cppdraft_translate/cppdraft/simd/permute/memory.md

[simd.permute.memory]

29 Numerics library [numerics]

29.10 Data-parallel types [simd]

29.10.8 basic_vec non-member operations [simd.nonmembers]

29.10.8.10 simd memory permute [simd.permute.memory]

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template<class V = see below, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr V unchecked_gather_from(R&& in, const I& indices, flags<Flags...> f = {}); template<class V = see below, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr V unchecked_gather_from(R&& in, const typename I::mask_type& mask, const I& indices, flags<Flags...> f = {});

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Let mask be typename I​::​mask_type(true) for the overload with no mask parameter.

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Preconditions: All values in select(mask, indices, typename I​::​value_type()) are in the range [0, ranges​::​size(in)).

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Effects: Equivalent to: return partial_gather_from(in, mask, indices, f);

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Remarks: The default argument for template parameter V isvec<ranges​::​range_value_t, I​::​​size()>.

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template<class V = see below, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr V partial_gather_from(R&& in, const I& indices, flags<Flags...> f = {}); template<class V = see below, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr V partial_gather_from(R&& in, const typename I::mask_type& mask, const I& indices, flags<Flags...> f = {});

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Let:

• (5.1)

mask be typename I​::​mask_type(true) for the overload with no mask parameter;

• (5.2)

T be typename V​::​value_type.

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Mandates:

• (6.1)

ranges​::​range_value_t is a vectorizable type,

• (6.2)

same_as<remove_cvref_t, V> is true,

• (6.3)

V is an enabled specialization of basic_vec,

• (6.4)

V​::​size() == I​::​size() is true, and

• (6.5)

if the template parameter pack Flags does not containconvert-flag, then the conversion fromranges​::​range_value_t to T is value-preserving.

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Preconditions:

• (7.1)

  If the template parameter pack Flags containsaligned-flag, ranges​::​data(in) points to storage aligned byalignment_v<V, ranges​::​range_value_t>.

• (7.2)

  If the template parameter pack Flags containsoveraligned-flag, ranges​::​data(in) points to storage aligned by N.

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Returns: A basic_vec object where the ith element is initialized to the result ofmask[i] && indices[i] < ranges::size(in) ? static_cast(ranges::data(in)[indices[i]]) : T() for all i in the range [0, I​::​size()).

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Remarks: The default argument for template parameter V isvec<ranges​::​range_value_t, I​::​​size()>.

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template<[simd-vec-type](simd.expos#concept:simd-vec-type "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") V, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr void unchecked_scatter_to(const V& v, R&& out, const I& indices, flags<Flags...> f = {}); template<[simd-vec-type](simd.expos#concept:simd-vec-type "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") V, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr void unchecked_scatter_to(const V& v, R&& out, const typename I::mask_type& mask, const I& indices, flags<Flags...> f = {});

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Let mask be typename I​::​mask_type(true) for the overload with no mask parameter.

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Preconditions: All values in select(mask, indices, typename I​::​value_type()) are in the range [0, ranges​::​size(out)).

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Effects: Equivalent to: partial_scatter_to(v, out, mask, indices, f);

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template<[simd-vec-type](simd.expos#concept:simd-vec-type "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") V, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr void partial_scatter_to(const V& v, R&& out, const I& indices, flags<Flags...> f = {}); template<[simd-vec-type](simd.expos#concept:simd-vec-type "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") V, ranges::[contiguous_range](range.refinements#concept:contiguous_range "25.4.6 Other range refinements [range.refinements]") R, [simd-integral](simd.expos#concept:simd-integral "29.10.2 Exposition-only types, variables, and concepts [simd.expos]") I, class... Flags> requires ranges::[sized_range](range.sized#concept:sized_range "25.4.4 Sized ranges [range.sized]")<R> constexpr void partial_scatter_to(const V& v, R&& out, const typename I::mask_type& mask, const I& indices, flags<Flags...> f = {});

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Let mask be typename I​::​mask_type(true) for the overload with no mask parameter.

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Constraints: V​::​size() == I​::​size() is true.

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Mandates:

• (15.1)

ranges​::​range_value_t is a vectorizable type, and

• (15.2)

if the template parameter pack Flags does not contain convert-flag, then the conversion from typename V​::​value_type to ranges​::​range_value_t is value-preserving.

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Preconditions:

• (16.1)

  For all selected indices i the values indices[i] are unique.

• (16.2)

  If the template parameter pack Flags contains aligned-flag,ranges​::​data(out) points to storage aligned byalignment_v<V, ranges​::​range_value_t>.

• (16.3)

  If the template parameter pack Flags containsoveraligned-flag,ranges​::​data(out) points to storage aligned by N.

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Effects: For all i in the range [0, I​::​size()), if mask[i] &&(indices[i] < ranges​::​size(out)) is true, evaluatesranges​::​data(out)[indices[i]] = v[i].