) {
-				while (blocked) {
-					while(v_context->flags & FLAG_DMA_RUN) {
-						vdp_run_dma_done(v_context, gen->frame_end);
-						if (v_context->cycles >= gen->frame_end) {
-							uint32_t cycle_diff = v_context->cycles - context->current_cycle;
-							uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K;
-							if (m68k_cycle_diff < cycle_diff) {
-								m68k_cycle_diff += MCLKS_PER_68K;
-							}
-							context->current_cycle += m68k_cycle_diff;
-							gen->bus_busy = 1;
-							sync_components(context, 0);
-							gen->bus_busy = 0;
-						}
-						if (!(v_context->flags & FLAG_DMA_RUN)) {
-							//two more slots of delay are needed to kill sufficient sprite capacity in Overdrive
-							//TODO: Measure exact value with logic analyzer
-							vdp_run_context(v_context, v_context->cycles + 1);
-							vdp_run_context(v_context, v_context->cycles + 1);
-						}
-					}
-					
-					if (blocked < 0) {
-						blocked = vdp_control_port_write(v_context, value);
-					} else {
-						blocked = 0;
-					}
-				}
-			} else {
-				context->sync_cycle = gen->frame_end = vdp_cycles_to_frame_end(v_context);
-				//printf("Set sync cycle to: %d @ %d, vcounter: %d, hslot: %d\n", context->sync_cycle, context->current_cycle, v_context->vcounter, v_context->hslot);
-				adjust_int_cycle(context, v_context);
-			}
-		} else {
-			fatal_error("Illegal write to HV Counter port %X\n", vdp_port);
-		}
-		if (v_context->cycles != before_cycle) {
-			//printf("68K paused for %d (%d) cycles at cycle %d (%d) for write\n", v_context->cycles - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
-			uint32_t cycle_diff = v_context->cycles - context->current_cycle;
-			uint32_t m68k_cycle_diff = (cycle_diff / MCLKS_PER_68K) * MCLKS_PER_68K;
-			if (m68k_cycle_diff < cycle_diff) {
-				m68k_cycle_diff += MCLKS_PER_68K;
-			}
-			context->current_cycle += m68k_cycle_diff;
-#ifdef REFRESH_EMULATION
-			last_sync_cycle = context->current_cycle;
-#endif
-			//Lock the Z80 out of the bus until the VDP access is complete
-			gen->bus_busy = 1;
-			sync_z80(gen->z80, v_context->cycles);
-			gen->bus_busy = 0;
-		}
-	} else if (vdp_port < 0x18) {
-		psg_write(gen->psg, value);
-	} else {
-		//TODO: Implement undocumented test register(s)
-	}
-	return context;
-}
-
-m68k_context * vdp_port_write_b(uint32_t vdp_port, m68k_context * context, uint8_t value)
-{
-	return vdp_port_write(vdp_port, context, vdp_port < 0x10 ? value | value << 8 : ((vdp_port & 1) ? value : 0));
-}
-
-void * z80_vdp_port_write(uint32_t vdp_port, void * vcontext, uint8_t value)
-{
-	z80_context * context = vcontext;
-	genesis_context * gen = context->system;
-	vdp_port &= 0xFF;
-	if (vdp_port & 0xE0) {
-		fatal_error("machine freeze due to write to Z80 address %X\n", 0x7F00 | vdp_port);
-	}
-	if (vdp_port < 0x10) {
-		//These probably won't currently interact well with the 68K accessing the VDP
-		vdp_run_context(gen->vdp, context->current_cycle);
-		if (vdp_port < 4) {
-			vdp_data_port_write(gen->vdp, value << 8 | value);
-		} else if (vdp_port < 8) {
-			vdp_control_port_write(gen->vdp, value << 8 | value);
-		} else {
-			fatal_error("Illegal write to HV Counter port %X\n", vdp_port);
-		}
-	} else if (vdp_port < 0x18) {
-		sync_sound(gen, context->current_cycle);
-		psg_write(gen->psg, value);
-	} else {
-		vdp_test_port_write(gen->vdp, value);
-	}
-	return context;
