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/*
* © Copyright 2018 Alyssa Rosenzweig
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
*/
#include <stdio.h>
#include "pan_blending.h"
#include "pan_context.h"
#include "gallium/auxiliary/util/u_blend.h"
#include "util/u_format.h"
/*
* Implements fixed-function blending on Midgard.
*
* Midgard splits blending into a fixed-function fast path and a programmable
* slow path. The fixed function blending architecture is based on "dominant"
* blend factors. Blending is encoded separately (but identically) between RGB
* and alpha functions.
*
* Essentially, for a given blending operation, there is a single dominant
* factor. The following dominant factors are possible:
*
* - zero
* - source color
* - destination color
* - source alpha
* - destination alpha
* - constant float
*
* Further, a dominant factor's arithmetic compliment could be used. For
* instance, to encode GL_ONE_MINUS_SOURCE_ALPHA, the dominant factor would be
* MALI_DOMINANT_SRC_ALPHA with the complement_dominant bit set.
*
* A single constant float can be passed to the fixed-function hardware,
* allowing CONSTANT_ALPHA support. Further, if all components of the constant
* glBlendColor are identical, CONSTANT_COLOR can be implemented with the
* constant float mode. If the components differ, programmable blending is
* required.
*
* The nondominant factor can be either:
*
* - the same as the dominant factor (MALI_BLEND_NON_MIRROR)
* - zero (MALI_BLEND_NON_ZERO)
*
* Exactly one of the blend operation's source or destination can be used as
* the dominant factor; this is selected by the
* MALI_BLEND_DOM_SOURCE/DESTINATION flag.
*
* By default, all blending follows the standard OpenGL addition equation:
*
* out = source_value * source_factor + destination_value * destination_factor
*
* By setting the negate_source or negate_dest bits, other blend functions can
* be created. For instance, for SUBTRACT mode, set the "negate destination"
* flag, and similarly for REVERSE_SUBTRACT with "negate source".
*
* Finally, there is a "clip modifier" controlling the final blending
* behaviour, allowing for the following modes:
*
* - normal
* - force source factor to one (MALI_BLEND_MODE_SOURCE_ONE)
* - force destination factor to one (MALI_BLEND_MODE_DEST_ONE)
*
* The clipping flags can be used to encode blend modes where the nondominant
* factor is ONE.
*
* As an example putting it all together, to encode the following blend state:
*
* glBlendEquation(GL_FUNC_REVERSE_SUBTRACT);
* glBlendFunc(GL_ONE_MINUS_SRC_ALPHA, GL_ONE);
*
* We need the following configuration:
*
* - negate source (for REVERSE_SUBTRACT)
* - dominant factor "source alpha"
* - complement dominant
* - source dominant
* - force destination to ONE
*
* The following routines implement this fixed function blending encoding
*/
/* Not all formats can be blended by fixed-function hardware */
bool
panfrost_can_fixed_blend(enum pipe_format format)
{
/* Fixed-function can handle sRGB */
format = util_format_linear(format);
/* Decompose the format */
const struct util_format_description *desc =
util_format_description(format);
/* Any 8-bit unorm is supported */
if (util_format_is_unorm8(desc))
return true;
/* Certain special formats are, too */
switch (format) {
case PIPE_FORMAT_B5G6R5_UNORM:
case PIPE_FORMAT_B4G4R4A4_UNORM:
case PIPE_FORMAT_B5G5R5A1_UNORM:
case PIPE_FORMAT_R10G10B10A2_UNORM:
return true;
default:
return false;
}
}
/* Helper to find the uncomplemented Gallium blend factor corresponding to a
