learn-fpga
trv
learn-fpga | trv | |
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22 | 11 | |
2,337 | 8 | |
- | - | |
7.3 | 1.8 | |
18 days ago | over 3 years ago | |
C++ | C | |
BSD 3-clause "New" or "Revised" License | - |
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learn-fpga
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FPGA Dev Boards for $150 or Less
I've followed this tutorial recently, and it's amazing:
https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/...
The author includes detailed instruction for how to build a micro-controller in Verilog on an icestick, starting from a very simple blinker all the way to a functional RISC-V core.
My other suggestion would be: for most of the toolchain, skip your package manager and directly install the binary artifacts published on this Github repo:
https://github.com/YosysHQ/oss-cad-suite-build
You'll spare yourself a world of pain.
- Top Ten Fallacies About RISC-V (David Patterson)
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What are the best learning resources for a beginner?
You might want to look at https://github.com/BrunoLevy/learn-fpga
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First FPGA Board
Lattice Icestick is pretty cheap and has just enough LUTs to run a small riscv. Also check out https://github.com/BrunoLevy/learn-fpga
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My first Risc-V core in FPGA
Thanks Bruno Levy
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How to Emulate a CPU on an FPGA
These are good starting points: https://github.com/BrunoLevy/learn-fpga/ and, from there, https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/README.md.
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PicoBlaze in Verilog / Vivado
The best point-of-entry for "tiny" MCUs these days is FemtoRV32-Quark or SERV. I also maintain my own small RISC-V core (Minimax), though it's early on in graduating from "experiment" to "real design".
- looking for ideas for a small project using digilent pmod on xilinx zynq 7 series fpga using hdl (verilog).
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Embedded Systems Weekly #125
Rust blinky on RISC-V soft core If you were looking for, an introduction example of an embedded Rust program, running on a RISC-V soft core, check out this blinky that is using the FemtoRV .
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Minimax: A Compressed-First, Microcoded RISC-V CPU
Nope - that's all there is.
It's possible to be incredibly expressive in Verilog and VHDL. This implementation is written in VHDL, which has an outdated reputation for being long-winded.
Also worth a look: FemtoRV32 Quark [0], which is written in Verilog.
[0]: https://github.com/BrunoLevy/learn-fpga/blob/master/FemtoRV/...
trv
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RPython-based emulator speeds up RISC-V simulation over 15x
Spike is a pure interpreter -- no JIT or anything like that. It is written to be very portable, very easy to add new instructions to, and easy to reason about whether you have done it correctly. Essentially no effort is made to get high performance. Spike was the "Golden Standard" for RISC-V semantics until some academics said "that's not good enough, you should use Sail because formal this, proof that".
The only time the RISC-V instruction set should be changing is when new instructions are being added, and during the extension development process the set of instructions and meaning or especially the binary encoding of individual instructions can change.
I have been the person doing the modifications to Spike during development of RISC-V extensions, and in particular during a quite fluid stage of the development of the Vector extension. I know how easy it is to do this. Just as easy as Sail, I would say.
Here's one example of why.
Most RISC-V emulators decode instructions using a series of nested switch statements. Zeroth, switch on non-C vs which page of C (if C is implemented) bits 1:0. First switch on the "opcode" field bits 6:2 e.g. OP-IMM or LOAD or BRANCH. Second, typically, switch on the "funct3" field bits 14:12 which distinguishes e.g. ADD / SLT / SLTU / AND / OR / XOR / SLL / SRL for arithmetic instructions or BEQ / BNE / BLT / BLTU / BGE / BGEU for conditional branches, or operand size for loads and stores. Third, for some instructions switch on the "funct7" field bits 31:25 to distinguish between e.g. ADD / SUB or SRL / SRA.
This is pretty fast and efficient and makes compact code/tables, but it is high maintenance.
Spike decodes instructions with a loop searching a linear list of MASK and MATCH values until it finds the correct instruction. So, by the way, does my simple "trv" emulator.
Here is my own complete executable C definition of RV32I:
https://github.com/brucehoult/trv/blob/main/instructions.inc
The 3rd and 4th values (the hex ones) are the MATCH and MASK values. The logic is "if ((instruction & MASK) == MATCH)" for example:
if ((instruction & 0xfe00707f) == 0x40000033) rd = rs1 - rs2; // sub
- Top Ten Fallacies About RISC-V (David Patterson)
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Handy commands for using the RISC-V gnu toolchain and generate .elf or .hex w/ libgcc
bruce@rip:~$ git clone https://github.com/brucehoult/trv.git Cloning into 'trv'... remote: Enumerating objects: 10, done. remote: Counting objects: 100% (10/10), done. remote: Compressing objects: 100% (8/8), done. remote: Total 10 (delta 2), reused 10 (delta 2), pack-reused 0 Receiving objects: 100% (10/10), 4.37 KiB | 4.37 MiB/s, done. Resolving deltas: 100% (2/2), done. bruce@rip:~$ cd trv bruce@rip:~/trv$ gcc -O trv.c -o trv bruce@rip:~/trv$ cat >foo.s < .globl main > main: > li a0,3 > li a1,23 > call __mulsi3 > ret > END bruce@rip:~/trv$ riscv64-unknown-elf-gcc -O -march=rv32i -mabi=ilp32 foo.s -o foo bruce@rip:~/trv$ qemu-riscv32 foo bruce@rip:~/trv$ echo $? 69 bruce@rip:~/trv$ riscv64-unknown-elf-objcopy -O ihex foo foo.hex bruce@rip:~/trv$ ./trv foo.hex bruce@rip:~/trv$ echo $? 69
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Hardware/software to run RISC-V ASM?
I completely understand. I have a toy RV32I emulator myself at https://github.com/brucehoult/trv which desperately needs even a README. I want to do it, but I keep forgetting to do it...
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rvscript: Fast RISC-V-based scripting backend for game engines
I didn't see what actual emulator this uses, but I have a super-simple one (sadly undocumented but the code is short!) that runs Intel hex files at https://github.com/brucehoult/trv
- Why RISC-V Is Succeeding
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8-bit Breadboard Computer
The easiest way would be to get a C compiler for 6502 or z80 and compile a simple RISC-V emulator such as my one at https://github.com/brucehoult/trv
- Built a 65C02 emulator
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Linux in a Pixel Shader – A RISC-V Emulator for VRChat
If you're making the actual game, and can therefore implement the virtual machine in native code on the host machine (instead of in a shader on the GPU as here) then you can very easily get 10 to 100 MIPS performance in an emulated machine with a very simple emulator. Such as https://github.com/brucehoult/trv
Bear in mind that the original Mac was roughly a 2 MIPS machine and an early Pentium or PowerMac 100 MIPS.
- ELF binary executable format and sections.
What are some alternatives?
riscv-v-spec - Working draft of the proposed RISC-V V vector extension
ch32v307 - Including the SDK、HDK、Datasheet of RISC-V MCU CH32V307 and other relevant development materials
bubbleos
riscv-gnu-toolchain - GNU toolchain for RISC-V, including GCC
wain - WebAssembly implementation from scratch in Safe Rust with zero dependencies
nanoCH32V305
openfpga - Open FPGA tools
riscv-isa-sim - Spike, a RISC-V ISA Simulator
rust-wasm - A simple and spec-compliant WebAssembly interpreter
Lifeslice - Automatically take webcam pics, screenshot, and other metrics throughout the day.
wasm-lisp - Experimental Lisp to WebAssembly Compiler
flameshot - Powerful yet simple to use screenshot software :desktop_computer: :camera_flash: