/* * 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 "midgard_pack.h" #include "pan_encoder.h" /* This file handles attribute descriptors. 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 < 10) return idx; else return (idx + 1) & ~1; } 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 */ 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; } /* 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, struct mali_attribute_buffer_packed *attr, bool instanced) { /* We factor the padded count as shift/odd and that's it */ pan_pack(attr, ATTRIBUTE_BUFFER, cfg) { cfg.special = MALI_ATTRIBUTE_SPECIAL_VERTEX_ID; cfg.type = 0; if (instanced) { cfg.divisor_r = __builtin_ctz(padded_count); cfg.divisor_p = padded_count >> (cfg.divisor_r + 1); } else { /* Match the blob... */ cfg.divisor_r = 0x1F; cfg.divisor_p = 0x4; } } } void panfrost_instance_id( unsigned padded_count, struct mali_attribute_buffer_packed *attr, bool instanced) { pan_pack(attr, ATTRIBUTE_BUFFER, cfg) { cfg.special = MALI_ATTRIBUTE_SPECIAL_INSTANCE_ID; cfg.type = 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 (!instanced || padded_count <= 1) { /* Match the blob... */ cfg.stride = ((1u << 31) - 1); cfg.divisor_r = 0x1F; cfg.divisor_e = 0x1; } else if(util_is_power_of_two_or_zero(padded_count)) { /* By above, padded_count > 1 => padded_count >= 2 so * since we're a power of two, ctz(padded_count) = * log2(padded_count) >= log2(2) = 1, so * ctz(padded_count) - 1 >= 0, so this can't underflow * */ cfg.divisor_r = __builtin_ctz(padded_count) - 1; } else { cfg.stride = panfrost_compute_magic_divisor(padded_count, &cfg.divisor_r, &cfg.divisor_e); } } }