#!/usr/bin/env python

# usage: bytestream bytes_per_second chunks_per_second

# writes bytes_per_second bytes each second to stdout, in chunks_per_second
# chunks each second

from __future__ import division
import sys
import time
import array
import itertools


try:
    bytes_per_second, chunks_per_second = (int(arg) for arg in sys.argv[1:])
except:
    print >> sys.stderr, '''bytestream

usage: bytestream bytes_per_second chunks_per_second

Writes bytes_per_second bytes to stdout in chunks_per_second chunks per second.
Use this as an unbounded stream of bytes.
'''
    sys.exit(1)

prog = sys.argv[0].split('/')[-1] + ':'
print >> sys.stderr, prog, 'command-line:'
print >> sys.stderr, prog, sys.argv

bytes_per_chunk = bytes_per_second // chunks_per_second
chunk = array.array('B', (x % 256 for x in xrange(bytes_per_chunk))).tostring()
print >> sys.stderr,  prog, 'chunksize', len(chunk)
assert len(chunk) > 0

time_inc = 1 / chunks_per_second
print >> sys.stderr, prog, 'time_inc', time_inc
print >> sys.stderr, prog, 'bytes per second', len(chunk) / time_inc

tick_tock = itertools.count(1).next
start_time = time.time()
def escapement():
    end_time = start_time + time_inc * tick_tock()
    sleep_time = end_time - time.time()
    if sleep_time <= 0: return
    time.sleep(sleep_time)

while True:
    sys.stdout.write(chunk)
    escapement()