feat(mt): move compression job creation policy into Rust

Move the multithreaded compression job-creation decision tree into a Rust
projection while keeping C-owned job descriptors, input buffers, pools,
synchronization, worker callbacks, and terminal empty-block serialization
behind explicit callbacks. The Rust policy now preserves ring-table full
checks, prepared-job retry state, prefix advancement, frame checksum rules,
and the non-first empty terminal job path without crossing private C layouts.

Test Plan:
- cargo test --manifest-path rust/Cargo.toml --all-targets -- --test-threads=1
- cargo test --manifest-path rust/Cargo.toml --no-default-features --features compression,decompression,dict-builder,legacy-v01,legacy-v02,legacy-v03,legacy-v04,legacy-v05,legacy-v06,legacy-v07 --all-targets -- --test-threads=1
- cargo clippy --manifest-path rust/Cargo.toml --all-targets -- -D warnings
- make -B -C lib -j2 lib
- make -B -C tests -j2 test-zstd test-pool test-legacy test-invalidDictionaries
This commit is contained in:
2026-07-18 23:28:36 +02:00
parent e38c14b324
commit 45d54a71ad
2 changed files with 499 additions and 66 deletions
+142 -66
View File
@@ -202,6 +202,56 @@ ZSTDMT_RustEmptyBlockResult ZSTDMT_rust_writeLastEmptyBlock(
const ZSTDMT_RustEmptyBlockJobProjection* projection,
void* opaque, ZSTDMT_bufferGetFn getBuffer);
typedef struct {
unsigned doneJobID;
unsigned nextJobID;
unsigned jobIDMask;
unsigned jobReady;
const void* srcStart;
size_t srcSize;
size_t inBuffFilled;
const void* prefixStart;
size_t prefixSize;
size_t targetPrefixSize;
unsigned endFrame;
unsigned checksumFlag;
} ZSTDMT_RustCreateJobProjection;
typedef struct {
const void* srcStart;
size_t srcSize;
const void* prefixStart;
size_t prefixSize;
const void* nextPrefixStart;
size_t nextPrefixSize;
size_t roundBuffPosDelta;
unsigned jobNumber;
unsigned firstJob;
unsigned lastJob;
unsigned frameChecksumNeeded;
unsigned clearChecksumFlag;
} ZSTDMT_RustJobInitialization;
typedef struct {
size_t returnCode;
unsigned action;
unsigned jobID;
unsigned jobNumber;
unsigned nextJobID;
unsigned jobReady;
} ZSTDMT_RustCreateJobResult;
enum {
ZSTDMT_CREATE_JOB_TABLE_FULL = 0,
ZSTDMT_CREATE_JOB_POST = 1,
ZSTDMT_CREATE_JOB_EMPTY = 2
};
typedef void (*ZSTDMT_prepareJobFn)(void* opaque, unsigned jobID,
const ZSTDMT_RustJobInitialization* init);
typedef void (*ZSTDMT_writeEmptyJobFn)(void* opaque, unsigned jobID);
typedef int (*ZSTDMT_tryAddJobFn)(void* opaque, unsigned jobID);
ZSTDMT_RustCreateJobResult ZSTDMT_rust_createCompressionJob(
const ZSTDMT_RustCreateJobProjection* projection,
void* opaque, ZSTDMT_prepareJobFn prepareJob,
ZSTDMT_writeEmptyJobFn writeEmptyJob, ZSTDMT_tryAddJobFn tryAddJob);
typedef struct {
rawSeq* seq;
size_t pos;
@@ -1477,82 +1527,108 @@ static void ZSTDMT_writeLastEmptyBlock(ZSTDMT_jobDescription* job)
assert(!ZSTD_isError(job->cSize));
}
static void ZSTDMT_prepareCompressionJob(
void* opaque, unsigned jobID,
const ZSTDMT_RustJobInitialization* initialization)
{
ZSTDMT_CCtx* const mtctx = (ZSTDMT_CCtx*)opaque;
ZSTDMT_jobDescription* const job = &mtctx->jobs[jobID];
BYTE const* const src = (const BYTE*)initialization->srcStart;
