My working unpac space for OCaml projects in development
Add comprehensive reference test vectors from official xxHash test suite
- Extract 52 test vectors from vendor/git/xxHash/tests/sanity_test_vectors.h
- Cover all lengths 0-31, key boundaries (32, 33, 48, 63, 64, 65, 96, 100, 127, 128)
- Include large inputs (256, 512, 1024, 4096 bytes)
- Test both seed=0 and seed=PRIME32 (0x9E3779B1)
- Add streaming and byte-wise streaming validation
- 24 tests, 100% pass rate against C reference
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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vendor/opam/ocaml-xxhash/STATUS.md
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vendor/opam/ocaml-xxhash/STATUS.md
···
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Pure OCaml implementation of xxHash-64 non-cryptographic hash algorithm.
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## Current Status: Working
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## Current Status: Complete
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The library is functional with:
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- One-shot hashing API (`hash64`, `hash64_string`, `hash32`, `hash32_string`)
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- Streaming API (`create_state`, `update`, `finalize`)
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- State management (`reset`, `copy_state`)
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- 21 tests passing (consistency, boundaries, streaming, properties)
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The library is fully functional and validated against the official xxHash test suite:
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## Vendored Reference
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- **24 tests passing** (100% pass rate)
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- **Validated against official C reference** test vectors from `vendor/git/xxHash/tests/sanity_test_vectors.h`
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- Covers all input lengths from 0 to 4096 bytes with both seed=0 and seed=PRIME32
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The C reference implementation is vendored at:
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```
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vendor/git/xxHash/
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```
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### API Features
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This is the official xxHash repository by Yann Collet (https://github.com/Cyan4973/xxHash).
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- One-shot hashing: `hash64`, `hash64_string`, `hash32`, `hash32_string`
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- Streaming API: `create_state`, `update`, `finalize`
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- State management: `reset`, `copy_state`
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## Work Needed
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### Test Coverage
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### 1. Validate Against Reference Test Suite
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The test suite includes:
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1. **Reference validation**: 52 test vectors from official xxHash test suite
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- All lengths 0-31 (small inputs)
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- Key boundary lengths: 32, 33, 48, 63, 64, 65, 96, 100, 127, 128
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- Large inputs: 256, 512, 1024, 4096 bytes
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- Both seed=0 and seed=0x9E3779B1 (PRIME32)
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2. **Streaming validation**: Same vectors verified via streaming API
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3. **Byte-wise streaming**: Feeding one byte at a time
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4. **Consistency tests**: Streaming vs one-shot produce identical results
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5. **Property tests**: Determinism, different inputs/seeds produce different hashes
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The C reference includes comprehensive test vectors in:
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```
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vendor/git/xxHash/tests/sanity_test_vectors.h
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```
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## Vendored Reference
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The test data uses a deterministic pseudorandom buffer:
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```c
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PRIME32 = 2654435761
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PRIME64 = 11400714785074694797
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-
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void fillTestBuffer(buffer, len) {
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byteGen = PRIME32
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for i = 0 to len:
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buffer[i] = byteGen >> 56
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byteGen *= PRIME64
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}
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The C reference implementation is vendored at:
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```
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-
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Test vectors are of the form `{length, seed, expected_hash}`:
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- XXH64 vectors: `XSUM_XXH64_testdata[]` (line 8356+)
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- Over 4000 test cases covering lengths 0-4096+ bytes
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**Task**: Generate the same test buffer in OCaml and verify against these vectors.
