1 files changed, 93 insertions, 0 deletions
diff --git a/tools/rust/src/nvme.rs b/tools/rust/src/nvme.rs
new file mode 100644
index 0000000..fdcec0e
--- /dev/null
+++ b/tools/rust/src/nvme.rs
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: MIT
+use crate::println;
+use alloc::boxed::Box;
+use core::cmp::min;
+use core::ffi::c_void;
+use fatfs::SeekFrom;
+
+extern "C" {
+    fn nvme_read(nsid: u32, lba: u64, buffer: *mut c_void) -> bool;
+}
+
+const SECTOR_SIZE: usize = 4096;
+
+pub type Error = ();
+
+#[repr(C, align(4096))]
+struct SectorBuffer([u8; SECTOR_SIZE]);
+
+fn alloc_sector_buf() -> Box<SectorBuffer> {
+    let p: Box<SectorBuffer> = unsafe { Box::new_zeroed().assume_init() };
+    debug_assert_eq!(0, p.0.as_ptr().align_offset(4096));
+    p
+}
+
+pub struct NVMEStorage {
+    nsid: u32,
+    offset: u64,
+    lba: Option<u64>,
+    buf: Box<SectorBuffer>,
+    pos: u64,
+}
+
+impl NVMEStorage {
+    pub fn new(nsid: u32, offset: u64) -> NVMEStorage {
+        NVMEStorage {
+            nsid: nsid,
+            offset: offset,
+            lba: None,
+            buf: alloc_sector_buf(),
+            pos: 0,
+        }
+    }
+}
+
+impl fatfs::IoBase for NVMEStorage {
+    type Error = Error;
+}
+
+impl fatfs::Read for NVMEStorage {
+    fn read(&mut self, mut buf: &mut [u8]) -> Result<usize, Self::Error> {
+        let mut read = 0;
+
+        while !buf.is_empty() {
+            let lba = self.pos / SECTOR_SIZE as u64;
+            let off = self.pos as usize % SECTOR_SIZE;
+
+            if Some(lba) != self.lba {
+                self.lba = Some(lba);
+                let lba = lba + self.offset;
+                if !unsafe { nvme_read(self.nsid, lba, self.buf.0.as_mut_ptr() as *mut c_void) } {
+                    println!("nvme_read({}, {}) failed", self.nsid, lba);
+                    return Err(());
+                }
+            }
+            let copy_len = min(SECTOR_SIZE - off, buf.len());
+            buf[..copy_len].copy_from_slice(&self.buf.0[off..off + copy_len]);
+            buf = &mut buf[copy_len..];
+            read += copy_len;
+            self.pos += copy_len as u64;
+        }
+        Ok(read)
+    }
+}
+
+impl fatfs::Write for NVMEStorage {
+    fn write(&mut self, _buf: &[u8]) -> Result<usize, Self::Error> {
+        Err(())
+    }
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        Err(())
+    }
+}
+
+impl fatfs::Seek for NVMEStorage {
+    fn seek(&mut self, from: SeekFrom) -> Result<u64, Self::Error> {
+        self.pos = match from {
+            SeekFrom::Start(n) => n,
+            SeekFrom::End(_n) => panic!("SeekFrom::End not supported"),
+            SeekFrom::Current(n) => self.pos.checked_add_signed(n).ok_or(())?,
+        };
+        Ok(self.pos)
+    }
+}