build: Add headers

Signed-off-by: Ian Moffett <ian@mirocom.org>

.gitignore

@@ -1,3 +1,3 @@
-cescal
+/cescal
 *.o
 *.d

include/cescal/readbuf.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#ifndef CESCAL_READBUF_H
+#define CESCAL_READBUF_H 1
+
+#include <sys/types.h>
+#include <stdint.h>
+#include <stddef.h>
+
+#define READBUF_CAP 128
+
+/*
+ * Represents a read buffer that reduces system call
+ * overhead.
+ *
+ * @buf:   Read buffer
+ * @size:  Total populated size of offer
+ * @tail:  Tail pointer from start of buffer
+ */
+struct readbuf {
+    char buf[READBUF_CAP];
+    size_t size;
+    size_t tail;
+};
+
+/*
+ * Initialize a read buffer
+ *
+ * @rb: Readbuffer to initialize
+ *
+ * Returns zero on success
+ */
+int readbuf_init(struct readbuf *rb);
+
+/*
+ * Read from a read buffer and populate if needed
+ *
+ * @rb:  Target readbuffer
+ * @fd:  File descriptor to read from
+ *
+ * Returns the character read on success, '\0' on
+ * failure.
+ */
+char readbuf_read(struct readbuf *rb, int fd);
+
+#endif  /* !CESCAL_READBUF_H */

include/cescal/state.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2026, Chloe M.
+ * Provided under the BSD-3 clause
+ */
+
+#ifndef CESCAL_STATE_H
+#define CESCAL_STATE_H 1
+
+#include <stdint.h>
+#include "cescal/readbuf.h"
+
+/*
+ * Compiler state machine
+ *
+ * @in_fd: Input file descriptor
+ * @rb:    Read buffer
+ */
+struct cescal_state {
+    int in_fd;
+    struct readbuf rb;
+};
+
+/*
+ * Initialize the compiler state machine
+ *
+ * @state:      Compiler state machine
+ * @pathname:   Path of input source file
+ *
+ * Returns zero on success
+ */
+int state_init(struct cescal_state *state, const char *pathname);
+
+/*
+ * Close the compiler state machine
+ *
+ * @state: Compiler state machine to close
+ */
+void state_close(struct cescal_state *state);
+
+#endif  /* !CESCAL_STATE_H */