made updates after converting core from fsm to pipeline

README.md

@@ -1,24 +1,32 @@
 ## About
-Design implementation of the RISC-V Integer core in Verilog HDL. The core is currently FSM-based (no pipelining) and supports the Zicsr (Control Status Registers) extension. This core is RISC-V compliant and passed `rv32ui` (RV32 User-Mode Integer-Only) and `rv32mi` (RV32 Machine-Mode Integer-Only) [tests of RISC-V International.](https://github.com/riscv-software-src/riscv-tests)
+Design implementation of the RISC-V Base 32 Integer core in Verilog HDL. This is a 5-stage pipeline processor core and supports the Zicsr (Control Status Registers) extension. This is RISC-V compliant and passed `rv32ui` (RV32 User-Mode Integer-Only) and `rv32mi` (RV32 Machine-Mode Integer-Only) [tests of RISC-V International.](https://github.com/riscv-software-src/riscv-tests)
 
 Inside the `rtl/` folder are the following:  
- - `rv32i_soc.v` = complete package containing the rv32i_core and memory module for the instruction and data
+ - `rv32i_soc.v` = complete package containing the rv32i_core and memory module for the instructions and data
  - `rv32i_core.v` = top module for the RV32I core  
- - `rv32i_fsm.v` = FSM controller for the fetch, decode, execute, memory access, and writeback processes
- - `rv32i_basereg.v` = interface for the regfile of the 32 integer base registers 
- - `rv32i_decoder.v`= logic for the decoding of a 32 bit instruction [DECODE STAGE]
+ - `rv32i_basereg.v` = regfile controller for the 32 integer base registers 
+ - `rv32i_fetch.v` =  retrieves instruction from the memory [FETCH STAGE]
+ - `rv32i_decoder.v`= decodes the 32 bit instruction [DECODE STAGE]
  - `rv32i_alu.v` =  arithmetic logic unit [EXECUTE STAGE]
- - `rv32i_memoryaccess.v` = logic controller for data memory access [MEMORYACCESS STAGE]
+ - `rv32i_memoryaccess.v` = sends and retrieves data to and from the memory [MEMORYACCESS STAGE]
  - `rv32i_csr.v` = Zicsr extension module [executes parallel to MEMORYACCESS STAGE]
- - `rv32i_writeback.v` = logic controller for trap-handling and determining the next `PC` and `rd` value [WRITEBACK STAGE]
+ - `rv32i_writeback.v` = handles traps and determines the next `PC` and `rd` values [WRITEBACK STAGE]
 
  Inside the `test/` folder are the following: 
  - `test.sh` = bash script for automating the testbench
  - `sections.py` = python script used by `test.sh` to extract the text and data sections from the binary file output of the compiler
  - `rv32i_soc_TB.v` = testbench for `rv32i_soc`
  - `wave.do` = Modelsim waveform file
- - `extra/` folder = contains my own assembly testfiles for all basic and system instructions (CSRs, interrupts, exceptions)
+ - `extra/` folder = contains my own assembly testfiles for all basic instructions, system instructions, and pipeline hazards
 
+## Pipeline Features
+ - 5 pipeline stages  
+ - Separate data and instruction memory interface [Harvard architecture]  
+ - Load instructions take a minimum of 2 clk cycles   
+ - Taken branch and jump instructions take a minimum of 6 clk cycles [No Branch Prediction Used]  
+ - Two **consecutive** instructions with data dependency take a minimum of 2 clk cycles. Nonconsecutive instructions with data dependency take a minimum of 1 clk cycle [Operation Forwarding used]   
+ - All remaining instructions take a minimum of 1 clk cycle   
+
 ## Supported Features of Zicsr Extension Module
  - **CSR instructions**: `CSRRW`, `CSRRS`, `CSRRC`, `CSRRWI`, `CSRRSI`, `CSRRCI`
  - **Interrupts**: `External Interrupt`, `Timer Interrupt`, `Software Interrupt`
@@ -32,7 +40,7 @@ The RISCV toolchain `riscv64-unknown-elf-` and Modelsim executables `vsim` and `
  - `$ ./test.sh` = run regression tests for both `riscv-tests/isa/rv32ui/` and `riscv-tests/isa/rv32mi/`
  - `$ ./test.sh rv32ui` = run regression tests only for the `riscv-tests/isa/rv32ui/`
  - `$ ./test.sh rv32mi` = run regression tests only for the `riscv-tests/isa/rv32mi/`
- - `$ ./test.sh extra` =  run regression tests for `extra/` (contains tests for interrupts which the official tests don't have)
+ - `$ ./test.sh extra` =  run regression tests for `extra/` (contains tests for interrupts and pipeline hazards which the official tests don't have)
  - `$ ./test.sh all` = run regression tests for `riscv-tests/isa/rv32ui/`, `riscv-tests/isa/rv32mi/`, and `extra/`  
 
  Some commmands for **debugging the design**:
@@ -41,14 +49,16 @@ The RISCV toolchain `riscv64-unknown-elf-` and Modelsim executables `vsim` and `
  - `$ ./test.sh <testfile> -gui` = test and debug testfile <testfile> and open wave in Modelsim
 
 Below is the expected output after running `$ ./test.sh`:   
-![script_out_2](https://user-images.githubusercontent.com/87559347/169702033-ac69dd82-9976-4895-9978-660f8c366b53.png)
+
+![script_updated](https://user-images.githubusercontent.com/87559347/175277402-d0fbb6ba-53c4-4457-8730-0ce0b3c58a43.png)  
+
 
 ## Goal Checklist
  :white_check_mark: Add more testcases for the testbench    
  :white_check_mark: Automate the testbench   
  :white_check_mark: Add Zicsr extension   
  :white_check_mark: Pass the Official RISC-V International Tests   
- :black_square_button: Convert FSM based core implementation to pipeline       
- :black_square_button: Add RV32 extensions    
+ :white_check_mark: Convert FSM based core implementation to pipeline     
+ :black_square_button: Add AXI interface  
 
 # [UNDER CONSTRUCTION]