From 17195680ee673f3c7cbc5868f9562226d66fa1fb Mon Sep 17 00:00:00 2001
From: Steven Franke <s.j.franke@icloud.com>
Date: Tue, 15 Dec 2020 14:31:46 -0600
Subject: [PATCH] Don't waste time on excess BP iterations when doing K=50.
 Decode a little deeper.

---
 lib/fst4/decode240_74.f90  | 5 +++++
 lib/fst4/fastosd240_74.f90 | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/fst4/decode240_74.f90 b/lib/fst4/decode240_74.f90
index 20a83362f..f5aac2e10 100644
--- a/lib/fst4/decode240_74.f90
+++ b/lib/fst4/decode240_74.f90
@@ -25,6 +25,8 @@ subroutine decode240_74(llr,Keff,maxosd,norder,apmask,message74,cw,ntype,nharder
    include "ldpc_240_74_parity.f90"
 
    maxiterations=30
+   if(Keff.eq.50) maxiterations=1
+
    nosd=0
    if(maxosd.gt.3) maxosd=3
    if(maxosd.eq.0) then ! osd with channel llrs
@@ -36,6 +38,8 @@ subroutine decode240_74(llr,Keff,maxosd,norder,apmask,message74,cw,ntype,nharder
       nosd=0
    endif
 
+   if(maxosd.eq.0) goto 73
+
    toc=0
    tov=0
    tanhtoc=0
@@ -133,6 +137,7 @@ subroutine decode240_74(llr,Keff,maxosd,norder,apmask,message74,cw,ntype,nharder
 
    enddo   ! bp iterations
 
+73 continue
    do i=1,nosd
       zn=zsave(:,i)
 !      call osd240_74(zn,Keff,apmask,norder,message74,cw,nharderror,dminosd)
diff --git a/lib/fst4/fastosd240_74.f90 b/lib/fst4/fastosd240_74.f90
index 03ae4071c..f4bb61d60 100644
--- a/lib/fst4/fastosd240_74.f90
+++ b/lib/fst4/fastosd240_74.f90
@@ -181,8 +181,8 @@ subroutine fastosd240_74(llr,k,apmask,ndeep,message74,cw,nhardmin,dmin)
          nsyncmax=11
       elseif(ndeep.eq.4) then
          nord=4
-         xlambda=3.5
-         nsyndmax=11
+         xlambda=3.4
+         nsyndmax=12
       endif
 
       s1=sum(absrx(1:k))