Backend refactor (#120)

* remove spqlios, split cpu_ref and cpu_avx into different crates

* remove spqlios submodule

* update crate naming & add avx tests

poulpy-cpu-avx/src/scratch.rs

@@ -0,0 +1,81 @@
+use std::marker::PhantomData;
+
+use poulpy_hal::{
+    DEFAULTALIGN, alloc_aligned,
+    api::ScratchFromBytes,
+    layouts::{Backend, Scratch, ScratchOwned},
+    oep::{ScratchAvailableImpl, ScratchFromBytesImpl, ScratchOwnedAllocImpl, ScratchOwnedBorrowImpl, TakeSliceImpl},
+};
+
+use crate::FFT64Avx;
+
+unsafe impl<B: Backend> ScratchOwnedAllocImpl<B> for FFT64Avx {
+    fn scratch_owned_alloc_impl(size: usize) -> ScratchOwned<B> {
+        let data: Vec<u8> = alloc_aligned(size);
+        ScratchOwned {
+            data,
+            _phantom: PhantomData,
+        }
+    }
+}
+
+unsafe impl<B: Backend> ScratchOwnedBorrowImpl<B> for FFT64Avx
+where
+    B: ScratchFromBytesImpl<B>,
+{
+    fn scratch_owned_borrow_impl(scratch: &mut ScratchOwned<B>) -> &mut Scratch<B> {
+        Scratch::from_bytes(&mut scratch.data)
+    }
+}
+
+unsafe impl<B: Backend> ScratchFromBytesImpl<B> for FFT64Avx {
+    fn scratch_from_bytes_impl(data: &mut [u8]) -> &mut Scratch<B> {
+        unsafe { &mut *(data as *mut [u8] as *mut Scratch<B>) }
+    }
+}
+
+unsafe impl<B: Backend> ScratchAvailableImpl<B> for FFT64Avx {
+    fn scratch_available_impl(scratch: &Scratch<B>) -> usize {
+        let ptr: *const u8 = scratch.data.as_ptr();
+        let self_len: usize = scratch.data.len();
+        let aligned_offset: usize = ptr.align_offset(DEFAULTALIGN);
+        self_len.saturating_sub(aligned_offset)
+    }
+}
+
+unsafe impl<B: Backend> TakeSliceImpl<B> for FFT64Avx
+where
+    B: ScratchFromBytesImpl<B>,
+{
+    fn take_slice_impl<T>(scratch: &mut Scratch<B>, len: usize) -> (&mut [T], &mut Scratch<B>) {
+        let (take_slice, rem_slice) = take_slice_aligned(&mut scratch.data, len * std::mem::size_of::<T>());
+
+        unsafe {
+            (
+                &mut *(std::ptr::slice_from_raw_parts_mut(take_slice.as_mut_ptr() as *mut T, len)),
+                Scratch::from_bytes(rem_slice),
+            )
+        }
+    }
+}
+
+fn take_slice_aligned(data: &mut [u8], take_len: usize) -> (&mut [u8], &mut [u8]) {
+    let ptr: *mut u8 = data.as_mut_ptr();
+    let self_len: usize = data.len();
+
+    let aligned_offset: usize = ptr.align_offset(DEFAULTALIGN);
+    let aligned_len: usize = self_len.saturating_sub(aligned_offset);
+
+    if let Some(rem_len) = aligned_len.checked_sub(take_len) {
+        unsafe {
+            let rem_ptr: *mut u8 = ptr.add(aligned_offset).add(take_len);
+            let rem_slice: &mut [u8] = &mut *std::ptr::slice_from_raw_parts_mut(rem_ptr, rem_len);
+
+            let take_slice: &mut [u8] = &mut *std::ptr::slice_from_raw_parts_mut(ptr.add(aligned_offset), take_len);
+
+            (take_slice, rem_slice)
+        }
+    } else {
+        panic!("Attempted to take {take_len} from scratch with {aligned_len} aligned bytes left");
+    }
+}