cmd="""
# ----------------
# setup as root !!
# ----------------
/usr/bin/umount /ram-dir

# create ramfs
mkdir -p /ram-dir
/usr/bin/mount ramfs -t ramfs /ram-dir
## or tmpfs
## /usr/bin/mount tmpfs -t tmpfs -o uid=bob -o gid=bob /ram-disk

mkdir /ram-dir/user
chown user:user /ram-dir/user
dd if=/dev/zero of=/ram-dir/user/x bs=100M count=10 status=progress
dd if=/dev/zero of=/ram-dir-x bs=100M count=10 status=progress

mount | grep ram-dir
# ----------------
"""

#print(cmd)

import time
#fname = "/ram-dir/user/data.bin"
#fname = "/media/user/FAT2G-BLACK/data.bin"
fname = "/tmp/data.bin"

print(fname)
def init_bin(f):
    f.seek(0)
    for i in range(512):
        f.write(b'\x00')
        f.flash()

data = [0]*512

#bytearray
import struct
import os

def patch(i,v):
    try:
        #f=open(fname,"a+b", buffering=0)
        f=open(fname,"r+b", buffering=0)
        r=f.seek(0) #,whence=os.SEEK_SET)
        #f.truncate()
        print(r)
        r=f.seek(i) #,whence=os.SEEK_SET)
        #f.truncate()
        print(r)
        if v > 255:
            v=255
        v=struct.pack('B',v)
        print("write",round(time.time(),3),":",i,v)
        f.write(v)
        f.flush()
    except Exception as e:
        print("server-err",e)


def server():
    try:
        f=open(fname,"wb", buffering=0)
        #f.seek(0)
        init_bin(f)
        
    except Exception as e:
        print("server-err",e)
        time.sleep(1)
    print(dir(f))
    print(data)
    while 1:
        try:
            f.seek(0)
            for i in range(200,0,-1):
                i+=20
                if i >= len(data):
                    continue

                f.seek(i)
                v=data[i]
                #print(data)
                v+=1+i
                if v > 255:
                    v=1
                data[i]=v

                #v=bytes(v)
                v=struct.pack('B',v)
                print(round(time.time(),3),":",i,v)
                f.write(v)
                f.flush()
                time.sleep(0.02)           
            time.sleep(10)           
        except Exception as e:
            print("server-err",e)
            time.sleep(1)


def client():
    try:
        f=open(fname,"rb", buffering=0)
        
    except Exception as e:
        print("client-err",e)
        time.sleep(1)
    v=''
    i=0
    while 1:
        try:
            start = time.time()
            f=open(fname,"rb", buffering=0)
            i=0
            f.seek(0)
            v = f.read(1)
            while v:
                v2=b''
                if v:
                    v2=struct.unpack('B',v)
                if v != data[i]:
                    print(round(time.time(),4),i,v,v2)
                    data[i] = v
                v = f.read(1)
                i+=1
                
            time.sleep(0.01)
        except Exception as e:
            print("client-err",e)
            time.sleep(1)

import sys

if __name__ == "__main__":
    print("ARGV", sys.argv)

    if "server" in sys.argv:
        server()

    elif "client" in sys.argv:
        client()

    elif "patch" in sys.argv:
        patch(int(sys.argv[2]),int(sys.argv[3]))