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/*
* Copyright (C) 2019 Collabora, Ltd.
*
* 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 "util/u_math.h"
#include "panfrost-job.h"
#include "pan_encoder.h"
/* This file handles attribute descriptors (mali_attr_meta). The
* bulk of the complexity is from instancing. See mali_job for
* notes on how this works. But basically, for small vertex
* counts, we have a lookup table, and for large vertex counts,
* we look at the high bits as a heuristic. This has to match
* exactly how the hardware calculates this (which is why the
* algorithm is so weird) or else instancing will break. */
/* Given an odd number (of the form 2k + 1), compute k */
#define ODD(odd) ((odd - 1) >> 1)
static unsigned
panfrost_small_padded_vertex_count(unsigned idx)
{
if (idx == 11 || idx == 13 || idx == 15 || idx == 19)
return idx + 1;
else
return idx;
}
static unsigned
panfrost_large_padded_vertex_count(uint32_t vertex_count)
{
/* First, we have to find the highest set one */
unsigned highest = 32 - __builtin_clz(vertex_count);
/* Using that, we mask out the highest 4-bits */
unsigned n = highest - 4;
unsigned nibble = (vertex_count >> n) & 0xF;
/* Great, we have the nibble. Now we can just try possibilities. Note
* that we don't care about the bottom most bit in most cases, and we
* know the top bit must be 1 */
unsigned middle_two = (nibble >> 1) & 0x3;
switch (middle_two) {
case 0b00:
if (!(nibble & 1))
return (1 << n) * 9;
else
return (1 << (n + 1)) * 5;
case 0b01:
return (1 << (n + 2)) * 3;
case 0b10:
return (1 << (n + 1)) * 7;
case 0b11:
return (1 << (n + 4));
default:
return 0; /* unreachable */
}
}
unsigned
panfrost_padded_vertex_count(unsigned vertex_count)
{
if (vertex_count < 20)
return panfrost_small_padded_vertex_count(vertex_count);
else
return panfrost_large_padded_vertex_count(vertex_count);
}
/* The much, much more irritating case -- instancing is enabled. See
* panfrost_job.h for notes on how this works */
static unsigned
panfrost_compute_magic_divisor(unsigned hw_divisor, unsigned *o_shift, unsigned *extra_flags)
{
/* We have a NPOT divisor. Here's the fun one (multipling by
* the inverse and shifting) */
/* floor(log2(d)) */
unsigned shift = util_logbase2(hw_divisor);
/* m = ceil(2^(32 + shift) / d) */
uint64_t shift_hi = 32 + shift;
uint64_t t = 1ll << shift_hi;
double t_f = t;
double hw_divisor_d = hw_divisor;
double m_f = ceil(t_f / hw_divisor_d);
unsigned m = m_f;
/* Default case */
uint32_t magic_divisor = m;
/* e = 2^(shift + 32) % d */
uint64_t e = t % hw_divisor;
/* Apply round-down algorithm? e <= 2^shift?. XXX: The blob
* seems to use a different condition */
if (e <= (1ll << shift)) {
magic_divisor = m - 1;
*extra_flags = 1;
}
/* Top flag implicitly set */
assert(magic_divisor & (1u << 31));
magic_divisor &= ~(1u << 31);
*o_shift = shift;
return magic_divisor;
}
unsigned
panfrost_vertex_instanced(
unsigned padded_count,
unsigned instance_shift, unsigned instance_odd,
unsigned divisor,
union mali_attr *attrs)
{
/* Depending if there is an instance divisor or not, packing varies.
* When there is a divisor, the hardware-level divisor is actually the
* product of the instance divisor and the padded count */
unsigned hw_divisor = padded_count * divisor;
if (divisor == 0) {
/* Per-vertex attributes use the MODULO mode. First, compute
* the modulus */
attrs->elements |= MALI_ATTR_MODULO;
attrs->shift = instance_shift;
attrs->extra_flags = instance_odd;
return 1;
} else if (util_is_power_of_two_or_zero(hw_divisor)) {
/* If there is a divisor but the hardware divisor works out to
* a power of two (not terribly exceptional), we can use an
* easy path (just shifting) */
attrs->elements |= MALI_ATTR_POT_DIVIDE;
attrs->shift = __builtin_ctz(hw_divisor);
return 1;
} else {
unsigned shift = 0, extra_flags = 0;
attrs[1].magic_divisor =
panfrost_compute_magic_divisor(hw_divisor, &shift, &extra_flags);
/* Upload to two different slots */
attrs[0].elements |= MALI_ATTR_NPOT_DIVIDE;
attrs[0].shift = shift;
attrs[0].extra_flags = extra_flags;
attrs[1].unk = 0x20;
attrs[1].zero = 0;
attrs[1].divisor = divisor;
return 2;
}
}
/* Records for gl_VertexID and gl_InstanceID use a slightly special encoding,
* but the idea is the same */
void
panfrost_vertex_id(
unsigned padded_count,
union mali_attr *attr)
{
/* We factor the padded count as shift/odd and that's it */
attr->elements = MALI_ATTR_VERTEXID;
attr->shift = __builtin_ctz(padded_count);
attr->extra_flags = padded_count >> (attr->shift + 1);
attr->stride = attr->size = 0;
}
void
panfrost_instance_id(
unsigned padded_count,
union mali_attr *attr)
{
attr->elements = MALI_ATTR_INSTANCEID;
attr->stride = 0;
attr->extra_flags = 0;
attr->size = 0;
/* POT records have just a shift directly with an off-by-one for
* unclear reasons. NPOT records have a magic divisor smushed into the
* stride field (which is unused for these special records) */
if (util_is_power_of_two_or_zero(padded_count)) {
attr->shift = __builtin_ctz(padded_count) - 1;
} else {
unsigned shift = 0, flags = 0;
attr->stride = panfrost_compute_magic_divisor(padded_count, &shift, &flags);
attr->shift = shift;
attr->extra_flags = flags;
}
}
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