--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/blastem.c	Wed Dec 26 21:50:48 2012 -0800
@@ -0,0 +1,503 @@
+#include "68kinst.h"
+#include "m68k_to_x86.h"
+#include "mem.h"
+#include "vdp.h"
+#include "render.h"
+#include "blastem.h"
+#include <stdio.h>
+#include <stdlib.h>
+
+#define CARTRIDGE_WORDS 0x200000
+#define RAM_WORDS 32 * 1024
+#define MCLKS_PER_68K 7
+//TODO: Figure out the exact value for this
+#define MCLKS_PER_FRAME (MCLKS_LINE*262)
+#define CYCLE_NEVER 0xFFFFFFFF
+
+uint16_t cart[CARTRIDGE_WORDS];
+uint16_t ram[RAM_WORDS];
+
+io_port gamepad_1;
+io_port gamepad_2;
+
+#ifndef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+int load_rom(char * filename)
+{
+	FILE * f = fopen(filename, "rb");
+	if (!f) {
+		return 0;
+	}
+	fseek(f, 0, SEEK_END);
+	long filesize = ftell(f);
+	fseek(f, 0, SEEK_SET);
+	fread(cart, 2, MIN(filesize/2, CARTRIDGE_WORDS), f);
+	fclose(f);
+	for(unsigned short * cur = cart; cur - cart < (filesize/2); ++cur)
+	{
+		*cur = (*cur >> 8) | (*cur << 8);
+	}
+	//TODO: Mirror ROM
+	return 1;
+}
+
+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 div by 2
+	if (address < 0x200000) {
+		return cart[address];
+	} else if(address >= 0x700000) {
+		return ram[address & 0x7FFF];
+	}
+	//TODO: Figure out what happens when you try to DMA from weird adresses like IO or banked Z80 area
+	return 0;
+}
+
+#define VINT_CYCLE ((MCLKS_LINE * 226)/MCLKS_PER_68K)
+
+m68k_context * sync_components(m68k_context * context)
+{
+	//TODO: Handle sync targets smaller than a single frame
+	vdp_context * v_context = context->next_context;
+	uint32_t mclks = context->current_cycle * MCLKS_PER_68K;
+	if (mclks >= MCLKS_PER_FRAME) {
+		//printf("reached frame end | 68K Cycles: %d, MCLK Cycles: %d\n", context->current_cycle, mclks);
+		vdp_run_context(v_context, MCLKS_PER_FRAME);
+		wait_render_frame(v_context);
+		mclks -= MCLKS_PER_FRAME;
+		vdp_adjust_cycles(v_context, MCLKS_PER_FRAME);
+		io_adjust_cycles(&gamepad_1, context->current_cycle, MCLKS_PER_FRAME/MCLKS_PER_68K);
+		io_adjust_cycles(&gamepad_2, context->current_cycle, MCLKS_PER_FRAME/MCLKS_PER_68K);
+		context->current_cycle -= MCLKS_PER_FRAME/MCLKS_PER_68K;
+		if (mclks) {
+			vdp_run_context(v_context, mclks);
+		}
+		if (v_context->regs[REG_MODE_2] & 0x20 && ((context->status & 0x7) < 6)) {
+			if (context->int_cycle > VINT_CYCLE) {
+				context->int_cycle = VINT_CYCLE;
+				context->int_num = 6;
+				if (context->int_cycle < context->sync_cycle) {
+					context->target_cycle = context->int_cycle;
+				}
+			}
+		} else {
+			context->int_cycle = 0xFFFFFFFF;
+			context->target_cycle = context->sync_cycle;
+		}
+	} else {
+		//printf("running VDP for %d cycles\n", mclks - v_context->cycles);
+		vdp_run_context(v_context, mclks);
+		if (v_context->regs[REG_MODE_2] & 0x20 && ((context->status & 0x7) < 6)) {
+			if (context->int_cycle > VINT_CYCLE) {
+				context->int_cycle = VINT_CYCLE;
+				context->int_num = 6;
+				if (context->int_cycle < context->sync_cycle && context->int_cycle < context->current_cycle) {
+					context->target_cycle = context->int_cycle;
+				}
+			}
+			if (context->int_cycle <= context->current_cycle) {
+				context->int_cycle = CYCLE_NEVER;
+				context->target_cycle = context->sync_cycle;
+			}
+		} else {
+			context->int_cycle = CYCLE_NEVER;
+			context->target_cycle = context->sync_cycle;
+		}
+	}
+	return context;
+}
+
+m68k_context * vdp_port_write(uint32_t vdp_port, m68k_context * context, uint16_t value)
+{
+	//printf("vdp_port write: %X, value: %X, cycle: %d\n", vdp_port, value, context->current_cycle);