-}
-
-uint16_t vdp_port_read(uint32_t vdp_port, m68k_context * context)
-{
-	if (vdp_port & 0x2700E0) {
-		fatal_error("machine freeze due to read from address %X\n", 0xC00000 | vdp_port);
-	}
-	vdp_port &= 0x1F;
-	uint16_t value;
-	sync_components(context, 0);
-	genesis_context *gen = context->system;
-	vdp_context * v_context = gen->vdp;
-	uint32_t before_cycle = v_context->cycles;
-	if (vdp_port < 0x10) {
-		if (vdp_port < 4) {
-			value = vdp_data_port_read(v_context);
-		} else if(vdp_port < 8) {
-			value = vdp_control_port_read(v_context);
-		} else {
-			value = vdp_hv_counter_read(v_context);
-			//printf("HV Counter: %X at cycle %d\n", value, v_context->cycles);
-		}
-	} else if (vdp_port < 0x18){
-		fatal_error("Illegal read from PSG  port %X\n", vdp_port);
-	} else {
-		value = vdp_test_port_read(v_context);
-	}
-	if (v_context->cycles != before_cycle) {
-		//printf("68K paused for %d (%d) cycles at cycle %d (%d) for read\n", v_context->cycles - context->current_cycle, v_context->cycles - before_cycle, context->current_cycle, before_cycle);
-		context->current_cycle = v_context->cycles;
-#ifdef REFRES_EMULATION
-		last_sync_cycle = context->current_cycle;
-#endif
-		//Lock the Z80 out of the bus until the VDP access is complete
-		genesis_context *gen = context->system;
-		gen->bus_busy = 1;
-		sync_z80(gen->z80, v_context->cycles);
-		gen->bus_busy = 0;
-	}
-	return value;
-}
-
-uint8_t vdp_port_read_b(uint32_t vdp_port, m68k_context * context)
-{
-	uint16_t value = vdp_port_read(vdp_port, context);
-	if (vdp_port & 1) {
-		return value;
-	} else {
-		return value >> 8;
-	}
-}
-
-uint8_t z80_vdp_port_read(uint32_t vdp_port, void * vcontext)
-{
-	z80_context * context = vcontext;
-	if (vdp_port & 0xE0) {
-		fatal_error("machine freeze due to read from Z80 address %X\n", 0x7F00 | vdp_port);
-	}
-	genesis_context * gen = context->system;
-	//VDP access goes over the 68K bus like a bank area access
-	//typical delay from bus arbitration
-	context->current_cycle += 3 * MCLKS_PER_Z80;
-	//TODO: add cycle for an access right after a previous one
-	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
-	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
-	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
-
-
-	vdp_port &= 0x1F;
-	uint16_t ret;
-	if (vdp_port < 0x10) {
-		//These probably won't currently interact well with the 68K accessing the VDP
-		vdp_run_context(gen->vdp, context->current_cycle);
-		if (vdp_port < 4) {
-			ret = vdp_data_port_read(gen->vdp);
-		} else if (vdp_port < 8) {
-			ret = vdp_control_port_read(gen->vdp);
-		} else {
-			fatal_error("Illegal write to HV Counter port %X\n", vdp_port);
-		}
-	} else {
-		//TODO: Figure out the correct value today
-		ret = 0xFFFF;
-	}
-	return vdp_port & 1 ? ret : ret >> 8;
-}
-
-uint32_t zram_counter = 0;
-
-m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value)
-{
-	genesis_context * gen = context->system;
-	if (location < 0x10000) {
-		//Access to Z80 memory incurs a one 68K cycle wait state
-		context->current_cycle += MCLKS_PER_68K;
-		if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) {
-			location &= 0x7FFF;
-			if (location < 0x4000) {
-				z80_ram[location & 0x1FFF] = value;
-#ifndef NO_Z80
-				z80_handle_code_write(location & 0x1FFF, gen->z80);
-#endif
-			} else if (location < 0x6000) {
-				sync_sound(gen, context->current_cycle);
