/* 
  FILE...: ldpc_dec.c
  AUTHOR.: Matthew C. Valenti, Rohit Iyer Seshadri, David Rowe
  CREATED: Sep 2016

  Command line C LDPC decoder derived from MpDecode.c in the CML
  library.  Allows us to run the same decoder in Octave and C.  The
  code is defined by the parameters and array stored in the include
  file below, which can be machine generated from the Octave function
  ldpc_fsk_lib.m:ldpc_decode()

  The include file also contains test input/output vectors for the LDPC
  decoder for testing this program.

  Build:

    $ gcc -O2 -o ldpc_dec ldpc_dec.c mpdecode_core.c -Wall -lm -g

  Note: -O2 option was required to get identical results to MpDecode,
  which is also compiled with -O2.  Without it the number of bit errors
  between C and Octave was different, especially when the code did
  not converge and hit max_iters.

*/

#include <assert.h>
#include <errno.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "mpdecode_core_test.h"
#include "ofdm_internal.h"

/* Machine generated consts, H_rows, H_cols, test input/output data to
   change LDPC code regenerate this file. */

/* TODO: Better octave/C support for multuple codes */

#include "H2064_516_sparse_test.h"  
#include "HRA_112_112_test.h"  

int opt_exists(char *argv[], int argc, char opt[]) {
    int i;
    for (i=0; i<argc; i++) {
        if (strcmp(argv[i], opt) == 0) {
            return i;
        }
    }
    return 0;
}

int main(int argc, char *argv[])
{    
    int         CodeLength, NumberParityBits;
    int         i, r, num_ok, num_runs, codename, parityCheckCount, mute;
    int         state, next_state, hframe, testframes;
    // int        frame;
    int         data_bits_per_frame;
    char       *adetected_data;
    struct LDPC ldpc;
    float      *ainput;
    int         iter, total_iters;
    int         Tbits, Terrs, Tbits_raw, Terrs_raw;
    
    if (argc < 2) {
        fprintf(stderr, "\n");
        fprintf(stderr, "usage: %s --test [--code CodeName]\n\n", argv[0]);
        fprintf(stderr, "  Run internal self test and print code parameters.\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "usage: %s --listcodes\n\n", argv[0]);
        fprintf(stderr, "  List supported codes (more can be added via using Octave ldpc scripts)\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "usage: %s InOneSymbolPerDouble OutOneBitPerByte [--sd] [--half] [--code CodeName] [--testframes]\n\n", argv[0]);
        fprintf(stderr, "   InOneSymbolPerDouble    Input file of double LLRs, use - for the \n");        
        fprintf(stderr, "                           file names to use stdin/stdout\n");
        fprintf(stderr, "   --code                  Use LDPC code CodeName\n");
        fprintf(stderr, "   --listcodes             List available LDPC codes\n");
        fprintf(stderr, "   --sd                    Treat input file samples as Soft Decision\n");
        fprintf(stderr, "                           demod outputs rather than LLRs\n");
        fprintf(stderr, "   --half                  Load framesize/2 input samples for each decode\n");
        fprintf(stderr, "                           attempt, only output decoded bits\n");
        fprintf(stderr, "                           converges.  Form of frame sync.\n");
        fprintf(stderr, "   --mute                  Only output frames with < 10%% parity check fails\n");
        fprintf(stderr, "   --testframes            built in test frame modem, requires --testframes at encoder\n");
        fprintf(stderr, "\n");

        fprintf(stderr, "Example in testframe mode:\n\n");
        fprintf(stderr, " $ ./ldpc_enc /dev/zero - --sd --code HRA_112_112 --testframes 10 |\n");
        fprintf(stderr, "   ./ldpc_dec - /dev/null --code HRA_112_112 --sd --testframes\n");
        exit(0);
    }


    if ((codename = opt_exists(argv, argc, "--listcodes")) != 0) {
        fprintf(stderr,"\n");
        fprintf(stderr,"H2064_516_sparse\n");
        fprintf(stderr,"HRA_112_112\n");
        fprintf(stderr,"\n");
        exit(0);
    }