+	sync_components(context);
+	vdp_context * v_context = context->next_context;
+	if (vdp_port < 0x10) {
+		if (vdp_port < 4) {
+			vdp_data_port_write(v_context, value);
+		} else if(vdp_port < 8) {
+			int blocked = vdp_control_port_write(v_context, value);
+			if (blocked) {
+				while(v_context->flags & FLAG_DMA_RUN) {
+					vdp_run_dma_done(v_context, MCLKS_PER_FRAME);
+					if (v_context->cycles >= MCLKS_PER_FRAME) {
+						wait_render_frame(v_context);
+						vdp_adjust_cycles(v_context, MCLKS_PER_FRAME);
+						io_adjust_cycles(&gamepad_1, v_context->cycles/MCLKS_PER_68K, MCLKS_PER_FRAME/MCLKS_PER_68K);
+						io_adjust_cycles(&gamepad_2, v_context->cycles/MCLKS_PER_68K, MCLKS_PER_FRAME/MCLKS_PER_68K);
+					}
+				}
+				context->current_cycle = v_context->cycles / MCLKS_PER_68K;
+			} else {
+				if (v_context->regs[REG_MODE_2] & 0x20 && ((context->status & 0x7) < 6)) {
+					if (context->int_cycle > VINT_CYCLE) {
+						context->int_cycle = VINT_CYCLE;
+						context->int_num = 6;
+						if (context->int_cycle < context->sync_cycle) {
+							context->target_cycle = context->int_cycle;
+						}
+					}
+				} else {
+					context->int_cycle = 0xFFFFFFFF;
+					context->target_cycle = context->sync_cycle;
+				}
+			}
+		} else {
+			printf("Illegal write to HV Counter port %X\n", vdp_port);
+			exit(1);
+		}
+		context->current_cycle = v_context->cycles/MCLKS_PER_68K;
+	} else if (vdp_port < 0x18) {
+		//TODO: Implement PSG
+	} else {
+		//TODO: Implement undocumented test register(s)
+	}
+	return context;
+}
+
+m68k_context * vdp_port_read(uint32_t vdp_port, m68k_context * context)
+{
+	sync_components(context);
+	vdp_context * v_context = context->next_context;
+	if (vdp_port < 0x10) {
+		if (vdp_port < 4) {
+			context->value = vdp_data_port_read(v_context);
+		} else if(vdp_port < 8) {
+			context->value = vdp_control_port_read(v_context);
+		} else {
+			//TODO: Implement H/V counter
+			context->value = 0;
+		}
+		context->current_cycle = v_context->cycles/MCLKS_PER_68K;
+	} else {
+		printf("Illegal read from PSG or test register port %X\n", vdp_port);
+		exit(1);
+	}
+	return context;
+}
+
+#define TH 0x40
+#define TH_TIMEOUT 8000
+#define Z80_ACK_DELAY 3 //TODO: Calculate this on the fly based on how synced up the Z80 and 68K clocks are
+
+uint8_t reset = 1;
+uint8_t busreq = 0;
+uint8_t busack = 0;
+uint32_t busack_cycle = CYCLE_NEVER;
+uint8_t new_busack = 0;
+
+void io_adjust_cycles(io_port * pad, uint32_t current_cycle, uint32_t deduction)
+{
+	uint8_t control = pad->control | 0x80;
+	uint8_t th = control & pad->output;
+	if (pad->input[GAMEPAD_TH0] || pad->input[GAMEPAD_TH1]) {
+		printf("adjust_cycles | control: %X, TH: %X, GAMEPAD_TH0: %X, GAMEPAD_TH1: %X, TH Counter: %d, Timeout: %d, Cycle: %d\n", control, th, pad->input[GAMEPAD_TH0], pad->input[GAMEPAD_TH1], pad->th_counter,pad->timeout_cycle, current_cycle);
+	}
+	if (current_cycle >= pad->timeout_cycle) {
+		pad->th_counter = 0;
+	} else {
+		pad->timeout_cycle -= deduction;
+	}
+	if (busack_cycle < CYCLE_NEVER && current_cycle < busack_cycle) {
+		busack_cycle -= deduction;
+	}
+}
+
+void io_data_write(io_port * pad, m68k_context * context, uint8_t value)
+{
+	if (pad->control & TH) {
+		//check if TH has changed
+		if ((pad->output & TH) ^ (value & TH)) {
+			if (context->current_cycle >= pad->timeout_cycle) {
+				pad->th_counter = 0;
+			}
+			if (!(value & TH)) {
+				pad->th_counter++;
+			}
+			pad->timeout_cycle = context->current_cycle + TH_TIMEOUT;
