From cd25fe0560f746bedad0d16c173deeaa8db6b562 Mon Sep 17 00:00:00 2001
From: "Alejandro W. Sior" <aho@sior.be>
Date: Fri, 10 Feb 2023 19:24:23 +0100
Subject: initial commit

---
 bfs/bootsector.ha | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 bfs/bootsector.ha

(limited to 'bfs/bootsector.ha')

diff --git a/bfs/bootsector.ha b/bfs/bootsector.ha
new file mode 100644
index 0000000..dcf33dd
--- /dev/null
+++ b/bfs/bootsector.ha
@@ -0,0 +1,41 @@
+// BFS bootsector, first 512 bytes of a block device
+export type bootsector = struct {
+	// Signature of BFS, 0xCAAA
+	@offset(446) signature: u16,
+
+	// LBA of lowest yet unallocated
+	// free block
+	@offset(448) freeblock: u64,
+
+	// LBA of next block in block
+	// freelist
+	@offset(456) nextblock: u64,
+	@offset(464) lastblock: u64,
+
+	// Inode ID of next free inode block
+	@offset(472) nextinblk: u64,
+	@offset(480) lastinblk: u64,
+
+	// Inode ID of root directory
+	@offset(488) rootinode: u64,
+
+	// Log2 of size of blocks on filesystem 
+	@offset(496) blocksize: u8,
+};
+
+// Fill a bootsector with everything necessary for it to be valid
+export fn bootsector_make(self: *bootsector, rsvdblocks: u64) void = {
+	self.signature = 0xCAAA;
+	self.freeblock = rsvdblocks + 1;
+	self.nextblock = 0;
+	self.lastblock = 0;
+	self.nextinblk = 0;
+	self.lastinblk = 0;
+	self.rootinode = 0;
+	self.blocksize = 12;
+};
+
+// Return whether the bootsector is valid
+export fn bootsector_validate(self: *bootsector) bool = {
+	return self.signature == 0xCAAA;
+};
-- 
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