-				if (location & 1) {
-					ym_data_write(gen->ym, value);
-				} else if(location & 2) {
-					ym_address_write_part2(gen->ym, value);
-				} else {
-					ym_address_write_part1(gen->ym, value);
-				}
-			} else if (location == 0x6000) {
-				gen->z80->bank_reg = (gen->z80->bank_reg >> 1 | value << 8) & 0x1FF;
-				if (gen->z80->bank_reg < 0x80) {
-					gen->z80->mem_pointers[1] = (gen->z80->bank_reg << 15) + ((char *)gen->z80->mem_pointers[2]);
-				} else {
-					gen->z80->mem_pointers[1] = NULL;
-				}
-			} else {
-				fatal_error("68K write to unhandled Z80 address %X\n", location);
-			}
-		}
-	} else {
-		location &= 0x1FFF;
-		if (location < 0x100) {
-			switch(location/2)
-			{
-			case 0x1:
-				io_data_write(gen->ports, value, context->current_cycle);
-				break;
-			case 0x2:
-				io_data_write(gen->ports+1, value, context->current_cycle);
-				break;
-			case 0x3:
-				io_data_write(gen->ports+2, value, context->current_cycle);
-				break;
-			case 0x4:
-				gen->ports[0].control = value;
-				break;
-			case 0x5:
-				gen->ports[1].control = value;
-				break;
-			case 0x6:
-				gen->ports[2].control = value;
-				break;
-			}
-		} else {
-			if (location == 0x1100) {
-				if (value & 1) {
-					dputs("bus requesting Z80");
-					if (z80_enabled) {
-						z80_assert_busreq(gen->z80, context->current_cycle);
-					} else {
-						gen->z80->busack = 1;
-					}
-				} else {
-					if (gen->z80->busreq) {
-						dputs("releasing z80 bus");
-						#ifdef DO_DEBUG_PRINT
-						char fname[20];
-						sprintf(fname, "zram-%d", zram_counter++);
-						FILE * f = fopen(fname, "wb");
-						fwrite(z80_ram, 1, sizeof(z80_ram), f);
-						fclose(f);
-						#endif
-					}
-					if (z80_enabled) {
-						z80_clear_busreq(gen->z80, context->current_cycle);
-					} else {
-						gen->z80->busack = 0;
-					}
-				}
-			} else if (location == 0x1200) {
-				sync_z80(gen->z80, context->current_cycle);
-				if (value & 1) {
-					if (z80_enabled) {
-						z80_clear_reset(gen->z80, context->current_cycle);
-					} else {
-						gen->z80->reset = 0;
-					}
-				} else {
-					if (z80_enabled) {
-						z80_assert_reset(gen->z80, context->current_cycle);
-					} else {
-						gen->z80->reset = 1;
-					}
-				}
-			}
-		}
-	}
-	return context;
-}
-
-m68k_context * io_write_w(uint32_t location, m68k_context * context, uint16_t value)
-{
-	if (location < 0x10000 || (location & 0x1FFF) >= 0x100) {
-		return io_write(location, context, value >> 8);
-	} else {
-		return io_write(location, context, value);
-	}
-}
-
-#define USA 0x80
-#define JAP 0x00
-#define EUR 0xC0
-#define NO_DISK 0x20
-uint8_t version_reg = NO_DISK | USA;
-
-uint8_t io_read(uint32_t location, m68k_context * context)
-{
-	uint8_t value;
-	genesis_context *gen = context->system;
-	if (location < 0x10000) {
-		//Access to Z80 memory incurs a one 68K cycle wait state
-		context->current_cycle += MCLKS_PER_68K;
-		if (!z80_enabled || z80_get_busack(gen->z80, context->current_cycle)) {
-			location &= 0x7FFF;
-			if (location < 0x4000) {
-				value = z80_ram[location & 0x1FFF];
-			} else if (location < 0x6000) {
-				sync_sound(gen, context->current_cycle);
-				value = ym_read_status(gen->ym);
-			} else {
-				value = 0xFF;
-			}
-		} else {
-			value = 0xFF;
-		}
-	} else {
-		location &= 0x1FFF;
-		if (location < 0x100) {
-			switch(location/2)
-			{
