Author : Revanth Kamaraj (revanth91kamaraj@gmail.com)
ZAP is a pipelined ARM processor core that can execute the ARMv4T instruction set. It is equipped with ARMv4 compatible split writeback caches and memory management capabilities. The processor core uses a 10 stage pipeline.
Alpha. DESIGN IS IN AN EXPERIMENTAL STATE.
Issues with the Thumb ISA.
SWAP does not keep CYC signal asserted
Wishbone B3 compatible 32-bit bus.
Fully synthesizable Verilog-2001 core.
Store buffer for improved performance.
Can execute ARMv4T code. Note that compressed instruction support is EXPERIMENTAL.
Wishbone B3 compatible interface. Cache unit supports burst access.
10-stage pipeline design. Pipeline has bypass network to resolve dependencies.
2 write ports for the register file to allow LDR/STR with writeback to execute as a single instruction.
Branch prediction supported.
Split I and D writeback cache (Size can be configured using parameters).
Split I and D MMUs (TLB size can be configured using parameters).
Base restored abort model to simplify data abort handling.
FETCH => FIFO => DECOMPRESS => PRE-DECODE => DECODE => ISSUE => SHIFTER => ALU => MEMORY => WRITEBACK
The pipeline is fully bypassed to allow most dependent instructions to execute without stalls. The pipeline stalls for 3 cycles if there is an attempt to use a value loaded from memory immediately following it. 32x32+32=32 operations take 6 clock cycles while 32x32+64=64 takes 12 clock cycles. Multiplication and non trivial shifts require registers a cycle early else the pipeline stalls for 1 cycle.
Please see the docs folder.
Please provide your feedback on the google forum : https://groups.google.com/d/forum/zap-devel
Enter hw/sim and run run_sim_gui.pl
Copyright (C) 2016, 2017 Revanth Kamaraj.
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 2 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, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.