rename "ArgumentType" to "ArgumentParser"

.gitignore

@@ -13,3 +13,4 @@ doxygen/*
 buildbot-upload/*
 */config.mak
 *\~
+__pycache__

src/apps/gbdb.c

@@ -37,6 +37,7 @@ static int64_t parse_val(const char *str);
 static const char prompt[] = "gbdb > ";
 static const char usage[] =
 	"Available commands:\n"
+	"load <file>: loads the given file as the gameboy cartridge\n"
 	"run: runs the CPU until a breakpoint or halt is hit\n"
 	"break <addr>: Adds a breakpoint for the given addess\n"
 	"step <cycles>: executes \"cycle\" instructions (default 1)\n"
@@ -47,7 +48,6 @@ static const char usage[] =
 static struct lr35902_ops cpu_ops;
 static struct lr35902_state cpu;
 static struct gb_video video;
-static struct gb_interrupt interrupt;
 static void *memory = NULL;
 
 static int paused_breakpoint = 0;
@@ -108,14 +108,13 @@ static void strip_newline(char *string)
 	}
 }
 
-static void init(const char *bootrom, const char *rom)
+static void init(void)
 {
 	cpu_ops.undef_d3 = breakpoint_cb;
 
-	gb_interrupt_init(&interrupt, &cpu);
+	lr35902_init(&cpu, memory, &cpu_ops);
-	lr35902_init(&cpu, &interrupt, memory, &cpu_ops);
+	gb_video_init(&video, memory);
-	gb_video_init(&video, memory, &interrupt);
+	gb_mem_init(memory, &video);
-	gb_mem_init(memory, &video, &interrupt, bootrom, rom);
 
 	config.log_fd = -1;
 	config.trace_fd = -1;
@@ -571,6 +570,31 @@ static void mem(struct tokens **tokens)
 	}
 }
 
+static void load(struct tokens **tokens)
+{
+	char *token = token_next(tokens);
+	if (token == NULL) {
+		gb_error("usage: load <file>\n");
+		return;
+	}
+
+	gb_log("loading %s\n", token);
+
+	gb_memory_load_file(memory, GB_MEMORY_CART, token);
+}
+
+static void load_bootrom(struct tokens **tokens)
+{
+	char *token = token_next(tokens);
+	if (token == NULL) {
+		gb_error("usage: bootrom <file>\n");
+		return;
+	}
+
+	gb_memory_load_file(memory, GB_MEMORY_BOOTROM, token);
+}
+
+
 static void quit(struct tokens **tokens)
 {
 	exit(0);
@@ -845,10 +869,9 @@ static int load_initfile(const char *initfile_path, struct tri *commands)
 	return 0;
 }
 
-int main(int argc, const char **argv)
+int main(int argc, char **argv)
 {
 	struct tri commands;
-	const char *rom, *bootrom;
 
 	tri_init(&commands);
 	tri_add_string(&commands, "#", comment);
@@ -859,6 +882,8 @@ int main(int argc, const char **argv)
 	tri_add_string(&commands, "stats", stats);
 	tri_add_string(&commands, "exit", quit);
 	tri_add_string(&commands, "quit", quit);
+	tri_add_string(&commands, "load", load);
+	tri_add_string(&commands, "bootrom", load_bootrom);
 	tri_add_string(&commands, "mem", mem);
 	/* FIXME */
 	/* tri_add_string(&commands, "dump", mem_dump); */
@@ -872,22 +897,11 @@ int main(int argc, const char **argv)
 	tri_add_string(&commands, "set", set);
 	tri_add_string(&commands, "echo", echo);
 
+	init();
 
-	if (argc < 3) {
+	if (argc > 1) {
-		gb_error("usage: %s <BOOT_ROM> <ROM> INIT_SCRIPT\n", argv[0]);
+		if (load_initfile(argv[1], &commands)) {
-		exit(1);
-	}
-
-	bootrom = argv[1];
-	rom = argv[2];
-
-	init(bootrom, rom);
-
-	if (argc > 3) {
-		gb_log("%s\n", argv[0]);
-		if (load_initfile(argv[3], &commands)) {
 			gb_error("Failed to load initfile\n");
-			exit(1);
 		}
 	}
 

src/common/common.h

@@ -10,16 +10,6 @@
 
 #define ARRAY_SIZE(x) (sizeof((x)) / (sizeof((x)[0])))
 
-#define SET_BIT(x, idx) do {(x) |= (1 << (idx));} while (0)
-#define CLR_BIT(x, idx) do {(x) &= ~(1 << (idx));} while (0)
-#define GET_BIT(x, bit) (((x) >> (bit)) & 1)
-#define WRITE_BIT(x, idx, bit)					\
-	do {										\
-		(x) &= ~(1 << (idx));					\
-		(x) |= (bit) << (idx);					\
-	} while(0)
-
-
 /*
  * Replaces any characters from A-Z with their lowercase counterpart.
  * All other characters preceding '\0' are ignored

src/gbemu/cpu.c

@@ -10,6 +10,15 @@
 #include "gbemu/cpu.h"
 #include "common/common.h"
 
+#define SET_BIT(x, idx) do {(x) |= (1 << (idx));} while (0)
+#define CLR_BIT(x, idx) do {(x) &= ~(1 << (idx));} while (0)
+#define GET_BIT(x, bit) (((x) >> (bit)) & 1)
+#define WRITE_BIT(x, idx, bit)					\
+	do {										\
+		(x) &= ~(1 << (idx));					\
+		(x) |= (bit) << (idx);					\
+	} while(0)
+
 #define CALC_H_ADD(a, b) ((((a) & 0xf) + ((b) & 0xf)) > 0xf)
 #define CALC_H_SUB(a, b) (((a) & 0xf) < ((b) & 0xf))
 
@@ -21,8 +30,6 @@
 #define CALC_C_ADD_8(a, b) (0xff - (a) < (b))
 #define CALC_C_SUB(a, b) ((a) < (b))
 
-static void lr35902_handle_pending(struct lr35902_state *cpu);
-
 static int cpu_reg16_to_idx[NUM_LR35902_REGS_16] = {
 	[LR35902_REG_BC] = 0,
 	[LR35902_REG_DE] = 1,
@@ -72,13 +79,11 @@ void lr35902_set_reg_8(struct lr35902_state *cpu, lr35902_regs_8 reg,
 }
 
 void lr35902_init(struct lr35902_state *cpu,
-				  struct gb_interrupt *interrupt,
 				  struct gb_memory *memory,
                   const struct lr35902_ops *ops)
 {
 	int i;
 
