Refactor exec_jec #207

uncomputable · 2024-02-14T18:13:04Z

A small change that fits into no other PR.

uncomputable · 2024-02-14T18:25:07Z

Added another bugfix that fits nowhere else.

src/bit_machine/mod.rs

The lifetime of the error message was tied to the lifetime of the Value.

We have already generalized Arc<Transaction>

Add getters for members that we read. Clarify that the unit of `len` is bits.

uncomputable · 2024-02-20T09:17:29Z

Rebased on master. Creating the buffers inside the helper methods is much cleaner than passing mutable references. Added assertions that the active read / write frame are large enough. Resolved misunderstanding that jet source / target type is as wide as active read / write frame (actually the relation is type ≤ frame).

apoelstra · 2024-02-20T17:39:20Z

src/bit_machine/mod.rs

+        /// ## Panics
+        ///
+        /// Active read frame has fewer bits than `bit_width`.
+        unsafe fn get_input_frame(


In b561354:

Ok, awesome, this is looking much cleaner.

Should add a ## Safety section to the doc simply saying that it returns a CFrameItem which points into the returned Vec and that the Vec must outlive the CFrameItem.

Alternately we could create a new opaque type struct BackedCFrameItem which holds the Vec, implements Deref<CFrameItem>, and which would then ensure that you were obeying the lifetime rules. I think that if you did this, you could eliminate unsafe from this method.

Ok, will do. I haven't been working much with unsafe, so these comments on how to write unsafe Rust (somewhat) safely are appreciated :)

apoelstra · 2024-02-20T17:40:14Z

src/bit_machine/mod.rs

+        /// ## Panics
+        ///
+        /// Active write frame has fewer bits than `bit_width`.
+        fn update_active_write_frame(mac: &mut BitMachine, bit_width: usize, buffer: &[UWORD]) {


In b561354:

Here you still need unsafe because the passed buffer might now be wide enough for your c_readBit calls. I think you can add another assert! that buffer.len() is the right length to avoid this unsafety.

Split the function into parts: 1. Write input to C read frame 2. Prepare output C write frame 3. Execute jet 4. Read output from C write frame I also find it easier to keep separate input and output buffers. Both buffers are allocated with their final capacity so the performance should be the same. Introduce active_{read, write}_bit_width methods to keep code better readable.

apoelstra

ACK 44d20a9

apoelstra reviewed Feb 15, 2024

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