modifiers are supported (with absolute value being applied first).
TGSI_OPCODE_MOV is considered to have float input type for applying modifiers.
-For inputs which have signed type only the negate modifier is supported. This
-includes instructions which are otherwise ignorant if the type is signed or
-unsigned, such as TGSI_OPCODE_UADD.
-
-For inputs with unsigned type no modifiers are allowed.
+For inputs which have signed or unsigned type only the negate modifier is
+supported.
Instruction Set
---------------
.. opcode:: RSQ - Reciprocal Square Root
-This instruction replicates its result.
+This instruction replicates its result. The results are undefined for src <= 0.
.. math::
- dst = \frac{1}{\sqrt{|src.x|}}
+ dst = \frac{1}{\sqrt{src.x}}
.. opcode:: SQRT - Square Root
-This instruction replicates its result.
+This instruction replicates its result. The results are undefined for src < 0.
.. math::
dst.w = partialy(src.w)
-.. opcode:: KILP - Predicated Discard
-
- discard
-
-
.. opcode:: PK2H - Pack Two 16-bit Floats
TBD
dst.w = round(src.w)
-.. opcode:: BRA - Branch
-
- pc = target
-
-.. note::
-
- Considered for removal.
-
-.. opcode:: CAL - Subroutine Call
-
- push(pc)
- pc = target
-
-
-.. opcode:: RET - Subroutine Call Return
-
- pc = pop()
-
-
.. opcode:: SSG - Set Sign
.. math::
dst.w = (src0.w < 0) ? src1.w : src2.w
-.. opcode:: KIL - Conditional Discard
+.. opcode:: KILL_IF - Conditional Discard
+
+ Conditional discard. Allowed in fragment shaders only.
.. math::
endif
+.. opcode:: KILL - Discard
+
+ Unconditional discard. Allowed in fragment shaders only.
+
+
.. opcode:: SCS - Sine Cosine
.. math::
dst = texture_sample(unit, coord, lod)
-.. opcode:: BRK - Break
-
- TBD
-
-
-.. opcode:: IF - If
-
- TBD
-
-
-.. opcode:: ELSE - Else
-
- TBD
-
-
-.. opcode:: ENDIF - End If
-
- TBD
-
-
.. opcode:: PUSHA - Push Address Register On Stack
push(src.x)
Considered for removal.
+.. opcode:: BRA - Branch
+
+ pc = target
+
+.. note::
+
+ Considered for removal.
+
+
+.. opcode:: CALLNZ - Subroutine Call If Not Zero
+
+ TBD
+
+.. note::
+
+ Considered for cleanup.
+
+.. note::
+
+ Considered for removal.
+
+
Compute ISA
^^^^^^^^^^^^^^^^^^^^^^^^
These opcodes are primarily provided for special-use computational shaders.
Support for these opcodes indicated by a special pipe capability bit (TBD).
-XXX so let's discuss it, yeah?
+XXX doesn't look like most of the opcodes really belong here.
.. opcode:: CEIL - Ceiling
dst.w = \lceil src.w\rceil
-.. opcode:: I2F - Integer To Float
+.. opcode:: TRUNC - Truncate
+
+.. math::
+
+ dst.x = trunc(src.x)
+
+ dst.y = trunc(src.y)
+
+ dst.z = trunc(src.z)
+
+ dst.w = trunc(src.w)
+
+
+.. opcode:: MOD - Modulus
+
+.. math::
+
+ dst.x = src0.x \bmod src1.x
+
+ dst.y = src0.y \bmod src1.y
+
+ dst.z = src0.z \bmod src1.z
+
+ dst.w = src0.w \bmod src1.w
+
+
+.. opcode:: UARL - Integer Address Register Load
+
+ Moves the contents of the source register, assumed to be an integer, into the
+ destination register, which is assumed to be an address (ADDR) register.
