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hamt: doc comments and cleanup

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This commit is contained in:
Edward Amsden 2023-12-09 11:46:47 -06:00
parent 95e05b2dad
commit baebb515e2
1 changed files with 11 additions and 5 deletions
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16
rust/ares/src/hamt.rs
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@ -162,6 +162,17 @@ impl<T: Copy> MutHamt<T> {
}
}
/**
* This is the core memory structure of an immutable HAMT.
*
* The root Stem lives in its own memory allocation, addressed by the pointer wrapped by [Hamt].
* All other Stems and Leaves live in memory blocks pointed to by [buffer]. The memory pointed to
* by this field may be zero to 32 entries, depending on the *number of bits set* in bitmap.
*
* Addressing a chunk of the key's hash is done by counting the number of set bits in the bitmap
* before the chunk'th bit. The typemap is a parallel bitmap in which bits are set if the
* corresponding entry is a stem, and cleared if it is a leaf.
*/
#[repr(packed)]
#[repr(C)]
struct Stem<T: Copy> {
@ -643,8 +654,6 @@ impl<T: Copy + Persist> Persist for Hamt<T> {
}
}
// XX this is subtly wrong, we need to track destination pointers somehow and not just write
// into the traversal stack
unsafe fn copy_to_buffer(&mut self, stack: &mut NockStack, pma: &PMA, buffer: &mut *mut u8) {
if pma.contains(self.0, 1) {
return;
@ -704,7 +713,6 @@ impl<T: Copy + Persist> Persist for Hamt<T> {
traversal[depth + 1] = *stem_ptr;
depth += 1;
continue;
} else {
// Leaf case
let leaf_ptr: *mut Leaf<T> = &mut (*next_entry_ptr).leaf;
@ -727,8 +735,6 @@ impl<T: Copy + Persist> Persist for Hamt<T> {
leaf_idx += 1;
}
continue;
}
}
}