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// Copyright 2018 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include "common/assert.h"
#include "common/common_types.h"
#include "video_core/engines/shader_bytecode.h"
#include "video_core/shader/node_helper.h"
#include "video_core/shader/shader_ir.h"
namespace VideoCommon::Shader {
using Tegra::Shader::Instruction;
using Tegra::Shader::OpCode;
u32 ShaderIR::DecodeBfe(NodeBlock& bb, u32 pc) {
const Instruction instr = {program_code[pc]};
const auto opcode = OpCode::Decode(instr);
Node op_a = GetRegister(instr.gpr8);
Node op_b = [&] {
switch (opcode->get().GetId()) {
case OpCode::Id::BFE_R:
return GetRegister(instr.gpr20);
case OpCode::Id::BFE_C:
return GetConstBuffer(instr.cbuf34.index, instr.cbuf34.GetOffset());
case OpCode::Id::BFE_IMM:
return Immediate(instr.alu.GetSignedImm20_20());
default:
UNREACHABLE();
return Immediate(0);
}
}();
UNIMPLEMENTED_IF_MSG(instr.bfe.rd_cc, "Condition codes in BFE is not implemented");
const bool is_signed = instr.bfe.is_signed;
// using reverse parallel method in
// https://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel
// note for later if possible to implement faster method.
if (instr.bfe.brev) {
const auto swap = [&](u32 s, u32 mask) {
Node v1 =
SignedOperation(OperationCode::ILogicalShiftRight, is_signed, op_a, Immediate(s));
if (mask != 0) {
v1 = SignedOperation(OperationCode::IBitwiseAnd, is_signed, std::move(v1), Immediate(mask));
}
Node v2 = op_a;
if (mask != 0) {
v2 = SignedOperation(OperationCode::IBitwiseAnd, is_signed, std::move(v2), Immediate(mask));
}
v2 = SignedOperation(OperationCode::ILogicalShiftLeft, is_signed, std::move(v2), Immediate(s));
return SignedOperation(OperationCode::IBitwiseOr, is_signed, std::move(v1), std::move(v2));
};
op_a = swap(1, 0x55555555U);
op_a = swap(2, 0x33333333U);
op_a = swap(4, 0x0F0F0F0FU);
op_a = swap(8, 0x00FF00FFU);
op_a = swap(16, 0);
}
const auto offset = SignedOperation(OperationCode::IBitfieldExtract, is_signed, op_b,
Immediate(0), Immediate(8));
const auto bits = SignedOperation(OperationCode::IBitfieldExtract, is_signed, op_b,
Immediate(8), Immediate(8));
const auto result =
SignedOperation(OperationCode::IBitfieldExtract, is_signed, op_a, offset, bits);
SetRegister(bb, instr.gpr0, std::move(result));
return pc;
}
} // namespace VideoCommon::Shader
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