-/* readwrite.h:
+/* readwrite.h:
*
- * Routines for reading/writing multibyte data from/to files. They ensure a
- * defined endianness.
+ * Routines for reading and writing files.
*/
#ifndef READWRITE_H
#define READWRITE_H
-#include <stdio.h>
-#include <stdint.h>
-extern uint16_t read_uint16_bigendian(FILE * file);
-extern uint32_t read_uint32_bigendian(FILE * file);
-extern void write_uint16_bigendian(uint16_t x, FILE * file);
-extern void write_uint32_bigendian(uint32_t x, FILE * file);
+
+#include <stdio.h> /* for FILE typedef */
+#include <stdint.h> /* for uint8_t, uint16_t, uint32_t */
+
+
+
+/* Learn from "file" the largest line length (pointed to by "linemax_p"; length
+ * includes newline chars) and (pointed to by "n_lines_p" if it is not set to
+ * NULL) the number of lines (= number of newline chars).
+ *
+ * Returns 0 on success, 1 on error of fseek() (called to return to initial file
+ * reading position).
+ */
+extern uint8_t textfile_sizes(FILE * file, uint16_t * linemax_p,
+ uint16_t * n_lines_p);
+
+
+
+/* These routines for reading values "x" from / writing values to "file" ensure a
+ * defined endianness and consistent error codes: return 0 on success and 1 on
+ * fgetc()/fputc() failure.
+ */
+extern uint8_t read_uint8(FILE * file, uint8_t * x);
+extern uint8_t read_uint16_bigendian(FILE * file, uint16_t * x);
+extern uint8_t read_uint32_bigendian(FILE * file, uint32_t * x);
+extern uint8_t write_uint8(uint8_t x, FILE * file);
+extern uint8_t write_uint16_bigendian(uint16_t x, FILE * file);
+extern uint8_t write_uint32_bigendian(uint32_t x, FILE * file);
#endif