How to Store Each Character from a File into an Array using Verilog

Learn how to read characters from an input file and store them in an array using `Verilog`, with a step-by-step guide and example code.
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How to Store Each Character from a File into an Array using Verilog

When working with Verilog, you might find yourself needing to read data from a file and manipulate it. A common scenario involves reading characters line by line and storing them into an array for further processing. In this post, we will explore how to achieve that easily, focusing on using the $fgets and $fscanf methods effectively.

The Problem

Imagine you have an input file with lines of text like this:

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Your goal is to read each character from this file and store it into an array so that you can access each character individually, for instance, storing f in str[0][0], o in str[0][1], and so on.

Proposed Solution

To accomplish this, we can use the $fscanf() function in Verilog which allows us to read lines one by one while discarding newlines and storing words in a temporary string variable. Here's a step-by-step breakdown of how to implement this solution.

Step 1: Initialize Variables

You need to set up your variables first. We'll need a file descriptor and a string array to store the strings. Here’s how to declare them:

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Step 2: Open the File

Next, you need to open the input file using $fopen(). This function takes the filename and the mode as arguments. For reading, we use "r":

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Make sure the file name matches the one you have.

Step 3: Read and Store Characters

Now, we will loop through the file until the end, using $fscanf() to read each line into the word variable and store it in the str array. Here’s how it looks:

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The $feof(fd) function checks if the end of the file has been reached.

Step 4: Display the Characters

Finally, you can access the first word stored in str and print each character. The following code will display the individual characters:

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Complete Code Example

Combining all the segments, here’s the complete code you would use:

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Conclusion

Using the steps outlined above, you can efficiently read each line from a file in Verilog and store each character into an array for further usage. This approach allows for flexibility in how you manage input data in digital design and testing scenarios. Experiment with the code, and soon you'll be manipulating strings with ease!