gentypen
shuffle
(
| gentypem x, |
ugentypen mask) |
gentypen
shuffle2
(
| gentypem x, |
| gentypem y, | |
ugentypen mask) |
Description
The shuffle and shuffle2
built-in functions construct a permutation of elements from one or two input
vectors respectively that are of the same type, returning a vector with the
same element type as the input and length that is the same as the shuffle
mask. The size of each element in the mask must match the
size of each element in the result. For shuffle, only the
ilogb(2m-1)
least significant bits of each mask
element are considered. For shuffle2, only the
ilogb(2m-1)+1
least significant bits of each mask element are considered. Other
bits in the mask shall be ignored.
The elements of the input vectors are numbered from left to right across one or
both of the vectors. For this purpose, the number of elements in a vector is given by
vec_step(gentypem).
The shuffle mask operand specifies, for each element of the result
vector, which element of the one or two input vectors the result element gets.
We use the generic type name gentypen
(or gentypem) to indicate the
built-in data types char{2|4|8|16}, uchar{2|4|8|16},
short{2|4|8|16}, ushort{2|4|8|16}, int{2|4|8|16},
uint{2|4|8|16}, long{2|4|8|16}, ulong{2|4|8|16},
float{2|4|8|16} or double{2|4|8|16}
as the type for the arguments unless otherwise
stated. We use the generic name ugentypen
to indicate the built-in unsigned integer data types.
The generic type name gentypen
(or gentypem)
may indicate the data type half{2|4|8|16} if the
cl_khr_fp16 extension
is supported.
Example
| uint4 mask = (uint4)(3, 2, 1, 0); float4 a; float4 r = shuffle(a, mask); // r.s0123 = a.wzyx uint8 mask = (uint8)(0, 1, 2, 3, 4, 5, 6, 7); float4 a, b; float8 r = shuffle2(a, b, mask); // r.s0123 = a.xyzw // r.s4567 = b.xyzw uint4 mask; float8 a; float4 b; b = shuffle(a, mask); |
Examples that are not valid are:
| uint8 mask; short16 a; short8 b; b = shuffle(a, mask); |
Copyright © 2007-2013 The Khronos Group Inc.
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