+.. _samplingopcodes:
+
+Resource Sampling Opcodes
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Those opcodes follow very closely semantics of the respective Direct3D
+instructions. If in doubt double check Direct3D documentation.
+
+.. opcode:: SAMPLE - Using provided address, sample data from the
+ specified texture using the filtering mode identified
+ by the gven sampler. The source data may come from
+ any resource type other than buffers.
+ SAMPLE dst, address, sampler_view, sampler
+ e.g.
+ SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
+
+.. opcode:: SAMPLE_I - Simplified alternative to the SAMPLE instruction.
+ Using the provided integer address, SAMPLE_I fetches data
+ from the specified sampler view without any filtering.
+ The source data may come from any resource type other
+ than CUBE.
+ SAMPLE_I dst, address, sampler_view
+ e.g.
+ SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]
+ 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 exact 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.
+
+.. opcode:: SAMPLE_I_MS - Just like SAMPLE_I but allows fetch data from
+ multi-sampled surfaces.
+
+.. opcode:: SAMPLE_B - Just like the SAMPLE instruction with the
+ exception that an additiona bias is applied to the
+ level of detail computed as part of the instruction
+ execution.
+ SAMPLE_B dst, address, sampler_view, sampler, lod_bias
+ e.g.
+ SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
+
+.. opcode:: SAMPLE_C - Similar to the SAMPLE instruction but it
+ performs a comparison filter. The operands to SAMPLE_C
+ are identical to SAMPLE, except that tere is an additional
+ float32 operand, reference value, which must be a register
+ with single-component, or a scalar literal.
+ SAMPLE_C makes the hardware use the current samplers
+ compare_func (in pipe_sampler_state) to compare
+ reference value against the red component value for the
+ surce resource at each texel that the currently configured
+ texture filter covers based on the provided coordinates.
+ SAMPLE_C dst, address, sampler_view.r, sampler, ref_value
+ e.g.
+ SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
+
+.. opcode:: SAMPLE_C_LZ - Same as SAMPLE_C, but LOD is 0 and derivatives
+ are ignored. The LZ stands for level-zero.
+ SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value
+ e.g.
+ SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
+
+
+.. opcode:: SAMPLE_D - SAMPLE_D is identical to the SAMPLE opcode except
+ that the derivatives for the source address in the x
+ direction and the y direction are provided by extra
+ parameters.
+ SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y
+ e.g.
+ SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]
+
+.. opcode:: SAMPLE_L - SAMPLE_L is identical to the SAMPLE opcode except
+ that the LOD is provided directly as a scalar value,
+ representing no anisotropy. Source addresses A channel
+ is used as the LOD.
+ SAMPLE_L dst, address, sampler_view, sampler
+ e.g.
+ SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
+
+.. opcode:: GATHER4 - Gathers the four texels to be used in a bi-linear
+ filtering operation and packs them into a single register.
+ Only works with 2D, 2D array, cubemaps, and cubemaps arrays.
+ For 2D textures, only the addressing modes of the sampler and
+ the top level of any mip pyramid are used. Set W to zero.
+ It behaves like the SAMPLE instruction, but a filtered
+ sample is not generated. The four samples that contribute
+ to filtering are placed into xyzw in counter-clockwise order,
+ starting with the (u,v) texture coordinate delta at the
+ following locations (-, +), (+, +), (+, -), (-, -), where
+ the magnitude of the deltas are half a texel.
+
+
+.. opcode:: SVIEWINFO - query the dimensions of a given sampler view.
+ dst receives width, height, depth or array size and
+ number of mipmap levels. The dst can have a writemask
+ which will specify what info is the caller interested
+ in.
+ SVIEWINFO dst, src_mip_level, sampler_view
+ e.g.
+ SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]
+ src_mip_level is an unsigned integer scalar. If it's
+ out of range then returns 0 for width, height and
+ depth/array size but the total number of mipmap is
+ still returned correctly for the given sampler view.
+ The returned width, height and depth values are for
+ the mipmap level selected by the src_mip_level and
+ are in the number of texels.
+ For 1d texture array width is in dst.x, array size
+ is in dst.y and dst.zw are always 0.
+
+.. opcode:: SAMPLE_POS - query the position of a given sample.
+ dst receives float4 (x, y, 0, 0) indicated where the
+ sample is located. If the resource is not a multi-sample
+ resource and not a render target, the result is 0.
+
+.. opcode:: SAMPLE_INFO - dst receives number of samples in x.
+ If the resource is not a multi-sample resource and
+ not a render target, the result is 0.
+
+
+.. _resourceopcodes:
+
+Resource Access Opcodes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. opcode:: LOAD - Fetch data from a shader resource
+
+ Syntax: ``LOAD dst, resource, address``
+
+ Example: ``LOAD TEMP[0], RES[0], TEMP[1]``
+
+ Using the provided integer address, LOAD fetches data
+ from the specified buffer or texture without any
+ filtering.
+
+ The 'address' is specified as a vector of unsigned
+ integers. If the 'address' is out of range the result
+ is unspecified.
+
+ Only the first mipmap level of a resource can be read
+ from using this instruction.
