From 9beb3fd39decafec9f79192ed782e46019bde7c7 Mon Sep 17 00:00:00 2001
From: Laurence Withers <l@lwithers.me.uk>
Date: Tue, 9 Sep 2014 12:46:25 +0000
Subject: [PATCH] Implement fir3db tool

---
 config                       |  2 -
 src/fir3db/000_TopSource.c   | 10 +++++
 src/fir3db/200_load_filter.c |  1 +
 src/fir3db/800_fir3db.c      | 77 ++++++++++++++++++++++++++++++++
 src/fir3db/999_main.c        | 85 ++++++++++++++++++++++++++++++++++++
 src/fir3db/build.app         |  3 +-
 6 files changed, 175 insertions(+), 3 deletions(-)
 create mode 120000 src/fir3db/200_load_filter.c
 create mode 100644 src/fir3db/800_fir3db.c
 create mode 100644 src/fir3db/999_main.c

diff --git a/config b/config
index 4ed2a98..afea285 100644
--- a/config
+++ b/config
@@ -33,8 +33,6 @@ source "scripts/paths"
 # Project-specific variables below.
 [ -z "${LIBFIR_CFLAGS}" ] && LIBFIR_CFLAGS="$(libfir-config --cflags)"
 [ -z "${LIBFIR_LIBS}" ] && LIBFIR_LIBS="$(libfir-config --libs)"
-[ -z "${GSL_CFLAGS}" ] && GSL_CFLAGS="$(gsl-config --cflags)"
-[ -z "${GSL_LIBS}" ] && GSL_LIBS="$(gsl-config --libs)"
 
 [ -z "${CC}" ] && CC="gcc"
 [ -z "${CFLAGS}" ] && CFLAGS="-g -O2 -W -Wall"
diff --git a/src/fir3db/000_TopSource.c b/src/fir3db/000_TopSource.c
index 599a1a7..eeb1ac0 100644
--- a/src/fir3db/000_TopSource.c
+++ b/src/fir3db/000_TopSource.c
@@ -6,6 +6,16 @@
  */
 
 /* Below are all the includes used throughout the application. */
+#include <ctype.h>
+#include <errno.h>
+#include <getopt.h>
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <fir.h>
 
 /* options for text editors
 vim: expandtab:ts=4:sw=4
diff --git a/src/fir3db/200_load_filter.c b/src/fir3db/200_load_filter.c
new file mode 120000
index 0000000..a40a060
--- /dev/null
+++ b/src/fir3db/200_load_filter.c
@@ -0,0 +1 @@
+../fir2csv/200_load_filter.c
\ No newline at end of file
diff --git a/src/fir3db/800_fir3db.c b/src/fir3db/800_fir3db.c
new file mode 100644
index 0000000..a182ddd
--- /dev/null
+++ b/src/fir3db/800_fir3db.c
@@ -0,0 +1,77 @@
+/* fir-tools/src/fir3db/800_fir3db.c
+ *
+ *  Copyright: ©2014, Laurence Withers
+ *  Author: Laurence Withers <l@lwithers.me.uk>
+ *  License: GPLv3
+ */
+
+
+
+enum {
+    /* number of points for initial coarse search */
+    npoints = 1000,
+
+    /* number of iterations when finding -3dB point */
+    niter = 10,
+};
+
+
+
+void
+fir3db_aux(struct fir_filter_t* fi, double freq1, double freq2, double gain)
+{
+    int i;
+    double complex resp;
+    double fmid, mag;
+
+    for(i = 0; i < niter; ++i) {
+        fmid = (freq1 + freq2) / 2;
+        resp = fir_filter_response(fi, fmid);
+        mag = cabs(resp);
+
+        if(mag > gain) {
+            freq2 = fmid;
+        } else {
+            freq1 = fmid;
+        }
+    }
+
+    printf("%.8g\n", fmid);
+}
+
+
+
+void
+fir3db(struct fir_filter_t* fi, double gain)
+{
+    double freq, freq_last, mag, mag_last;
+    double complex resp;
+    int i;
+
+    resp = fir_filter_response(fi, 0);
+    mag_last = cabs(resp);
+    freq_last = 0;
+
+    for(i = 1; i < npoints; ++i) {
+        freq = (i * 0.5) / (npoints - 1);
+        resp = fir_filter_response(fi, freq);
+        mag = cabs(resp);
+
+        if(mag_last < gain && mag >= gain) {
+            fir3db_aux(fi, freq_last, freq, gain);
+        }
+
+        if(mag_last >= gain && mag < gain) {
+            fir3db_aux(fi, freq, freq_last, gain);
+        }
+
+        mag_last = mag;
+        freq_last = freq;
+    }
+}
+
+
+
+/* options for text editors
+vim: expandtab:ts=4:sw=4
+*/
diff --git a/src/fir3db/999_main.c b/src/fir3db/999_main.c
new file mode 100644
index 0000000..cdadebf
--- /dev/null
+++ b/src/fir3db/999_main.c
@@ -0,0 +1,85 @@
+/* fir-tools/src/fir3db/999_main.c
+ *
+ *  Copyright: ©2014, Laurence Withers
+ *  Author: Laurence Withers <l@lwithers.me.uk>
+ *  License: GPLv3
+ */
+
+
+
+void
+usage(void)
+{
+    fputs("Usage:\n\n"
+        "    " APP_NAME " [options] coeff.txt\n\n"
+        "Options:\n"
+        " -h, --help            Display this screen.\n"
+        " -V, --version         Display version number.\n"
+        " -g, --gain <gain>     Gain to search for (default: 0.5).\n"
+    "", stdout);
+}
+
+
+
+const struct option options[] = {
+    { "help", no_argument, 0, 'h' },
+    { "version", no_argument, 0, 'V' },
+    { "gain", no_argument, 0, 'g' },
+    { 0, 0, 0, 0 }
+};
+
+const char* optstr = "g:hV";
+
+
+
+int
+main(int argc, char* argv[])
+{
+    struct fir_filter_t* fi;
+    double gain = 0.5;
+    char* endp;
+
+    while(1) {
+        switch(getopt_long(argc, argv, optstr, options, 0)) {
+        case -1:
+            goto opts_done;
+
+        case '?':
+            return 1;
+
+        case 'h':
+            usage();
+            return 0;
+
+        case 'V':
+            fputs(APP_NAME " " VERSION "\n", stdout);
+            return 0;
+
+        case 'g':
+            errno = 0;
+            gain = strtod(optarg, &endp);
+            if(errno || !endp || *endp || gain <= 0) {
+                fputs(APP_NAME ": invalid gain. Expecting magnitude > 0.\n",
+                    stderr);
+                return 1;
+            }
+            break;
+        }
+    }
+  opts_done:
+    if(optind != (argc - 1)) {
+        usage();
+        return 1;
+    }
+
+    fi = load_filter(argv[optind]);
+    fir3db(fi, gain);
+
+    return 0;
+}
+
+
+
+/* options for text editors
+vim: expandtab:ts=4:sw=4
+*/
diff --git a/src/fir3db/build.app b/src/fir3db/build.app
index 12c1bd8..eb46bfc 100644
--- a/src/fir3db/build.app
+++ b/src/fir3db/build.app
@@ -6,7 +6,8 @@
 if [ -z ${fir3db_BUILT} ]
 then
     fir3db="obj/fir3db"
-    EXTRAS="-std=gnu99 -D_GNU_SOURCE -DAPP_NAME=\"fir3db\"" # TODO: more flags
+    EXTRAS="-std=gnu99 -D_GNU_SOURCE -DAPP_NAME=\"fir3db\" -lm \
+        ${LIBFIR_CFLAGS} ${LIBFIR_LIBS}"
 
     echo "Building application ${fir3db}..."