+
+
+.. opcode:: SAD - Sum Of Absolute Differences
+
+.. math::
+
+ dst.x = |src0.x - src1.x| + src2.x
+
+ dst.y = |src0.y - src1.y| + src2.y
+
+ dst.z = |src0.z - src1.z| + src2.z
+
+ dst.w = |src0.w - src1.w| + src2.w
+
+
+.. opcode:: TXF - Texel Fetch (as per NV_gpu_shader4), extract a single texel
+ from a specified texture image. The source sampler may
+ not be a CUBE or SHADOW.
+ src 0 is a four-component signed integer vector used to
+ identify the single texel accessed. 3 components + level.
+ src 1 is a 3 component constant signed integer vector,
+ with each component only have a range of
+ -8..+8 (hw only seems to deal with this range, interface
+ allows for up to unsigned int).
+ TXF(uint_vec coord, int_vec offset).
+
+
+.. opcode:: TXQ - Texture Size Query (as per NV_gpu_program4)
+ retrieve the dimensions of the texture
+ depending on the target. For 1D (width), 2D/RECT/CUBE
+ (width, height), 3D (width, height, depth),
+ 1D array (width, layers), 2D array (width, height, layers)
+
+.. math::
+
+ lod = src0.x
+
+ dst.x = texture_width(unit, lod)
+
+ dst.y = texture_height(unit, lod)
+
+ dst.z = texture_depth(unit, lod)
+
+
+Integer ISA
+^^^^^^^^^^^^^^^^^^^^^^^^
+These opcodes are used for integer operations.
+Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?)
+
+
+.. opcode:: I2F - Signed Integer To Float
+
+ Rounding is unspecified (round to nearest even suggested).
.. math::
dst.w = (float) src.w
-.. opcode:: NOT - Bitwise Not
+.. opcode:: U2F - Unsigned Integer To Float
+
+ Rounding is unspecified (round to nearest even suggested).
.. math::
- dst.x = ~src.x
+ dst.x = (float) src.x
- dst.y = ~src.y
+ dst.y = (float) src.y
- dst.z = ~src.z
+ dst.z = (float) src.z
- dst.w = ~src.w
+ dst.w = (float) src.w
-.. opcode:: TRUNC - Truncate
+.. opcode:: F2I - Float to Signed Integer
+
+ Rounding is towards zero (truncate).
+ Values outside signed range (including NaNs) produce undefined results.
.. math::
- dst.x = trunc(src.x)
+ dst.x = (int) src.x
- dst.y = trunc(src.y)
+ dst.y = (int) src.y
- dst.z = trunc(src.z)
+ dst.z = (int) src.z
- dst.w = trunc(src.w)
+ dst.w = (int) src.w
-.. opcode:: SHL - Shift Left
+.. opcode:: F2U - Float to Unsigned Integer
+
+ Rounding is towards zero (truncate).
+ Values outside unsigned range (including NaNs) produce undefined results.
.. math::
- dst.x = src0.x << src1.x
+ dst.x = (unsigned) src.x
- dst.y = src0.y << src1.x
+ dst.y = (unsigned) src.y
- dst.z = src0.z << src1.x
+ dst.z = (unsigned) src.z
- dst.w = src0.w << src1.x
+ dst.w = (unsigned) src.w
-.. opcode:: SHR - Shift Right
+.. opcode:: UADD - Integer Add
+
+ This instruction works the same for signed and unsigned integers.
+ The low 32bit of the result is returned.
.. math::
- dst.x = src0.x >> src1.x
+ dst.x = src0.x + src1.x
- dst.y = src0.y >> src1.x
+ dst.y = src0.y + src1.y
- dst.z = src0.z >> src1.x
+ dst.z = src0.z + src1.z
- dst.w = src0.w >> src1.x
+ dst.w = src0.w + src1.w
+
+
+.. opcode:: UMAD - Integer Multiply And Add
+
+ This instruction works the same for signed and unsigned integers.
+ The multiplication returns the low 32bit (as does the result itself).
+
+.. math::
+
+ dst.x = src0.x \times src1.x + src2.x
+
+ dst.y = src0.y \times src1.y + src2.y
+
+ dst.z = src0.z \times src1.z + src2.z
+
+ dst.w = src0.w \times src1.w + src2.w
+
+
+.. opcode:: UMUL - Integer Multiply
+
+ This instruction works the same for signed and unsigned integers.