-	cpu->interrupt = interrupt;
 	cpu->memory = memory;
 
 	cpu->undef_d3 = ops->undef_d3;
@@ -1633,7 +1638,7 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		break;
 	case 0xd9: /* RETI */
 		RET(cpu);
-		gb_interrupt_ime_set(cpu->interrupt);
+		cpu->int_state = LR35902_INT_ON;
 		break;
 	case 0xda: /* JP C, a16 */
 		val_16 = gb_mem_read(cpu->memory, cpu->pc++);
@@ -1733,8 +1738,7 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		cpu->a = gb_mem_read(cpu->memory, 0xFF00 + cpu->c);
 		break;
 	case 0xf3: /* DI */
-		gb_interrupt_ime_clear(cpu->interrupt);
+		/*TODO: implement me */
-		break;
 	case 0xf4: /* UNDEF */
 		break;
 	case 0xf5: /* PUSH AF */
@@ -1772,8 +1776,7 @@ int lr35902_cycle(struct lr35902_state *cpu)
 		cpu->a = gb_mem_read(cpu->memory, val_16);
 		break;
 	case 0xfb: /* EI */
-		gb_log("EI\n");
+		/* TODO: implement me */
-		gb_interrupt_ime_set(cpu->interrupt);
 		break;
 	case 0xfc: /* UNDEF */
 		ASSERT(0);
@@ -1791,33 +1794,3 @@ int lr35902_cycle(struct lr35902_state *cpu)
 	cpu->metrics.cycles += cycles + 1;
 	return cycles + 1;
 }
-
-void lr35902_interrupt(struct lr35902_state *cpu, enum gb_interrupt_kind kind)
-{
-	uint16_t addr;
-
-	gb_log("Interrupt! (%d)\n", kind);
-
-	switch (kind) {
-	case GB_INT_VBLANK:
-		addr = 0x40;
-		break;
-	case GB_INT_LCD_STAT:
-		addr = 0x48;
-		break;
-	case GB_INT_TIMER:
-		addr = 0x50;
-		break;
-	case GB_INT_SERIAL:
-		addr = 0x58;
-		break;
-	case GB_INT_JOYPAD:
-		addr = 0x60;
-		break;
-	default:
-		ASSERT(0);
-	}
-
-	PUSH_16(cpu, cpu->pc);
-	cpu->pc = addr;
-}

src/gbemu/cpu.h

@@ -9,8 +9,6 @@
 #define GB_CPU_H
 
 #include "gbemu/memory.h"
-#include "gbemu/cpu.h"
-#include "gbemu/interrupt.h"
 
 #include <stdint.h>
 
@@ -72,7 +70,6 @@ struct lr35902_event {
 struct lr35902_state {
 
 	struct gb_memory *memory;
-	struct gb_interrupt *interrupt;
 
 	union {
 		/*
@@ -125,7 +122,6 @@ struct lr35902_ops {
 };
 
 void lr35902_init(struct lr35902_state *cpu,
-				  struct gb_interrupt *interrupt,
 				  struct gb_memory *memory,
 				  const struct lr35902_ops *ops);
 
@@ -145,6 +141,4 @@ void lr35902_set_reg_8(struct lr35902_state *cpu,
 
 int lr35902_cycle(struct lr35902_state *cpu);
 
-void lr35902_interrupt(struct lr35902_state *cpu, enum gb_interrupt_kind kind);
-
 #endif

src/gbemu/interrupt.c

@@ -1,90 +0,0 @@
-#include "gbemu/interrupt.h"
-#include "gbemu/cpu.h"
-
-#include "common/common.h"
-
-void gb_interrupt_init(struct gb_interrupt *interrupt, struct lr35902_state *cpu)
-{
-	interrupt->flags = 0;
-	interrupt->enable = 0;
-
-	interrupt->cpu = cpu;
-}
-
-static void fire_if_pending(struct gb_interrupt *interrupt)
-{
-	uint8_t active_interrupts = interrupt->flags & interrupt->enable;
-	enum gb_interrupt_kind kind;
-
-	if (!interrupt->master_enable) {
-		return;
-	}
-
-	if (!active_interrupts) {
-		return;
-	}
-
-	kind = __builtin_ctz(active_interrupts);
-	ASSERT(kind >= GB_INT_MIN);
-	ASSERT(kind <= GB_INT_MAX);
-
-	interrupt->master_enable = false;
-	CLR_BIT(interrupt->flags, kind);
-	lr35902_interrupt(interrupt->cpu, kind);
-}
-
-int gb_interrupt_set(struct gb_interrupt *interrupt, enum gb_interrupt_kind kind)
-{
-	uint8_t old = interrupt->flags;
-	uint8_t new = interrupt->flags;
-
-	ASSERT(kind >= GB_INT_MIN);
-	ASSERT(kind <= GB_INT_MAX);
-
-	SET_BIT(new, kind);
-
-	fire_if_pending(interrupt);
-}
-
-int gb_interrupt_clear(struct gb_interrupt *interrupt, enum gb_interrupt_kind kind)
-{
-	ASSERT(kind >= GB_INT_MIN);
-	ASSERT(kind <= GB_INT_MAX);
-	CLR_BIT(interrupt->flags, kind);
-}
-
-uint8_t gb_interrupt_if_read(struct gb_interrupt *interrupt)
-{
-	return interrupt->flags;
-}
-
-void gb_interrupt_if_write(struct gb_interrupt *interrupt, uint8_t val)
-{
-	interrupt->flags = val;
-	fire_if_pending(interrupt);
-}
-
-uint8_t gb_interrupt_ie_read(struct gb_interrupt *interrupt)
-{
-	return interrupt->enable;
-}
-
-void gb_interrupt_ie_write(struct gb_interrupt *interrupt, uint8_t val)
-{
-	uint8_t active_interrupts = interrupt->flags & interrupt->enable;
-	enum gb_interrupt_kind kind;
-
-	interrupt->enable = val;
-}
-
-void gb_interrupt_ime_set(struct gb_interrupt *interrupt)
-{
-	interrupt->master_enable = true;
-
-	fire_if_pending(interrupt);
-}
-
-void gb_interrupt_ime_clear(struct gb_interrupt *interrupt)
-{
-	interrupt->master_enable = false;
-}