    /* default Wenet High Alitiude Balloon rate 0.8 code */

    ldpc.max_iter = MAX_ITER;
    ldpc.dec_type = 0;
    ldpc.q_scale_factor = 1;
    ldpc.r_scale_factor = 1;
    ldpc.CodeLength = CODELENGTH;
    ldpc.NumberParityBits = NUMBERPARITYBITS;
    ldpc.NumberRowsHcols = NUMBERROWSHCOLS;
    ldpc.max_row_weight = MAX_ROW_WEIGHT;
    ldpc.max_col_weight = MAX_COL_WEIGHT;
    ldpc.H_rows = H_rows;
    ldpc.H_cols = H_cols;
    ainput = input;
    adetected_data = detected_data;

    if ((codename = opt_exists(argv, argc, "--code")) != 0) {

        /* short rate 1/2 code for FreeDV HF digital voice */
        
        if (strcmp(argv[codename+1], "HRA_112_112") == 0) {
            fprintf(stderr, "code: %s\n", argv[codename+1]);
            ldpc.max_iter = HRA_112_112_MAX_ITER;
            ldpc.dec_type = 0;
            ldpc.q_scale_factor = 1;
            ldpc.r_scale_factor = 1;
            ldpc.CodeLength = HRA_112_112_CODELENGTH;
            ldpc.NumberParityBits = HRA_112_112_NUMBERPARITYBITS;
            ldpc.NumberRowsHcols = HRA_112_112_NUMBERROWSHCOLS;
            ldpc.max_row_weight = HRA_112_112_MAX_ROW_WEIGHT;
            ldpc.max_col_weight = HRA_112_112_MAX_COL_WEIGHT;
            ldpc.H_rows = HRA_112_112_H_rows;
            ldpc.H_cols = HRA_112_112_H_cols;
            ainput = HRA_112_112_input;
            adetected_data = HRA_112_112_detected_data;
        }
    }

    if ((i = opt_exists(argv, argc, "--max_iter")) > 0) {
        ldpc.max_iter = atoi(argv[i+1]);
        fprintf(stderr, "max_iter: %d\n", ldpc.max_iter);
    }

    CodeLength = ldpc.CodeLength;                    /* length of entire codeword */
    NumberParityBits = ldpc.NumberParityBits;
    data_bits_per_frame = ldpc.NumberRowsHcols;
    unsigned char ibits[data_bits_per_frame];
    unsigned char pbits[NumberParityBits];
    char out_char[CodeLength];

    testframes = 0;
    total_iters = 0;
    Tbits = Terrs = Tbits_raw = Terrs_raw = 0;

    if (!strcmp(argv[1],"--test")) {

        /* test mode --------------------------------------------------------*/

        fprintf(stderr, "Starting test using pre-compiled test data .....\n");
        fprintf(stderr, "Codeword length: %d\n",  CodeLength);
        fprintf(stderr, "Parity Bits....: %d\n",  NumberParityBits);

        num_runs = 1; num_ok = 0;

        for(r=0; r<num_runs; r++) {

            iter = run_ldpc_decoder(&ldpc, out_char, ainput, &parityCheckCount);
            //fprintf(stderr, "iter: %d\n", iter);
            total_iters += iter;

            int ok = 0;
            for (i=0; i<CodeLength; i++) {
                if (out_char[i] == adetected_data[i])                    
                    ok++;
            }

            if (ok == CodeLength)
                num_ok++;            
        }

        fprintf(stderr, "test runs......: %d\n",  num_runs);
        fprintf(stderr, "test runs OK...: %d\n",  num_ok);
        if (num_runs == num_ok)
            fprintf(stderr, "test runs OK...: PASS\n");
        else
            fprintf(stderr, "test runs OK...: FAIL\n");
    }
    else {
        FILE *fin, *fout;
        int   sdinput, readhalfframe, nread, offset;

        /* File I/O mode ------------------------------------------------*/

        if (strcmp(argv[1], "-")  == 0) fin = stdin;
        else if ( (fin = fopen(argv[1],"rb")) == NULL ) {
            fprintf(stderr, "Error opening input SD file: %s: %s.\n",
                    argv[1], strerror(errno));
            exit(1);
        }
        
        if (strcmp(argv[2], "-") == 0) fout = stdout;
        else if ( (fout = fopen(argv[2],"wb")) == NULL ) {
            fprintf(stderr, "Error opening output bit file: %s: %s.\n",
                    argv[2], strerror(errno));
            exit(1);
        }

        sdinput = 0;
        readhalfframe = 0;
        mute = 0; state = 0; hframe = 0;
        if (opt_exists(argv, argc, "--sd")) {
            sdinput = 1;
        }
        if (opt_exists(argv, argc, "--half")) {
            readhalfframe = 1;
        }
        if (opt_exists(argv, argc, "--mute")) {
            mute = 1;
        }
        if (opt_exists(argv, argc, "--testframes")) {
            testframes = 1;
            uint16_t r[data_bits_per_frame];
            ofdm_rand(r, data_bits_per_frame);