+ The low 32bit of the result is returned.
+
+.. math::
+
+ dst.x = src0.x \times src1.x
+
+ dst.y = src0.y \times src1.y
+
+ dst.z = src0.z \times src1.z
+
+ dst.w = src0.w \times src1.w
+
+
+.. opcode:: IDIV - Signed Integer Division
+
+ TBD: behavior for division by zero.
+
+.. math::
+
+ dst.x = src0.x \ src1.x
+
+ dst.y = src0.y \ src1.y
+
+ dst.z = src0.z \ src1.z
+
+ dst.w = src0.w \ src1.w
+
+
+.. opcode:: UDIV - Unsigned Integer Division
+
+ For division by zero, 0xffffffff is returned.
+
+.. math::
+
+ dst.x = src0.x \ src1.x
+
+ dst.y = src0.y \ src1.y
+
+ dst.z = src0.z \ src1.z
+
+ dst.w = src0.w \ src1.w
+
+
+.. opcode:: UMOD - Unsigned Integer Remainder
+
+ If second arg is zero, 0xffffffff is returned.
+
+.. math::
+
+ dst.x = src0.x \ src1.x
+
+ dst.y = src0.y \ src1.y
+
+ dst.z = src0.z \ src1.z
+
+ dst.w = src0.w \ src1.w
+
+
+.. opcode:: NOT - Bitwise Not
+
+.. math::
+
+ dst.x = ~src.x
+
+ dst.y = ~src.y
+
+ dst.z = ~src.z
+
+ dst.w = ~src.w
.. opcode:: AND - Bitwise And
dst.w = src0.w | src1.w
-.. opcode:: MOD - Modulus
+.. opcode:: XOR - Bitwise Xor
.. math::
- dst.x = src0.x \bmod src1.x
+ dst.x = src0.x \oplus src1.x
- dst.y = src0.y \bmod src1.y
+ dst.y = src0.y \oplus src1.y
- dst.z = src0.z \bmod src1.z
+ dst.z = src0.z \oplus src1.z
- dst.w = src0.w \bmod src1.w
+ dst.w = src0.w \oplus src1.w
-.. opcode:: XOR - Bitwise Xor
+.. opcode:: IMAX - Maximum of Signed Integers
.. math::
- dst.x = src0.x \oplus src1.x
+ dst.x = max(src0.x, src1.x)
- dst.y = src0.y \oplus src1.y
+ dst.y = max(src0.y, src1.y)
- dst.z = src0.z \oplus src1.z
+ dst.z = max(src0.z, src1.z)
- dst.w = src0.w \oplus src1.w
+ dst.w = max(src0.w, src1.w)
+
+
+.. opcode:: UMAX - Maximum of Unsigned Integers
+
+.. math::
+
+ dst.x = max(src0.x, src1.x)
+
+ dst.y = max(src0.y, src1.y)
+
+ dst.z = max(src0.z, src1.z)
+
+ dst.w = max(src0.w, src1.w)
+
+
+.. opcode:: IMIN - Minimum of Signed Integers
+
+.. math::
+
+ dst.x = min(src0.x, src1.x)
+
+ dst.y = min(src0.y, src1.y)
+
+ dst.z = min(src0.z, src1.z)
+
+ dst.w = min(src0.w, src1.w)
+
+
+.. opcode:: UMIN - Minimum of Unsigned Integers
+
+.. math::
+
+ dst.x = min(src0.x, src1.x)
+
+ dst.y = min(src0.y, src1.y)
+
+ dst.z = min(src0.z, src1.z)
+
+ dst.w = min(src0.w, src1.w)
+
+
+.. opcode:: SHL - Shift Left
+
+.. math::
+
+ dst.x = src0.x << src1.x
+
+ dst.y = src0.y << src1.x
+
+ dst.z = src0.z << src1.x
+
+ dst.w = src0.w << src1.x
+
+
+.. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)
+
+.. math::
+
+ dst.x = src0.x >> src1.x
+
+ dst.y = src0.y >> src1.x
+
+ dst.z = src0.z >> src1.x
+
+ dst.w = src0.w >> src1.x
+
+
+.. opcode:: USHR - Logical Shift Right
+
+.. math::
+
+ dst.x = src0.x >> (unsigned) src1.x
+
+ dst.y = src0.y >> (unsigned) src1.x
+
+ dst.z = src0.z >> (unsigned) src1.x
+
+ dst.w = src0.w >> (unsigned) src1.x
.. opcode:: UCMP - Integer Conditional Move
dst.w = src0.w ? src1.w : src2.w
-.. opcode:: UARL - Integer Address Register Load
- Moves the contents of the source register, assumed to be an integer, into the
- destination register, which is assumed to be an address (ADDR) register.