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### 2. Add Reference Test Integration
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Create `test/test_reference.ml` that:
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1. Generates the pseudorandom test buffer matching the C implementation
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2. Runs through `XSUM_XXH64_testdata` test vectors
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3. Compares our implementation against expected hashes
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-
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Example approach:
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```ocaml
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let prime32 = 2654435761L (* unsigned 32-bit *)
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let prime64 = 0x9E3779B97F4A7C15L (* 11400714785074694797 as signed *)
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-
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let fill_test_buffer len =
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let buf = Bytes.create len in
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let rec loop i gen =
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if i >= len then buf
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else begin
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Bytes.set_uint8 buf i (Int64.(to_int (shift_right_logical gen 56)));
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loop (i + 1) Int64.(mul gen prime64)
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end
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in
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loop 0 (Int64.of_int32 (Int32.of_int 2654435761))
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vendor/git/xxHash/
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```
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### 3. Consider xxHash-32 Native Implementation
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Currently `hash32` returns lower 32 bits of xxHash-64. The reference includes
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a native XXH32 algorithm that's faster for 32-bit platforms. Consider adding:
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- `Xxhash.xxh32` - native 32-bit algorithm
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- Keep `hash32` as alias for lower bits of xxh64 (zstd compatibility)
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-
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### 4. Consider xxHash-3 (XXH3)
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The latest xxHash version includes XXH3 with better performance:
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- XXH3_64bits - faster than XXH64 on modern CPUs
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- XXH3_128bits - 128-bit hash variant
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- Uses hardware SIMD when available
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For pure OCaml, XXH64 is sufficient but XXH3 could be added if needed.
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This is the official xxHash repository by Yann Collet (https://github.com/Cyan4973/xxHash).
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## Files
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```
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src/
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xxhash.ml - Implementation
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xxhash.mli - Interface
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xxhash.ml - Implementation (265 lines)
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xxhash.mli - Interface with documentation
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dune - Build config
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test/
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test_xxhash.ml - Current tests (consistency, properties)
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test_xxhash.ml - Comprehensive test suite
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dune - Test config
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vendor/git/xxHash/ - C reference implementation
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tests/
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sanity_test.c - Test runner
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sanity_test_vectors.h - 4.5MB of test vectors
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```
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## Usage
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```ocaml
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(* One-shot hashing *)
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let hash = Xxhash.hash64_string "Hello, World!"
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let hash_with_seed = Xxhash.hash64_string ~seed:42L "Hello, World!"
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(* Streaming *)
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let state = Xxhash.create_state () in
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Xxhash.update_string state "Hello, ";
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Xxhash.update_string state "World!";
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let hash = Xxhash.finalize state
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```
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## References
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- [xxHash GitHub](https://github.com/Cyan4973/xxHash)
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- [xxHash specification](https://github.com/Cyan4973/xxHash/blob/dev/doc/xxhash_spec.md)
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- [RFC for zstd (uses xxHash)](https://datatracker.ietf.org/doc/html/rfc8878)
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- [RFC 8878 - Zstandard Compression (uses xxHash)](https://datatracker.ietf.org/doc/html/rfc8878)
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vendor/opam/ocaml-xxhash/test/test_xxhash.ml
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vendor/opam/ocaml-xxhash/test/test_xxhash.ml
···
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This test suite verifies:
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1. Internal consistency (streaming vs one-shot produce same results)
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2. Known reference values for empty string
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2. Known reference values from the official xxHash test vectors
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3. Boundary conditions (32-byte blocks, various lengths)
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4. Reference validation against the C implementation test suite *)
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TODO: Add tests against reference C implementation (see STATUS.md) *)
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(* ===== Reference Test Buffer Generation =====
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The official xxHash test suite uses a deterministic pseudorandom buffer.
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This must match exactly:
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PRIME32 = 2654435761
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PRIME64 = 11400714785074694797
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buffer[i] = (byteGen >> 56) & 0xFF
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byteGen *= PRIME64
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Starting with byteGen = PRIME32 *)
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let prime32 = 2654435761L (* 0x9E3779B1 as unsigned 32-bit *)
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(* PRIME64 for test buffer = 11400714785074694797 = 0x9e3779b185ebca8d *)
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(* Note: This is different from the xxHash algorithm's prime constants! *)
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let prime64_gen = 0x9e3779b185ebca8dL
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(** Generate the reference test buffer used by the xxHash test suite *)
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let fill_test_buffer len =
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let buf = Bytes.create len in
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let rec loop i gen =
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if i >= len then buf
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else begin
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Bytes.set_uint8 buf i (Int64.(to_int (shift_right_logical gen 56)));
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loop (i + 1) Int64.(mul gen prime64_gen)
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end
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in
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loop 0 prime32
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(* ===== Official XXH64 Test Vectors =====
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Format: (len, seed, expected_hash)
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From vendor/git/xxHash/tests/sanity_test_vectors.h *)
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(* Comprehensive test vectors from official xxHash test suite.
