// -*- mode:c++ -*-

// Copyright (c) 2007 MIPS Technologies, Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met: redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer;
// redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution;
// neither the name of the copyright holders nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

////////////////////////////////////////////////////////////////////
//
// Control transfer instructions
//

output header {{

#include <iostream>

    /**
     * Base class for instructions whose disassembly is not purely a
     * function of the machine instruction (i.e., it depends on the
     * PC).  This class overrides the disassemble() method to check
     * the PC and symbol table values before re-using a cached
     * disassembly string.  This is necessary for branches and jumps,
     * where the disassembly string includes the target address (which
     * may depend on the PC and/or symbol table).
     */
    class PCDependentDisassembly : public MipsStaticInst
    {
      protected:
        /// Cached program counter from last disassembly
        mutable Addr cachedPC;

        /// Cached symbol table pointer from last disassembly
        mutable const loader::SymbolTable *cachedSymtab;

        /// Constructor
        PCDependentDisassembly(const char *mnem, MachInst _machInst,
                               OpClass __opClass)
            : MipsStaticInst(mnem, _machInst, __opClass),
              cachedPC(0), cachedSymtab(0)
        {
        }

        const std::string &
        disassemble(Addr pc, const loader::SymbolTable *symtab) const;
    };

    /**
     * Base class for branches (PC-relative control transfers),
     * conditional or unconditional.
     */
    class Branch : public PCDependentDisassembly
    {
      protected:
        /// target address (signed) Displacement .
        int32_t disp;

        /// Constructor.
        Branch(const char *mnem, MachInst _machInst, OpClass __opClass)
            : PCDependentDisassembly(mnem, _machInst, __opClass),
              disp(OFFSET << 2)
        {
            //If Bit 17 is 1 then Sign Extend
            if ( (disp & 0x00020000) > 0  ) {
                disp |= 0xFFFE0000;
            }
        }

        std::unique_ptr<PCStateBase> branchTarget(
                const PCStateBase &branch_pc) const override;

        /// Explicitly import the otherwise hidden branchTarget
        using StaticInst::branchTarget;

        std::string generateDisassembly(
                Addr pc, const loader::SymbolTable *symtab) const override;
    };

    /**
     * Base class for jumps (register-indirect control transfers).  In
     * the Mips ISA, these are always unconditional.
     */
    class Jump : public PCDependentDisassembly
    {
      protected:

        /// Displacement to target address (signed).
        int32_t disp;

        uint32_t target;

      public:
        /// Constructor
        Jump(const char *mnem, MachInst _machInst, OpClass __opClass)
            : PCDependentDisassembly(mnem, _machInst, __opClass),
              disp(JMPTARG << 2)
        {
        }

        std::unique_ptr<PCStateBase> branchTarget(
                ThreadContext *tc) const override;

        /// Explicitly import the otherwise hidden branchTarget
        using StaticInst::branchTarget;

        std::string generateDisassembly(
                Addr pc, const loader::SymbolTable *symtab) const override;
    };
}};

output decoder {{
    std::unique_ptr<PCStateBase>
    Branch::branchTarget(const PCStateBase &branch_pc) const
    {
        PCStateBase *target_ptr = branch_pc.clone();
        auto &target = target_ptr->as<MipsISA::PCState>();
        target.advance();
        target.npc(branch_pc.instAddr() + sizeof(MachInst) + disp);
        target.nnpc(target.npc() + sizeof(MachInst));
        return std::unique_ptr<PCStateBase>{target_ptr};
    }

    std::unique_ptr<PCStateBase>
    Jump::branchTarget(ThreadContext *tc) const
    {
        PCStateBase *target_ptr = tc->pcState().clone();
        auto &target = target_ptr->as<MipsISA::PCState>();
        Addr pc = target.pc();
        target.advance();
        target.npc((pc & 0xF0000000) | disp);
        target.nnpc(target.npc() + sizeof(MachInst));
        return std::unique_ptr<PCStateBase>{target_ptr};
    }

    const std::string &
    PCDependentDisassembly::disassemble(
            Addr pc, const loader::SymbolTable *symtab) const
    {
        if (!cachedDisassembly || pc != cachedPC || symtab != cachedSymtab) {
            if (!cachedDisassembly)
                cachedDisassembly.reset(new std::string);

