Start on FILE i/O

src/file.c

@@ -0,0 +1,63 @@
+#include "file.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+// Up to 256 files can be open
+FILE *files[256];
+
+int openFile(int fd, const char *path) {
+  files[fd] = fopen(path, "r+");
+  if (files[fd] == NULL) {
+    return errno;
+  }
+
+  return 0;
+}
+
+int closeFile(int fd) {
+  int ret = fclose(files[fd]);
+  if (ret != 0) {
+    return errno;
+  }
+
+  return 0;
+}
+
+int readByte(const int fd, int *data) {
+  int status = 0;
+  int count = fread(&data, 1, 1, files[fd]);
+  // Error or EOF
+  if (count != 1) {
+    int error = ferror(files[fd]);
+    int eof = feof(files[fd]);
+    if (error != 0) {
+      status = 0x2;
+    } else if (eof != 0) {
+      status = 0x1;
+    } else {
+      status = 0x4;
+    }
+  }
+
+  return status;
+}
+
+int writeByte(const int fd, const int data) {
+  int status = 0;
+  int count = fwrite(&data, 1, 1, files[fd]);
+  // Error or EOF
+  if (count != 1) {
+    int error = ferror(files[fd]);
+    int eof = feof(files[fd]);
+    if (error != 0) {
+      status = 0x2;
+    } else if (eof != 0) {
+      status = 0x1;
+    } else {
+      status = 0x4;
+    }
+  }
+
+  return status;
+}