src/gbemu/interrupt.h

@@ -1,61 +0,0 @@
-#ifndef INTERRUPT_H
-#define INTERRUPT_H
-
-#include <stdint.h>
-#include <stdbool.h>
-
-struct lr35902_state;
-
-enum gb_interrupt_kind {
-	GB_INT_MIN = 0,
-	GB_INT_VBLANK = 0,
-	GB_INT_LCD_STAT = 1,
-	GB_INT_TIMER = 2,
-	GB_INT_SERIAL = 3,
-	GB_INT_JOYPAD = 4,
-	GB_INT_MAX,
-};
-
-struct gb_interrupt {
-	uint8_t flags; /* IF */
-	uint8_t enable; /* IE */
-	bool master_enable; /* IME */
-
-	struct lr35902_state *cpu;
-};
-
-void gb_interrupt_init(struct gb_interrupt *interrupt, struct lr35902_state *cpu);
-
-/*
- * The "hardware" interface to setting/clearing interrupts
- */
-int gb_interrupt_set(struct gb_interrupt *interrupt, enum gb_interrupt_kind kind);
-
-int gb_interrupt_clear(struct gb_interrupt *interrupt, enum gb_interrupt_kind kind);
-
-/*
- * IF - Interrupt Flags
- */
-
-uint8_t gb_interrupt_if_read(struct gb_interrupt *interrupt);
-
-void gb_interrupt_if_write(struct gb_interrupt *interrupt, uint8_t val);
-
-/*
- * IE - Interrupt Enable
- */
-
-uint8_t gb_interrupt_ie_read(struct gb_interrupt *interrupt);
-
-void gb_interrupt_ie_write(struct gb_interrupt *interrupt, uint8_t val);
-
-
-/*
- * IME - Interrupt Master Enable
- */
-
-void gb_interrupt_ime_set(struct gb_interrupt *interrupt);
-
-void gb_interrupt_ime_clear(struct gb_interrupt *interrupt);
-
-#endif

src/gbemu/memory.c

@@ -4,7 +4,6 @@
 
 #include "gbemu/memory.h"
 #include "gbemu/video.h"
-#include "gbemu/cpu.h"
 
 #include "common/common.h"
 
@@ -20,46 +19,17 @@
 #define UNMAP_BOOTROM_ADDR 0xff50
 
 static struct gb_video *video;
-static struct gb_interrupt *interrupt;
 
 static uint8_t ram[MAX_RAM_LEN];
 static unsigned char bootrom[0x100] = {0};
 static unsigned char cart_low[0x100] = {0};
 static int bootrom_mapped = 1;
 
-static void load_file_to_buffer(const char *filename, uint8_t *buffer, size_t size)
+void gb_mem_init(struct gb_memory *memory, struct gb_video *v)
 {
-	//TODO: Check error codes like a real programmer :P
-	FILE* prog_file;
-	long filesize;
-
-	prog_file = fopen(filename, "r");
-	if(prog_file < 0) {
-		printf("Failed to load game file: %d\n", errno);
-		return;
-	}
-
-	fseek(prog_file, 0, SEEK_END);
-	filesize = ftell(prog_file);
-	fseek(prog_file, 0, SEEK_SET);
-
-	if (fread(buffer, MIN(filesize, size), 1, prog_file) < 0) {
-		printf("Failed to read filed: %d\n", errno);
-	}
-	fclose(prog_file);
-}
-
-void gb_mem_init(struct gb_memory *memory, struct gb_video *v, struct gb_interrupt *i,
-				 const char *bootrom_file, const char *rom_file)
-{
-	interrupt = i;
 	video = v;
 	memset(&ram, 0, MAX_RAM_LEN);
 	bootrom_mapped = 1;
-	load_file_to_buffer(rom_file, cart_low, sizeof(cart_low));
-	load_file_to_buffer(rom_file, ram, sizeof(ram));
-	load_file_to_buffer(bootrom_file, bootrom, sizeof(bootrom));
-	load_file_to_buffer(bootrom_file, ram, sizeof(ram));
 }
 
 static uint8_t ser_byte = 0;
@@ -110,10 +80,6 @@ uint8_t gb_mem_read(struct gb_memory *memory, uint16_t addr)
 		return gb_serial_read(memory, addr);
 	case 0xFF40 ... 0xFF4B:
 		return gb_video_mem_read(video, addr);
-	case 0xFF0F:
-		return gb_interrupt_if_read(interrupt);
-	case 0xFFFF:
-		return gb_interrupt_ie_read(interrupt);
 	default:
 		return ram[addr];
 	}
@@ -143,12 +109,8 @@ void gb_mbc3_write(struct gb_memory *memory, uint16_t addr, uint8_t val)
 	case 0xFF40 ... 0xFF4B:
 		gb_video_mem_write(video, addr, val);
 		break;
-	case 0xFF0F:
-		gb_interrupt_if_write(interrupt, val);
-		break;
 	case 0xFFFF:
-		gb_interrupt_ie_write(interrupt, val);
+		gb_log("Writing to interrupt mask: 0x%02x\n", val);
-		break;
 	default:
 		ram[addr] = val;
 	}
@@ -175,12 +137,6 @@ void gb_mem_write(struct gb_memory *memory, uint16_t addr, uint8_t val)
 	case 0xFF40 ... 0xFF4B:
 		gb_video_mem_write(video, addr, val);
 		return;
-	case 0xFF0F:
-		gb_interrupt_if_write(interrupt, val);
-		return;
-	case 0xFFFF:
-		gb_interrupt_ie_write(interrupt, val);
-		return;
 	case 0x8000 ... 0x87FF:
 	case 0x9800 ... 0x9BFF:
 		break;
@@ -189,6 +145,9 @@ void gb_mem_write(struct gb_memory *memory, uint16_t addr, uint8_t val)
 			return;
 		}
 		break;
+	case 0xFFFF:
+		gb_log("Writing to interrupt mask: 0x%02x\n", val);
+		break;
 	}
 
 	ram[addr] = val;
@@ -210,3 +169,67 @@ void gb_mem_force_write(struct gb_memory *memory, uint16_t addr, uint8_t val)
 	}
 