DEBUGLOG(5, "ZSTDMT_createCompressionJob: preparing job %u to compress %u bytes with %u preload ",
initialization->jobNumber, (U32)initialization->srcSize,
(U32)initialization->prefixSize);
assert(mtctx->inBuff.filled >= initialization->srcSize);
job->src = (Range){ src, initialization->srcSize };
job->prefix = (Range){
(const BYTE*)initialization->prefixStart, initialization->prefixSize
};
job->consumed = 0;
job->cSize = 0;
job->params = mtctx->params;
job->cdict = initialization->firstJob ? mtctx->cdict : NULL;
job->fullFrameSize = mtctx->frameContentSize;
job->dstBuff = g_nullBuffer;
job->cctxPool = mtctx->cctxPool;
job->bufPool = mtctx->bufPool;
job->seqPool = mtctx->seqPool;
job->serial = &mtctx->serial;
job->jobID = initialization->jobNumber;
job->firstJob = initialization->firstJob;
job->lastJob = initialization->lastJob;
job->frameChecksumNeeded = initialization->frameChecksumNeeded;
job->dstFlushed = 0;
/* Update the round buffer position and clear the input buffer to be reset. */
mtctx->roundBuff.pos += initialization->roundBuffPosDelta;
mtctx->inBuff.buffer = g_nullBuffer;
mtctx->inBuff.filled = 0;
mtctx->inBuff.prefix = (Range){
(const BYTE*)initialization->nextPrefixStart,
initialization->nextPrefixSize
};
if (initialization->lastJob) {
mtctx->frameEnded = 1;
if (initialization->clearChecksumFlag)
mtctx->params.fParams.checksumFlag = 0;
}
}
static void ZSTDMT_writeEmptyCompressionJob(void* opaque, unsigned jobID)
{
ZSTDMT_CCtx* const mtctx = (ZSTDMT_CCtx*)opaque;
ZSTDMT_writeLastEmptyBlock(&mtctx->jobs[jobID]);
}
static int ZSTDMT_tryAddCompressionJob(void* opaque, unsigned jobID)
{
ZSTDMT_CCtx* const mtctx = (ZSTDMT_CCtx*)opaque;
return POOL_tryAdd(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[jobID]);
}
static size_t ZSTDMT_createCompressionJob(ZSTDMT_CCtx* mtctx, size_t srcSize, ZSTD_EndDirective endOp)
{
unsigned const jobID = mtctx->nextJobID & mtctx->jobIDMask;
int const endFrame = (endOp == ZSTD_e_end);
ZSTDMT_RustCreateJobProjection const projection = {
mtctx->doneJobID,
mtctx->nextJobID,
mtctx->jobIDMask,
mtctx->jobReady,
mtctx->inBuff.buffer.start,
srcSize,
mtctx->inBuff.filled,
mtctx->inBuff.prefix.start,
mtctx->inBuff.prefix.size,
mtctx->targetPrefixSize,
(unsigned)(endOp == ZSTD_e_end),
(unsigned)mtctx->params.fParams.checksumFlag
};
ZSTDMT_RustCreateJobResult const result = ZSTDMT_rust_createCompressionJob(
&projection, mtctx, ZSTDMT_prepareCompressionJob,
ZSTDMT_writeEmptyCompressionJob, ZSTDMT_tryAddCompressionJob);
if (mtctx->nextJobID > mtctx->doneJobID + mtctx->jobIDMask) {
if (result.action == ZSTDMT_CREATE_JOB_TABLE_FULL) {
DEBUGLOG(5, "ZSTDMT_createCompressionJob: will not create new job : table is full");
assert((mtctx->nextJobID & mtctx->jobIDMask) == (mtctx->doneJobID & mtctx->jobIDMask));
return 0;
return result.returnCode;
}
if (!mtctx->jobReady) {
BYTE const* src = (BYTE const*)mtctx->inBuff.buffer.start;
DEBUGLOG(5, "ZSTDMT_createCompressionJob: preparing job %u to compress %u bytes with %u preload ",
mtctx->nextJobID, (U32)srcSize, (U32)mtctx->inBuff.prefix.size);
mtctx->jobs[jobID].src.start = src;
mtctx->jobs[jobID].src.size = srcSize;
assert(mtctx->inBuff.filled >= srcSize);
mtctx->jobs[jobID].prefix = mtctx->inBuff.prefix;