* complemented Gallium blend factor */
static int
complement_factor(int factor)
{
switch (factor) {
case PIPE_BLENDFACTOR_INV_SRC_COLOR:
return PIPE_BLENDFACTOR_SRC_COLOR;
case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
return PIPE_BLENDFACTOR_SRC_ALPHA;
case PIPE_BLENDFACTOR_INV_DST_ALPHA:
return PIPE_BLENDFACTOR_DST_ALPHA;
case PIPE_BLENDFACTOR_INV_DST_COLOR:
return PIPE_BLENDFACTOR_DST_COLOR;
case PIPE_BLENDFACTOR_INV_CONST_COLOR:
return PIPE_BLENDFACTOR_CONST_COLOR;
case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
return PIPE_BLENDFACTOR_CONST_ALPHA;
default:
return -1;
}
}
/* Helper to strip the complement from any Gallium blend factor */
static int
uncomplement_factor(int factor)
{
int complement = complement_factor(factor);
return (complement == -1) ? factor : complement;
}
/* Attempt to find the dominant factor given a particular factor, complementing
* as necessary */
static bool
panfrost_make_dominant_factor(unsigned src_factor, enum mali_dominant_factor *factor)
{
switch (src_factor) {
case PIPE_BLENDFACTOR_SRC_COLOR:
case PIPE_BLENDFACTOR_INV_SRC_COLOR:
*factor = MALI_DOMINANT_SRC_COLOR;
break;
case PIPE_BLENDFACTOR_SRC_ALPHA:
case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
*factor = MALI_DOMINANT_SRC_ALPHA;
break;
case PIPE_BLENDFACTOR_DST_COLOR:
case PIPE_BLENDFACTOR_INV_DST_COLOR:
*factor = MALI_DOMINANT_DST_COLOR;
break;
case PIPE_BLENDFACTOR_DST_ALPHA:
case PIPE_BLENDFACTOR_INV_DST_ALPHA:
*factor = MALI_DOMINANT_DST_ALPHA;
break;
case PIPE_BLENDFACTOR_ONE:
case PIPE_BLENDFACTOR_ZERO:
*factor = MALI_DOMINANT_ZERO;
break;
case PIPE_BLENDFACTOR_CONST_ALPHA:
case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
case PIPE_BLENDFACTOR_CONST_COLOR:
case PIPE_BLENDFACTOR_INV_CONST_COLOR:
*factor = MALI_DOMINANT_CONSTANT;
break;
default:
/* Fancy blend modes not supported */
return false;
}
return true;
}
/* Check if this is a special edge case blend factor, which may require the use
* of clip modifiers */
static bool
is_edge_blendfactor(unsigned factor)
{
return factor == PIPE_BLENDFACTOR_ONE || factor == PIPE_BLENDFACTOR_ZERO;
}
/* Perform the actual fixed function encoding. Encode the function with negate
* bits. Check for various cases to work out the dominant/nondominant split and
* accompanying flags. */
static bool
panfrost_make_fixed_blend_part(unsigned func, unsigned src_factor, unsigned dst_factor, unsigned *out)
{
struct mali_blend_mode part = { 0 };
/* Make sure that the blend function is representible */
switch (func) {
case PIPE_BLEND_ADD:
break;
/* TODO: Reenable subtraction modes when those fixed */
case PIPE_BLEND_SUBTRACT:
case PIPE_BLEND_REVERSE_SUBTRACT:
default:
return false;
}
part.clip_modifier = MALI_BLEND_MOD_NORMAL;
/* Decide which is dominant, source or destination. If one is an edge
* case, use the other as a factor. If they're the same, it doesn't
* matter; we just mirror. If they're different non-edge-cases, you
* need a blend shader (don't do that). */
if (is_edge_blendfactor(dst_factor)) {
part.dominant = MALI_BLEND_DOM_SOURCE;
part.nondominant_mode = MALI_BLEND_NON_ZERO;
if (dst_factor == PIPE_BLENDFACTOR_ONE)
part.clip_modifier = MALI_BLEND_MOD_DEST_ONE;
} else if (is_edge_blendfactor(src_factor)) {
part.dominant = MALI_BLEND_DOM_DESTINATION;
part.nondominant_mode = MALI_BLEND_NON_ZERO;
if (src_factor == PIPE_BLENDFACTOR_ONE)
part.clip_modifier = MALI_BLEND_MOD_SOURCE_ONE;
} else if (src_factor == dst_factor) {
/* XXX: Why? */
part.dominant = func == PIPE_BLEND_ADD ?
MALI_BLEND_DOM_DESTINATION : MALI_BLEND_DOM_SOURCE;
part.nondominant_mode = MALI_BLEND_NON_MIRROR;
} else if (src_factor == complement_factor(dst_factor)) {
/* TODO: How does this work exactly? */
part.dominant = MALI_BLEND_DOM_SOURCE;
part.nondominant_mode = MALI_BLEND_NON_MIRROR;
part.clip_modifier = MALI_BLEND_MOD_DEST_ONE;
/* The complement is handled by the clip modifier, don't set a
* complement flag */
dst_factor = src_factor;
} else if (dst_factor == complement_factor(src_factor)) {
part.dominant = MALI_BLEND_DOM_SOURCE;
part.nondominant_mode = MALI_BLEND_NON_MIRROR;
part.clip_modifier = MALI_BLEND_MOD_SOURCE_ONE;
src_factor = dst_factor;
} else {
return false;
}
unsigned in_dominant_factor =
part.dominant == MALI_BLEND_DOM_SOURCE ? src_factor : dst_factor;
if (part.clip_modifier == MALI_BLEND_MOD_NORMAL && in_dominant_factor == PIPE_BLENDFACTOR_ONE) {
part.clip_modifier = part.dominant == MALI_BLEND_DOM_SOURCE ? MALI_BLEND_MOD_SOURCE_ONE : MALI_BLEND_MOD_DEST_ONE;
in_dominant_factor = PIPE_BLENDFACTOR_ZERO;
}
enum mali_dominant_factor dominant_factor;
if (!panfrost_make_dominant_factor(in_dominant_factor, &dominant_factor))
return false;
part.dominant_factor = dominant_factor;
part.complement_dominant = util_blend_factor_is_inverted(in_dominant_factor);
/* It's not clear what this does, but fixes some ADD blending tests.
* More research is needed XXX */
if ((part.clip_modifier == MALI_BLEND_MOD_SOURCE_ONE) && (part.dominant == MALI_BLEND_DOM_SOURCE))
part.negate_dest = true;
/* Write out mode */
memcpy(out, &part, sizeof(part));
return true;
}
/* We can upload a single constant for all of the factors. So, scan
* the factors for constants used to create a mask to check later. */
static unsigned
panfrost_constant_mask(unsigned *factors, unsigned num_factors)
{
unsigned mask = 0;
for (unsigned i = 0; i < num_factors; ++i) {
unsigned factor = uncomplement_factor(factors[i]);
if (factor == PIPE_BLENDFACTOR_CONST_COLOR)
mask |= 0b0111; /* RGB */
else if (factor == PIPE_BLENDFACTOR_CONST_ALPHA)
mask |= 0b1000; /* A */
}
return mask;
}
/* Create the descriptor for a fixed blend mode given the corresponding Gallium
* state, if possible. Return true and write out the blend descriptor into
* blend_equation. If it is not possible with the fixed function
* representating, return false to handle degenerate cases with a blend shader
*/
bool
panfrost_make_fixed_blend_mode(
const struct pipe_rt_blend_state *blend,
struct mali_blend_equation *out,
unsigned *constant_mask,
unsigned colormask)
{
/* Gallium and Mali represent colour masks identically. XXX: Static
* assert for future proof */
out->color_mask = colormask;
/* If no blending is enabled, default back on `replace` mode */
if (!blend->blend_enable) {
out->rgb_mode = 0x122;
out->alpha_mode = 0x122;
return true;
}
/* At draw-time, we'll need to analyze the blend constant, so
* precompute a mask for it -- even if we don't end up able to use
* fixed-function blending */
unsigned factors[] = {
blend->rgb_src_factor, blend->rgb_dst_factor,
blend->alpha_src_factor, blend->alpha_dst_factor,
};
*constant_mask = panfrost_constant_mask(factors, ARRAY_SIZE(factors));
/* Try to compile the actual fixed-function blend */
unsigned rgb_mode = 0;
unsigned alpha_mode = 0;
if (!panfrost_make_fixed_blend_part(
blend->rgb_func, blend->rgb_src_factor, blend->rgb_dst_factor,
&rgb_mode))
return false;
if (!panfrost_make_fixed_blend_part(
blend->alpha_func, blend->alpha_src_factor, blend->alpha_dst_factor,
&alpha_mode))
return false;
out->rgb_mode = rgb_mode;
out->alpha_mode = alpha_mode;
return true;
}
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