 }
+
+static void load_file_to_buffer(char *filename, uint8_t *buffer, size_t size)
+{
+	//TODO: Check error codes like a real programmer :P
+	FILE* prog_file;
+	long filesize;
+
+	prog_file = fopen(filename, "r");
+	if(prog_file < 0) {
+		printf("Failed to load game file: %d\n", errno);
+		return;
+	}
+
+	fseek(prog_file, 0, SEEK_END);
+	filesize = ftell(prog_file);
+	fseek(prog_file, 0, SEEK_SET);
+
+	if (fread(buffer, MIN(filesize, size), 1, prog_file) < 0) {
+		printf("Failed to read filed: %d\n", errno);
+	}
+	fclose(prog_file);
+
+}
+
+int gb_memory_load_file(struct gb_memory *memory, enum gb_memory_range destination, char *filename)
+{
+	//TODO: Check error codes like a real programmer :P
+	FILE* prog_file;
+	long filesize;
+
+	switch (destination) {
+	case GB_MEMORY_BOOTROM:
+		load_file_to_buffer(filename, bootrom, sizeof(bootrom));
+		load_file_to_buffer(filename, ram, sizeof(bootrom));
+
+		break;
+	case GB_MEMORY_CART:
+		load_file_to_buffer(filename, ram, sizeof(ram));
+		load_file_to_buffer(filename, cart_low, sizeof(cart_low));
+		break;
+	default:
+		return -1;
+	}
+}
+
+/* static void mem_dump(char *filename) */
+/* { */
+/* 	//TODO: Check error codes like a real programmer :P */
+/* 	FILE* dump_file; */
+/* 	char *token = strtok(filename, " "); */
+
+/* 	if (token == NULL) { */
+/* 		gb_log("usage: load <file>\n"); */
+/* 		return; */
+/* 	} */
+/* 	strip_newline(token); */
+/* 	dump_file = fopen(token, "w"); */
+/* 	if(dump_file == NULL) { */
+/* 		gb_log("Failed to open mem dump file: %d\n", errno); */
+/* 		return; */
+/* 	} */
+/* 	fwrite(ram, MAX_RAM_LEN, 1, dump_file); */
+/* 	fclose(dump_file); */
+/* } */

src/gbemu/memory.h

@@ -5,11 +5,17 @@
 
 struct gb_memory;
 struct gb_video;
-struct gb_interrupt;
 
-void gb_mem_init(struct gb_memory *memory, struct gb_video *v,
+enum gb_memory_range {
-				 struct gb_interrupt *interrupt,
+	GB_MEMORY_BOOTROM,
-				 const char *bootrom, const char *rom);
+	GB_MEMORY_CART,
+};
+
+void gb_mem_init(struct gb_memory *memory, struct gb_video *v);
+
+int gb_memory_load_file(struct gb_memory *memory,
+						enum gb_memory_range destination,
+						char *filename);
 
 uint8_t gb_mem_read(struct gb_memory *mem, uint16_t addr);
 

src/gbemu/video.c

@@ -1,6 +1,5 @@
 #include "gbemu/video.h"
 #include "gbemu/memory.h"
-#include "gbemu/interrupt.h"
 #include "common/common.h"
 #include "common/bmp.h"
 
@@ -10,6 +9,7 @@
 /* TODO: This whole implementation is very simple.*/
 /* TODO: Actual graphics output */
 /* TODO: Implementation of most registers */
+/* TODO: Interrupts */
 
 static struct bmp *bmp;
 
@@ -28,13 +28,12 @@ static uint8_t color_tbl[4] = {
 	0,
 };
 
-void gb_video_init(struct gb_video *video, struct gb_memory *memory, struct gb_interrupt *interrupt)
+void gb_video_init(struct gb_video *video, struct gb_memory *memory)
 {
 	memset(video, 0, sizeof(*video));
 
 	video->debug_logging = 0;
 	video->memory = memory;
-	video->interrupt = interrupt;
 
 	bmp = bmp_new(BMP_GRAYSCALE, BUFFER_WIDTH, BUFFER_HEIGHT);
 }
@@ -115,15 +114,12 @@ void gb_video_cycle(struct gb_video *video, int cycles)
 		video->curline += 1;
 		if (video->curline > LCD_Y_MAX) {
 			video->curline = 0;
-			gb_interrupt_clear(video->interrupt, GB_INT_VBLANK);
 			if (video->lcdcont & (1 << 7)) {
 				screenshot_count++;
 				if (screenshot_count % 30 == 0) {
 					gb_video_screenshot(video);
 				}
 			}
-		} else if (video->curline == 144) {
-			gb_interrupt_set(video->interrupt, GB_INT_VBLANK);
 		}
 	}
 }

src/gbemu/video.h

@@ -95,10 +95,9 @@ struct gb_video {
 	int debug_logging;
 
 	struct gb_memory *memory;
-	struct gb_interrupt *interrupt;
 };
 
-void gb_video_init(struct gb_video *video, struct gb_memory *memory, struct gb_interrupt *interrupt);
+void gb_video_init(struct gb_video *video, struct gb_memory *memory);
 void gb_video_cycle(struct gb_video *video, int cycles);
 uint8_t gb_video_mem_read(struct gb_video *video, uint16_t addr);
 void gb_video_mem_write(struct gb_video *video, uint16_t addr, uint8_t val);

src/python/src/gbasm/arguments/ArgumentParser.py

@@ -0,0 +1,7 @@
+class ArgumentParser(object):
+
+    def can_parse(token: str) -> bool:
+        raise NotImplementedError()
+
+    def get_name() -> str:
+        raise NotImplementedError()