-			case 0x0:
-				//version bits should be 0 for now since we're not emulating TMSS
-				value = version_reg;
-				break;
-			case 0x1:
-				value = io_data_read(gen->ports, context->current_cycle);
-				break;
-			case 0x2:
-				value = io_data_read(gen->ports+1, context->current_cycle);
-				break;
-			case 0x3:
-				value = io_data_read(gen->ports+2, context->current_cycle);
-				break;
-			case 0x4:
-				value = gen->ports[0].control;
-				break;
-			case 0x5:
-				value = gen->ports[1].control;
-				break;
-			case 0x6:
-				value = gen->ports[2].control;
-				break;
-			default:
-				value = 0xFF;
-			}
-		} else {
-			if (location == 0x1100) {
-				value = z80_enabled ? !z80_get_busack(gen->z80, context->current_cycle) : !gen->z80->busack;
-				value |= (get_open_bus_value() >> 8) & 0xFE;
-				dprintf("Byte read of BUSREQ returned %d @ %d (reset: %d)\n", value, context->current_cycle, gen->z80->reset);
-			} else if (location == 0x1200) {
-				value = !gen->z80->reset;
-			} else {
-				value = 0xFF;
-				printf("Byte read of unknown IO location: %X\n", location);
-			}
-		}
-	}
-	return value;
-}
-
-uint16_t io_read_w(uint32_t location, m68k_context * context)
-{
-	uint16_t value = io_read(location, context);
-	if (location < 0x10000 || (location & 0x1FFF) < 0x100) {
-		value = value | (value << 8);
-	} else {
-		value <<= 8;
-		value |= get_open_bus_value() & 0xFF;
-	}
-	return value;
-}
-
-void * z80_write_ym(uint32_t location, void * vcontext, uint8_t value)
-{
-	z80_context * context = vcontext;
-	genesis_context * gen = context->system;
-	sync_sound(gen, context->current_cycle);
-	if (location & 1) {
-		ym_data_write(gen->ym, value);
-	} else if (location & 2) {
-		ym_address_write_part2(gen->ym, value);
-	} else {
-		ym_address_write_part1(gen->ym, value);
-	}
-	return context;
-}
-
-uint8_t z80_read_ym(uint32_t location, void * vcontext)
-{
-	z80_context * context = vcontext;
-	genesis_context * gen = context->system;
-	sync_sound(gen, context->current_cycle);
-	return ym_read_status(gen->ym);
-}
-
-uint8_t z80_read_bank(uint32_t location, void * vcontext)
-{
-	z80_context * context = vcontext;
-	genesis_context *gen = context->system;
-	if (gen->bus_busy) {
-		context->current_cycle = context->sync_cycle;
-	}
-	//typical delay from bus arbitration
-	context->current_cycle += 3 * MCLKS_PER_Z80;
-	//TODO: add cycle for an access right after a previous one
-	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
-	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
-	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
-
-	location &= 0x7FFF;
-	if (context->mem_pointers[1]) {
-		return context->mem_pointers[1][location ^ 1];
-	}
-	uint32_t address = context->bank_reg << 15 | location;
-	if (address >= 0xC00000 && address < 0xE00000) {
-		return z80_vdp_port_read(location & 0xFF, context);
-	} else {
-		fprintf(stderr, "Unhandled read by Z80 from address %X through banked memory area (%X)\n", address, context->bank_reg << 15);
-	}
-	return 0;
-}
-
-void *z80_write_bank(uint32_t location, void * vcontext, uint8_t value)
-{
-	z80_context * context = vcontext;
-	genesis_context *gen = context->system;
-	if (gen->bus_busy) {
-		context->current_cycle = context->sync_cycle;
-	}
-	//typical delay from bus arbitration
-	context->current_cycle += 3 * MCLKS_PER_Z80;
-	//TODO: add cycle for an access right after a previous one
