t04_gen_sram.py

# BSD-3-clause
#
# Copyright (c) 2024 tsinghua-ideal
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#
#
# This code shows a method for generating SRAM presets. There are also several
# ways to save SRAM presets.

from math import log2
from math import floor


def gen_signal_sram(n):
    logN = int(log2(n))
    sram = []
    # signals = []
    for q in range(n):
        if q % 2 == 0:
            continue

        # generate signals for phi = q
        signals = []
        for i in range(logN - 1):
            hn = 1 << (logN - i - 2)
            s = [0] * hn + [int(floor(q / 2)) % (1 << (i + 1))] * hn
            signals.append(s)
        signals.append([0])

        # reduce signals
        for i in range(logN - 1, 0, -1):
            for j in range(1 << (logN - i - 1)):
                child_i = i - 1
                sn = 1 << (logN - i - 1)
                hn = 1 << (child_i + 1)
                j0 = j
                j1 = j + sn
                x = signals[i][j]
                q = x // 2
                r = x % 2
                signals[i][j] = r
                signals[child_i][j0] += q
                signals[child_i][j1] += q
                signals[child_i][j0] %= hn
                signals[child_i][j1] %= hn

        # signals to sram line
        line = []
        for s in signals:
            line.extend(s)
        assert line[-1] == 0
        del line[-1]

        sram.append(line)

    assert len(sram) == (n // 2)
    assert len(sram[0]) == (n - 2)

    return sram


def save_sram_png(sram, file_path):
    from PIL import Image

    # Get the number of rows and columns in the 2D array
    rows = len(sram)
    cols = len(sram[0])

    # Calculate the width and height of the image (each element corresponds to a 2x2 square)
    width = cols * 2
    height = rows * 2

    # Create an image with a white background
    img = Image.new("RGB", (width, height), "white")

    # Iterate through the 2D array and draw squares of corresponding colors based on element values
    for i in range(rows):
        for j in range(cols):
            if sram[i][j] == 1:
                # If the element value is 1, draw a black square at the corresponding position
                for x in range(j * 2, (j + 1) * 2):
                    for y in range(i * 2, (i + 1) * 2):
                        img.putpixel((x, y), (0, 0, 0))  # Black

    # Save the image in PNG format
    img.save(file_path)


def save_sram_txt(sram, filename):
    # Open the file in write mode
    with open(filename, "w") as file:
        # Iterate through each row in the 2D array
        for row in sram:
            # Convert the row to a string of 0s and 1s without any separators
            row_str = "".join(str(bit) for bit in row)
            # Write the row string to the file followed by a newline character
            file.write(row_str + "\n")


def save_sram_bin(sram, filename):
    # Open the file in binary write mode
    with open(filename, "wb") as file:
        # Iterate through each row in the 2D array
        for row in sram:
            # Process the row in chunks of 8 elements to form bytes
            for i in range(0, len(row), 8):
                # Get the next 8 elements, or fewer if at the end of the row
                byte_chunk = row[i : i + 8]
                # Pad with zeros if there are fewer than 8 elements
                byte_chunk += [0] * (8 - len(byte_chunk))
                # Convert the 8 elements to a single byte
                byte_value = int("".join(str(bit) for bit in byte_chunk), 2)
                # Write the byte to the file
                file.write(byte_value.to_bytes(1, byteorder="big"))


if __name__ == "__main__":
    sram = gen_signal_sram(256)
    save_sram_png(sram, "sram.png")
    save_sram_txt(sram, "sram.txt")
    save_sram_bin(sram, "sram.bin")