src/python/src/gbasm/arguments/ArgumentParsers.py

@@ -0,0 +1,138 @@
+from .ArgumentParser import ArgumentParser
+from . import Arguments
+
+
+class Address(ArgumentParser):
+
+    NAME = "Address"
+
+    def __init__(self):
+        pass
+
+    def can_parse(self, token: str) -> bool:
+        try:
+            addr = int(token, base=0)
+            return addr < 0x8000 and addr >= 0
+        except ValueError:
+            return False
+
+    def get_name(self) -> str:
+        return Address.NAME
+
+
+class Label(ArgumentParser):
+
+    NAME = "Label"
+
+    def __init__(self):
+        pass
+
+    def can_parse(self, token: str) -> bool:
+        if not token[0] in string.ascii_letters + ['_']:
+            return False
+        return True
+
+    def parse(self, token) -> Arguments.Register8:
+        return Arguments.Label(token)
+
+    def get_name(self) -> str:
+        return Label.NAME
+
+
+class Register8(ArgumentParser):
+
+    NAME = "Register8"
+
+    def __init__(self, indirect: bool=False, indirect_increment: bool=False):
+        self.indirect = indirect
+
+    def can_parse(self, token: str) -> bool:
+        if token in Arguments.Register8.REGISTERS:
+            return True
+        if self.indirect and token in Arguments.Register8.REGISTERS_INDIRECT:
+            return True
+        if self.indirect_increment \
+           and token in Arguments.Register8.REGISTERS_INDIRECT_INCREMENT:
+            return True
+        return False
+
+    def parse(self, token) -> Arguments.Register8:
+        return Arguments.Register8(token)
+
+    def get_name(self) -> str:
+        return Register8.NAME
+
+
+class Register16(ArgumentParser):
+
+    NAME = "Immediate8"
+
+    def __init__(self, indirect: bool=False, indirect_increment: bool=False):
+        self.indirect = indirect
+
+    def can_parse(self, token: str) -> bool:
+        return token in Arguments.Register16.REGISTERS
+
+    def to_argument(self, token: str):
+        return None
+
+    def parse(self, token) -> Arguments.Register16:
+        return Arguments.Register16(token)
+
+    def get_name(self) -> str:
+        return Register16.NAME
+
+
+class Immediate8(ArgumentParser):
+
+    NAME = "Immediate8"
+
+    def __init__(self):
+        pass
+
+    def can_parse(self, token: str) -> bool:
+        try:
+            addr = int(token, base=0)
+            return addr <= 0xFF and addr >= 0
+        except ValueError:
+            return False
+
+    def get_name(self) -> str:
+        return Immediate8.NAME
+
+class Immediate16(ArgumentParser):
+
+    NAME = "Immediate16"
+
+    def __init__(self):
+        pass
+
+    def can_parse(self, token: str) -> bool:
+        try:
+            addr = int(token, base=0)
+            return addr <= 0xFFFF and addr >= 0
+        except ValueError:
+            return False
+
+    def parse(self, token) -> Arguments.Immediate16:
+        return Arguments.Immediate16(token)
+
+    def get_name(self) -> str:
+        return Immediate16.NAME
+
+
+class Flag(ArgumentParser):
+
+    NAME = "Flag"
+
+    def __init__(self):
+        pass
+
+    def can_parse(self, token: str) -> bool:
+        return token in Arguments.Flag.FLAGS
+
+    def parse(self, token) -> Arguments.Immediate16:
+        return Arguments.Flag(token)
+
+    def get_name(self) -> str:
+        return Flag.NAME

src/python/src/gbasm/arguments/Arguments.py

@@ -0,0 +1,72 @@
+class Argument(object):
+
+    def __init__(self):
+        pass
+
+class Address(Argument):
+
+    NAME = "Address"
+
+    def __init__(self, value: int):
+        self.value = value
+
+
+class Label(Argument):
+
+    NAME = "Label"
+
+    def __init__(self, value: str):
+        self.value = value
+
+
+class Register8(Argument):
+
+    NAME = "Register8"
+    REGISTERS = ["A", "B", "C", "D", "E", "H", "L"]
+    REGISTERS_INDIRECT = ["(HL)"]
+    REGISTERS_INDIRECT_INCREMENT = ["(HL)", "(HL+)", "(HL-)"]
+
+    def __init__(self, value: str):
+        if value not in Register8.REGISTERS \
+           + Register8.REGISTERS_INDIRECT_INCREMENT:
+            raise ValueError("Unknown Register8: {}".format(value))
+        self.value = value
+
+
+class Register16(Argument):
+
+    NAME = "Immediate8"
+
+    REGISTERS = ["BC", "DE", "DE", "HL", "SP"]
+
+    def __init__(self, value: int):
+        if value not in Register16.REGISTERS:
+            raise ValueError("Unknown Register16: {}".format(value))
+        self.value = value
+
+class Immediate8(Argument):
+
+    NAME = "Immediate8"
+
+    def __init__(self, value: int):
+        self.value = value
+
+
+class Immediate16(Argument):
+
+    NAME = "Immediate16"
+
+    def __init__(self, value: int):
+        self.value = value
+
+
+class Flag(Argument):
+
+    NAME = "Immediate8"
+
+    FLAGS = ["Z", "C", "NZ", "NC"]
+
+    def __init__(self, value: str):
+        if value not in Flag.FLAGS:
+            raise ValueError("Unknown Flag: {}".format(value))
+        self.value = value

src/python/src/gbasm/arguments/__init__.py

@@ -0,0 +1,3 @@
+from .ArgumentParser import ArgumentParser
+from .ArgumentParsers import Label, Address, Immediate8, Immediate16, Register8, Register16
+from .Arguments import Argument