-	//TODO: Below cycle time is an estimate based on the time between 68K !BG goes low and Z80 !MREQ goes high
-	//      Needs a new logic analyzer capture to get the actual delay on the 68K side
-	gen->m68k->current_cycle += 8 * MCLKS_PER_68K;
-
-	location &= 0x7FFF;
-	uint32_t address = context->bank_reg << 15 | location;
-	if (address >= 0xE00000) {
-		address &= 0xFFFF;
-		((uint8_t *)ram)[address ^ 1] = value;
-	} else if (address >= 0xC00000) {
-		z80_vdp_port_write(location & 0xFF, context, value);
-	} else {
-		fprintf(stderr, "Unhandled write by Z80 to address %X through banked memory area\n", address);
-	}
-	return context;
-}
-
-void *z80_write_bank_reg(uint32_t location, void * vcontext, uint8_t value)
-{
-	z80_context * context = vcontext;
 
-	context->bank_reg = (context->bank_reg >> 1 | value << 8) & 0x1FF;
-	if (context->bank_reg < 0x100) {
-		genesis_context *gen = context->system;
-		context->mem_pointers[1] = get_native_pointer(context->bank_reg << 15, (void **)gen->m68k->mem_pointers, &gen->m68k->options->gen);
-	} else {
-		context->mem_pointers[1] = NULL;
-	}
 
-	return context;
-}
 
-void set_speed_percent(genesis_context * context, uint32_t percent)
-{
-	uint32_t old_clock = context->master_clock;
-	context->master_clock = ((uint64_t)context->normal_clock * (uint64_t)percent) / 100;
-	while (context->ym->current_cycle != context->psg->cycles) {
-		sync_sound(context, context->psg->cycles + MCLKS_PER_PSG);
-}
-	ym_adjust_master_clock(context->ym, context->master_clock);
-	psg_adjust_master_clock(context->psg, context->master_clock);
-}
 
 char * save_filename;
 genesis_context *genesis;
@@ -873,124 +129,9 @@ void persist_save()
 	printf("Saved %s to %s\n", game_context->save_type == SAVE_I2C ? "EEPROM" : "SRAM", save_filename);
 }
 
-#ifndef NO_Z80
-const memmap_chunk z80_map[] = {
-	{ 0x0000, 0x4000,  0x1FFF, 0, 0, MMAP_READ | MMAP_WRITE | MMAP_CODE, z80_ram, NULL, NULL, NULL,              NULL },
-	{ 0x8000, 0x10000, 0x7FFF, 0, 0, 0,                                  NULL,    NULL, NULL, z80_read_bank,     z80_write_bank},
-	{ 0x4000, 0x6000,  0x0003, 0, 0, 0,                                  NULL,    NULL, NULL, z80_read_ym,       z80_write_ym},
-	{ 0x6000, 0x6100,  0xFFFF, 0, 0, 0,                                  NULL,    NULL, NULL, NULL,              z80_write_bank_reg},
-	{ 0x7F00, 0x8000,  0x00FF, 0, 0, 0,                                  NULL,    NULL, NULL, z80_vdp_port_read, z80_vdp_port_write}
-};
-#endif
-
-genesis_context *alloc_init_genesis(rom_info *rom, int fps, uint32_t ym_opts)
-{
-	genesis_context *gen = calloc(1, sizeof(genesis_context));
-	gen->master_clock = gen->normal_clock = fps == 60 ? MCLKS_NTSC : MCLKS_PAL;
-
-	gen->vdp = malloc(sizeof(vdp_context));
-	init_vdp_context(gen->vdp, version_reg & 0x40);
-	gen->frame_end = vdp_cycles_to_frame_end(gen->vdp);
-	char * config_cycles = tern_find_path(config, "clocks\0max_cycles\0").ptrval;
-	gen->max_cycles = config_cycles ? atoi(config_cycles) : DEFAULT_SYNC_INTERVAL;
-
-	char * lowpass_cutoff_str = tern_find_path(config, "audio\0lowpass_cutoff\0").ptrval;
-	uint32_t lowpass_cutoff = lowpass_cutoff_str ? atoi(lowpass_cutoff_str) : DEFAULT_LOWPASS_CUTOFF;
-	
-	gen->ym = malloc(sizeof(ym2612_context));
-	ym_init(gen->ym, render_sample_rate(), gen->master_clock, MCLKS_PER_YM, render_audio_buffer(), ym_opts, lowpass_cutoff);
 