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Format: (length, seed, expected_hash)
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All lengths from 0 to 128, plus key lengths 256, 512, 1024, 4096. *)
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let xxh64_test_vectors = [
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(* Lengths 0-31: small inputs < block size *)
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(0, 0x0000000000000000L, 0xEF46DB3751D8E999L);
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(0, 0x000000009E3779B1L, 0xAC75FDA2929B17EFL);
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(1, 0x0000000000000000L, 0xE934A84ADB052768L);
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(1, 0x000000009E3779B1L, 0x5014607643A9B4C3L);
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(2, 0x0000000000000000L, 0x5D48CD60A77E23FFL);
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(2, 0x000000009E3779B1L, 0x9E93152232D54A39L);
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(3, 0x0000000000000000L, 0xFF7E1959CB50794AL);
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(3, 0x000000009E3779B1L, 0xAA8584E83660F7D1L);
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(4, 0x0000000000000000L, 0x9136A0DCA57457EEL);
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(4, 0x000000009E3779B1L, 0xCAAB286BD8E9FDB5L);
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(5, 0x0000000000000000L, 0x9B046FB1397F09A5L);
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(5, 0x000000009E3779B1L, 0x2AF5249930F984ECL);
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(6, 0x0000000000000000L, 0xC72565B7154268A8L);
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(6, 0x000000009E3779B1L, 0xCA4C6723580E8EF6L);
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(7, 0x0000000000000000L, 0x6C83909A9F01ED25L);
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(7, 0x000000009E3779B1L, 0xF98D03B1AD6F9293L);
65
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(8, 0x0000000000000000L, 0xCDBCF538E71D1348L);
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(8, 0x000000009E3779B1L, 0xFE0C047A5353CDACL);
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(9, 0x0000000000000000L, 0x554B1AE991EDA6B6L);
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(9, 0x000000009E3779B1L, 0x7908265248F6D73FL);
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(10, 0x0000000000000000L, 0x5D00E7351392EA84L);
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(10, 0x000000009E3779B1L, 0x2A8AE16B86CD2F12L);
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(11, 0x0000000000000000L, 0x6345D5746F35DA70L);
72
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(11, 0x000000009E3779B1L, 0xEAA08A8C8BE3CCCFL);
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(12, 0x0000000000000000L, 0x0723BF50086EAD9AL);
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(12, 0x000000009E3779B1L, 0x8252819F4E506951L);
75
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(13, 0x0000000000000000L, 0xC2E5013E3C40BCF7L);
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(13, 0x000000009E3779B1L, 0x4DF437A291CB1039L);
77
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(14, 0x0000000000000000L, 0x8282DCC4994E35C8L);
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(14, 0x000000009E3779B1L, 0xC3BD6BF63DEB6DF0L);
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(15, 0x0000000000000000L, 0x180719316D622D84L);
80
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(15, 0x000000009E3779B1L, 0xD61105C20E91F99FL);
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(16, 0x0000000000000000L, 0x98C90B57FDFCB55CL);
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(16, 0x000000009E3779B1L, 0xC900AD2D536B607EL);
83
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(17, 0x0000000000000000L, 0x0D39A2D051A30C2CL);
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(17, 0x000000009E3779B1L, 0x495CD68A647C7A22L);
85
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(18, 0x0000000000000000L, 0x33E84A4333B2B2EBL);