src/python/src/gbasm/gbasm.py

@@ -0,0 +1,157 @@
+#!/usr/bin/python3
+
+import argparse
+import logging
+import sys
+
+from .instructions import Instruction
+from .instructions.inc import Inc
+from .instructions.dec import Dec
+from .instructions.nop import Nop
+from .instructions.stop import Stop
+from .instructions.jr import Jr
+from .instructions.ld import Ld
+from .arguments import ArgumentParser, Argument
+
+from typing import Callable, Dict, List, Optional
+
+logger = logging.getLogger(__name__)
+
+COMMENT_CHAR = '#'
+LABEL_SUFFIX = ':'
+
+GB_INSTRUCTIONS = [
+    Nop(),
+    Stop(),
+    Inc(),
+    Dec(),
+    Jr(),
+    Ld(),
+]
+
+def build_instruction_map() -> Dict[str, Instruction]:
+    d = {}  # type: Dict[str, Instruction]
+    for i in GB_INSTRUCTIONS:
+        d[i.token] = i
+    return d
+
+def try_parse_arguments(args: List[str],
+                        arg_types: List[ArgumentParser]) -> Optional[List[Argument]]:
+    if len(args) != len(arg_types):
+        return None
+
+    out_args = []
+
+    for (arg, arg_type) in zip(args, arg_types):
+        try:
+            out_args.append(arg_type.parse(arg))
+        except ValueError:
+            return None
+
+    return out_args
+
+def parse_line_size(instruction: Instruction,
+               arguments: List[str]) -> bytes:
+
+    for argtype_list in instruction.argument_specs:
+        args = try_parse_arguments(arguments, argtype_list)
+        if args is not None:
+            return instruction.num_bytes(args)
+
+    raise ValueError("Failed to parse line.")
+
+def parse_line_bytes(instruction: Instruction,
+                     arguments: List[str],
+                     instruction_addr: int,
+                     label_resolver: Callable[[str], int]) -> bytes:
+
+    for argtype_list in instruction.argument_specs:
+        args = try_parse_arguments(arguments, argtype_list)
+        if args is not None:
+            return instruction.to_bytes(args, instruction_addr, label_resolver)
+
+    raise ValueError("Failed to parse line.")
+
+def assemble_file(infile) -> bytes:
+    program = infile.readlines()
+    return assemble(infile)
+
+def assemble(lines: str) -> bytes:
+
+    instruction_map = build_instruction_map()
+    logger.debug("Instruction map: %s", instruction_map)
+
+    labels = {}  # type: Dict[str, int]
+    program = bytes()
+
+    def label_resolver(label: str) -> int:
+        nonlocal labels
+        return labels[label]
+
+    for step in ["SIZE", "CONTENT"]:
+        logger.debug("Starting step: %s", step)
+        byte_offset = 0
+
+        for line_num, line in enumerate(lines):
+            # Remove comments
+            line = line.split(COMMENT_CHAR)[0]
+
+            # Tokenize
+            tokens = line.split()
+
+            if len(tokens) == 0:
+                continue
+
+            instruction_name = tokens[0]
+            args = tokens[1:]
+            try:
+                instruction = instruction_map[instruction_name]
+            except KeyError:
+                if instruction_name[-1] == LABEL_SUFFIX:
+                    if step == 'SIZE':
+                        label = instruction_name[:-1]
+                        logger.debug("Found label '%s' at %s", label, byte_offset)
+                        if label in labels.keys():
+                            raise KeyError("Label '%s' defined at %s and %s",
+                                           label, labels[label], line_num)
+                        labels[label] = byte_offset
+                    continue
+                raise KeyError("Unknown instruction \"%s\" on line %s",
+                               instruction_name, line_num)
+
+            if step == 'CONTENT':
+                try:
+                    program += parse_line_bytes(instruction, args, byte_offset, label_resolver)
+                except ValueError:
+                    raise ValueError("Failed to parse line %s,\n%s", line_num, line)
+
+            byte_offset += parse_line_size(instruction, args)
+        if step == 'SIZE':
+            logger.info("Program size: %s bytes", byte_offset)
+            logger.debug("Found labels: %s", labels)
+
+    return program
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description= "An assembler for Gameboy assembly")
+
+    parser.add_argument("--infile", "-i", type=argparse.FileType("r"), default=sys.stdin)
+    parser.add_argument("--outfile", "-o", type=argparse.FileType("wb"), default=sys.stdout)
+    parser.add_argument("--verbose", "-v", action='store_true')
+
+    args = parser.parse_args()
+
+    logging.basicConfig(format="%(levelname)s: %(message)s")
+    logger.setLevel(logging.INFO)
+
+    if args.verbose:
+        logging.basicConfig(format="%(levelname)s: %(filename)s:%(lineno)d: %(message)s")
+        logger.setLevel(logging.DEBUG)
+
+    program = assemble_file(args.infile)
+    outfile.write(program)
+
+
+if __name__ == "__main__":
+    main()

src/python/src/gbasm/instructions/Instruction.py

@@ -0,0 +1,17 @@
+from typing import Callable, List
+from ..arguments import Argument, ArgumentParser
+
+class Instruction(object):
+
+    def __init__(self, token: str, argument_specs: List[List[ArgumentParser]]):
+        self.token = token
+        self.argument_specs = argument_specs
+
+    def num_bytes(self, arguments) -> int:
+        raise NotImplementedError()
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_addr: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+        raise NotImplementedError()

src/python/src/gbasm/instructions/__init__.py

@@ -0,0 +1 @@
+from . Instruction import Instruction

src/python/src/gbasm/instructions/dec.py

@@ -0,0 +1,51 @@
+from .Instruction import Instruction
+from ..arguments.ArgumentParsers import Register8, Register16
+from ..arguments import Argument
+from typing import Callable, List
+
+
+class Dec(Instruction):
+
+    def __init__(self):
+        argtypes = [[Register8()], [Register16()]]
+        super().__init__("DEC", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        return 1
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_addr: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        if len(arguments) != 1:
+            raise ValueError("Incorrect number of arguments")
+
+        value = arguments[0].value
+
+        if value == "BC":
+            return bytes([0x0B])
+        if value == "DE":
+            return bytes([0x1B])
+        if value == "HL":
+            return bytes([0x2B])
+        if value == "SP":
+            return bytes([0x3B])
+        if value == "A":
+            return bytes([0x3D])
+        if value == "B":
+            return bytes([0x05])
+        if value == "C":
+            return bytes([0x0D])
+        if value == "D":
+            return bytes([0x15])
+        if value == "E":
+            return bytes([0x1D])
+        if value == "H":
+            return bytes([0x25])
+        if value == "L":
+            return bytes([0x2D])
+        if value == "(HL)":
+            return bytes([0x35])
+
+        raise ValueError("Unknown value: {}".format(value))

src/python/src/gbasm/instructions/inc.py

@@ -0,0 +1,51 @@
+from .Instruction import Instruction
+from ..arguments.ArgumentParsers import Register8, Register16
+from ..arguments import Argument
+from typing import Callable, List
+
+
+class Inc(Instruction):
+
+    def __init__(self):
+        argtypes = [[Register8()], [Register16()]]
+        super().__init__("INC", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        return 1
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_addr: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        if len(arguments) != 1:
+            raise ValueError("Incorrect number of arguments")
+
+        value = arguments[0].value
+
+        if value == "BC":
+            return bytes([0x03])
+        if value == "DE":
+            return bytes([0x13])
+        if value == "HL":
+            return bytes([0x23])
+        if value == "SP":
+            return bytes([0x33])
+        if value == "A":
+            return bytes([0x3C])
+        if value == "B":
+            return bytes([0x04])
+        if value == "C":
+            return bytes([0x0C])
+        if value == "D":
+            return bytes([0x14])
+        if value == "E":
+            return bytes([0x1C])
+        if value == "H":
+            return bytes([0x24])
+        if value == "L":
+            return bytes([0x2C])
+        if value == "(HL)":
+            return bytes([0x34])
+
+        raise ValueError("Unknown value: {}".format(value))

