diff --git a/src/octave/ddpm_mod.m b/src/octave/ddpm_mod.m
index a31527ec..33c24565 100644
--- a/src/octave/ddpm_mod.m
+++ b/src/octave/ddpm_mod.m
@@ -6,14 +6,33 @@
   
   ddpm_s = zeros(size(s));
   
-  for tidx = 1:length(s)
-    for bidx = 1:nbits
-      if bitand(count(tidx), (2^(nbits-bidx)-1) ) == 2^(nbits-1-bidx)
-          if bitand(s(tidx),bitshift(1,bidx))
-            ddpm_s(tidx) = 1;
-          end
+  if 0
+    % loop form (slower)
+    
+    for tidx = 1:length(s)
+      for bidx = 1:nbits
+        if bitand(count(tidx), (2^(nbits-bidx)-1) ) == 2^(nbits-1-bidx)
+            if bitand(s(tidx),bitshift(1,bidx))
+              ddpm_s(tidx) = 1;
+            end
+        end
       end
     end
-  end
   
+  else
+    % matrix form (faster)
+  
+   for bidx = 1:nbits
+    idxs = find( 
+    (bitand(count, (2^(nbits-bidx)-1) ) == 2^(nbits-1-bidx) ) &
+    ( bitand(s,bitshift(1,bidx)) > 0 )
+    );        
+    
+    % size(idxs)
+
+    ddpm_s(idxs) = ones(size(idxs));
+   end
+  
+  end
+    
 end
\ No newline at end of file
diff --git a/src/octave/sd1_mod.m b/src/octave/sd1_mod.m
index ad27b9dd..e709187d 100644
--- a/src/octave/sd1_mod.m
+++ b/src/octave/sd1_mod.m
@@ -15,10 +15,18 @@
   minval = 0;
     
   for idx = 2:length(inval)
-      delta(idx)  = saturated_adder( inval(idx),  qerr(idx-1),   maxval, minval);
+      if 1
+        delta(idx)  = saturated_adder( inval(idx),  qerr(idx-1),   maxval, minval);
+      else
+        % just slightly faster
+        delta(idx)  = inval(idx) + qerr(idx-1);
+      end
       qerr(idx)   = bitand( delta(idx), 2^(nbits-nbits_out) - 1);
       sd_out(idx) = bitshift(delta(idx),-(nbits-nbits_out));
   end
+  
+  % check for saturation
+  saturation_check(delta, maxval, minval);  
     
   if 1
     fh = figure(541);
@@ -53,6 +61,20 @@
   
     ret = a + b;
     
+    if ret > maxval
+      ret = maxval;
+    else
+      if ret < minval
+        ret = minval;
+      end
+    end
+   
+end
+
+function ret = saturated_adder_vec(a, b, maxval, minval)
+  
+    ret = a + b;
+    
     maxidx = find(ret > maxval);
     ret(maxidx) = maxval * ones(size(maxidx));
     
@@ -61,3 +83,13 @@
    
 end
 
+function saturation_check(s, maxval, minval)
+  
+    maxidx = find(s > maxval);
+    assert(isempty(maxidx));
+        
+    minidx = find(s < minval);
+    assert(isempty(maxidx));
+   
+end
+
diff --git a/src/octave/sim_top.m b/src/octave/sim_top.m
index a0d9de38..b01e5c3c 100644
--- a/src/octave/sim_top.m
+++ b/src/octave/sim_top.m
@@ -3,7 +3,9 @@
 clear all;
 close all;
 
-pkg load signal
+profile off;
+profile clear;
+profile on;
 
 % inputs
 fclock = 12.5; # khz
@@ -16,8 +18,16 @@
   nbit_pwm_phase = 8;
   nbit_sine_phase = 8;
   nbit_pwm_amplitude = 8;
-  nperiods = 5;
+  nperiods = 5; 
 end
+
+if 0
+  nbit_pwm_phase = 10;
+  nbit_sine_phase = 6;
+  nbit_pwm_amplitude = nbit_pwm_phase;
+  nperiods = 3; 
+end
+
 nbit_sd_amplitude = nbit_pwm_amplitude + 2;
 
 % parameters
@@ -66,16 +76,16 @@
   xlim((1/fclock)*[0 (2^nbit_phase)-1]);
 end
 
-if 0 
-  figure(111);
-  stairs(t,s);
-  hold on; grid on;
-  stairs(t,max(s)*sd1_s,'r');
-  xlabel('time [ms]');
-  ylabel('amplitude [LSB]');
-  legend('quant sine','sd1');
-  xlim((1/fclock)*[0 (2^nbit_phase)-1]);
-end
+##if 0 
+##  figure(111);
+##  stairs(t,s);
+##  hold on; grid on;
+##  stairs(t,max(s)*sd1_s,'r');
+##  xlabel('time [ms]');
+##  ylabel('amplitude [LSB]');
+##  legend('quant sine','sd1');
+##  xlim((1/fclock)*[0 (2^nbit_phase)-1]);
+##end
 
 if 1 
   fh = figure(1111);
@@ -108,7 +118,7 @@
   xlim((1/fclock)*[0 (2^nbit_phase)-1]);
   
   saveas(fh, 'timedomain', 'png');
-  close(fh)
+  % close(fh)
 end
 
 %% freq domain plots %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -147,4 +157,9 @@
   legend('pwm', 'ddpm', 'sd1','Location','southwest');
   saveas(fh, 'freqdomain', 'png');
   % close(fh)
-end
\ No newline at end of file
+end
+
+profile off;
+prof = profile ('info');
+profshow(prof);
+% profexplore(prof);