+.. opcode:: ISSG - Integer Set Sign
+.. math::
-.. opcode:: IABS - Integer Absolute Value
+ dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0
+
+ dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0
+
+ dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0
+
+ dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0
+
+
+
+.. opcode:: ISLT - Signed Integer Set On Less Than
.. math::
- dst.x = |src.x|
+ dst.x = (src0.x < src1.x) ? ~0 : 0
- dst.y = |src.y|
+ dst.y = (src0.y < src1.y) ? ~0 : 0
- dst.z = |src.z|
+ dst.z = (src0.z < src1.z) ? ~0 : 0
- dst.w = |src.w|
+ dst.w = (src0.w < src1.w) ? ~0 : 0
-.. opcode:: SAD - Sum Of Absolute Differences
+.. opcode:: USLT - Unsigned Integer Set On Less Than
.. math::
- dst.x = |src0.x - src1.x| + src2.x
+ dst.x = (src0.x < src1.x) ? ~0 : 0
- dst.y = |src0.y - src1.y| + src2.y
+ dst.y = (src0.y < src1.y) ? ~0 : 0
- dst.z = |src0.z - src1.z| + src2.z
+ dst.z = (src0.z < src1.z) ? ~0 : 0
- dst.w = |src0.w - src1.w| + src2.w
+ dst.w = (src0.w < src1.w) ? ~0 : 0
-.. opcode:: TXF - Texel Fetch (as per NV_gpu_shader4), extract a single texel
- from a specified texture image. The source sampler may
- not be a CUBE or SHADOW.
- src 0 is a four-component signed integer vector used to
- identify the single texel accessed. 3 components + level.
- src 1 is a 3 component constant signed integer vector,
- with each component only have a range of
- -8..+8 (hw only seems to deal with this range, interface
- allows for up to unsigned int).
- TXF(uint_vec coord, int_vec offset).
+.. opcode:: ISGE - Signed Integer Set On Greater Equal Than
+.. math::
-.. opcode:: TXQ - Texture Size Query (as per NV_gpu_program4)
- retrieve the dimensions of the texture
- depending on the target. For 1D (width), 2D/RECT/CUBE
- (width, height), 3D (width, height, depth),
- 1D array (width, layers), 2D array (width, height, layers)
+ dst.x = (src0.x >= src1.x) ? ~0 : 0
+
+ dst.y = (src0.y >= src1.y) ? ~0 : 0
+
+ dst.z = (src0.z >= src1.z) ? ~0 : 0
+
+ dst.w = (src0.w >= src1.w) ? ~0 : 0
+
+
+.. opcode:: USGE - Unsigned Integer Set On Greater Equal Than
.. math::
- lod = src0
+ dst.x = (src0.x >= src1.x) ? ~0 : 0
- dst.x = texture_width(unit, lod)
+ dst.y = (src0.y >= src1.y) ? ~0 : 0
- dst.y = texture_height(unit, lod)
+ dst.z = (src0.z >= src1.z) ? ~0 : 0
- dst.z = texture_depth(unit, lod)
+ dst.w = (src0.w >= src1.w) ? ~0 : 0
-.. opcode:: CONT - Continue
+.. opcode:: USEQ - Integer Set On Equal
- TBD
+.. math::
-.. note::
+ dst.x = (src0.x == src1.x) ? ~0 : 0
- Support for CONT is determined by a special capability bit,
- ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
+ dst.y = (src0.y == src1.y) ? ~0 : 0
+
+ dst.z = (src0.z == src1.z) ? ~0 : 0
+
+ dst.w = (src0.w == src1.w) ? ~0 : 0
+
+
+.. opcode:: USNE - Integer Set On Not Equal
+
+.. math::
+
+ dst.x = (src0.x != src1.x) ? ~0 : 0
+
+ dst.y = (src0.y != src1.y) ? ~0 : 0
+
+ dst.z = (src0.z != src1.z) ? ~0 : 0
+
+ dst.w = (src0.w != src1.w) ? ~0 : 0
+
+
+.. opcode:: INEG - Integer Negate
+
+ Two's complement.