src/python/src/gbasm/instructions/jr.py

@@ -0,0 +1,60 @@
+from .Instruction import Instruction
+from ..arguments.ArgumentParsers import Flag, Label
+from ..arguments import Argument
+from typing import Callable, List
+
+
+class Jr(Instruction):
+
+    INSTRUCTION_SIZE = 2
+
+    def __init__(self):
+        argtypes = [[Label()], [Flag(), Label()]]
+        super().__init__("JR", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        return Jr.INSTRUCTION_SIZE
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_address: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        out_bytes = bytearray()
+
+        if len(arguments) == 1:
+            out_bytes.append(0x18)
+            dest_arg = arguments[0].value
+
+        elif len(arguments) == 2:
+            flag_dict = {
+                "NZ": 0x20,
+                "NC": 0x30,
+                "Z": 0x28,
+                "C": 0x38
+            }
+            flag = arguments[0].value
+            try:
+                out_bytes.append(flag_dict[flag])
+            except KeyError:
+                logger.exception("Instruction JR does not accept flag %s", arg)
+            dest_arg = arguments[1].value
+
+        else:
+            raise ValueError("Incorrect number of arguments")
+
+        if isinstance(dest_arg, str):
+            label = dest_arg
+            dest_addr = label_resolver(label)
+        else:
+            dest_addr = dest_arg
+
+        addr_offset = dest_addr - (instruction_address + Jr.INSTRUCTION_SIZE)
+        if addr_offset > 127 or addr_offset < -128:
+            raise ValueError("JR instruction cannot jump to {} ({}), from {}, {} bytes away"
+                             .format(label, dest_addr, instruction_address, addr_offset))
+        if addr_offset < 0:
+            addr_offset += 256
+
+        out_bytes.append(addr_offset)
+        return bytes(out_bytes)

src/python/src/gbasm/instructions/ld.py

@@ -0,0 +1,45 @@
+from .Instruction import Instruction
+from ..arguments.ArgumentParsers import Register16, Immediate16
+from ..arguments import Argument
+from typing import Callable, List
+
+class Ld(Instruction):
+
+    def __init__(self):
+        argtypes = [[Register16(), Immediate16()]]
+        super().__init__("LD", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        # the instruction_address and label_resolver are unused
+        return len(self.to_bytes(arguments, 0, lambda x: None))
+
+    def encode_reg_16(self,
+                      register: Register16,
+                      immediate: Immediate16) -> bytes:
+        reg_dict = {
+            "BC": 0x01,
+            "DE": 0x11,
+            "HL": 0x21,
+            "SP": 0x31
+        }
+        imm = int(immediate.value, 0)
+        print("immediate", imm)
+        out = bytearray()
+        out.append(reg_dict[register.value])
+        out.extend(imm.to_bytes(2, "little", signed=imm < 0))
+        return bytes(out)
+    
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_address: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        # print(arguments)
+        # print("Register16", type(arguments[0]))
+        # print("Immediate16", isinstance(arguments[1], Immediate16))
+
+        # if isinstance(arguments[0], Register16) and \
+        #    isinstance(arguments[1], Immediate16):
+        return self.encode_reg_16(arguments[0], arguments[1])
+
+        raise TypeError("Unhandled argument types")

src/python/src/gbasm/instructions/nop.py

@@ -0,0 +1,23 @@
+from .Instruction import Instruction
+from ..arguments import Argument
+from typing import Callable, List
+
+
+class Nop(Instruction):
+
+    def __init__(self):
+        argtypes = [[]]
+        super().__init__("NOP", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        return 1
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_addr: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        if len(arguments) != 0:
+            raise ValueError("Incorrect number of arguments")
+
+        return bytes([0x00])

src/python/src/gbasm/instructions/stop.py

@@ -0,0 +1,23 @@
+from .Instruction import Instruction
+from ..arguments import Argument
+from typing import Callable, List
+
+
+class Stop(Instruction):
+
+    def __init__(self):
+        argtypes = [[]]
+        super().__init__("STOP", argtypes)
+
+    def num_bytes(self, arguments) -> int:
+        return 1
+
+    def to_bytes(self,
+                 arguments: List[Argument],
+                 instruction_addr: int,
+                 label_resolver: Callable[[str], int]) -> bytes:
+
+        if len(arguments) != 0:
+            raise ValueError("Incorrect number of arguments")
+
+        return bytes([0x10])

src/python/test/cases/format.yaml

@@ -0,0 +1,20 @@
+---
+name: two_nop
+program: |
+  NOP
+  NOP
+expected:
+  - 0x00
+  - 0x00
+---
+name: unused_labels
+program: |
+  start:
+    NOP
+  middle:
+    NOP
+  end:
+expected:
+  - 0x00
+  - 0x00
+---

src/python/test/cases/format/format.yaml

@@ -0,0 +1,19 @@
+---
+name: two_nop
+program: |
+  NOP
+  NOP
+expected:
+  - 0x00
+  - 0x00
+---
+name: unused_labels
+program: |
+  start:
+    NOP
+  middle:
+    NOP
+  end:
+expected:
+  - 0x00
+  - 0x00

src/python/test/cases/instructions/dec.yaml

@@ -0,0 +1,74 @@
+---
+name: dec_a
+program: |
+  DEC A
+expected:
+  - 0x3D
+
+---
+name: dec_b
+program: |
+  DEC B
+expected:
+  - 0x05
+---
+name: dec_c
+program: |
+  DEC C
+expected:
+  - 0x0D
+---
+name: dec_d
+program: |
+  DEC D
+expected:
+  - 0x15
+---
+name: dec_e
+program: |
+  DEC E
+expected:
+  - 0x1D
+---
+name: dec_h
+program: |
+  DEC H
+expected:
+  - 0x25
+---
+name: dec_l
+program: |
+  DEC L
+expected:
+  - 0x2D
+---
+name: dec_(hl)
+program: |
+  DEC (HL)
+expected:
+  - 0x35
+
+---
+name: dec_bc
+program: |
+  DEC BC
+expected:
+  - 0x0B
+---
+name: dec_de
+program: |
+  DEC DE
+expected:
+  - 0x1B
+---
+name: dec_hl
+program: |
+  DEC HL
+expected:
+  - 0x2B
+---
+name: dec_sp
+program: |
+  DEC SP
+expected:
+  - 0x3B