mtctx->jobs[jobID].consumed = 0;
mtctx->jobs[jobID].cSize = 0;
mtctx->jobs[jobID].params = mtctx->params;
mtctx->jobs[jobID].cdict = mtctx->nextJobID==0 ? mtctx->cdict : NULL;
mtctx->jobs[jobID].fullFrameSize = mtctx->frameContentSize;
mtctx->jobs[jobID].dstBuff = g_nullBuffer;
mtctx->jobs[jobID].cctxPool = mtctx->cctxPool;
mtctx->jobs[jobID].bufPool = mtctx->bufPool;
mtctx->jobs[jobID].seqPool = mtctx->seqPool;
mtctx->jobs[jobID].serial = &mtctx->serial;
mtctx->jobs[jobID].jobID = mtctx->nextJobID;
mtctx->jobs[jobID].firstJob = (mtctx->nextJobID==0);
mtctx->jobs[jobID].lastJob = endFrame;
mtctx->jobs[jobID].frameChecksumNeeded = mtctx->params.fParams.checksumFlag && endFrame && (mtctx->nextJobID>0);
mtctx->jobs[jobID].dstFlushed = 0;
/* Update the round buffer pos and clear the input buffer to be reset */
mtctx->roundBuff.pos += srcSize;
mtctx->inBuff.buffer = g_nullBuffer;
mtctx->inBuff.filled = 0;
/* Set the prefix for next job */
if (!endFrame) {
size_t const newPrefixSize = MIN(srcSize, mtctx->targetPrefixSize);
mtctx->inBuff.prefix.start = src + srcSize - newPrefixSize;
mtctx->inBuff.prefix.size = newPrefixSize;
} else { /* endFrame==1 => no need for another input buffer */
mtctx->inBuff.prefix = kNullRange;
mtctx->frameEnded = endFrame;
if (mtctx->nextJobID == 0) {
/* single job exception : checksum is already calculated directly within worker thread */
mtctx->params.fParams.checksumFlag = 0;
} }
if ( (srcSize == 0)
&& (mtctx->nextJobID>0)/*single job must also write frame header*/ ) {
DEBUGLOG(5, "ZSTDMT_createCompressionJob: creating a last empty block to end frame");
assert(endOp == ZSTD_e_end); /* only possible case : need to end the frame with an empty last block */
ZSTDMT_writeLastEmptyBlock(mtctx->jobs + jobID);
mtctx->nextJobID++;
return 0;
}
mtctx->nextJobID = result.nextJobID;
mtctx->jobReady = result.jobReady;
if (result.action == ZSTDMT_CREATE_JOB_EMPTY) {
DEBUGLOG(5, "ZSTDMT_createCompressionJob: creating a last empty block to end frame");
assert(endOp == ZSTD_e_end); /* only possible case : need to end the frame with an empty last block */
return result.returnCode;
}
DEBUGLOG(5, "ZSTDMT_createCompressionJob: posting job %u : %u bytes (end:%u, jobNb == %u (mod:%u))",
mtctx->nextJobID,
(U32)mtctx->jobs[jobID].src.size,
mtctx->jobs[jobID].lastJob,
mtctx->nextJobID,
jobID);
if (POOL_tryAdd(mtctx->factory, ZSTDMT_compressionJob, &mtctx->jobs[jobID])) {
mtctx->nextJobID++;
mtctx->jobReady = 0;
} else {
DEBUGLOG(5, "ZSTDMT_createCompressionJob: no worker available for job %u", mtctx->nextJobID);
mtctx->jobReady = 1;
}
return 0;
result.jobNumber,
(U32)mtctx->jobs[result.jobID].src.size,
mtctx->jobs[result.jobID].lastJob,
result.jobNumber,
result.jobID);
if (result.jobReady)
DEBUGLOG(5, "ZSTDMT_createCompressionJob: no worker available for job %u", result.jobNumber);
return result.returnCode;
}
+357
View File
@@ -240,6 +240,207 @@ pub unsafe extern "C" fn ZSTDMT_rust_writeLastEmptyBlock(
unsafe { write_last_empty_block_with(projection, || get_buffer(opaque)) }
}
const CREATE_JOB_TABLE_FULL: c_uint = 0;
const CREATE_JOB_POST: c_uint = 1;
const CREATE_JOB_EMPTY: c_uint = 2;
/// Scalar MT state supplied by C for one compression-job creation attempt.
