docs, obfuscation

ndk/obfuscate/obfuscate_file.h

@@ -0,0 +1,28 @@
+#ifndef OBFUSCATE_FILE_H
+#define OBFUSCATE_FILE_H
+
+#include "obfuscate.h"
+#include <stddef.h>
+#include <stdint.h>
+
+/* 32-bit dummy header/tail — skipped by decode; only uint64_t payloads are processed. */
+#define OBF_FILE_HDR_SIZE  4u
+#define OBF_FILE_TAIL_SIZE 4u
+#define OBF_FILE_OVERHEAD  (OBF_FILE_HDR_SIZE + OBF_FILE_TAIL_SIZE)
+
+#define OBF_ERR_IO        -4
+#define OBF_ERR_FORMAT    -5
+#define OBF_ERR_OVERFLOW  -6
+
+int32_t write_to(const char *path, uint64_t val, uint64_t seed);
+int32_t read_from(const char *path, uint64_t seed, uint64_t *out);
+
+int32_t write_many_to(const char *path, const uint64_t *vals, size_t count, uint64_t seed);
+
+int32_t read_many_from(const char *path, uint64_t seed, uint64_t *out_vals, size_t out_cap,
+		       size_t *out_count);
+
+/* How many uint64_t payloads are stored (excludes 32-bit head/tail). */
+int32_t obf_file_payload_count(long file_size, size_t *count_out);
+
+#endif /* OBFUSCATE_FILE_H */