Memory Operations¶

Header: libxs_mem.h

Byte-level memory macros, pointer alignment queries, buffer comparison, and matrix copy/transposition.

Memory Macros¶

LIBXS_MEMSET(DST, SRC, SIZE)

Set SIZE bytes at DST to the value SRC, unrolled at compile-time.

LIBXS_MEMZERO(DST)

Zero all bytes of DST (size derived from sizeof(DST)).

LIBXS_MEMCPY(DST, SRC, SIZE)

Copy SIZE bytes from SRC to DST, unrolled at compile time.

LIBXS_ASSIGN(DST, SRC)

Copy sizeof(SRC) bytes from SRC to DST. Asserts sizeof(SRC) <= sizeof(*DST).

LIBXS_MEMSWP(PTR_A, PTR_B, SIZE)

Swap SIZE bytes between PTR_A and PTR_B. Asserts PTR_A != PTR_B.

LIBXS_VALUE_ASSIGN(DST, SRC)
LIBXS_VALUE_SWAP(A, B)

Operate on L-values directly (address-of is taken internally). VALUE_ASSIGN can cast away const qualifiers. VALUE_SWAP asserts equal size.

Offset and Alignment¶

size_t libxs_offset(size_t ndims, const size_t offset[],
  const size_t shape[], size_t* size);

Compute the linear offset of an n-dimensional coordinate within a shape. Optionally returns the total linear size of the shape.

int libxs_aligned(const void* ptr, const size_t* inc,
  int* alignment);

Check whether ptr is SIMD-aligned (optionally considering the next access at ptr + inc). Optionally writes the pointer alignment in bytes to alignment.

Comparison¶

unsigned char libxs_diff(const void* a, const void* b,
  unsigned char size);

Compare two short buffers. Returns zero when equal, non-zero otherwise. Uses SSE/AVX2/AVX-512 when available.

unsigned int libxs_diff_n(const void* a, const void* bn,
  unsigned char elemsize, unsigned char stride,
  unsigned int hint, unsigned int count);

Compare a against count elements in bn. Returns the first index that matches a, or count if none match. hint supplies the initial search position.

int libxs_memcmp(const void* a, const void* b, size_t size);

Boolean variant of the C memcmp. Returns zero when equal. Uses SSE/AVX2/AVX-512 when available.

Matrix Copy and Transposition¶

void libxs_matcopy(void* out, const void* in,
  unsigned int typesize, int m, int n, int ldi, int ldo);
void libxs_matcopy_task(void* out, const void* in,
  unsigned int typesize, int m, int n, int ldi, int ldo,
  int tid, int ntasks);

Copy an m-by-n matrix from in to out with leading dimensions ldi and ldo. If in is NULL the destination is zeroed. The _task variant distributes work across ntasks threads (caller passes its tid).

void libxs_otrans(void* out, const void* in,
  unsigned int typesize, int m, int n, int ldi, int ldo);
void libxs_otrans_task(void* out, const void* in,
  unsigned int typesize, int m, int n, int ldi, int ldo,
  int tid, int ntasks);

Out-of-place matrix transposition. The _task variant distributes work across ntasks threads.

void libxs_itrans(void* inout, unsigned int typesize,
  int m, int n, int ldi, int ldo, void* scratch);
void libxs_itrans_task(void* inout, unsigned int typesize,
  int m, int n, int ldi, int ldo, void* scratch,
  int tid, int ntasks);

In-place matrix transposition (square or via scratch buffer). scratch can be NULL (auto-allocated).

void libxs_itrans_batch(void* inout, unsigned int typesize,
  int m, int n, int ldi, int ldo,
  int index_base, int index_stride,
  const int stride[], int batchsize,
  int tid, int ntasks);

Batch of in-place matrix transpositions (per-thread form).