#!/usr/bin/env python

from gnuradio import gr
from gnuradio import trellis, digital
from gnuradio import eng_notation
import math
import sys
import random
import fsm_utils


def run_test (fo,fi,interleaver,Kb,bitspersymbol,K,dimensionality,constellation,Es,N0,IT,seed):
    tb = gr.top_block ()


    # TX
    src = gr.lfsr_32k_source_s()
    src_head = gr.head (gr.sizeof_short,Kb/16) # packet size in shorts
    s2fsmi = gr.packed_to_unpacked_ss(bitspersymbol,gr.GR_MSB_FIRST) # unpack shorts to symbols compatible with the outer FSM input cardinality
    #src = gr.vector_source_s([0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1],False)
    enc = trellis.pccc_encoder_ss(fo,0,fi,0,interleaver,K)
    code = gr.vector_sink_s()
    mod = gr.chunks_to_symbols_sf(constellation,dimensionality)

    # CHANNEL
    add = gr.add_ff()
    noise = gr.noise_source_f(gr.GR_GAUSSIAN,math.sqrt(N0/2),seed)

    # RX
    metrics_in = trellis.metrics_f(fi.O()*fo.O(),dimensionality,constellation,digital.TRELLIS_EUCLIDEAN) # data preprocessing to generate metrics for innner SISO
    scale = gr.multiply_const_ff(1.0/N0)
    dec = trellis.pccc_decoder_s(fo,0,-1,fi,0,-1,interleaver,K,IT,trellis.TRELLIS_MIN_SUM)
 
    fsmi2s = gr.unpacked_to_packed_ss(bitspersymbol,gr.GR_MSB_FIRST) # pack FSM input symbols to shorts
    dst = gr.check_lfsr_32k_s()
    
    tb.connect (src,src_head,s2fsmi,enc,mod)
    #tb.connect (src,enc,mod)
    #tb.connect(enc,code)
    tb.connect (mod,(add,0))
    tb.connect (noise,(add,1))
    tb.connect (add,metrics_in,scale,dec,fsmi2s,dst)

    tb.run()
 
    #print code.data()
    
    ntotal = dst.ntotal ()
    nright = dst.nright ()
    runlength = dst.runlength ()
    return (ntotal,ntotal-nright)


def main(args):
    nargs = len (args)
    if nargs == 5:
        fname_out=args[0]
        fname_in=args[1]
        esn0_db=float(args[2]) # Es/No in dB
        IT=int(args[3])
        rep=int(args[4]) # number of times the experiment is run to collect enough errors
    else:
        sys.stderr.write ('usage: test_pccc_turbo.py fsm_name_1 fsm_fname_2 Es/No_db iterations repetitions\n')
        sys.exit (1)

    # system parameters
    Kb=1024*16  # packet size in bits (make it multiple of 16 so it can be packed in a short)
    fo=trellis.fsm(fname_out) # get the outer FSM specification from a file
    fi=trellis.fsm(fname_in) # get the innner FSM specification from a file
    bitspersymbol = int(round(math.log(fo.I())/math.log(2))) # bits per FSM input symbol
    if fo.I() != fi.I():
        sys.stderr.write ('Incompatible input cardinality between two FSMs.\n')
        sys.exit (1)
    K=Kb/bitspersymbol # packet size in trellis steps
    interleaver=trellis.interleaver(K,666) # construct a random interleaver
    #modulation = fsm_utils.psk8 # see fsm_utlis.py for available predefined modulations
    dimensionality = 4
    constellation = [ 1, 0, 1, 0,\
                      1, 0,-1, 0,\
                      1, 0, 0, 1,\
                      1, 0, 0,-1,\
                     -1, 0, 1, 0,\
                     -1, 0,-1, 0,\
                     -1, 0, 0, 1,\
                     -1, 0, 0,-1,\
                      0, 1, 1, 0,\
                      0, 1,-1, 0,\
                      0, 1, 0, 1,\
                      0, 1, 0,-1,\
                      0,-1, 1, 0,\
                      0,-1,-1, 0,\
                      0,-1, 0, 1,\
                      0,-1, 0,-1,] # equivalent to 2 QPSK symbols
    if len(constellation)/dimensionality != fi.O()*fo.O():
        sys.stderr.write ('Incompatible FSM output cardinality and modulation size.\n')
        sys.exit (1)
    # calculate average symbol energy
    Es = 0
    for i in range(len(constellation)):
        Es = Es + constellation[i]**2
    Es = Es / (len(constellation)/dimensionality)
    N0=Es/pow(10.0,esn0_db/10.0); # calculate noise variance
    
    tot_s=0 # total number of transmitted shorts
    terr_s=0 # total number of shorts in error
    terr_p=0 # total number of packets in error
    for i in range(rep):
        (s,e)=run_test(fo,fi,interleaver,Kb,bitspersymbol,K,dimensionality,constellation,Es,N0,IT,-long(666+i)) # run experiment with different seed to get different noise realizations
        tot_s=tot_s+s
        terr_s=terr_s+e
        terr_p=terr_p+(terr_s!=0)
        if ((i+1)%10==0): # display progress
            print i+1,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)
    # estimate of the (short or bit) error rate
    print rep,terr_p, '%.2e' % ((1.0*terr_p)/(i+1)),tot_s,terr_s, '%.2e' % ((1.0*terr_s)/tot_s)


if __name__ == '__main__':
    main (sys.argv[1:])