-	gen->psg = malloc(sizeof(psg_context));
-	psg_init(gen->psg, render_sample_rate(), gen->master_clock, MCLKS_PER_PSG, render_audio_buffer(), lowpass_cutoff);
-
-	gen->z80 = calloc(1, sizeof(z80_context));
-#ifndef NO_Z80
-	z80_options *z_opts = malloc(sizeof(z80_options));
-	init_z80_opts(z_opts, z80_map, 5, NULL, 0, MCLKS_PER_Z80);
-	init_z80_context(gen->z80, z_opts);
-	z80_assert_reset(gen->z80, 0);
-#endif
-
-	gen->z80->system = gen;
-	gen->z80->mem_pointers[0] = z80_ram;
-	gen->z80->mem_pointers[1] = gen->z80->mem_pointers[2] = (uint8_t *)cart;
-
-	gen->cart = cart;
-	gen->work_ram = ram;
-	gen->zram = z80_ram;
-	setup_io_devices(config, rom, gen);
-
-	gen->save_type = rom->save_type;
-	gen->save_type = rom->save_type;
-	if (gen->save_type != SAVE_NONE) {
-		gen->save_ram_mask = rom->save_mask;
-		gen->save_size = rom->save_size;
-		gen->save_storage = rom->save_buffer;
-		gen->eeprom_map = rom->eeprom_map;
-		gen->num_eeprom = rom->num_eeprom;
-		if (gen->save_type == SAVE_I2C) {
-			eeprom_init(&gen->eeprom, gen->save_storage, gen->save_size);
-		}
-	} else {
-		gen->save_storage = NULL;
-	}
-
-	m68k_options *opts = malloc(sizeof(m68k_options));
-	init_m68k_opts(opts, rom->map, rom->map_chunks, MCLKS_PER_68K);
-	//TODO: make this configurable
-	opts->gen.flags |= M68K_OPT_BROKEN_READ_MODIFY;
-	gen->m68k = init_68k_context(opts, NULL);
-	gen->m68k->system = gen;
-
-	for (int i = 0; i < rom->map_chunks; i++)
-	{
-		if (rom->map[i].flags & MMAP_PTR_IDX) {
-			gen->m68k->mem_pointers[rom->map[i].ptr_index] = rom->map[i].buffer;
-		}
-	}
-
-	return gen;
-}
-
-void free_genesis(genesis_context *gen)
-{
-	vdp_free(gen->vdp);
-	m68k_options_free(gen->m68k->options);
-	free(gen->m68k);
-	z80_options_free(gen->z80->options);
-	free(gen->z80);
-	ym_free(gen->ym);
-	psg_free(gen->psg);
-	free(gen->save_storage);
-	free(gen->save_dir);
-	free(gen->lock_on);
-}
-
-void start_genesis(genesis_context *gen, char *statefile, uint8_t *debugger)
-{
-
-	if (statefile) {
-		uint32_t pc = load_gst(gen, statefile);
-		if (!pc) {
-			fatal_error("Failed to load save state %s\n", statefile);
-		}
-		printf("Loaded %s\n", statefile);
-		if (debugger) {
-			insert_breakpoint(gen->m68k, pc, debugger);
-		}
-		adjust_int_cycle(gen->m68k, gen->vdp);
-		start_68k_context(gen->m68k, pc);
-	} else {
-		if (debugger) {
-			uint32_t address = cart[2] << 16 | cart[3];
-			insert_breakpoint(gen->m68k, address, debugger);
-		}
-		m68k_reset(gen->m68k);
-	}
-}
 
 char *title;
-
 void update_title(char *rom_name)
 {
 	if (title) {
@@ -1001,25 +142,6 @@ void update_title(char *rom_name)
 	render_update_caption(title);
 }
 
-void set_region(rom_info *info, uint8_t region)
-{
-	if (!region) {
-		char * def_region = tern_find_ptr(config, "default_region");
-		if (def_region && (!info->regions || (info->regions & translate_region_char(toupper(*def_region))))) {
-			region = translate_region_char(toupper(*def_region));
-		} else {
-			region = info->regions;
-		}
-	}
-	if (region & REGION_E) {
-		version_reg = NO_DISK | EUR;
-	} else if (region & REGION_J) {
-		version_reg = NO_DISK | JAP;
-	} else {
-		version_reg = NO_DISK | USA;
-	}
-}
-
 void setup_saves(char *fname, rom_info *info, genesis_context *context)
 {
 	char * barename = basename_no_extension(fname);
@@ -1059,12 +181,12 @@ int main(int argc, char ** argv)
 	int debug = 0;
 	int ym_log = 0;