///
/// The job descriptor, input-buffer ownership, and synchronization objects
/// remain private to C. Rust owns the ring-capacity and scheduling policy over
/// this scalar view.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTDMT_createJobProjection {
pub doneJobID: c_uint,
pub nextJobID: c_uint,
pub jobIDMask: c_uint,
pub jobReady: c_uint,
pub srcStart: *const c_void,
pub srcSize: usize,
pub inBuffFilled: usize,
pub prefixStart: *const c_void,
pub prefixSize: usize,
pub targetPrefixSize: usize,
pub endFrame: c_uint,
pub checksumFlag: c_uint,
}
/// The scalar fields needed by C to initialize its private job descriptor and
/// the surrounding input state after Rust chooses to prepare a new job.
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTDMT_jobInitialization {
pub srcStart: *const c_void,
pub srcSize: usize,
pub prefixStart: *const c_void,
pub prefixSize: usize,
pub nextPrefixStart: *const c_void,
pub nextPrefixSize: usize,
pub roundBuffPosDelta: usize,
pub jobNumber: c_uint,
pub firstJob: c_uint,
pub lastJob: c_uint,
pub frameChecksumNeeded: c_uint,
pub clearChecksumFlag: c_uint,
}
#[repr(C)]
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct ZSTDMT_createJobResult {
pub returnCode: usize,
pub action: c_uint,
pub jobID: c_uint,
pub jobNumber: c_uint,
pub nextJobID: c_uint,
pub jobReady: c_uint,
}
pub type ZSTDMT_prepareJobFn = unsafe extern "C" fn(
opaque: *mut c_void,
job_id: c_uint,
initialization: *const ZSTDMT_jobInitialization,
);
pub type ZSTDMT_writeEmptyJobFn = unsafe extern "C" fn(opaque: *mut c_void, job_id: c_uint);
pub type ZSTDMT_tryAddJobFn = unsafe extern "C" fn(opaque: *mut c_void, job_id: c_uint) -> c_int;
#[inline]
fn create_job_table_full(projection: ZSTDMT_createJobProjection) -> ZSTDMT_createJobResult {
ZSTDMT_createJobResult {
action: CREATE_JOB_TABLE_FULL,
jobID: projection.nextJobID & projection.jobIDMask,
jobNumber: projection.nextJobID,
nextJobID: projection.nextJobID,
jobReady: projection.jobReady,
..ZSTDMT_createJobResult::default()
}
}
#[inline]
fn create_job_initialization(
projection: ZSTDMT_createJobProjection,
) -> (c_uint, ZSTDMT_jobInitialization) {
let job_number = projection.nextJobID;
let first_job = (job_number == 0) as c_uint;
let last_job = (projection.endFrame != 0) as c_uint;
let frame_checksum_needed =
(projection.checksumFlag != 0 && last_job != 0 && job_number > 0) as c_uint;
let (next_prefix_start, next_prefix_size) = if last_job != 0 {
(ptr::null(), 0)
} else {
let next_prefix_size = projection.srcSize.min(projection.targetPrefixSize);
let next_prefix_start = projection
.srcStart
.cast::<u8>()
.wrapping_add(projection.srcSize - next_prefix_size)
.cast();
(next_prefix_start, next_prefix_size)
};
(
projection.nextJobID & projection.jobIDMask,
ZSTDMT_jobInitialization {
srcStart: projection.srcStart,
srcSize: projection.srcSize,
prefixStart: projection.prefixStart,
prefixSize: projection.prefixSize,
nextPrefixStart: next_prefix_start,
nextPrefixSize: next_prefix_size,
roundBuffPosDelta: projection.srcSize,
jobNumber: job_number,
firstJob: first_job,
lastJob: last_job,
frameChecksumNeeded: frame_checksum_needed,
clearChecksumFlag: (last_job != 0 && first_job != 0) as c_uint,
},
)
}
#[inline]
fn create_compression_job_with<P, E, T>(
projection: ZSTDMT_createJobProjection,
mut prepare_job: P,
mut write_empty_job: E,
mut try_add_job: T,
) -> ZSTDMT_createJobResult
where
P: FnMut(c_uint, &ZSTDMT_jobInitialization),