+
+.. math::
+
+ dst.x = -src.x
+
+ dst.y = -src.y
+
+ dst.z = -src.z
+
+ dst.w = -src.w
+
+
+.. opcode:: IABS - Integer Absolute Value
+
+.. math::
+
+ dst.x = |src.x|
+
+ dst.y = |src.y|
+
+ dst.z = |src.z|
+
+ dst.w = |src.w|
Geometry ISA
.. opcode:: EMIT - Emit
- TBD
+ Generate a new vertex for the current primitive using the values in the
+ output registers.
.. opcode:: ENDPRIM - End Primitive
- TBD
+ Complete the current primitive (consisting of the emitted vertices),
+ and start a new one.
GLSL ISA
These opcodes are part of :term:`GLSL`'s opcode set. Support for these
opcodes is determined by a special capability bit, ``GLSL``.
+Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
+
+.. opcode:: CAL - Subroutine Call
+
+ push(pc)
+ pc = target
+
+
+.. opcode:: RET - Subroutine Call Return
+
+ pc = pop()
+
+
+.. opcode:: CONT - Continue
+
+ Unconditionally moves the point of execution to the instruction after the
+ last bgnloop. The instruction must appear within a bgnloop/endloop.
+
+.. note::
+
+ Support for CONT is determined by a special capability bit,
+ ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
+
.. opcode:: BGNLOOP - Begin a Loop
- TBD
+ Start a loop. Must have a matching endloop.
.. opcode:: BGNSUB - Begin Subroutine
- TBD
+ Starts definition of a subroutine. Must have a matching endsub.
.. opcode:: ENDLOOP - End a Loop
- TBD
+ End a loop started with bgnloop.
.. opcode:: ENDSUB - End Subroutine
- TBD
+ Ends definition of a subroutine.
.. opcode:: NOP - No Operation
Do nothing.
-.. opcode:: NRM4 - 4-component Vector Normalise
+.. opcode:: BRK - Break
-This instruction replicates its result.
+ Unconditionally moves the point of execution to the instruction after the
+ next endloop or endswitch. The instruction must appear within a loop/endloop
+ or switch/endswitch.
-.. math::
- dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
+.. opcode:: BREAKC - Break Conditional
+ Conditionally moves the point of execution to the instruction after the
+ next endloop or endswitch. The instruction must appear within a loop/endloop
+ or switch/endswitch.
+ Condition evaluates to true if src0.x != 0 where src0.x is interpreted
+ as an integer register.
-ps_2_x
-^^^^^^^^^^^^
+.. note::
-XXX wait what
+ Considered for removal as it's quite inconsistent wrt other opcodes
+ (could emulate with UIF/BRK/ENDIF).
-.. opcode:: CALLNZ - Subroutine Call If Not Zero
- TBD
+.. opcode:: IF - Float If
+ Start an IF ... ELSE .. ENDIF block. Condition evaluates to true if
-.. opcode:: BREAKC - Break Conditional
+ src0.x != 0.0
+
+ where src0.x is interpreted as a floating point register.
+
+
+.. opcode:: UIF - Bitwise If
+
+ Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if
+
+ src0.x != 0
+
+ where src0.x is interpreted as an integer register.