 	int loaded = 0;
-	uint8_t force_version = 0;
+	uint8_t force_region = 0;
 	char * romfname = NULL;
 	FILE *address_log = NULL;
 	char * statefile = NULL;
 	int rom_size, lock_on_size;
-	uint16_t *lock_on = NULL;
+	uint16_t *cart = NULL, *lock_on = NULL;
 	uint8_t * debuggerfun = NULL;
 	uint8_t fullscreen = FULLSCREEN_DEFAULT, use_gl = 1;
 	uint8_t debug_target = 0;
@@ -1111,8 +233,8 @@ int main(int argc, char ** argv)
 				if (i >= argc) {
 					fatal_error("-r must be followed by region (J, U or E)\n");
 				}
-				force_version = translate_region_char(toupper(argv[i][0]));
-				if (!force_version) {
+				force_region = translate_region_char(toupper(argv[i][0]));
+				if (!force_region) {
 					fatal_error("'%c' is not a valid region character for the -r option\n", argv[i][0]);
 				}
 				break;
@@ -1134,15 +256,10 @@ int main(int argc, char ** argv)
 				if (i >= argc) {
 					fatal_error("-o must be followed by a lock on cartridge filename\n");
 				}
-				uint16_t *tmp = cart;
-				lock_on_size = load_rom(argv[i]);
-				if (lock_on_size) {
-					byteswap_rom(lock_on_size);
-					lock_on = cart;
-				} else {
+				lock_on_size = load_rom(argv[i], &lock_on);
+				if (!lock_on_size) {
 					fatal_error("Failed to load lock on cartridge %s\n", argv[i]);
 				}
-				cart = tmp;
 				break;
 			}
 			case 'h':
@@ -1166,7 +283,7 @@ int main(int argc, char ** argv)
 				fatal_error("Unrecognized switch %s\n", argv[i]);
 			}
 		} else if (!loaded) {
-			if (!(rom_size = load_rom(argv[i]))) {
+			if (!(rom_size = load_rom(argv[i], &cart))) {
 				fatal_error("Failed to open %s for reading\n", argv[i]);
 			}
 			romfname = argv[i];
@@ -1185,7 +302,7 @@ int main(int argc, char ** argv)
 			romfname = "menu.bin";
 		}
 		if (is_absolute_path(romfname)) {
-			if (!(rom_size = load_rom(romfname))) {
+			if (!(rom_size = load_rom(romfname, &cart))) {
 				fatal_error("Failed to open UI ROM %s for reading", romfname);
 			}
 		} else {
@@ -1199,34 +316,10 @@ int main(int argc, char ** argv)
 				cart = realloc(cart, rom_size);
 			}
 		}
-		//TODO: load relative to executable or from assets depending on platform
 
 		loaded = 1;
 	}
-	char *m68k_divider = tern_find_path(config, "clocks\0m68k_divider\0").ptrval;
-	if (!m68k_divider) {
-		m68k_divider = "7";
-	}
-	MCLKS_PER_68K = atoi(m68k_divider);
-	if (!MCLKS_PER_68K) {
-		MCLKS_PER_68K = 7;
-	}
-	ram = malloc(RAM_WORDS * sizeof(uint16_t));
-	memmap_chunk base_map[] = {
-		{0xE00000, 0x1000000, 0xFFFF,   0, 0, MMAP_READ | MMAP_WRITE | MMAP_CODE, ram,
-		           NULL,          NULL,         NULL,            NULL},
-		{0xC00000, 0xE00000,  0x1FFFFF, 0, 0, 0,                                  NULL,
-		           (read_16_fun)vdp_port_read,  (write_16_fun)vdp_port_write,
-		           (read_8_fun)vdp_port_read_b, (write_8_fun)vdp_port_write_b},
-		{0xA00000, 0xA12000,  0x1FFFF,  0, 0, 0,                                  NULL,
-		           (read_16_fun)io_read_w,      (write_16_fun)io_write_w,
-		           (read_8_fun)io_read,         (write_8_fun)io_write}
-	};
-	tern_node *rom_db = load_rom_db();
-	rom_info info = configure_rom(rom_db, cart, rom_size, lock_on, lock_on_size, base_map, sizeof(base_map)/sizeof(base_map[0]));
-	byteswap_rom(rom_size);
-	set_region(&info, force_version);
-	update_title(info.name);
+	
 	int def_width = 0;
 	char *config_width = tern_find_path(config, "video\0width\0").ptrval;
