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// Simulator for the RISC-V[ECTOR] mini-ISA
// Copyright (C) 2025 Siddarth Suresh
// Copyright (C) 2025 bdunahu
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
#ifndef ID_H
#define ID_H
#include "instr.h"
#include "instrDTO.h"
#include "response.h"
#include "stage.h"
class ID : public Stage
{
public:
using Stage::advance;
using Stage::Stage;
/* The following methods are made public so that they may be tested, and are
* not to be called from outside classes during standard execution.
*/
Response set_vlen();
private:
/**
* Helper for `get_instr_fields`
* Attempts to parse and dereference instruction arguments. Uses read and
* write guards to prevent RAW conflicts.
*
* @param the resulting first field. To call this function properly, this
* field must contain the section of the instruction to be parsed.
* @param the resulting second field.
* @param the resulting third field.
*/
void advance_helper() override;
/**
* Parse an instruction into a type, opcode, and fields. If the type is
* invalid, only the type field will be set.
*
* This method is marked public so it may be tested, and is not used outside
* of this class during normal execution.
*
* @param the resulting first field, which varies per type. To call this
* function properly, this field must contain the full instruction bytes on
* function entry.
* @param the resulting second field, which varies per type.
* @param the resulting third field, which varies per type.
* @param the resulting mnemonic.
*/
void get_instr_fields(signed int instr_bits);
void decode_R_type(signed int &s1);
void decode_I_type(signed int &s1);
void decode_J_type(signed int &s1);
/**
* Helper for `get_instr_fields`.
* Given a raw instruction, returns the mnemonic and type.
* This operation will destroy the original arguments.
* @param the raw bits to parse.
* @param the resulting mnemonic.
* @param the resulting type.
*/
void split_instr(signed int &raw, unsigned int &type, Mnemonic &m);
/**
* Facilitates register checkout and data hazard management.
* Checks out a register and returns it.
*
* @param the registers number, to be dereferenced and checked out.
*/
template <typename T> T write_guard(int v)
{
T r;
// these registers shouldn't be written.
if (v != 0 && v != 16) {
// keep track in the instrDTO for displaying to user and writeback
// keep track in checked_out so we can still access this
// information!
this->checked_out.push_back(v);
this->curr_instr->checked_out = v;
}
r = this->dereference_register<T>(v);
return r;
}
/**
* Facilitates register checkout and data hazard management.
* It does this by checking that the register passed in is not currently
* checked out. If true, then sets `result' with the value of the register
* and returns OK. If false, returns STALLED.
*
* @param the registers number
* @param the dereferenced register value
* @return OK if `reg` is not checked out, STALLED otherwise.
*/
template <typename T> Response read_guard(int reg, T &result)
{
Response response;
if (this->is_checked_out(reg))
response = STALLED;
else {
response = OK;
result = this->dereference_register<T>(reg);
}
return response;
}
};
#endif /* ID_H_INCLUDED */
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