chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/memory/userptr.rs

@@ -0,0 +1,77 @@
+//! Operations specific to UserPtr-type buffers.
+
+use super::*;
+use crate::bindings;
+
+pub struct UserPtr;
+
+impl Memory for UserPtr {
+    const MEMORY_TYPE: MemoryType = MemoryType::UserPtr;
+    type RawBacking = core::ffi::c_ulong;
+
+    unsafe fn get_plane_buffer_backing(
+        m: &bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.userptr
+    }
+
+    unsafe fn get_single_planar_buffer_backing(
+        m: &bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.userptr
+    }
+
+    unsafe fn get_plane_buffer_backing_mut(
+        m: &mut bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.userptr
+    }
+
+    unsafe fn get_single_planar_buffer_backing_mut(
+        m: &mut bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.userptr
+    }
+}
+
+impl Imported for UserPtr {}
+
+/// Handle for a USERPTR plane. These buffers are backed by userspace-allocated
+/// memory, which translates well into Rust's slice of `u8`s. Since slices also
+/// carry size information, we know that we are not passing unallocated areas
+/// of the address-space to the kernel.
+///
+/// USERPTR buffers have the particularity that the `length` field of `struct
+/// v4l2_buffer` must be set before doing a `QBUF` ioctl. This handle struct
+/// also takes care of that.
+#[derive(Debug)]
+pub struct UserPtrHandle<T: AsRef<[u8]> + Debug + Send + 'static>(pub T);
+
+impl<T: AsRef<[u8]> + Debug + Send + Clone> Clone for UserPtrHandle<T> {
+    fn clone(&self) -> Self {
+        UserPtrHandle(self.0.clone())
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send + 'static> AsRef<[u8]> for UserPtrHandle<T> {
+    fn as_ref(&self) -> &[u8] {
+        self.0.as_ref()
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send> From<T> for UserPtrHandle<T> {
+    fn from(buffer: T) -> Self {
+        UserPtrHandle(buffer)
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send + 'static> PlaneHandle for UserPtrHandle<T> {
+    type Memory = UserPtr;
+
+    fn fill_v4l2_plane(&self, plane: &mut bindings::v4l2_plane) {
+        let slice = AsRef::<[u8]>::as_ref(&self.0);
+
+        plane.m.userptr = slice.as_ptr() as std::os::raw::c_ulong;
+        plane.length = slice.len() as u32;
+    }
+}