            for(i=0; i<data_bits_per_frame; i++) {
                ibits[i] = r[i] > 16384;
            }
            encode(&ldpc, ibits, pbits);  
       }

       double *input_double = calloc(CodeLength, sizeof(double));
       float  *input_float  = calloc(CodeLength, sizeof(float));

       nread = CodeLength;
       offset = 0;
       if (readhalfframe) {
           nread = CodeLength/2;
           offset = CodeLength/2;
           for(i=0; i<offset; i++) {
               input_double[i] = 0.0;
           }
       }

       fprintf(stderr, "Codeword length: %d\n",  CodeLength);
       fprintf(stderr, "Parity Bits....: %d\n",  NumberParityBits);

       //frame = 0;
       while(fread(&input_double[offset], sizeof(double), nread, fin) == nread) {
            //fprintf(stderr, "Frame %d\n", frame);
            if (sdinput) {
                if (testframes) {
                    char in_char;
                    for (i=0; i<data_bits_per_frame; i++) {
                        in_char = input_double[i] < 0;
                        if (in_char != ibits[i]) {
                            Terrs_raw++;
                        }
                        Tbits_raw++;
                    }
                    for (i=0; i<NumberParityBits; i++) {
                        in_char = input_double[i+data_bits_per_frame] < 0;
                        if (in_char != pbits[i]) {
                            Terrs_raw++;
                        }
                        Tbits_raw++;
                    }
                }
                sd_to_llr(input_float, input_double, CodeLength);
            }

            iter = run_ldpc_decoder(&ldpc, out_char, input_float,
                                    &parityCheckCount);
            //fprintf(stderr, "iter: %d\n", iter);
            total_iters += iter;
            
            if (mute) {

                // Output data bits if decoder converged, or was
                // within 10% of all parity checks converging (10% est
                // BER).  useful for real world operation as it can
                // resync and won't send crappy packets to the decoder
                
                float ber_est = (float)(ldpc.NumberParityBits - parityCheckCount)/ldpc.NumberParityBits;
                //fprintf(stderr, "iter: %4d parityCheckErrors: %4d ber: %3.2f\n", iter, ldpc.NumberParityBits - parityCheckCount, ber_est);
                if (ber_est < 0.1) {
                    fwrite(out_char, sizeof(char), ldpc.NumberRowsHcols, fout);
                }

            } else {
                
                if (readhalfframe) {
                    // Establish which half hframe we want to sync on,
                    // used for testing with cohpsk_put_bits, as it
                    // maintains sync with test bits state machine.
                
                    next_state = state;
                    switch(state) {
                    case 0:
                        if (iter < ldpc.max_iter) {
                            /* OK we've found which hframe to sync on */
                            next_state = 1;
                            hframe = 0;
                        }
                        break;
                    case 1:
                        hframe++;
                        if ((hframe % 2) == 0) {
                            /* write decoded packets every second input hframe */
                            fwrite(out_char, sizeof(char), ldpc.NumberRowsHcols, fout);
                        }
                        break;
                    }
                    state = next_state;
                    //fprintf(stderr, "state: %d iter: %d\n", state, iter);
                }

                for(i=0; i<offset; i++) {
                    input_double[i] = input_double[i+offset];
                }
            }

            fwrite(out_char, sizeof(char), data_bits_per_frame, fout);

            if (testframes) {
                for (i=0; i<data_bits_per_frame; i++) {
                    //fprintf(stderr, "%d %d\n", out_char[i], ibits[i]);
                    if (out_char[i] != ibits[i]) {
                        Terrs++;
                    }
                    Tbits++;
                }
            }
        //frame ++;
        }

        free(input_double);
        if (fin  != NULL) fclose(fin);
        if (fout != NULL) fclose(fout);
    }

    fprintf(stderr, "total iters %d\n", total_iters);

    if (testframes) {
        fprintf(stderr, "Raw Tbits..: %d Terr: %d BER: %4.3f\n", Tbits_raw, Terrs_raw,
                (float)Terrs_raw/(Tbits_raw+1E-12));
        fprintf(stderr, "Coded Tbits: %d Terr: %d BER: %4.3f\n", Tbits, Terrs, (float)Terrs/(Tbits+1E-12));
    }

    //ldpc_free_mem(&ldpc);
    
    return 0;
}