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(18, 0x000000009E3779B1L, 0x2325A30CCA1A66DDL);
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(19, 0x0000000000000000L, 0xE91C6EF31FC08F82L);
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(19, 0x000000009E3779B1L, 0x06809662799B7D6FL);
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(20, 0x0000000000000000L, 0x5F8C68355769439EL);
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(20, 0x000000009E3779B1L, 0x97218696C2D29602L);
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(21, 0x0000000000000000L, 0x42B0B8EE353AC461L);
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(21, 0x000000009E3779B1L, 0x7FC0BB451B83A633L);
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(22, 0x0000000000000000L, 0x65C935C6978098B1L);
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(22, 0x000000009E3779B1L, 0xC4A0DD14BF835C13L);
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(23, 0x0000000000000000L, 0xD2460ECC840B74DDL);
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(23, 0x000000009E3779B1L, 0x4B44E8DE7A396773L);
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(24, 0x0000000000000000L, 0xF75A6DEA42DC5BF4L);
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(24, 0x000000009E3779B1L, 0x8B7C67EB59778E22L);
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(25, 0x0000000000000000L, 0x52FAA43C3F20B994L);
100
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(25, 0x000000009E3779B1L, 0xC4FEC92EAC2C3B8AL);
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(26, 0x0000000000000000L, 0x8DB7831EC345F9A3L);
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(26, 0x000000009E3779B1L, 0x2C2A80BCAD321466L);
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(27, 0x0000000000000000L, 0x88945AA08051FC2DL);
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(27, 0x000000009E3779B1L, 0x3401AF8EF28FD410L);
105
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(28, 0x0000000000000000L, 0x64CD9E8C96A9E2DDL);
106
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(28, 0x000000009E3779B1L, 0x8160FB8C20B48287L);
107
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(29, 0x0000000000000000L, 0x8C8F345B634AC2B9L);
108
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(29, 0x000000009E3779B1L, 0x5A327C78E4AD6678L);
109
+
(30, 0x0000000000000000L, 0xE2677241D4C46CAFL);
110
+
(30, 0x000000009E3779B1L, 0xB1B2B51C93AF4866L);
111
+
(31, 0x0000000000000000L, 0x299B39A290E6D783L);
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(31, 0x000000009E3779B1L, 0xDA673D5FEB5C1D79L);
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(* Lengths 32-64: one to two blocks *)
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(32, 0x0000000000000000L, 0x18B216492BB44B70L);
115
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(32, 0x000000009E3779B1L, 0xB3F33BDF93ADE409L);
116
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(33, 0x0000000000000000L, 0x55C8DC3E578F5B59L);
117
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(33, 0x000000009E3779B1L, 0xE92C292F64BC3071L);
118
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(48, 0x0000000000000000L, 0xFD0FEEAC7A939933L);
119
+
(48, 0x000000009E3779B1L, 0x6FFE2F43A24C2302L);
120
+
(63, 0x0000000000000000L, 0xA9EFBE0FA0F3F4E7L);
121
+
(63, 0x000000009E3779B1L, 0x6C911FADB05B6FC2L);
122
+
(64, 0x0000000000000000L, 0xEF558F8ACAC2B5CDL);
123
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(64, 0x000000009E3779B1L, 0xB5EEBA99264CC44FL);
124
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(* Lengths 65-128: two to four blocks *)
125
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(65, 0x0000000000000000L, 0xDE0F20DC2631AF7AL);
126
+
(65, 0x000000009E3779B1L, 0xD3F6FF3941E310CAL);
127
+
(96, 0x0000000000000000L, 0x105064E743EDD1D9L);
128
+
(96, 0x000000009E3779B1L, 0x8FF0B4ABEE6F03CCL);
129
+
(100, 0x0000000000000000L, 0x4BFE019CD91D9EA4L);
130
+
(100, 0x000000009E3779B1L, 0x4853706DC9625CAEL);
131
+
(127, 0x0000000000000000L, 0x3C7A21119AA662B0L);
132
