yosys | Unofficial Yosys WebAssembly packages | Binary Executable Format library
kandi X-RAY | yosys Summary
kandi X-RAY | yosys Summary
This package provides [Yosys][] binaries built for [WebAssembly][]. See the [overview of the YoWASP project][yowasp] for details. [yosys]: [webassembly]: [yowasp]:
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QUESTION
I have the Verilog statement below:
...ANSWER
Answered 2021-Jul-29 at 12:39Interesting! I noticed that if you assign an initial value of zero to the register (e.g. output reg B = 1'b0
) you do get a flip-flop. (I used read_verilog ; synth ; show
.)
However, an initial value of one still produces the constant output you mention. So perhaps what's happening here (and I'm only speculating) is that when an initial value is not given, yosys is free to pick its own, in which case it picks 1'b1
, so that the whole circuit is equivalent to a simple hard-wired constant? Only when the initial value is zero is the flip-flop necessary?
QUESTION
In this question, I was suggested to use the existing libraries in order to test a PLL for the iCE40 Ultra Plus 5k.
I bought the Icebreaker V1.0e board and it looks like this:
External 12 MHz oscilator is connected to the pin 35 (marked green) of the Lattice iCE40UP5k (package SG48).
Pin 35 has function:
IOT_46b_G0
, type:DPIO/GBIN0
and is located in bank:0
).
When I searched the library that I posted above, I found a nice primitive SB_PLL40_PAD
on the page 98. This primitive's description precisely matches what was done on the Icebreaker V1.0e schematics. Here is the description:
Please observe that it matches with the pin description above! Now, I want to use this in my VHDL so for start I only wrote a VHDL wrapper for this primitive:
...ANSWER
Answered 2021-Jun-24 at 12:04It looks like I can't read. Lattice technology library mentions SB_PLL40_PAD
:
and I used SB_PLL_40_PAD
... So of course it could not work! Now it compiles!
So I have a start here in order to create a nice PLL example that is using pre-existing hardware inside FPGA!
QUESTION
I am trying to formally verify my verilog FPGA design led_walker.v
. So I first synthesize it to an .smt2
file:
ANSWER
Answered 2021-May-14 at 10:34I found a solution. Problem is with the precompiled binaries! If I get the latest development sources from the GitHub and then compile, everything works.
This is how to properly do it:
QUESTION
I am using Verilog to set up FPGA so that it blinks an LED once per second. And this is one way to do it:
...ANSWER
Answered 2021-May-07 at 13:12As your error message states, it is illegal to make a procedural assignment to a wire
. A procedural assignment is an assignment made inside an always
block, for example. You declared o_led
as a wire
, but then you assigned to it in an always
block. You should use a reg
type inside an always
block. Refer to IEEE Std 1800-2017, section 10.4 Procedural assignments.
Change:
QUESTION
I have recently started using yosys, synthesized a DSP block with cmos_cells.lib and got following results:
...ANSWER
Answered 2021-Jan-01 at 23:40There's no getting around needing a cell library for (roughly) the process you want. Once you have one, map to it and then run stat -liberty cells.lib
to calculate total cell area.
QUESTION
I'm extending Yosys with a pass I made myself. In this pass, I call the techmap pass multiple times, with a path to the map to apply.
However, depending on the directory I'm in while calling my pass, the correct paths to the maps differ. Is there a variable that points to Yosys's main directory I can use?
The following code line shows how I currently call techmap.
...ANSWER
Answered 2020-Nov-20 at 20:00The + prefix refers to the Yosys share directory - if you need an example of this, have a look at the various FPGA synthesis passes
QUESTION
Im currently working on the Shift-Add Algorithm (32x32 bit Multiplication) in System Verilog. System Verilog cant find any error and my code is working correctly according to GTKwave. When I synthesize my circuit with yosys, Latches will be added. And that is the Problem. I dont want Latches in my Circuit. Heres my Code:
...ANSWER
Answered 2020-Nov-13 at 00:41From the comment you have a bunch of variables which are not assigned in the second case statement causing synthesis to generate latches. To avoid it you need to assign all the vars in all branches of the case statement and conditional statements recursively.
However, if there is a default value you can assign to all of them, you can use a pattern similar to the one from the second always block, just assigning default values before the 'case' statement. This way you do not even need the default clause and you can get rid of it in the second always block as well.
QUESTION
I am trying to port some Verilog source code to SystemVerilog. This question is specific to Icarus Verilog (tested with 10.3 and 11 providing the same result), since I did not get any errors with tools (e.g. Yosys 0.9.0, Cadence Xcelium 19.09). The issue I have boils down to the following minimal example:
...ANSWER
Answered 2020-Nov-06 at 06:15The code runs correctly on EDAplayground with an older Icarus 10.0. So my guess is you didn't enable the SystemVerilog flag -g2012
. By default Icarus runs in Verilog IEEE1364-2005 [1]; which is the same as setting the flag -g2005
Verilog only allows wire
s to be driven by assign
statements or output ports.
SystemVerilog relaxed the rule so reg
and logic
driven by assign
statements or output ports so long as that is the only driver. (Bit off topic but, I personally prefer following the stricter Verilog rules because not all tools have strong single source driver checking for reg
and logic
driven by assign
statements or output ports)
Anyway, try this command:
QUESTION
first of all, I'd like to say I'm not well versed in c++ or verilog at all, so I have a few problems implementing things in Yosys.
I'm currently looking for a way to implement a naive information flow tracking approach to write_verilog. The way I intent to implement it, is by creating a new var for each input/output etc. All operations types will be exchanged with simple 'or's. The doubled variables serve as taint bits. Doubling all the wires was an easy task. However when I try to add a new cell, I run into a 'std::out_of_range' error (edit: just as I was trying it again, it appears to be an 'Found error in internal cell' error now) while dumping the module. As the error happens while calling the dump_module function, I assume the module model broke.
What I've done is that for every wire in the module, I've added the same wire just with '_taint' appended to its name, its properties stays the same as the original wire, I've basically used a slightly modified version of add_wire from /passes/add.cc.
...ANSWER
Answered 2020-Oct-27 at 08:07Internal cells, beginning with $, have a particular contract they must follow in terms of ports, parameters etc and that an empty cell won't fulfil. Use functions like addOr rather than addCell to create these.
QUESTION
While attempting to synthesize with Yosys, I am unable to map the logic circuit using only AND, XOR, NOT, and MUX's. This is because I get an error whenever my liberty file excludes BUFX2: Error:
...ANSWER
Answered 2020-Oct-02 at 08:05You can actually achieve point 1 with some trickery.
Yosys' internal cells start with $
, e.g. $_AND_
which you can see if you run abc
without any other arguments. One of these internal cells is $_BUF_
which represents a buffer cell. Since to Yosys buffer cells are identical to wires, the opt
command will replace all instances of $_BUF_
with simple wires.
This means you can instantiate $_BUF_
cells by replacing the BUFX2
cell name with "$_BUF_"
(the quotes are needed to escape the $
), keeping ABC happy because there's a cell buffer, and then after running an opt
pass, the buffers have disappeared from your netlist.
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