Merge pull request #2572 from plaes/nrf-spim-chunked-dma

NRF: Implement chunked DMA transfers for SPIM

1 files changed, 13 insertions, 0 deletions

diff --git a/embassy-nrf/src/util.rs b/embassy-nrf/src/util.rs
index b408c517b..6cdb97f08 100644
--- a/embassy-nrf/src/util.rs
+++ b/embassy-nrf/src/util.rs
@@ -4,6 +4,19 @@ use core::mem;
 const SRAM_LOWER: usize = 0x2000_0000;
 const SRAM_UPPER: usize = 0x3000_0000;
 
+// #![feature(const_slice_ptr_len)]
+// https://github.com/rust-lang/rust/issues/71146
+pub(crate) fn slice_ptr_len<T>(ptr: *const [T]) -> usize {
+    use core::ptr::NonNull;
+    let ptr = ptr.cast_mut();
+    if let Some(ptr) = NonNull::new(ptr) {
+        ptr.len()
+    } else {
+        // We know ptr is null, so we know ptr.wrapping_byte_add(1) is not null.
+        NonNull::new(ptr.wrapping_byte_add(1)).unwrap().len()
+    }
+}
+
 // TODO: replace transmutes with core::ptr::metadata once it's stable
 pub(crate) fn slice_ptr_parts<T>(slice: *const [T]) -> (*const T, usize) {
     unsafe { mem::transmute(slice) }