anchor.diff:                 gupdate = 0.5d0*dtdx1d(i) * bpasdq(m,i)
                  gaddm(m,i,2) = gaddm(m,i,2) - gupdate
                  gaddp(m,i,2) = gaddp(m,i,2) - gupdate
  -  180          continue
  +         end do
  +      end do
   c
     999 continue
         return
  
positive.code:                gupdate = 0.5d0*dtdx1d(i-1) * bpasdq(m,i)
                 gaddm(m,i-1,2) = gaddm(m,i-1,2) - gupdate
                 gaddp(m,i-1,2) = gaddp(m,i-1,2) - gupdate
    160          continue
  c
  c     # split the right-going flux difference into down-going and up-going:
        call rpt2(ixy,2,maxm,meqn,mwaves,maux,mbc,mx,
  
negative.code: c
  c
        use clawpack5_amr_module
        implicit none
  
        external rpn2, rpt2
  
        integer ixy,maxm,meqn,maux,mbc,mx
        double precision    q1d(meqn,1-mbc:maxm+mbc)
        double precision   amdq(meqn,1-mbc:maxm+mbc)
        double precision   apdq(meqn,1-mbc:maxm+mbc)
        double precision bmasdq(meqn,1-mbc:maxm+mbc)
        double precision bpasdq(meqn,1-mbc:maxm+mbc)
        double precision   cqxx(meqn,1-mbc:maxm+mbc)
        double precision   faddm(meqn,1-mbc:maxm+mbc)
        double precision   faddp(meqn,1-mbc:maxm+mbc)
        double precision   gaddm(meqn,1-mbc:maxm+mbc, 2)
        double precision   gaddp(meqn,1-mbc:maxm+mbc, 2)
        double precision dtdx1d(1-mbc:maxm+mbc)
        double precision aux1(maux,1-mbc:maxm+mbc)
        double precision aux2(maux,1-mbc:maxm+mbc)
        double precision aux3(maux,1-mbc:maxm+mbc)
  c
        double precision     s(mwaves, 1-mbc:maxm+mbc)
        double precision  wave(meqn, mwaves, 1-mbc:maxm+mbc)
  c
        logical limit
  
        double precision dtcom, dxcom, dycom, tcom
        integer icom, jcom
        common /comxyt/ dtcom,dxcom,dycom,tcom,icom,jcom
  
        integer mw, i, m
        double precision cfl1d, dtdxave, abs_sign, gupdate
  c
        limit = .false.
        do mw = 1,mwaves
           if (mthlim(mw) .gt. 0) then
              limit = .true.
           endif
        end do
  c
  c     # initialize flux increments:
  c     -----------------------------
  c
         do i = 1-mbc, mx+mbc
           do m = 1,meqn
              faddm(m,i) = 0.d0
              faddp(m,i) = 0.d0
              gaddm(m,i,1) = 0.d0
              gaddp(m,i,1) = 0.d0
              gaddm(m,i,2) = 0.d0
              gaddp(m,i,2) = 0.d0
           end do
        end do
  c
  c
  c     # solve Riemann problem at each interface and compute Godunov updates
  