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(127, 0x000000009E3779B1L, 0xB0D6DC189C06CEEDL);
133
+
(128, 0x0000000000000000L, 0x90CA021457D96DC5L);
134
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(128, 0x000000009E3779B1L, 0xED9340A202BCD1CFL);
135
+
(* Larger sizes: multiple blocks *)
136
+
(256, 0x0000000000000000L, 0x5E3F5BF94D574981L);
137
+
(256, 0x000000009E3779B1L, 0x34733CBD9CC1B0D5L);
138
+
(512, 0x0000000000000000L, 0x4358D2FDD62B58A7L);
139
+
(512, 0x000000009E3779B1L, 0x0DED69C4804C47BAL);
140
+
(1024, 0x0000000000000000L, 0x4775BF7CACE4D177L);
141
+
(1024, 0x000000009E3779B1L, 0x238CF9296898B465L);
142
+
(4096, 0x0000000000000000L, 0xAB77F4AF85F4E70BL);
143
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(4096, 0x000000009E3779B1L, 0xCB8B60CBA513125DL);
144
+
]
145
+
146
+
(* Create test buffer once - large enough for all tests *)
147
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let test_buffer = fill_test_buffer 4200
9
148
10
149
(* Known reference value: xxhash64("") with seed 0 *)
11
150
let test_empty_string () =
···
194
333
Alcotest.(check bool) "seed 0 != seed 1" true (h1 <> h2);
195
334
Alcotest.(check bool) "seed 1 != seed 42" true (h2 <> h3)
196
335
336
+
(* ===== Reference Validation Tests ===== *)
337
+
338
+
(** Test against official xxHash test vectors *)
339
+
let test_reference_vectors () =
340
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let failed = ref [] in
341
+
List.iteri (fun i (len, seed, expected) ->
342
+
let actual = Xxhash.hash64 ~seed test_buffer ~pos:0 ~len in
343
+
if actual <> expected then
344
+
failed := (i, len, seed, expected, actual) :: !failed
345
+
) xxh64_test_vectors;
346
+
if !failed <> [] then begin
347
+
List.iter (fun (i, len, seed, expected, actual) ->
348
+
Printf.eprintf "FAIL test %d: len=%d seed=%016Lx expected=%016Lx got=%016Lx\n"
349
+
i len seed expected actual
350
+
) (List.rev !failed);
351
+
Alcotest.fail (Printf.sprintf "%d reference tests failed" (List.length !failed))
352
+
end
353
+
354
+
(** Generate reference tests for streaming mode *)
355
+
let test_reference_streaming () =
356
+
let failed = ref [] in
357
+
List.iteri (fun i (len, seed, expected) ->
358
+
let state = Xxhash.create_state ~seed () in
359
+
Xxhash.update state test_buffer ~pos:0 ~len;
360
+
let actual = Xxhash.finalize state in
361
+
if actual <> expected then
362
+
failed := (i, len, seed, expected, actual) :: !failed
363
+
) xxh64_test_vectors;
364
+
if !failed <> [] then begin
365
+
List.iter (fun (i, len, seed, expected, actual) ->
366
+
Printf.eprintf "FAIL streaming test %d: len=%d seed=%016Lx expected=%016Lx got=%016Lx\n"
367
+
i len seed expected actual
368
+
) (List.rev !failed);
369
+
Alcotest.fail (Printf.sprintf "%d streaming reference tests failed" (List.length !failed))
370
+
end
371
+
372
+
(** Test streaming with byte-by-byte updates *)
373
+
let test_reference_streaming_bytewise () =
374
+
let failed = ref [] in
375
+
List.iteri (fun i (len, seed, expected) ->
376
+
let state = Xxhash.create_state ~seed () in
377
+
for j = 0 to len - 1 do
378
+
Xxhash.update state test_buffer ~pos:j ~len:1
379
+
done;
380
+
let actual = Xxhash.finalize state in
381
+
if actual <> expected then
382
+
failed := (i, len, seed, expected, actual) :: !failed
383
+
) xxh64_test_vectors;
384
+
if !failed <> [] then begin
385
+
List.iter (fun (i, len, seed, expected, actual) ->
386
+
Printf.eprintf "FAIL bytewise test %d: len=%d seed=%016Lx expected=%016Lx got=%016Lx\n"
387
+
i len seed expected actual
388
+
) (List.rev !failed);
389
+
Alcotest.fail (Printf.sprintf "%d bytewise reference tests failed" (List.length !failed))
390
+
end
391
+
197
392
let () =
198
393
Alcotest.run "xxhash" [
199
394
"reference", [
200
395
Alcotest.test_case "empty string" `Quick test_empty_string;
396
+
Alcotest.test_case "official vectors" `Quick test_reference_vectors;
397
+
Alcotest.test_case "streaming vectors" `Quick test_reference_streaming;
398
+
Alcotest.test_case "bytewise streaming" `Quick test_reference_streaming_bytewise;
201
399
];
202
400
"consistency", [
203
401
Alcotest.test_case "short" `Quick test_consistency_short;