began chip8 interpreter, reading rom file

1 files changed, 41 insertions, 0 deletions

diff --git a/chip8.c b/chip8.c
new file mode 100644
index 0000000..3c41117
--- /dev/null
+++ b/chip8.c
@@ -0,0 +1,41 @@
+#include "chip8.h"
+
+uint8_t key[KEY_SIZE]; 		// hex key input
+uint32_t video[WIDTH*HEIGHT]; 	// video memory TODO: video should be 8 bit not 32
+uint8_t V[16];			// registers - 0x0 to 0xF
+uint16_t I;			// special I register, stores addresses
+uint16_t PC;			// program counter
+uint8_t SP;			// stack pointer
+uint16_t stack[STACK_SIZE];	// stack, for address storage when using subroutines, maximum of 16 levels of nested subroutines
+uint8_t memory[MEMORY_SIZE];	// 4KB of program memory
+
+int
+load_rom(char *rom)
+{
+	int ret = 1;
+	printf("loading rom %s..\n", rom);
+	FILE *romfile;
+	romfile = fopen(rom, "rb");
+	if (romfile == NULL)
+	{
+		fprintf(stderr, "cannot read rom %s: %s\n", rom, strerror(errno));
+		ret = 0;
+	}
+
+	/* read a maximum of MAX_ROM_SIZE bytes into memory starting after the reserved memory */
+	fread(&memory[0x200], 1, MAX_ROM_SIZE, romfile);
+
+	fclose(romfile);
+	return ret;
+}
+
+void
+chip8_init()
+{
+	/* clear everything */
+	memset(key, 0, 15);
+	memset(video, 0, (WIDTH*HEIGHT) * sizeof(uint32_t));
+	memset(V, 0, 16);
+	memset(stack, 0, (STACK_SIZE) * sizeof(uint16_t));
+	memset(memory, 0, MEMORY_SIZE);
+}