 	if (config_width) {
@@ -1237,21 +330,20 @@ int main(int argc, char ** argv)
 	}
 	width = width < 320 ? def_width : width;
 	height = height < 240 ? (width/320) * 240 : height;
-	uint32_t fps = 60;
-	if (version_reg & 0x40) {
-		fps = 50;
-	}
+
 	char *config_fullscreen = tern_find_path(config, "video\0fullscreen\0").ptrval;
 	if (config_fullscreen && !strcmp("on", config_fullscreen)) {
 		fullscreen = !fullscreen;
 	}
 	if (!headless) {
-		render_init(width, height, title, fps, fullscreen);
+		render_init(width, height, "BlastEm", fullscreen);
 	}
 
-	genesis = alloc_init_genesis(&info, fps, (ym_log && !menu) ? YM_OPT_WAVE_LOG : 0);
-	genesis->lock_on = lock_on;
+	rom_info info;
+	uint32_t ym_opts = (ym_log && !menu) ? YM_OPT_WAVE_LOG : 0;
+	genesis = alloc_config_genesis(cart, rom_size, lock_on, lock_on_size, ym_opts, force_region, &info);
 	setup_saves(romfname, &info, genesis);
+	update_title(info.name);
 	if (menu) {
 		menu_context = genesis;
 	} else {
@@ -1273,32 +365,23 @@ int main(int argc, char ** argv)
 					persist_save();
 					genesis = menu_context;
 				}
-				free(game_context->cart);
-				base_map[0].buffer = ram = game_context->work_ram;
-			} else {
-				base_map[0].buffer = ram = malloc(RAM_WORDS * sizeof(uint16_t));
-			}
-			memset(ram, 0, RAM_WORDS * sizeof(uint16_t));
-			if (!(rom_size = load_rom(menu_context->next_rom))) {
-				fatal_error("Failed to open %s for reading\n", menu_context->next_rom);
-			}
-			info = configure_rom(rom_db, cart, rom_size, NULL, 0, base_map, sizeof(base_map)/sizeof(base_map[0]));
-			byteswap_rom(rom_size);
-			set_region(&info, force_version);
-			update_title(info.name);
-			if (!game_context) {
-				//start a new arena and save old one in suspended genesis context
-				genesis->arena = start_new_arena();
-			} else {
+				//swap to game context arena and mark all allocated pages in it free
 				genesis->arena = set_current_arena(game_context->arena);
 				mark_all_free();
 				free_genesis(game_context);
+			} else {
+				//start a new arena and save old one in suspended genesis context
+				genesis->arena = start_new_arena();
+			}
+			if (!(rom_size = load_rom(menu_context->next_rom, &cart))) {
+				fatal_error("Failed to open %s for reading\n", menu_context->next_rom);
 			}
 			//allocate new genesis context
-			game_context = alloc_init_genesis(&info, fps, ym_log ? YM_OPT_WAVE_LOG : 0);
+			game_context = alloc_config_genesis(cart, rom_size, lock_on, lock_on_size, ym_opts,force_region, &info);
 			menu_context->next_context = game_context;
 			game_context->next_context = menu_context;
 			setup_saves(menu_context->next_rom, &info, game_context);
+			update_title(info.name);
 			free(menu_context->next_rom);
 			menu_context->next_rom = NULL;
 			menu = 0;
@@ -1309,16 +392,12 @@ int main(int argc, char ** argv)
 		} else if (menu && game_context) {
 			genesis->arena = set_current_arena(game_context->arena);
 			genesis = game_context;
-			cart = genesis->cart;
-			ram = genesis->work_ram;
 			menu = 0;
 			map_all_bindings(genesis->ports);
 			resume_68k(genesis->m68k);
 		} else if (!menu && menu_context) {
 			genesis->arena = set_current_arena(menu_context->arena);
 			genesis = menu_context;
-			cart = genesis->cart;
-			ram = genesis->work_ram;
 			menu = 1;
 			map_all_bindings(genesis->ports);
 			resume_68k(genesis->m68k);