            *cachedDisassembly = generateDisassembly(pc, symtab);
            cachedPC = pc;
            cachedSymtab = symtab;
        }

        return *cachedDisassembly;
    }

    std::string
    Branch::generateDisassembly(
            Addr pc, const loader::SymbolTable *symtab) const
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

        // There's only one register arg (RA), but it could be
        // either a source (the condition for conditional
        // branches) or a destination (the link reg for
        // unconditional branches)
        if (_numSrcRegs == 1) {
            printReg(ss, srcRegIdx(0));
            ss << ", ";
        } else if(_numSrcRegs == 2) {
            printReg(ss, srcRegIdx(0));
            ss << ", ";
            printReg(ss, srcRegIdx(1));
            ss << ", ";
        }

        Addr target = pc + 4 + disp;

        loader::SymbolTable::const_iterator it;
        if (symtab && (it = symtab->find(target)) != symtab->end())
            ss << it->name;
        else
            ccprintf(ss, "%#x", target);

        return ss.str();
    }

    std::string
    Jump::generateDisassembly(Addr pc, const loader::SymbolTable *symtab) const
    {
        std::stringstream ss;

        ccprintf(ss, "%-10s ", mnemonic);

        if ( strcmp(mnemonic,"jal") == 0 ) {
            Addr npc = pc + 4;
            ccprintf(ss,"0x%x",(npc & 0xF0000000) | disp);
        } else if (_numSrcRegs == 0) {
            loader::SymbolTable::const_iterator it;
            if (symtab && (it = symtab->find(disp)) != symtab->end())
                ss << it->name;
            else
                ccprintf(ss, "0x%x", disp);
        } else if (_numSrcRegs == 1) {
             printReg(ss, srcRegIdx(0));
        } else if(_numSrcRegs == 2) {
            printReg(ss, srcRegIdx(0));
            ss << ", ";
            printReg(ss, srcRegIdx(1));
        }

        return ss.str();
    }
}};

def format Branch(code, *opt_flags) {{
    not_taken_code = 'NNPC = NNPC; NPC = NPC;'

    #Build Instruction Flags
    #Use Link & Likely Flags to Add Link/Condition Code
    inst_flags = ('IsDirectControl', )
    for x in opt_flags:
        if x == 'Link':
            code += 'R31 = NNPC;\n'
        elif x == 'Likely':
            not_taken_code = 'NNPC = NPC; NPC = PC;'
        else:
            inst_flags += (x, )

    #Take into account uncond. branch instruction
    if 'cond = 1' in code:
         inst_flags += ('IsUncondControl', )
    else:
         inst_flags += ('IsCondControl', )

    #Condition code
    code = '''
    bool cond;
    %(code)s
    if (cond) {
        NNPC = NPC + disp;
    } else {
        %(not_taken_code)s
    }
    ''' % { "code" : code, "not_taken_code" : not_taken_code }

    iop = InstObjParams(name, Name, 'Branch', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

def format DspBranch(code, *opt_flags) {{
    not_taken_code = 'NNPC = NNPC; NPC = NPC;'

    #Build Instruction Flags
    #Use Link & Likely Flags to Add Link/Condition Code
    inst_flags = ('IsDirectControl', )
    for x in opt_flags:
        if x == 'Link':
            code += 'R32 = NNPC;'
        elif x == 'Likely':
            not_taken_code = 'NNPC = NPC, NPC = PC;'
        else:
            inst_flags += (x, )

    #Take into account uncond. branch instruction
    if 'cond = 1' in code:
         inst_flags += ('IsUncondControl', )
    else:
         inst_flags += ('IsCondControl', )

    #Condition code
    code = '''
    bool cond;
    uint32_t dspctl = DSPControl;
    %(code)s
    if (cond) {
        NNPC = NPC + disp;
    } else {
        %(not_taken_code)s
    }
    ''' % { "code" : code, "not_taken_code" : not_taken_code }

    iop = InstObjParams(name, Name, 'Branch', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

def format Jump(code, *opt_flags) {{
    #Build Instruction Flags
    #Use Link Flag to Add Link Code
    inst_flags = ('IsIndirectControl', 'IsUncondControl')
    for x in opt_flags:
        if x == 'Link':
            code = '''
            R31 = NNPC;
            ''' + code
        elif x == 'ClearHazards':
            code += '/* Code Needed to Clear Execute & Inst Hazards */\n'
        else:
            inst_flags += (x, )

    iop = InstObjParams(name, Name, 'Jump', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};