+		}
+	}
+	pad->output = value;
+}
+
+void io_data_read(io_port * pad, m68k_context * context)
+{
+	uint8_t control = pad->control | 0x80;
+	uint8_t th = control & pad->output;
+	uint8_t input;
+	if (context->current_cycle >= pad->timeout_cycle) {
+		pad->th_counter = 0;
+	}
+	if (pad->input[GAMEPAD_TH0] || pad->input[GAMEPAD_TH1]) {
+		printf("io_data_read | control: %X, TH: %X, GAMEPAD_TH0: %X, GAMEPAD_TH1: %X, TH Counter: %d, Timeout: %d, Cycle: %d\n", control, th, pad->input[GAMEPAD_TH0], pad->input[GAMEPAD_TH1], pad->th_counter,pad->timeout_cycle, context->current_cycle);
+	}
+	if (th) {
+		if (pad->th_counter == 2) {
+			input = pad->input[GAMEPAD_EXTRA];
+		} else {
+			input = pad->input[GAMEPAD_TH1];
+		}
+	} else {
+		if (pad->th_counter == 2) {
+			input = pad->input[GAMEPAD_TH0] | 0xF;
+		} else if(pad->th_counter == 3) {
+			input = pad->input[GAMEPAD_TH0]  & 0x30;
+		} else {
+			input = pad->input[GAMEPAD_TH0];
+		}
+	}
+	context->value = ((~input) & (~control)) | (pad->output & control);
+	/*if (pad->input[GAMEPAD_TH0] || pad->input[GAMEPAD_TH1]) {
+		printf ("value: %X\n", context->value);
+	}*/
+}
+
+m68k_context * io_write(uint32_t location, m68k_context * context, uint8_t value)
+{
+	if (location < 0x100) {
+		switch(location/2)
+		{
+		case 0x1:
+			io_data_write(&gamepad_1, context, value);
+			break;
+		case 0x2:
+			io_data_write(&gamepad_2, context, value);
+			break;
+		case 0x3://PORT C Data
+			break;
+		case 0x4:
+			gamepad_1.control = value;
+			break;
+		case 0x5:
+			gamepad_2.control = value;
+			break;
+		}
+	} else {
+		if (location == 0x1100) {
+			if (busack_cycle > context->current_cycle) {
+				busack = new_busack;
+				busack_cycle = CYCLE_NEVER;
+			}
+			if (value & 1) {
+				busreq = 1;
+				if(!reset) {
+					busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+					new_busack = 1;
+				}
+			} else {
+				busreq = 0;
+				busack_cycle = CYCLE_NEVER;
+				busack = 0;
+			}
+		} else if (location == 0x1200) {
+			if (value & 1) {
+				if (reset && busreq) {
+					new_busack = 1;
+					busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+				}
+				reset = 0;
+			} else {
+				busack = 0;
+				reset = 1;
+			}
+		}
+	}
+	return context;
+}
+
+m68k_context * io_write_w(uint32_t location, m68k_context * context, uint16_t value)
+{
+	if (location < 0x100) {
+		switch(location/2)
+		{
+		case 0x1:
+			io_data_write(&gamepad_1, context, value);
+			break;
+		case 0x2:
+			io_data_write(&gamepad_2, context, value);
+			break;
+		case 0x3://PORT C Data
+			break;
+		case 0x4:
+			gamepad_1.control = value;
+			break;
+		case 0x5:
+			gamepad_2.control = value;
+			break;
+		}
+	} else {
+		printf("IO Write of %X to %X\n", value, location);
+		if (location == 0x1100) {
+			if (busack_cycle > context->current_cycle) {
+				busack = new_busack;
+				busack_cycle = CYCLE_NEVER;
+			}
+			if (value & 0x100) {
+				busreq = 1;
+				if(!reset) {
+					busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+					new_busack = 1;
+				}
+			} else {
+				busreq = 0;
+				busack_cycle = CYCLE_NEVER;
+				busack = 0;
+			}
+		} else if (location == 0x1200) {
+			if (value & 0x100) {
+				if (reset && busreq) {
+					new_busack = 1;
+					busack_cycle = context->current_cycle + Z80_ACK_DELAY;
+				}
+				reset = 0;
+			} else {
+				busack = 0;
+				reset = 1;
+			}
+		}
+	}
+	return context;
+}
+
+m68k_context * io_read(uint32_t location, m68k_context * context)
+{
+	if (location < 0x100) {
+		switch(location/2)
+		{
+		case 0x0:
