implement Makefile and CPU module with reset and state print functions; update .gitignore to exclude build artifacts

.gitignore

@@ -74,4 +74,7 @@ dkms.conf
 .history
 .ionide
 
+bin/
+build/
+
 # End of https://www.toptal.com/developers/gitignore/api/c,visualstudiocode

Makefile

@@ -0,0 +1,32 @@
+cc := gcc
+CFLAGS := -std=c11 -Wall -Wextra -Wpedantic -O2
+CFLAGS_DEBUG := -std=c11 -Wall -Wextra -Wpedantic -g -O0
+
+SRC_DIR := src 
+BUILD_DIR := build 
+BIN_DIR := bin
+
+TARGET := $(BIN_DIR)/mos6502
+
+SRC := $(shell find  $(SRC_DIR) -name '*.c')
+OBJ := $(SRC:$(SRC_DIR)/%.c=$(BUILD_DIR)/%.o)
+
+all: $(TARGET)
+
+$(TARGET): $(OBJ)
+	@mkdir -p $(BIN_DIR)
+	$(cc) $(OBJ) -o $(TARGET)
+
+$(BUILD_DIR)/%.o: $(SRC_DIR)/%.c
+	@mkdir -p $(BUILD_DIR)
+	@mkdir -p $(dir $@)
+	$(cc) $(CFLAGS) -c $< -o $@
+
+debug: CFLAGS=$(CFLAGS_DEBUG)
+debug: clean $(TARGET)
+
+clean:
+	rm -rf $(BUILD_DIR) $(BIN_DIR)
+
+rebuild: clean all
+.PHONY: all clean rebuild debug

src/cpu.c

@@ -0,0 +1,23 @@
+#include <stdio.h>
+#include "cpu.h"
+
+void cpu_reset(CPU6502 *cpu)
+{
+    cpu->A = 0;
+    cpu->X = 0;
+    cpu->Y = 0;
+    cpu->SP = 0xFD;   // typical 6502 reset value??
+    cpu->P = FLAG_U;  // unused flag always 1
+    cpu->PC = 0x0000; // loaded later from reset vector
+}
+
+void cpu_print_state(CPU6502 *cpu)
+{
+    printf("CPU State:\n");
+    printf("A:  0x%02X\n", cpu->A);
+    printf("X:  0x%02X\n", cpu->X);
+    printf("Y:  0x%02X\n", cpu->Y);
+    printf("SP: 0x%02X\n", cpu->SP);
+    printf("PC: 0x%04X\n", cpu->PC);
+    printf("P:  0x%02X\n", cpu->P);
+}

src/cpu.h

@@ -0,0 +1,29 @@
+#ifndef CPU_H
+#define CPU_H
+
+#include <stdint.h>
+
+typedef struct
+{
+    uint8_t A;  // accumulator
+    uint8_t X;  // index X
+    uint8_t Y;  // index y
+    uint8_t SP; // stack pointer
+    uint8_t PC; // program counter
+    uint8_t P;  // status flags
+} CPU6502;
+
+// status flag masks
+#define FLAG_C 0x01
+#define FLAG_Z 0x02
+#define FLAG_I 0x04
+#define FLAG_D 0x08
+#define FLAG_B 0x10
+#define FLAG_U 0x20
+#define FLAG_V 0x40
+#define FLAG_N 0x80
+
+void cpu_reset(CPU6502 *cpu);
+void cpu_print_state(CPU6502 *cpu);
+
+#endif