From ac7c48b4dee99d4c772f133d70d8d1b38262fcd2 Mon Sep 17 00:00:00 2001
From: Author Name <david@rowetel.com>
Date: Fri, 7 Jul 2023 12:20:59 +0930
Subject: shallow zip-file copy from codec2 e9d726bf20

---
 src/ldpc_enc.c | 146 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 src/ldpc_enc.c

(limited to 'src/ldpc_enc.c')

diff --git a/src/ldpc_enc.c b/src/ldpc_enc.c
new file mode 100644
index 0000000..3652a6a
--- /dev/null
+++ b/src/ldpc_enc.c
@@ -0,0 +1,146 @@
+/* 
+  FILE...: ldpc_enc.c
+  AUTHOR.: Bill Cowley, David Rowe
+  CREATED: Sep 2016
+
+  RA LDPC encoder program. Using the elegant back substitution of RA
+  LDPC codes.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+
+#include "mpdecode_core.h"
+#include "ldpc_codes.h"
+#include "ofdm_internal.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[])
+{
+    FILE         *fin, *fout;
+    int           arg, sd, i, frames, codename, testframes, Nframes, data_bits_per_frame, parity_bits_per_frame;
+    struct LDPC   ldpc;
+    int unused_data_bits;
+    
+    if (argc < 2) {
+        fprintf(stderr, "\n");
+        fprintf(stderr, "usage: %s InputOneBytePerBit OutputFile [--sd] [--code CodeName] [--testframes Nframes] [--unused numUnusedDataBits]\n", argv[0]);
+        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");
+        exit(0);
+    }
+
+    /* todo: put this in a function file to share with ldpc_dec.c */
+
+    if ((codename = opt_exists(argv, argc, "--listcodes")) != 0) {
+        ldpc_codes_list();
+        exit(0);
+    }
+
+    /* set up LDPC code */
+
+    int code_index = 0;
+    if ((codename = opt_exists(argv, argc, "--code")) != 0)
+        code_index = ldpc_codes_find(argv[codename+1]);
+    memcpy(&ldpc,&ldpc_codes[code_index],sizeof(struct LDPC));
+    fprintf(stderr, "Using: %s\n", ldpc.name);
+    
+    data_bits_per_frame = ldpc.NumberRowsHcols;
+    parity_bits_per_frame = ldpc.NumberParityBits;
+    
+    unsigned char ibits[data_bits_per_frame];
+    unsigned char pbits[parity_bits_per_frame];
+    float         sdout[data_bits_per_frame+parity_bits_per_frame];
+
+    if (strcmp(argv[1], "-")  == 0) fin = stdin;
+    else if ( (fin = fopen(argv[1],"rb")) == NULL ) {
+        fprintf(stderr, "Error opening input bit 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);
+    }
+    
+    sd = 0;
+    if (opt_exists(argv, argc, "--sd")) {
+        sd = 1;
+    }
+
+    unused_data_bits = 0;
+    if ((arg = opt_exists(argv, argc, "--unused"))) {
+        unused_data_bits = atoi(argv[arg+1]);
+    }
+    
+    testframes = Nframes = 0;
+
+    if ((arg = (opt_exists(argv, argc, "--testframes")))) {
+        testframes = 1;
+        Nframes = atoi(argv[arg+1]);
+        fprintf(stderr, "Nframes: %d\n", Nframes);
+    }
+
+    frames = 0;
+    int written = 0;
+    
+    while (fread(ibits, sizeof(char), data_bits_per_frame, fin) == data_bits_per_frame) {
+        if (testframes) {
+            uint16_t r[data_bits_per_frame];
+            ofdm_rand(r, data_bits_per_frame);
+
+            for(i=0; i<data_bits_per_frame-unused_data_bits; i++) {
+                ibits[i] = r[i] > 16384;
+            }
+            for(i=data_bits_per_frame-unused_data_bits; i<data_bits_per_frame; i++) {
+                ibits[i] = 1;
+            }
+           
+        }
+        
+        encode(&ldpc, ibits, pbits);  
+        
+        if (sd) {
+            /* map to BPSK symbols */
+            for (i=0; i<data_bits_per_frame-unused_data_bits; i++)
+                sdout[i] = 1.0 - 2.0 * ibits[i];
+            for (i=0; i<parity_bits_per_frame; i++)
+                sdout[i+data_bits_per_frame-unused_data_bits] = 1.0 - 2.0 * pbits[i];
+            written += fwrite(sdout, sizeof(float), data_bits_per_frame-unused_data_bits+parity_bits_per_frame, fout); 
+        }
+        else {
+            written += fwrite(ibits, sizeof(char), data_bits_per_frame, fout); 
+            written += fwrite(pbits, sizeof(char), parity_bits_per_frame, fout); 
+        }
+        
+        frames++;       
+        if (testframes && (frames >= Nframes)) {
+            goto finished;
+        }
+    }
+
+ finished:
+
+    fprintf(stderr, "written: %d\n", written);
+    fclose(fin);  
+    fclose(fout); 
+
+    return 1;
+}
-- 
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