+			//version bits should be 0 for now since we're not emulating TMSS
+			//Not sure about the other bits
+			context->value = 0;
+			break;
+		case 0x1:
+			io_data_read(&gamepad_1, context);
+			break;
+		case 0x2:
+			io_data_read(&gamepad_2, context);
+			break;
+		case 0x3://PORT C Data
+			break;
+		case 0x4:
+			context->value = gamepad_1.control;
+			break;
+		case 0x5:
+			context->value = gamepad_2.control;
+			break;
+		}
+	} else {
+		if (location == 0x1100) {
+			if (busack_cycle > context->current_cycle) {
+				busack = new_busack;
+				busack_cycle = CYCLE_NEVER;
+			}
+			context->value = (!reset) && busack;
+			printf("Byte read of BUSREQ returned %d\n", context->value);
+		} else if (location == 0x1200) {
+			context->value = !reset;
+		} else {
+			printf("Byte read of unknown IO location: %X\n", location);
+		}
+	}
+	return context;
+}
+
+m68k_context * io_read_w(uint32_t location, m68k_context * context)
+{
+	if (location < 0x100) {
+		switch(location/2)
+		{
+		case 0x0:
+			//version bits should be 0 for now since we're not emulating TMSS
+			//Not sure about the other bits
+			context->value = 0;
+			break;
+		case 0x1:
+			io_data_read(&gamepad_1, context);
+			break;
+		case 0x2:
+			io_data_read(&gamepad_2, context);
+			break;
+		case 0x3://PORT C Data
+			break;
+		case 0x4:
+			context->value = gamepad_1.control;
+			break;
+		case 0x5:
+			context->value = gamepad_2.control;
+			break;
+		case 0x6:
+			//PORT C Control
+			context->value = 0;
+			break;
+		}
+		context->value = context->value | (context->value << 8);
+		printf("Word read to %X returned %d\n", location, context->value);
+	} else {
+		if (location == 0x1100) {
+			if (busack_cycle > context->current_cycle) {
+				busack = new_busack;
+				busack_cycle = CYCLE_NEVER;
+			}
+			context->value = ((!reset) && busack) << 8;
+			printf("Word read of BUSREQ returned %d\n", context->value);
+		} else if (location == 0x1200) {
+			context->value = (!reset) << 8;
+		} else {
+			printf("Word read of unknown IO location: %X\n", location);
+		}
+	}
+	return context;
+}
+
+int main(int argc, char ** argv)
+{
+	if (argc < 2) {
+		fputs("Usage: blastem FILENAME\n", stderr);
+		return 1;
+	}
+	if(!load_rom(argv[1])) {
+		fprintf(stderr, "Failed to open %s for reading\n", argv[1]);
+		return 1;
+	}
+	int width = 320;
+	int height = 240;
+	if (argc > 2) {
+		width = atoi(argv[2]);
+		if (argc > 3) {
+			height = atoi(argv[3]);
+		} else {
+			height = (width/320) * 240;
+		}
+	}
+	render_init(width, height);
+	size_t size = 1024 * 1024;
+	uint8_t * transbuf = alloc_code(&size);
+	
+	x86_68k_options opts;
+	m68k_context context;
+	vdp_context v_context;
+	
+	init_x86_68k_opts(&opts);
+	init_68k_context(&context, opts.native_code_map, &opts);
+	init_vdp_context(&v_context);
+	context.next_context = &v_context;
+	//cartridge ROM
+	context.mem_pointers[0] = cart;
+	context.target_cycle = context.sync_cycle = MCLKS_PER_FRAME/MCLKS_PER_68K;
+	//work RAM
+	context.mem_pointers[1] = ram;
+	uint32_t address;
+	address = cart[0x68/2] << 16 | cart[0x6A/2];
+	uint8_t * end = transbuf + size;
+	transbuf = translate_m68k_stream(transbuf, end, address, &context);
+	address = cart[0x70/2] << 16 | cart[0x72/2];
+	transbuf = translate_m68k_stream(transbuf, end, address, &context);
+	address = cart[0x78/2] << 16 | cart[0x7A/2];
+	transbuf = translate_m68k_stream(transbuf, end, address, &context);
+	address = cart[2] << 16 | cart[3];
+	translate_m68k_stream(transbuf, end, address, &context);
+	m68k_reset(&context);
+	return 0;
+}