+ The 'address' is specified as unsigned integers. If the
+ 'address' is out of range [0...(# texels - 1)] the
+ result of the fetch is always 0 in all components.
+ As such the instruction doesn't honor address wrap
+ modes, in cases where that behavior is desirable
+ 'sample' instruction should be used.
+ address.w always provides an unsigned integer mipmap
+ level. If the value is out of the range then the
+ instruction always returns 0 in all components.
+ address.yz are ignored for buffers and 1d textures.
+ address.z is ignored for 1d texture arrays and 2d
+ textures.
+ For 1D texture arrays address.y provides the array
+ index (also as unsigned integer). If the value is
+ out of the range of available array indices
+ [0... (array size - 1)] then the opcode always returns
+ 0 in all components.
+ For 2D texture arrays address.z provides the array
+ index, otherwise it exhibits the same behavior as in
+ the case for 1D texture arrays.
+ The exeact semantics of the source address are presented
+ in the table below:
+ resource type X Y Z W
+ ------------- ------------------------
+ PIPE_BUFFER x ignored
+ PIPE_TEXTURE_1D x mpl
+ PIPE_TEXTURE_2D x y mpl
+ PIPE_TEXTURE_3D x y z mpl
+ PIPE_TEXTURE_RECT x y mpl
+ PIPE_TEXTURE_CUBE not allowed as source
+ PIPE_TEXTURE_1D_ARRAY x idx mpl
+ PIPE_TEXTURE_2D_ARRAY x y idx mpl
+
+ Where 'mpl' is a mipmap level and 'idx' is the
+ array index.
+