E: FnMut(c_uint),
T: FnMut(c_uint) -> bool,
{
/* Match the original unsigned C comparison, including wraparound. */
if projection.nextJobID > projection.doneJobID.wrapping_add(projection.jobIDMask) {
return create_job_table_full(projection);
}
let job_id = projection.nextJobID & projection.jobIDMask;
let mut result = ZSTDMT_createJobResult {
action: CREATE_JOB_POST,
jobID: job_id,
jobNumber: projection.nextJobID,
nextJobID: projection.nextJobID,
jobReady: projection.jobReady,
..ZSTDMT_createJobResult::default()
};
if projection.jobReady == 0 {
debug_assert!(projection.inBuffFilled >= projection.srcSize);
let (_, initialization) = create_job_initialization(projection);
prepare_job(job_id, &initialization);
/* A non-first empty job is represented by the terminal empty block,
* not by a worker submission. */
if projection.srcSize == 0 && projection.nextJobID > 0 {
write_empty_job(job_id);
result.action = CREATE_JOB_EMPTY;
result.nextJobID = projection.nextJobID.wrapping_add(1);
result.jobReady = 0;
return result;
}
}
if try_add_job(job_id) {
result.nextJobID = projection.nextJobID.wrapping_add(1);
result.jobReady = 0;
} else {
result.jobReady = 1;
}
result
}
/// Apply MT scalar scheduling policy while C retains all private descriptor,
/// pool, mutex, condition-variable, and worker-callback operations.
#[cfg(not(test))]
#[no_mangle]
pub unsafe extern "C" fn ZSTDMT_rust_createCompressionJob(
projection: *const ZSTDMT_createJobProjection,
opaque: *mut c_void,
prepareJob: Option<ZSTDMT_prepareJobFn>,
writeEmptyJob: Option<ZSTDMT_writeEmptyJobFn>,
tryAddJob: Option<ZSTDMT_tryAddJobFn>,
) -> ZSTDMT_createJobResult {
let Some(projection) = (unsafe { projection.as_ref() }).copied() else {
return ZSTDMT_createJobResult::default();
};
let (Some(prepare_job), Some(write_empty_job), Some(try_add_job)) =
(prepareJob, writeEmptyJob, tryAddJob)
else {
return ZSTDMT_createJobResult::default();
};
create_compression_job_with(
projection,
|job_id, initialization| unsafe {
prepare_job(opaque, job_id, initialization);
},
|job_id| unsafe {
write_empty_job(opaque, job_id);
},
|job_id| unsafe { try_add_job(opaque, job_id) != 0 },
)
}
#[inline]
fn invalid_flush_publication(
output_pos: usize,
@@ -2155,6 +2356,162 @@ mod tests {
assert_eq!(output, original);
}
#[test]
fn create_job_rejects_full_table_without_callbacks() {
let projection = ZSTDMT_createJobProjection {
doneJobID: 0,
nextJobID: 8,
jobIDMask: 7,
..ZSTDMT_createJobProjection::default()
};
let result = create_compression_job_with(
projection,
|_job_id, _initialization| panic!("table-full job must not be prepared"),
|_job_id| panic!("table-full job must not be written"),
|_job_id| panic!("table-full job must not be posted"),
);
assert_eq!(result.action, CREATE_JOB_TABLE_FULL);
assert_eq!(result.jobID, 0);
assert_eq!(result.jobNumber, 8);
assert_eq!(result.nextJobID, 8);
assert_eq!(result.jobReady, 0);
}
#[test]
fn create_job_projects_ordinary_initialization_and_prefix_advance() {
let source = [0u8; 8];
let prefix = [1u8; 3];
let projection = ZSTDMT_createJobProjection {
doneJobID: 0,
nextJobID: 3,
jobIDMask: 7,
srcStart: source.as_ptr().cast(),
srcSize: source.len(),
inBuffFilled: source.len(),
prefixStart: prefix.as_ptr().cast(),
prefixSize: prefix.len(),
targetPrefixSize: 4,
checksumFlag: 1,
..ZSTDMT_createJobProjection::default()
};
let mut initialization = None;
let mut posted = None;
let result = create_compression_job_with(