+
+ For 1D or 2D texture arrays, the array index is
+ provided as an unsigned integer in address.y or
+ address.z, respectively. address.yz are ignored for
+ buffers and 1D textures. address.z is ignored for 1D
+ texture arrays and 2D textures. address.w is always
+ ignored.
+
+.. opcode:: STORE - Write data to a shader resource
+
+ Syntax: ``STORE resource, address, src``
+
+ Example: ``STORE RES[0], TEMP[0], TEMP[1]``
+
+ Using the provided integer address, STORE writes data
+ to the specified buffer or texture.
+
+ The 'address' is specified as a vector of unsigned
+ integers. If the 'address' is out of range the result
+ is unspecified.
+
+ Only the first mipmap level of a resource can be
+ written to using this instruction.
+
+ For 1D or 2D texture arrays, the array index is
+ provided as an unsigned integer in address.y or
+ address.z, respectively. address.yz are ignored for
+ buffers and 1D textures. address.z is ignored for 1D
+ texture arrays and 2D textures. address.w is always
+ ignored.
+
+
+.. _threadsyncopcodes:
+
+Inter-thread synchronization opcodes
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+These opcodes are intended for communication between threads running
+within the same compute grid. For now they're only valid in compute
+programs.
+
+.. opcode:: MFENCE - Memory fence
+
+ Syntax: ``MFENCE resource``
+
+ Example: ``MFENCE RES[0]``
+
+ This opcode forces strong ordering between any memory access
+ operations that affect the specified resource. This means that
+ previous loads and stores (and only those) will be performed and
+ visible to other threads before the program execution continues.
+
+
+.. opcode:: LFENCE - Load memory fence
+
+ Syntax: ``LFENCE resource``
+
+ Example: ``LFENCE RES[0]``
+
+ Similar to MFENCE, but it only affects the ordering of memory loads.
+
+
+.. opcode:: SFENCE - Store memory fence
+
+ Syntax: ``SFENCE resource``
+
+ Example: ``SFENCE RES[0]``
+
+ Similar to MFENCE, but it only affects the ordering of memory stores.
+
+
+.. opcode:: BARRIER - Thread group barrier
+
+ ``BARRIER``
+
+ This opcode suspends the execution of the current thread until all
+ the remaining threads in the working group reach the same point of
+ the program. Results are unspecified if any of the remaining
+ threads terminates or never reaches an executed BARRIER instruction.
+
+
+.. _atomopcodes:
+
+Atomic opcodes
+^^^^^^^^^^^^^^
+
+These opcodes provide atomic variants of some common arithmetic and
+logical operations. In this context atomicity means that another
+concurrent memory access operation that affects the same memory
+location is guaranteed to be performed strictly before or after the
+entire execution of the atomic operation.
+
+For the moment they're only valid in compute programs.
+
+.. opcode:: ATOMUADD - Atomic integer addition
+
+ Syntax: ``ATOMUADD dst, resource, offset, src``
+
+ Example: ``ATOMUADD TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = dst_i + src_i
+
+
+.. opcode:: ATOMXCHG - Atomic exchange
+
+ Syntax: ``ATOMXCHG dst, resource, offset, src``
+
+ Example: ``ATOMXCHG TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = src_i
+
+
+.. opcode:: ATOMCAS - Atomic compare-and-exchange
+
+ Syntax: ``ATOMCAS dst, resource, offset, cmp, src``
+
+ Example: ``ATOMCAS TEMP[0], RES[0], TEMP[1], TEMP[2], TEMP[3]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = (dst_i == cmp_i ? src_i : dst_i)
+
+
+.. opcode:: ATOMAND - Atomic bitwise And
+
+ Syntax: ``ATOMAND dst, resource, offset, src``
+
+ Example: ``ATOMAND TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = dst_i \& src_i
+
+
+.. opcode:: ATOMOR - Atomic bitwise Or
+
+ Syntax: ``ATOMOR dst, resource, offset, src``
+
+ Example: ``ATOMOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = dst_i | src_i
+
+
+.. opcode:: ATOMXOR - Atomic bitwise Xor
+
+ Syntax: ``ATOMXOR dst, resource, offset, src``
+
+ Example: ``ATOMXOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = dst_i \oplus src_i
+
+
+.. opcode:: ATOMUMIN - Atomic unsigned minimum
+
+ Syntax: ``ATOMUMIN dst, resource, offset, src``
+
+ Example: ``ATOMUMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
+
+
+.. opcode:: ATOMUMAX - Atomic unsigned maximum
+
+ Syntax: ``ATOMUMAX dst, resource, offset, src``
+
+ Example: ``ATOMUMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
+
+
+.. opcode:: ATOMIMIN - Atomic signed minimum
+
+ Syntax: ``ATOMIMIN dst, resource, offset, src``
+
+ Example: ``ATOMIMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
+
+
+.. opcode:: ATOMIMAX - Atomic signed maximum
+
+ Syntax: ``ATOMIMAX dst, resource, offset, src``
+
+ Example: ``ATOMIMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
+
+ The following operation is performed atomically on each component:
+
+.. math::
+
+ dst_i = resource[offset]_i
+
+ resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
+
+
+