src/arch/riscv/decoder.hh

   1 /*
   2  * Copyright (c) 2012 Google
   3  * Copyright (c) 2017 The University of Virginia
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions are
   8  * met: redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer;
  10  * redistributions in binary form must reproduce the above copyright
  11  * notice, this list of conditions and the following disclaimer in the
  12  * documentation and/or other materials provided with the distribution;
  13  * neither the name of the copyright holders nor the names of its
  14  * contributors may be used to endorse or promote products derived from
  15  * this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  20  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  21  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  27  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  *
  29  * Authors: Gabe Black
  30  *          Alec Roelke
  31  */
  32
  33 #ifndef __ARCH_RISCV_DECODER_HH__
  34 #define __ARCH_RISCV_DECODER_HH__
  35
  36 #include "arch/generic/decode_cache.hh"
  37 #include "arch/riscv/isa_traits.hh"
  38 #include "arch/riscv/types.hh"
  39 #include "base/misc.hh"
  40 #include "base/types.hh"
  41 #include "cpu/static_inst.hh"
  42 #include "debug/Decode.hh"
  43
  44 namespace RiscvISA
  45 {
  46
  47 class ISA;
  48 class Decoder
  49 {
  50   private:
  51     DecodeCache::InstMap instMap;
  52     bool aligned;
  53     bool mid;
  54     bool more;
  55
  56   protected:
  57     //The extended machine instruction being generated
  58     ExtMachInst emi;
  59     bool instDone;
  60
  61   public:
  62     Decoder(ISA* isa=nullptr) { reset(); }
  63
  64     void process() {}
  65     void reset();
  66
  67     inline bool compressed(ExtMachInst inst) { return (inst & 0x3) < 0x3; }
  68
  69     //Use this to give data to the decoder. This should be used
  70     //when there is control flow.
  71     void moreBytes(const PCState &pc, Addr fetchPC, MachInst inst);
  72
  73     bool needMoreBytes() { return more; }
  74     bool instReady() { return instDone; }
  75     void takeOverFrom(Decoder *old) {}
  76
  77     StaticInstPtr decodeInst(ExtMachInst mach_inst);
  78
  79     /// Decode a machine instruction.
  80     /// @param mach_inst The binary instruction to decode.
  81     /// @retval A pointer to the corresponding StaticInst object.
  82     StaticInstPtr decode(ExtMachInst mach_inst, Addr addr);
  83
  84     StaticInstPtr decode(RiscvISA::PCState &nextPC);
  85 };
  86
  87 } // namespace RiscvISA
  88
  89 #endif // __ARCH_RISCV_DECODER_HH__