projection,
|job_id, value| {
assert_eq!(job_id, 3);
initialization = Some(*value);
},
|_job_id| panic!("ordinary job must not use the empty-block path"),
|job_id| {
posted = Some(job_id);
true
},
);
let initialization = initialization.expect("job should be initialized");
assert_eq!(initialization.srcStart, source.as_ptr().cast());
assert_eq!(initialization.srcSize, source.len());
assert_eq!(initialization.prefixStart, prefix.as_ptr().cast());
assert_eq!(initialization.prefixSize, prefix.len());
assert_eq!(
initialization.nextPrefixStart,
source.as_ptr().wrapping_add(4).cast()
);
assert_eq!(initialization.nextPrefixSize, 4);
assert_eq!(initialization.roundBuffPosDelta, source.len());
assert_eq!(initialization.jobNumber, 3);
assert_eq!(initialization.firstJob, 0);
assert_eq!(initialization.lastJob, 0);
assert_eq!(initialization.frameChecksumNeeded, 0);
assert_eq!(posted, Some(3));
assert_eq!(result.action, CREATE_JOB_POST);
assert_eq!(result.jobID, 3);
assert_eq!(result.nextJobID, 4);
assert_eq!(result.jobReady, 0);
}
#[test]
fn create_job_projects_terminal_empty_frame() {
let prefix = [2u8; 2];
let projection = ZSTDMT_createJobProjection {
doneJobID: 0,
nextJobID: 2,
jobIDMask: 7,
inBuffFilled: 0,
prefixStart: prefix.as_ptr().cast(),
prefixSize: prefix.len(),
endFrame: 1,
checksumFlag: 1,
..ZSTDMT_createJobProjection::default()
};
let mut initialization = None;
let mut empty_job = None;
let result = create_compression_job_with(
projection,
|job_id, value| {
assert_eq!(job_id, 2);
initialization = Some(*value);
},
|job_id| empty_job = Some(job_id),
|_job_id| panic!("terminal empty job must not be posted"),
);
let initialization = initialization.expect("empty job should be initialized");
assert_eq!(initialization.srcSize, 0);
assert_eq!(initialization.prefixStart, prefix.as_ptr().cast());
assert_eq!(initialization.prefixSize, prefix.len());
assert!(initialization.nextPrefixStart.is_null());
assert_eq!(initialization.nextPrefixSize, 0);
assert_eq!(initialization.roundBuffPosDelta, 0);
assert_eq!(initialization.jobNumber, 2);
assert_eq!(initialization.firstJob, 0);
assert_eq!(initialization.lastJob, 1);
assert_eq!(initialization.frameChecksumNeeded, 1);
assert_eq!(initialization.clearChecksumFlag, 0);
assert_eq!(empty_job, Some(2));
assert_eq!(result.action, CREATE_JOB_EMPTY);
assert_eq!(result.nextJobID, 3);
assert_eq!(result.jobReady, 0);
}
#[test]
fn create_job_preserves_pool_success_and_failure_state() {
let projection = ZSTDMT_createJobProjection {
doneJobID: 0,
nextJobID: 4,
jobIDMask: 7,
jobReady: 1,
..ZSTDMT_createJobProjection::default()
};
let success = create_compression_job_with(
projection,
|_job_id, _initialization| panic!("prepared job must not be reinitialized"),
|_job_id| panic!("prepared job must not use the empty-block path"),
|job_id| {
assert_eq!(job_id, 4);
true
},
);
assert_eq!(success.action, CREATE_JOB_POST);
assert_eq!(success.nextJobID, 5);
assert_eq!(success.jobReady, 0);
let failure = create_compression_job_with(
projection,
|_job_id, _initialization| panic!("prepared job must not be reinitialized"),
|_job_id| panic!("prepared job must not use the empty-block path"),
|job_id| {
assert_eq!(job_id, 4);
false
},
);
assert_eq!(failure.action, CREATE_JOB_POST);
assert_eq!(failure.nextJobID, 4);
assert_eq!(failure.jobReady, 1);
}
#[test]
fn flush_state_machine_preserves_offsets_and_completes_job() {
let job = [0x60u8, 0x61, 0x62, 0x63, 0x64, 0x65];