now roms can be loaded into the chip8 memory

Makefile

@@ -37,7 +37,7 @@ build/screen.o: src/screen.c
 
 run: all
 	@$(ECHO) "Runing the Chip8 compiler"
-	@$(OUT)
+	@$(OUT) $(rom)
 
 clean:
 	@$(ECHO) "Cleaning files..."

include/chip8.h

@@ -1,6 +1,8 @@
 #ifndef __CHIP8_H
 #define __CHIP8_H
 
+#include <stddef.h>
+
 #include "config.h"
 #include "keyboard.h"
 #include "mem.h"
@@ -18,5 +20,7 @@ struct chip8
 };
 
 void chip8_init (struct chip8 *chip8);
+void chip8_load (struct chip8 *chip8, const char *buf, size_t size);
+void chip8_exec (struct chip8 *chip8, unsigned short opcode);
 
 #endif

include/config.h

@@ -5,6 +5,7 @@
 #define EMULATOR_WINDOW_MULTIPLIER 10
 
 #define CHIP8_MEMORY_SIZE 4096
+#define CHIP8_PROGRAM_LOAD_ADDRESS 0x200
 
 #define CHIP8_DISPLAY_WIDTH 64
 #define CHIP8_DISPLAY_HEIGHT 32

include/mem.h

@@ -10,5 +10,6 @@ struct chip8_memory
 
 void chip8_memory_set (struct chip8_memory *mem, int index, unsigned char val);
 unsigned char chip8_memory_get (struct chip8_memory *mem, int index);
+unsigned short chip8_memory_get_short (struct chip8_memory *mem, int index);
 
 #endif

src/chip8.c

@@ -1,4 +1,6 @@
 #include "chip8.h"
+
+#include <assert.h>
 #include <memory.h>
 
 const char chip8_default_character_set[] = {
@@ -26,3 +28,16 @@ chip8_init (struct chip8 *chip8)
 	memcpy (&chip8->memory.memory, chip8_default_character_set,
 					sizeof (chip8_default_character_set));
 }
+
+void
+chip8_load (struct chip8 *chip8, const char *buf, size_t size)
+{
+	assert (size + CHIP8_PROGRAM_LOAD_ADDRESS < CHIP8_MEMORY_SIZE);
+	memcpy (&chip8->memory.memory[CHIP8_PROGRAM_LOAD_ADDRESS], buf, size);
+	chip8->registers.PC = CHIP8_PROGRAM_LOAD_ADDRESS;
+}
+
+void
+chip8_exec (struct chip8 *chip8, unsigned short opcode)
+{
+}

src/main.c

@@ -8,12 +8,39 @@ const char keyboard_map[CHIP8_TOTAL_KEYS]
 				SDLK_8, SDLK_9, SDLK_a, SDLK_b, SDLK_c, SDLK_d, SDLK_e, SDLK_f };
 
 int
-main (int argc, char **argv)
+main (int argc, const char **argv)
 {
+	if (argc < 2)
+		{
+			fprintf (stderr, "you must provide a file to load.\n");
+			return EXIT_FAILURE;
+		}
+
+	const char *fname = argv[1];
+	printf ("the file to load is: %s\n", fname);
+
+	FILE *f = fopen (fname, "rb");
+	if (!f)
+		{
+			fprintf (stderr, "failed to open the file.\n");
+			return EXIT_FAILURE;
+		}
+
+	fseek (f, 0, SEEK_END);
+	long size = ftell (f);
+	fseek (f, 0, SEEK_SET);
+
+	char buf[size];
+	int res = fread (buf, size, 1, f);
+	if (res != 1)
+		{
+			fprintf (stderr, "failed to read from file.\n");
+			return EXIT_FAILURE;
+		}
+
 	struct chip8 chip8;
 	chip8_init (&chip8);
-	chip8_screen_draw_sprite (&chip8.screen, 62, 10,
-														(const char *)&chip8.memory.memory[0x00], 5);
+	chip8_load (&chip8, buf, size);
 
 	SDL_Init (SDL_INIT_EVERYTHING);
 	SDL_Window *window = SDL_CreateWindow (
@@ -23,6 +50,8 @@ main (int argc, char **argv)
 
 	SDL_Renderer *renderer
 			= SDL_CreateRenderer (window, -1, SDL_TEXTUREACCESS_TARGET);
+
+	chip8.registers.ST = 255;
 	while (1)
 		{
 			SDL_Event event;
@@ -85,9 +114,20 @@ main (int argc, char **argv)
 					sleep (100);
 					chip8.registers.DT -= 1;
 				}
+
+			if (chip8.registers.ST > 0)
+				{
+					/* TODO: Beep */
+					chip8.registers.ST -= 1;
+				}
+
+			unsigned short opcode
+					= chip8_memory_get_short (&chip8.memory, chip8.registers.PC);
+			chip8_exec (&chip8, opcode);
+			chip8.registers.PC += 2;
 		}
 
 out:
 	SDL_DestroyWindow (window);
-	return 0;
+	return EXIT_SUCCESS;
 }

src/mem.c

@@ -21,3 +21,11 @@ chip8_memory_get (struct chip8_memory *mem, int index)
 	chip8_is_mem_in_bounds (index);
 	return mem->memory[index];
 }
+
+unsigned short
+chip8_memory_get_short (struct chip8_memory *mem, int index)
+{
+	unsigned char byte1 = chip8_memory_get (mem, index);
+	unsigned char byte2 = chip8_memory_get (mem, index + 1);
+	return byte1 << 8 | byte2;
+}