Primitive Bitcast Conversion

Reinterprets the bits of an array as a different data type without modifying the underlying data.

Usage

prim_bitcast_convert(x, dtype)

Arguments

x

(arrayish)
One input. Can be any data type except bool. An R value materializes at its default data type.

dtype

(character(1) | DataType)
Any target data type except bool. One of the same bit width as the input's leaves the shape unchanged; a narrower one adds a leading axis holding the pieces; a wider one consumes the first axis, whose size must equal the ratio of the two widths. The pieces of one element are therefore adjacent in the column-major element order nv_flatten() reads, and a narrowing conversion lays the bytes out the way as_raw() writes them.

Value

(arrayish)
Has the given dtype, and the shape described under dtype.

Implemented Rules

• stablehlo

• reverse

StableHLO

Lowers to hlo_bitcast_convert(), specified under bitcast_convert. StableHLO puts the lane axis last, so a width-changing conversion is lowered with one hlo_transpose() that rotates it to the front, or off the front, depending on the direction.

See also

nv_bitcast_convert()

Examples

# same width: the bits are reread, the shape stays
prim_bitcast_convert(nv_array(1L, dtype = "i32"), dtype = "f32")
#> AnvlArray
#>  1.4013e-45
#> [ CPUf32{1} ] 

# narrower: a leading axis holds the four bytes of each i32
prim_bitcast_convert(nv_array(1L, dtype = "i32"), dtype = "i8")
#> AnvlArray
#>  1
#>  0
#>  0
#>  0
#> [ CPUi8{4,1} ] 

# wider: the first axis is consumed, and its size must be the width ratio
prim_bitcast_convert(nv_array(rep(1L, 4), dtype = "i8"), dtype = "i32")
#> AnvlArray
#>  1.6843e+07
#> [ CPUi32{} ]