dax_select - copy selected values from input to output
cc [ flag... ] file... -ldax [ library...] #include <dax.h> dax_result_t dax_select(dax_context_t *ctx, uint64_t flags, dax_vec_t *src, dax_vec_t *dst, dax_vec_t *mask);
This function copies selected elements of src to contiguous elements of dst. It selects the ith element in src if the ith bit in the mask bit vector is 1.
If src is zipped, translates each code word of src by using the src codec and produces a 1 to 8 byte symbol which it appends to an intermediate unzip stream. It then partitions the unzip stream into elements at src->elem_width boundaries, and selects the ith element in src if the ith bit in the mask bit vector is 1.
The parameters of this function must meet the following conditions:
Width of an element in src can be any of the following:
1 to 16 bits or 1 to 16 bytes in libdax version 1
1 to 24 bits or 1 to 16 bytes in libdax version 2
src must be fixed width.
Width of the mask element must be 1 bit, and format must be DAX_BITS.
The mask->offset field specifies the bit in the first mask data byte where the bit vector starts from 0 (MSB) to 7 (LSB).
The number of elements in mask must be at least the number of elements in src.
The dst->offset field must be 0.
Width of an element in dst can be any of 1, 2, 4, 8, or 16 bytes.
Number of elements in dst must be at least the number of selected elements. If this is not known, use the number of elements in src as an upper bound.
dst->data must start on a 64 byte boundary. You must round up the size of the dst->data as described in the dax_vec_t(3DAX) man page.
If the width of a src element is larger than the width of a dst element, this function truncates the element.
If the width of a src element is smaller, this function pads the element. For more information, see the dax_extract(3DAX) man page.
The following address ranges must not overlap:
Address range of the src->data vector and the dst->data vector.
Address range of the mask->data vector and the dst->data vector.
The libdax library checks the overlap in the address ranges only if the DAX_DEBUG_EXTRA debug option is set. If violations of the conditions occur and are not checked, you will get undefined results.
For more information, see the dax_extract(3DAX) man page.
Writes results to cache. If not specified, invalidates the address range for dst in the cache, and writes the result to the main memory. For more information, see the dax_scan_value(3DAX) man page.
If the DAX command queue is full, returns without submitting the command, instead of waiting to submit.
Returns the number of selected elements in the dax_result_t count field and sets the dax_result_t status field to one of the following values:
Operation completed successfully
Invalid argument, detected by libdax.
Invalid argument, detected by DAX.
The true value of an aux_data element is 0, or the width of a zip symbol is less than 1 or greater than 8, detected by DAX.
Output buffer overflow
ADI mismatch error for an input or output buffer
The calling thread did not create ctx
DAX is busy and nowait was requested.
Unknown internal error. Caller must stop using ctx.
See attributes(5) for descriptions of the following attributes: