From 0c03bcd68f94ceb96de7c9fd17410f08d3acff18 Mon Sep 17 00:00:00 2001
From: Paul Sutton <suttonpd@gmail.com>
Date: Wed, 16 Apr 2014 16:44:11 +0100
Subject: [PATCH 1/2] Adding arbitrary resampler with tests and benchmark

---
 lte/include/lte/resampling/resample_arb.h    |  49 ++++++++
 lte/lib/resampling/src/resample_arb.c        | 114 +++++++++++++++++++
 lte/lib/resampling/test/CMakeLists.txt       |  35 ++++++
 lte/lib/resampling/test/resample_arb_bench.c |  38 +++++++
 lte/lib/resampling/test/resample_arb_test.c  |  63 ++++++++++
 5 files changed, 299 insertions(+)
 create mode 100644 lte/include/lte/resampling/resample_arb.h
 create mode 100644 lte/lib/resampling/src/resample_arb.c
 create mode 100644 lte/lib/resampling/test/CMakeLists.txt
 create mode 100644 lte/lib/resampling/test/resample_arb_bench.c
 create mode 100644 lte/lib/resampling/test/resample_arb_test.c

diff --git a/lte/include/lte/resampling/resample_arb.h b/lte/include/lte/resampling/resample_arb.h
new file mode 100644
index 000000000..122e52a6d
--- /dev/null
+++ b/lte/include/lte/resampling/resample_arb.h
@@ -0,0 +1,49 @@
+/**
+ *
+ * \section COPYRIGHT
+ *
+ * Copyright 2013-2014 The libLTE Developers. See the
+ * COPYRIGHT file at the top-level directory of this distribution.
+ *
+ * \section LICENSE
+ *
+ * This file is part of the libLTE library.
+ *
+ * libLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * libLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * A copy of the GNU Lesser General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#ifndef RESAMPLE_ARB_
+#define RESAMPLE_ARB_
+
+#include <stdint.h>
+#include <complex.h>
+
+typedef _Complex float cf_t;
+
+#define RESAMPLE_ARB_N    32  // Polyphase filter rows
+#define RESAMPLE_ARB_M    8   // Polyphase filter columns
+
+typedef struct {
+  float rate;                // Resample rate
+  float step;                // Step increment through filter
+  float acc;                 // Index into filter
+  cf_t reg[RESAMPLE_ARB_M];  // Our window of samples
+}resample_arb_t;
+
+void resample_arb_init(resample_arb_t *q, float rate);
+int resample_arb_compute(resample_arb_t *q, cf_t *input, cf_t *output, int n_in);
+
+#endif //RESAMPLE_ARB_
diff --git a/lte/lib/resampling/src/resample_arb.c b/lte/lib/resampling/src/resample_arb.c
new file mode 100644
index 000000000..8ba00995a
--- /dev/null
+++ b/lte/lib/resampling/src/resample_arb.c
@@ -0,0 +1,114 @@
+/**
+ *
+ * \section COPYRIGHT
+ *
+ * Copyright 2013-2014 The libLTE Developers. See the
+ * COPYRIGHT file at the top-level directory of this distribution.
+ *
+ * \section LICENSE
+ *
+ * This file is part of the libLTE library.
+ *
+ * libLTE is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * libLTE is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * A copy of the GNU Lesser General Public License can be found in
+ * the LICENSE file in the top-level directory of this distribution
+ * and at http://www.gnu.org/licenses/.
+ *
+ */
+
+#include <math.h>
+#include <string.h>
+#include "lte/resampling/resample_arb.h"
+#include "lte/utils/debug.h"
+
+float polyfilt[RESAMPLE_ARB_N][RESAMPLE_ARB_M] =
+{{0,0.002400347599485495,-0.006922416132556366,0.0179104136912176,0.99453086623794,-0.008521087756729117,0.0008598969867484128,0.0004992625165376107},
+{-0.001903604727400391,0.004479591950094871,-0.01525319260830623,0.04647449496926549,0.9910477342662829,-0.03275243420114668,0.008048813755373533,-0.001216900416836847},
+{-0.001750442300940216,0.006728826416921727,-0.02407540632178267,0.07708575473589654,0.9841056525667189,-0.05473739187922162,0.01460652754040275,-0.002745266140572769},
+{-0.001807302702047332,0.009130494591071001,-0.03332524241797466,0.1096377743266821,0.9737536341125557,-0.07444712408657775,0.0205085154280773,-0.004077596041064956},
+{-0.002005048395707184,0.01166717081713966,-0.04292591596219218,0.1440068251440274,0.9600641782991848,-0.09187282739868929,0.02573649090563353,-0.005218582609802016},
+{-0.002303606593778858,0.01431549924598744,-0.05279365431190471,0.1800496557331084,0.9431333663677619,-0.107022659158021,0.03028295984887362,-0.006178495199082676},
+{-0.002673824939871474,0.01705308556587308,-0.06283262272105428,0.2176066284621515,0.9230793648715676,-0.1199244901666642,0.03414559686566755,-0.006951034565279722},
+{-0.003099294850834212,0.01985022208215894,-0.07294100481214681,0.2564996326404178,0.9000412628278351,-0.1306207218667012,0.03733448898243594,-0.007554128492547957},
+{-0.003564415127592977,0.02267702927238637,-0.08300660359189582,0.2965368855416621,0.874178327911914,-0.1391710078036285,0.03986356581130199,-0.007992692892036229},
+{-0.004060222849803048,0.02549633298710617,-0.09291211362877161,0.3375102453232687,0.8456688916962831,-0.1456479420005528,0.04175429631970297,-0.00827816851803391},
+{-0.004574770330592958,0.02827133859849648,-0.1025308044303699,0.379200979038518,0.8147072909915275,-0.1501397816831265,0.04303284689167361,-0.008423951215857236},
+{-0.005100453570725489,0.0309593063669097,-0.1117325201826136,0.4213772298764557,0.7815036335229155,-0.1527444636485677,0.0437349357738538,-0.008441129184587313},
+{-0.005625340687997995,0.03351877124912608,-0.1203802123857154,0.463798444519773,0.7462810500374923,-0.1535722712206338,0.04389261707032224,-0.008345136869130621},
+{-0.006140888413286479,0.03590276234084221,-0.1283350405000867,0.5062161107254219,0.7092744343987509,-0.152741400055636,0.04355110899623683,-0.008147838953503964},
+{-0.006634012711933725,0.03806645580467819,-0.1354549138065051,0.5483763739419955,0.6707272107491931,-0.1503798528838644,0.0427502160096194,-0.007865132034489236},
+{-0.007094909626785393,0.03996043743797257,-0.1415969539549883,0.5900207719663111,0.6308907308946271,-0.1466186670140106,0.04153829696698895,-0.007508971112586246},
+{-0.007508971112586246,0.04153829696698895,-0.1466186670140106,0.6308907308946271,0.5900207719663111,-0.1415969539549883,0.03996043743797257,-0.007094909626785393},
+{-0.007865132034489236,0.0427502160096194,-0.1503798528838644,0.6707272107491931,0.5483763739419955,-0.1354549138065051,0.03806645580467819,-0.006634012711933725},
+{-0.008147838953503964,0.04355110899623683,-0.152741400055636,0.7092744343987509,0.5062161107254219,-0.1283350405000867,0.03590276234084221,-0.006140888413286479},
+{-0.008345136869130621,0.04389261707032224,-0.1535722712206338,0.7462810500374923,0.463798444519773,-0.1203802123857154,0.03351877124912608,-0.005625340687997995},
+{-0.008441129184587313,0.0437349357738538,-0.1527444636485677,0.7815036335229155,0.4213772298764557,-0.1117325201826136,0.0309593063669097,-0.005100453570725489},
+{-0.008423951215857236,0.04303284689167361,-0.1501397816831265,0.8147072909915275,0.379200979038518,-0.1025308044303699,0.02827133859849648,-0.004574770330592958},
+{-0.00827816851803391,0.04175429631970297,-0.1456479420005528,0.8456688916962831,0.3375102453232687,-0.09291211362877161,0.02549633298710617,-0.004060222849803048},
+{-0.007992692892036229,0.03986356581130199,-0.1391710078036285,0.874178327911914,0.2965368855416621,-0.08300660359189582,0.02267702927238637,-0.003564415127592977},
+{-0.007554128492547957,0.03733448898243594,-0.1306207218667012,0.9000412628278351,0.2564996326404178,-0.07294100481214681,0.01985022208215894,-0.003099294850834212},
+{-0.006951034565279722,0.03414559686566755,-0.1199244901666642,0.9230793648715676,0.2176066284621515,-0.06283262272105428,0.01705308556587308,-0.002673824939871474},
+{-0.006178495199082676,0.03028295984887362,-0.107022659158021,0.9431333663677619,0.1800496557331084,-0.05279365431190471,0.01431549924598744,-0.002303606593778858},
+{-0.005218582609802016,0.02573649090563353,-0.09187282739868929,0.9600641782991848,0.1440068251440274,-0.04292591596219218,0.01166717081713966,-0.002005048395707184},
+{-0.004077596041064956,0.0205085154280773,-0.07444712408657775,0.9737536341125557,0.1096377743266821,-0.03332524241797466,0.009130494591071001,-0.001807302702047332},
+{-0.002745266140572769,0.01460652754040275,-0.05473739187922162,0.9841056525667189,0.07708575473589654,-0.02407540632178267,0.006728826416921727,-0.001750442300940216},
+{-0.001216900416836847,0.008048813755373533,-0.03275243420114668,0.9910477342662829,0.04647449496926549,-0.01525319260830623,0.004479591950094871,-0.001903604727400391},
+{0.0004992625165376107,0.0008598969867484128,-0.008521087756729117,0.99453086623794,0.0179104136912176,-0.006922416132556366,0.002400347599485495,0}};
+
+
+// TODO: use lte/utils/vector.h and Volk
+cf_t dot_prod(cf_t* x, float *y, int len)
+{
+  cf_t res = 0+0*I;
+  for(int i=0;i<len;i++){
+    res += x[i]*y[i];
+  }
+  return res;
+}
+
+// Right-shift our window of samples
+void push(resample_arb_t *q, cf_t x)
+{
+  memmove(&q->reg[1], &q->reg[0], (RESAMPLE_ARB_M-1)*sizeof(cf_t));
+  q->reg[0] = x;
+}
+
+// Initialize our struct
+void resample_arb_init(resample_arb_t *q, float rate){
+  memset(q->reg, 0, RESAMPLE_ARB_M*sizeof(cf_t));
+  q->acc = 0.0;
+  q->rate = rate;
+  q->step = (1/rate)*RESAMPLE_ARB_N;
+}
+
+// Resample a block of input data
+int resample_arb_compute(resample_arb_t *q, cf_t *input, cf_t *output, int n_in){
+  int cnt = 0;
+  int n_out = 0;
+  int idx = 0;
+
+  while(cnt < n_in)
+  {
+    *output = dot_prod(q->reg, polyfilt[idx], RESAMPLE_ARB_M);
+    output++;
+    n_out++;
+    q->acc += q->step;
+    idx = (int)roundf(q->acc);
+    while(idx >= RESAMPLE_ARB_N){
+      q->acc -= RESAMPLE_ARB_N;
+      idx -= RESAMPLE_ARB_N;
+      if(cnt < n_in)
+        push(q, input[cnt++]);
+    }
+  }
+  return n_out;
+}
diff --git a/lte/lib/resampling/test/CMakeLists.txt b/lte/lib/resampling/test/CMakeLists.txt
new file mode 100644
index 000000000..d2b6bd0f1
--- /dev/null
+++ b/lte/lib/resampling/test/CMakeLists.txt
@@ -0,0 +1,35 @@
+#
+# Copyright 2012-2013 The libLTE Developers. See the
+# COPYRIGHT file at the top-level directory of this distribution.
+#
+# This file is part of the libLTE library.
+#
+# libLTE is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as
+# published by the Free Software Foundation, either version 3 of
+# the License, or (at your option) any later version.
+#
+# libLTE is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# A copy of the GNU Lesser General Public License can be found in
+# the LICENSE file in the top-level directory of this distribution
+# and at http://www.gnu.org/licenses/.
+#
+
+########################################################################
+# RESAMPLING TEST  
+########################################################################
+
+ADD_EXECUTABLE(resample_arb_test resample_arb_test.c)
+TARGET_LINK_LIBRARIES(resample_arb_test lte)
+
+ADD_EXECUTABLE(resample_arb_bench resample_arb_bench.c)
+TARGET_LINK_LIBRARIES(resample_arb_bench lte)
+
+ADD_TEST(resample resample_arb_test)
+ 
+
+
diff --git a/lte/lib/resampling/test/resample_arb_bench.c b/lte/lib/resampling/test/resample_arb_bench.c
new file mode 100644
index 000000000..4a7d20b62
--- /dev/null
+++ b/lte/lib/resampling/test/resample_arb_bench.c
@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <unistd.h>
+#include <math.h>
+#include <time.h>
+
+#include "lte.h"
+#include "lte/resampling/resample_arb.h"
+
+typedef _Complex float cf_t;
+
+int main(int argc, char **argv) {
+  int N=10000000;
+  float rate = 24.0/25.0;
+  cf_t *in = malloc(N*sizeof(cf_t));
+  cf_t *out = malloc(N*sizeof(cf_t));
+
+  for(int i=0;i<N;i++)
+    in[i] = sin(i*2*M_PI/100);
+
+  resample_arb_t r;
+  resample_arb_init(&r, rate);
+
+  clock_t start = clock(), diff;
+  int n_out = resample_arb_compute(&r, in, out, N);
+  diff = clock() - start;
+
+  int msec = diff * 1000 / CLOCKS_PER_SEC;
+  float thru = (CLOCKS_PER_SEC/(float)diff)*(N/1e6);
+  printf("Time taken %d seconds %d milliseconds\n", msec/1000, msec%1000);
+  printf("Rate = %f MS/sec\n", thru);
+
+  free(in);
+  free(out);
+	printf("Done\n");
+	exit(0);
+}
diff --git a/lte/lib/resampling/test/resample_arb_test.c b/lte/lib/resampling/test/resample_arb_test.c
new file mode 100644
index 000000000..b899bbea1
--- /dev/null
+++ b/lte/lib/resampling/test/resample_arb_test.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+#include <unistd.h>
+#include <math.h>
+#include <time.h>
+
+#include "lte.h"
+#include "lte/resampling/resample_arb.h"
+
+typedef _Complex float cf_t;
+
+int main(int argc, char **argv) {
+  int N = 100;        // Number of sinwave samples
+  int delay = 5;      // Delay of our resampling filter
+  float down = 25.0;  // Downsampling rate
+
+  for(int up=1;up<down;up++)
+  {
+    float rate = up/down;
+    printf("Testing rate %f\n", rate);
+
+    cf_t *in = malloc(N*sizeof(cf_t));
+    if(!in) {
+      perror("malloc");
+      exit(-1);
+    }
+    cf_t *out = malloc(N*sizeof(cf_t));
+    if(!out) {
+      perror("malloc");
+      exit(-1);
+    }
+
+    for(int i=0;i<N;i++)
+      in[i] = sin(i*2*M_PI/N);
+
+    // Resample
+    resample_arb_t r;
+    resample_arb_init(&r, rate);
+    int n_out = resample_arb_compute(&r, in, out, N);
+
+    // Check interp values
+    for(int i=delay+1;i<n_out;i++){
+      float idx = i/rate;
+      int pre = floor(idx)-delay;
+      int post = ceil(idx)-delay;
+      int round = roundf(idx)-delay;
+      float diff = fabs(creal(in[pre])-creal(in[post]));
+      float diff2 = fabs(creal(out[i])-creal(in[round]));
+      if(diff2 > diff && pre != post){
+          printf("Interpolation failed at index %f", idx);
+          exit(-1);
+      }
+    }
+
+
+    free(in);
+    free(out);
+  }
+
+  printf("Ok\n");
+	exit(0);
+}

From ae50c990eca8b82d677ed00da4f8998b3f8e03a4 Mon Sep 17 00:00:00 2001
From: Paul Sutton <suttonpd@gmail.com>
Date: Wed, 16 Apr 2014 17:06:34 +0100
Subject: [PATCH 2/2] Adding matlab files for arbitrary resampler

---
 matlab/resampler/arb_filter.mat         | Bin 0 -> 1475 bytes
 matlab/resampler/arb_resample_linear.m  |  46 ++++++++++++++++++++++++
 matlab/resampler/arb_resample_nearest.m |  37 +++++++++++++++++++
 matlab/resampler/arb_resample_test.m    |  33 +++++++++++++++++
 4 files changed, 116 insertions(+)
 create mode 100644 matlab/resampler/arb_filter.mat
 create mode 100644 matlab/resampler/arb_resample_linear.m
 create mode 100644 matlab/resampler/arb_resample_nearest.m
 create mode 100644 matlab/resampler/arb_resample_test.m

diff --git a/matlab/resampler/arb_filter.mat b/matlab/resampler/arb_filter.mat
new file mode 100644
index 0000000000000000000000000000000000000000..735fbc233271f5701268d9738ba9ac073a1407c4
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diff --git a/matlab/resampler/arb_resample_linear.m b/matlab/resampler/arb_resample_linear.m
new file mode 100644
index 000000000..4bfb4df03
--- /dev/null
+++ b/matlab/resampler/arb_resample_linear.m
@@ -0,0 +1,46 @@
+function out = arb_resample_linear(sig, rate)
+
+N = 32;
+M = 8;
+step = (1/rate)*N;
+
+load('arb_filter.mat');
+
+figure;plot(Num);title('Filter impulse response');
+[h,w] = freqz(Num, 1);
+figure;plot(20*log10(abs(h)));title('Filter freq response');
+
+% Create polyphase partition
+poly = reshape(Num, N, M);
+
+% Filter
+sig = [zeros(1,(M/2)-1) sig];
+k=0;
+acc=0;
+index=0;
+frac=0;
+out = [];
+while k < length(sig)-M
+    sig_reg = fliplr(sig(k+1:k+M));
+    filt_reg1 = poly(index+1, :);
+    filt_reg2 = poly(mod(index+1,N)+1, :);
+    res1 = sig_reg*filt_reg1';
+    res2 = sig_reg*filt_reg2';
+    
+    if index+1 == 32
+        res = res1;
+    else
+        res = res1 + (res2-res1)*frac;
+    end
+    
+    out = [out res];
+    
+    acc = acc+step;
+    index = fix(acc);
+    while index >= N
+        acc = acc - N;
+        index = index - N;
+        k = k+1;
+    end
+    frac = abs(acc-index);
+end
diff --git a/matlab/resampler/arb_resample_nearest.m b/matlab/resampler/arb_resample_nearest.m
new file mode 100644
index 000000000..0601aa169
--- /dev/null
+++ b/matlab/resampler/arb_resample_nearest.m
@@ -0,0 +1,37 @@
+function out = arb_resample_nearest(sig, rate)
+
+N = 32;
+M = 8;
+step = (1/rate)*N;
+
+load('arb_filter.mat');
+
+figure;plot(Num);title('Filter impulse response');
+[h,w] = freqz(Num, 1);
+figure;plot(20*log10(abs(h)));title('Filter frequency response');
+
+% Create polyphase partition
+poly = reshape(Num, N, M);
+
+% Filter
+sig = [zeros(1,(M/2)-1) sig];
+k=0;
+acc=0;
+index=0;
+frac=0;
+out = [];
+while k < length(sig)-M
+    sig_reg = fliplr(sig(k+1:k+M));
+    filt_reg1 = poly(index+1, :);
+    res = sig_reg*filt_reg1';
+    
+    out = [out res];
+    
+    acc = acc+step;
+    index = round(acc);
+    while index >= N
+        acc = acc - N;
+        index = index - N;
+        k = k+1;
+    end
+end
\ No newline at end of file
diff --git a/matlab/resampler/arb_resample_test.m b/matlab/resampler/arb_resample_test.m
new file mode 100644
index 000000000..b6d661da4
--- /dev/null
+++ b/matlab/resampler/arb_resample_test.m
@@ -0,0 +1,33 @@
+close all 
+clear all
+
+up = 24;
+down = 25;
+d_rate = up/down;
+Fs = 100;          % Arbitrary sample rate (used for displays)
+Fsin = 1;
+
+% Create a sine wave
+t = 0:1/Fs:1-1/Fs;
+sig = sin(2*pi*t);
+
+out = arb_resample_nearest(sig,d_rate);
+
+% matlab resample for comparison
+out2 = resample(sig, up, down);
+figure;hold on;title('Ours and matlabs');
+l = min(length(out), length(out2));
+stem(out(1:l));
+stem(out2(1:l), 'r', 'filled');
+diff = out2(1:l)-out(1:l);
+figure;plot(diff);title('Difference between ours and matlabs');
+
+figure; hold on;title('Original and resampled - no time scaling');
+stem(sig);
+stem(out, 'r', 'filled');
+
+% Time align and plot
+figure;hold on;title('Original and resampled - with time scaling');
+stem((1:75)/Fs,real(sig(1:75)));  
+stem((1:72)/(Fs*d_rate),real(out(1:72)),'r','filled');
+xlabel('Time (sec)');ylabel('Signal value');
\ No newline at end of file