+
+
+.. opcode:: ELSE - Else
+
+ Starts an else block, after an IF or UIF statement.
+
+
+.. opcode:: ENDIF - End If
+
+ Ends an IF or UIF block.
+
+
+.. opcode:: SWITCH - Switch
+
+ Starts a C-style switch expression. The switch consists of one or multiple
+ CASE statements, and at most one DEFAULT statement. Execution of a statement
+ ends when a BRK is hit, but just like in C falling through to other cases
+ without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
+ just as last statement, and fallthrough is allowed into/from it.
+ CASE src arguments are evaluated at bit level against the SWITCH src argument.
+
+ Example:
+ SWITCH src[0].x
+ CASE src[0].x
+ (some instructions here)
+ (optional BRK here)
+ DEFAULT
+ (some instructions here)
+ (optional BRK here)
+ CASE src[0].x
+ (some instructions here)
+ (optional BRK here)
+ ENDSWITCH
+
+
+.. opcode:: CASE - Switch case
+
+ This represents a switch case label. The src arg must be an integer immediate.
+
+
+.. opcode:: DEFAULT - Switch default
+
+ This represents the default case in the switch, which is taken if no other
+ case matches.
+
+
+.. opcode:: ENDSWITCH - End of switch
+
+ Ends a switch expression.
+
+
+.. opcode:: NRM4 - 4-component Vector Normalise
+
+This instruction replicates its result.
+
+.. math::
+
+ dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
- TBD
.. _doubleopcodes:
drawn when the polygon mode converts triangles/quads/polygons into
points or lines.
+
TGSI_SEMANTIC_STENCIL
-""""""""""""""""""""""
+"""""""""""""""""""""
-For fragment shaders, this semantic label indicates than an output
+For fragment shaders, this semantic label indicates that an output
is a writable stencil reference value. Only the Y component is writable.
This allows the fragment shader to change the fragments stencilref value.
+TGSI_SEMANTIC_VIEWPORT_INDEX
+""""""""""""""""""""""""""""
+
+For geometry shaders, this semantic label indicates that an output
+contains the index of the viewport (and scissor) to use.
+Only the X value is used.
+
+
+TGSI_SEMANTIC_LAYER
+"""""""""""""""""""
+
+For geometry shaders, this semantic label indicates that an output
+contains the layer value to use for the color and depth/stencil surfaces.
+Only the X value is used. (Also known as rendertarget array index.)
+
+
+TGSI_SEMANTIC_CULLDIST
+""""""""""""""""""""""
+
+Used as distance to plane for performing application-defined culling
+of individual primitives against a plane. When components of vertex
+elements are given this label, these values are assumed to be a
+float32 signed distance to a plane. Primitives will be completely
+discarded if the plane distance for all of the vertices in the
+primitive are < 0. If a vertex has a cull distance of NaN, that
+vertex counts as "out" (as if its < 0);
+The limits on both clip and cull distances are bound
+by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
+the maximum number of components that can be used to hold the
+distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
+which specifies the maximum number of registers which can be
+annotated with those semantics.
+
+
+TGSI_SEMANTIC_CLIPDIST
+""""""""""""""""""""""
+
+When components of vertex elements are identified this way, these
+values are each assumed to be a float32 signed distance to a plane.
+Primitive setup only invokes rasterization on pixels for which
+the interpolated plane distances are >= 0. Multiple clip planes
+can be implemented simultaneously, by annotating multiple
+components of one or more vertex elements with the above specified
+semantic. The limits on both clip and cull distances are bound
+by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
+the maximum number of components that can be used to hold the
+distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
+which specifies the maximum number of registers which can be
+annotated with those semantics.
+
+
Declaration Interpolate
^^^^^^^^^^^^^^^^^^^^^^^
If INTEGER, the fractionary part of the position will be 0.0
Note that this does not affect the set of fragments generated by
-rasterization, which is instead controlled by gl_rasterization_rules in the
+rasterization, which is instead controlled by half_pixel_center in the
rasterizer.
OpenGL defaults to HALF_INTEGER, and is configurable with the
projects / mesa.git / blobdiff