From ae462a9cb8bb31073620113220fba082ce9baa11 Mon Sep 17 00:00:00 2001
From: Joe Taylor <joe@princeton.edu>
Date: Fri, 2 Feb 2024 13:22:42 -0500
Subject: [PATCH] More code cleanup.

---
 lib/superfox/rs_sf.c    | 53 ++++++++++++++++++++---------------------
 lib/superfox/rstest.f90 |  6 +++--
 2 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/lib/superfox/rs_sf.c b/lib/superfox/rs_sf.c
index 97e0acbd1..4bb9528a2 100644
--- a/lib/superfox/rs_sf.c
+++ b/lib/superfox/rs_sf.c
@@ -6,49 +6,48 @@ static int first=1;
 static int nn,kk,nroots,npad;
 
 void rs_init_sf_(int *mm, int *nq, int *nn0, int *kk0, int *nfz)
+// Initialize the RS decoder.
 {
+  // Save parameters nn, kk, nroots, npad for global access
   nn=*nn0;
   kk=*kk0;
   nroots=nn-kk;
   npad=*nq-1-nn;
-  if(*mm==6) rs_sf=init_rs_sf(*mm,0x43,*nfz,1,nroots,npad);   //M=6
-  if(*mm==7) rs_sf=init_rs_sf(*mm,0x89,*nfz,1,nroots,npad);   //M=7
-  if(*mm==8) rs_sf=init_rs_sf(*mm,0x11d,*nfz,1,nroots,npad);  //M=8
+
+  int gfpoly=0x43;    //For *mm=6
+  if(*mm==7) gfpoly=0x89;
+  if(*mm==8) gfpoly=0x11d;
+  rs_sf=init_rs_sf(*mm,gfpoly,*nfz,1,nroots,npad);
   first=0;
 }
 
 void rs_encode_sf_(int *dgen, int *sent)
-     // Encode JT65 data dgen[...], producing sent[...].
+// Encode the information symbols dgen[KK], producing channel symbols sent[NN].
 {
-  int dat1[256];
-  int b[256];
-  int i;
+  int b[256];                    //These are the parity symbols
+  encode_rs_sf(rs_sf,dgen,b);    //Compute the parity symbols
 
-  for(i=0; i<kk; i++) {          //Copy data into dat1
-    dat1[i]=dgen[i];
-  }
-
-  encode_rs_sf(rs_sf,dat1,b);    // Compute the parity symbols
-
-  // Copy parity symbols into sent[] array, followed by data
-  for (i = 0; i < nroots; i++) {
-    sent[i] = b[i];
-  }
-
-  for (i = 0; i < kk; i++) {
-    sent[i+nroots] = dat1[i];
+// Copy parity symbols into sent[] array, followed by information symbols
+  for (int i=0; i< nn; i++) {
+    if(i<nroots) {
+      sent[i]=b[i];
+    } else {
+      sent[i]=dgen[i-nroots];
+    }
   }
 }
 
-void rs_decode_sf_(int *recd, int *era_pos, int *numera, int *decoded, int *nerr)
-     // Decode JT65 received data recd0[63], producing decoded[12].
-     // Erasures are indicated in era0[numera].  The number of corrected
-     // errors is *nerr.  If the data are uncorrectable, *nerr=-1 is
-     // returned.
+void rs_decode_sf_(int *recd, int *era_pos, int *numera, int *decoded,
+		   int *nerr)
+/*
+Decode received data recd[NN], producing decoded[KK]. Positiions of 
+erased symbols are specified in array era_pos[numera]. The number of 
+corrected errors is *nerr; if the data are uncorrectable, *nerr=-1 
+is returned.
+*/
 {
-  int i;
   *nerr=decode_rs_sf(rs_sf,recd,era_pos,*numera);
-  for(i=0; i<kk; i++) {
+  for(int i=0; i<kk; i++) {
     decoded[i]=recd[nroots+i];
   }
 }
diff --git a/lib/superfox/rstest.f90 b/lib/superfox/rstest.f90
index e28721961..76d2b4697 100644
--- a/lib/superfox/rstest.f90
+++ b/lib/superfox/rstest.f90
@@ -9,8 +9,10 @@ program rstest
       
   nargs=iargc()
   if(nargs.ne.5) then
-     print*,'Usage:   rstest  M  N   K nera nerr'
-     print*,'Example: rstest  7 127 51   0   38'
+     print*,'Usage:    rstest  M  N   K nera nerr'
+     print*,'Examples: rstest  6 63  12   0   25'
+     print*,'          rstest  7 127 51   0   38'
+     print*,'          rstest  8 255 51   0  102'
      go to 999
   endif
   nkv=0