Feat: Add memcpy_dtoh to cust (#47)

to allow users of cust to also copy memory from device to host

Co-authored-by: Kjetil <kjetil@muybridge.xyz>

Author: kjetilkjeka

crates/cust/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 Notable changes to this project will be documented in this file.
 
+## Unreleased
+
+ - Add `memory::memcpy_dtoh` to allow copying from device to host.
+
 ## 0.3.2 - 2/16/22
 
 - Fixed `ModuleJitOptions` not working (due to cursed reasons).

crates/cust/src/memory/mod.rs

@@ -214,6 +214,17 @@ pub unsafe fn memcpy_htod(
     Ok(())
 }
 
+/// Simple wrapper over cuMemcpyDtoH_v2
+#[allow(clippy::missing_safety_doc)]
+pub unsafe fn memcpy_dtoh(
+    d_ptr: *mut c_void,
+    src_ptr: cust_raw::CUdeviceptr,
+    size: usize,
+) -> CudaResult<()> {
+    crate::sys::cuMemcpyDtoH_v2(d_ptr, src_ptr, size).to_result()?;
+    Ok(())
+}
+
 /// Get the current free and total memory.
 ///
 /// Returns in `.1` the total amount of memory available to the the current context.