src/python/test/cases/instructions/inc.yaml

@@ -0,0 +1,74 @@
+---
+name: inc_a
+program: |
+  INC A
+expected:
+  - 0x3c
+
+---
+name: inc_b
+program: |
+  INC B
+expected:
+  - 0x04
+---
+name: inc_c
+program: |
+  INC C
+expected:
+  - 0x0c
+---
+name: inc_d
+program: |
+  INC D
+expected:
+  - 0x14
+---
+name: inc_e
+program: |
+  INC E
+expected:
+  - 0x1c
+---
+name: inc_h
+program: |
+  INC H
+expected:
+  - 0x24
+---
+name: inc_l
+program: |
+  INC L
+expected:
+  - 0x2c
+---
+name: inc_(hl)
+program: |
+  INC (HL)
+expected:
+  - 0x34
+
+---
+name: inc_bc
+program: |
+  INC BC
+expected:
+  - 0x03
+---
+name: inc_de
+program: |
+  INC DE
+expected:
+  - 0x13
+---
+name: inc_hl
+program: |
+  INC HL
+expected:
+  - 0x23
+---
+name: inc_sp
+program: |
+  INC SP
+expected:
+  - 0x33

src/python/test/cases/instructions/jr.yaml

@@ -0,0 +1,370 @@
+---
+name: jr_bkwd
+program: |
+  label:
+  JR label
+expected:
+  - 0x18
+  - 0xFE
+---
+name: jr_fwd
+program: |
+  JR label
+  label:
+expected:
+  - 0x18
+  - 0x00
+
+---
+name: jr_z_bkwd
+program: |
+  label:
+  JR Z label
+expected:
+  - 0x28
+  - 0xFE
+---
+name: jr_z_fwd
+program: |
+  JR Z label
+  label:
+expected:
+  - 0x28
+  - 0x00
+
+---
+name: jr_nz_bkwd
+program: |
+  label:
+  JR NZ label
+expected:
+  - 0x20
+  - 0xFE
+---
+name: jr_nz_fwd
+program: |
+  JR NZ label
+  label:
+expected:
+  - 0x20
+  - 0x00
+
+---
+name: jr_c_bkwd
+program: |
+  label:
+  JR C label
+expected:
+  - 0x38
+  - 0xFE
+---
+name: jr_c_fwd
+program: |
+  JR C label
+  label:
+expected:
+  - 0x38
+  - 0x00
+
+---
+name: jr_nc_bkwd
+program: |
+  label:
+  JR NC label
+expected:
+  - 0x30
+  - 0xFE
+---
+name: jr_nc_fwd
+program: |
+  JR NC label
+  label:
+expected:
+  - 0x30
+  - 0x00
+
+---
+# Jump backward by the maximum amount
+name: jr_far_bkwd
+program: |
+  far_label:
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  JR far_label
+expected: [
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x18, 0x80 ]
+
+---
+# Jump forward by the maximum amount
+name: jr_far_fwd
+program: |
+  JR far_label
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  NOP
+  far_label:
+expected: [ 0x18, 0x7F,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  ]

src/python/test/cases/instructions/ld_reg16.yaml

@@ -0,0 +1,81 @@
+---
+name: ld_bc
+program: |
+  LD BC 0
+expected:
+  - 0x01
+  - 0x00
+  - 0x00
+---
+name: ld_de
+program: |
+  LD DE 0
+expected:
+  - 0x11
+  - 0x00
+  - 0x00
+---
+name: ld_hl
+program: |
+  LD HL 0
+expected:
+  - 0x21
+  - 0x00
+  - 0x00
+---
+name: ld_sp
+program: |
+  LD SP 0
+expected:
+  - 0x31
+  - 0x00
+  - 0x00
+
+---
+name: ld_16_max
+program: |
+  LD BC 65535
+expected:
+  - 0x01
+  - 0xFF
+  - 0xFF
+---
+name: ld_16_negative
+program: |
+  LD BC -1
+expected:
+  - 0x01
+  - 0xFF
+  - 0xFF
+---
+name: ld_16_min
+program: |
+  LD BC -32768
+expected:
+  - 0x01
+  - 0x00
+  - 0x80
+---
+name: ld_16_00FF
+program: |
+  LD BC 0x00FF
+expected:
+  - 0x01
+  - 0xFF
+  - 0x00
+---
+name: ld_16_FF00
+program: |
+  LD BC 0xFF00
+expected:
+  - 0x01
+  - 0x00
+  - 0xFF
+---
+name: ld_16_100
+program: |
+  LD BC 10
+expected:
+  - 0x01
+  - 0x0A
+  - 0x00

src/python/test/cases/instructions/special.yaml

@@ -0,0 +1,12 @@
+---
+name: nop
+program: |
+  NOP
+expected:
+  - 0x00
+---
+name: stop
+program: |
+  STOP
+expected:
+  - 0x10

src/python/test/test_assemble.py

@@ -0,0 +1,58 @@
+from gbasm.gbasm import assemble
+
+from pathlib import Path
+import os
+import yaml
+import pytest
+import logging
+
+logger = logging.getLogger(__name__)
+
+if __name__ == "__main__":
+    logging.basicConfig(format="")
+    logging.getLogger().setLevel(logging.INFO)
+
+
+class AssembleCase(object):
+
+    def __init__(self, name: str, program: str, expected: bytes):
+        self.name = name
+        self.program = program
+        self.expected = expected
+
+
+def find_case_files(subdir: str):
+    test_root = Path(os.path.dirname(os.path.abspath(__file__)))
+    case_root = test_root / "cases" / subdir
+    return case_root.glob("**/*.yaml")
+
+def get_test_cases(subdir: str):
+    cases = []
+    files = find_case_files(subdir)
+    for f in files:
+        index = 0
+        with open(str(f), "r") as yaml_file:
+            test_descs = yaml.safe_load_all(yaml_file)
+            for desc in test_descs:
+                try:
+                    case = AssembleCase(desc['name'], desc['program'], bytes(desc['expected']))
+                except TypeError:
+                    logger.exception("Failed to parse yaml: %s", desc)
+                cases.append(case)
+    return cases
+
+instruction_cases = get_test_cases("instructions")
+@pytest.mark.parametrize("case", instruction_cases,
+                         ids=[case.name for case in instruction_cases])
+def test_assemble_instruction(case):
+    lines = case.program.split("\n")
+    assembled = assemble(lines)
+    assert assembled == case.expected
+
+format_cases = get_test_cases("format")
+@pytest.mark.parametrize("case", format_cases,
+                         ids=[case.name for case in format_cases])
+def test_format_instruction(case):
+    lines = case.program.split("\n")
+    assembled = assemble(lines)
+    assert assembled == case.expected