From eee71b0597bab6329d66bb046b5bb9c19ae79b39 Mon Sep 17 00:00:00 2001
From: Steve Dibb <steve.dibb@gmail.com>
Date: Sat, 23 May 2020 18:43:55 -0600
Subject: [PATCH] Add bluray_chapter files

---
 bluray_chapter.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++
 bluray_chapter.h |  14 ++++++
 2 files changed, 125 insertions(+)
 create mode 100644 bluray_chapter.c
 create mode 100644 bluray_chapter.h

diff --git a/bluray_chapter.c b/bluray_chapter.c
new file mode 100644
index 0000000..d1140a2
--- /dev/null
+++ b/bluray_chapter.c
@@ -0,0 +1,111 @@
+#include "bluray_chapter.h"
+
+uint64_t bluray_chapter_first_position(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix) {
+
+	int32_t retval = 0;
+	retval = bd_select_title(bd, title_ix);
+
+	if(retval == 0)
+		return 0;
+
+	struct bd_title_info *bluray_title_info = NULL;
+	bluray_title_info = bd_get_title_info(bd, title_ix, 0);
+
+	if(bluray_title_info == NULL)
+		return 0;
+
+	uint32_t chapter_number;
+	chapter_number = chapter_ix + 1;
+
+	if(chapter_number > bluray_title_info->chapter_count)
+		return 0;
+
+	// libbluray.h has two functions to jump to a chapter and return a seek position.
+	// The first one, bd_seek_chapter returns the seek position after jumping to it,
+	// while the second one specifically is documented to return its start position.
+	// To be safe, jump to the chapter first, although it may not be needed.
+	bd_seek_chapter(bd, chapter_ix);
+
+	uint64_t position;
+	position = (uint64_t)bd_chapter_pos(bd, chapter_ix);
+
+	return position;
+
+}
+
+uint64_t bluray_chapter_last_position(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix) {
+
+	// Start with the first position. It's not safe to assume that it's
+	// already been checked before this.
+	uint64_t first_position = 0;
+	first_position = bluray_chapter_first_position(bd, title_ix, chapter_ix);
+
+	int32_t retval = 0;
+	retval = bd_select_title(bd, title_ix);
+
+	if(retval == 0)
+		return 0;
+
+	// Selecting other than the first angle is not supported right now
+	uint32_t angle = 0;
+
+	struct bd_title_info *bluray_title_info = NULL;
+	bluray_title_info = bd_get_title_info(bd, title_ix, angle);
+
+	if(bluray_title_info == NULL)
+		return 0;
+
+	uint32_t chapter_number;
+	chapter_number = chapter_ix + 1;
+
+	if(chapter_number > bluray_title_info->chapter_count)
+		return 0;
+
+	uint64_t last_position = 0;
+
+	// If only one chapter, or the final one, return the title size as the last position
+	if(bluray_title_info->chapter_count == 1 || chapter_number == bluray_title_info->chapter_count) {
+		// Casting this here makes me nervous, even though the highest a position
+		last_position = bd_get_title_size(bd);
+	}
+
+	// If this not the final chapter, simply calculate the position against the
+	// next chapter's position.
+	if(chapter_number != bluray_title_info->chapter_count) {
+		last_position = bluray_chapter_first_position(bd, title_ix, chapter_ix + 1);
+	}
+
+	// This shouldn't happen
+	if(last_position < first_position)
+		last_position = first_position;
+
+	return last_position;
+
+}
+
+/**
+ * In libbluray, number of bytes is the same value as the distance between positions.
+ *
+ * Each title has a padding of 768 bytes at its front, add it to the first chapter.
+ */
+
+uint64_t bluray_chapter_size(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix) {
+
+	uint64_t size;
+	uint64_t first_position;
+	uint64_t last_position;
+
+	first_position = bluray_chapter_first_position(bd, title_ix, chapter_ix);
+	last_position = bluray_chapter_last_position(bd, title_ix, chapter_ix);
+
+	if(last_position < first_position)
+		return 0;
+
+	size = last_position - first_position;
+
+	if(chapter_ix == 0)
+		size += 768;
+
+	return size;
+
+}
diff --git a/bluray_chapter.h b/bluray_chapter.h
new file mode 100644
index 0000000..9bdd9f3
--- /dev/null
+++ b/bluray_chapter.h
@@ -0,0 +1,14 @@
+#ifndef BLURAY_CHAPTER_H
+#define BLURAY_CHAPTER_H
+
+#include <stdlib.h>
+#include <inttypes.h>
+#include "libbluray/bluray.h"
+
+uint64_t bluray_chapter_first_position(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix);
+
+uint64_t bluray_chapter_last_position(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix);
+
+uint64_t bluray_chapter_size(struct bluray *bd, const uint32_t title_ix, const uint32_t chapter_ix);
+
+#endif