From f2ed7720feb3826128588acbc54357e5443d8d55 Mon Sep 17 00:00:00 2001
From: Connor Olding <cloningdonor@gmail.com>
Date: Mon, 17 Jun 2013 01:52:48 -0700
Subject: [PATCH] refactor, simple design program for calculating coeffs

---
 Makefile    | 26 +++++++++++++++++---------
 crap_eq.c   |  4 ++--
 crap_util.c | 21 ++++++++++++---------
 crap_util.h |  6 ++++--
 design.c    | 28 ++++++++++++++++++++++++++++
 5 files changed, 63 insertions(+), 22 deletions(-)
 create mode 100644 design.c

diff --git a/Makefile b/Makefile
index dc844a2..642373a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,15 +1,18 @@
 DISTNAME = crap
 VERSION = git
 
+EXE = design
 SHOBJ = crap_eq.so
 MID = crap_util.o
-OBJ = ${SHOBJ:.so=.o} ${MID}
-SRC = ${OBJ:.o=.c}
 HEADERS = crap_util.h ladspa.h
 
+OBJ = ${SHOBJ:.so=.o} ${EXE:=.o} ${MID}
+SRC = ${OBJ:.o=.c}
+
 PLACEBO_FLAGS = -fomit-frame-pointer -fstrength-reduce -funroll-loops -ffast-math
 ALL_CFLAGS = -O3 ${PLACEBO_FLAGS} -std=c99 -fPIC -Wall ${CFLAGS}
-ALL_LDFLAGS = -nostartfiles -shared ${LDFLAGS}
+ALL_LDFLAGS = -lm ${LDFLAGS}
+SHARED_LDFLAGS = -nostartfiles -shared
 
 PREFIX ?= /usr/local
 EXEC_PREFIX ?= ${PREFIX}
@@ -19,19 +22,24 @@ LADSPADIR ?= ${LIBDIR}/ladspa
 # should CFLAGS really be used in linking too? seems odd
 
 FULLNAME = ${DISTNAME}-${VERSION}
-ALL = ${OBJ} ${SHOBJ}
+ALL = ${OBJ} ${SHOBJ} ${EXE}
 LADSPADEST = ${DESTDIR}${LADSPADIR}
 
 all: options ${ALL}
 
 .PHONY: options
 options:
-	@echo "ALL_CFLAGS  = ${ALL_CFLAGS}"
-	@echo "CPPFLAGS    = ${CPPFLAGS}"
-	@echo "ALL_LDFLAGS = ${ALL_LDFLAGS}"
-	@echo "CC          = ${CC}"
+	@echo "ALL_CFLAGS     = ${ALL_CFLAGS}"
+	@echo "CPPFLAGS       = ${CPPFLAGS}"
+	@echo "ALL_LDFLAGS    = ${ALL_LDFLAGS}"
+	@echo "SHARED_LDFLAGS = ${SHARED_LDFLAGS}"
+	@echo "CC             = ${CC}"
 
-%.so: %.o
+%.so: %.o ${MID}
+	@echo LD $< ${MID} -o $@
+	@${CC} ${ALL_LDFLAGS} ${SHARED_LDFLAGS} $< ${MID} -o $@
+
+%: %.o ${MID}
 	@echo LD $< ${MID} -o $@
 	@${CC} ${ALL_LDFLAGS} $< ${MID} -o $@
 
diff --git a/crap_eq.c b/crap_eq.c
index c44bd9a..93e98d1 100644
--- a/crap_eq.c
+++ b/crap_eq.c
@@ -111,7 +111,7 @@ instantiate_eq(const LADSPA_Descriptor *descriptor, ulong s_rate) {
 		eq->old_chg[i] = g;
 		eq->old_chf[i] = f;
 		eq->old_chb[i] = b;
-		biquad_gen(&filters[i], 1, f, g, b, fs);
+		filters[i] = biquad_gen(1, f, g, b, fs);
 	}
 
 	return (LADSPA_Handle) eq;
@@ -138,7 +138,7 @@ run_eq_for_real(LADSPA_Handle instance, ulong sample_count, int running) {
 			eq->old_chg[i] = g;
 			eq->old_chf[i] = f;
 			eq->old_chb[i] = b;
-			biquad_gen(&filters[i], 1, f, g, b, fs);
+			filters[i] = biquad_gen(1, f, g, b, fs);
 		}
 	}
 
diff --git a/crap_util.c b/crap_util.c
index a5aeaa8..287e039 100644
--- a/crap_util.c
+++ b/crap_util.c
@@ -30,9 +30,9 @@ peaking(double cw, double Gf, double g) {
 biquad_interim
 highpass(double cw, double g) {
 	return (biquad_interim) {
-		.b0 = 1 + cw*0.5,
+		.b0 = (1 + cw)*0.5,
 		.b1 = -cw - 1,
-		.b2 = 1 + cw*0.5,
+		.b2 = (1 + cw)*0.5,
 		.a0 = 1 + g,
 		.a1 = -2*cw,
 		.a2 = 1 - g
@@ -92,8 +92,8 @@ orfanidi(double w0, double Gf, double g) {
 	};
 }
 
-void
-biquad_gen(biquad *bq, int type, double fc, double gain, double bw, double fs) {
+biquad
+biquad_gen(int type, double fc, double gain, double bw, double fs) {
 	/* TODO: use enum for type instead of just int */
 	double w0, cw, sw, Gf, Q, a_peak, a_pass;
 	w0 = ANGULAR_LIM(fc, fs);
@@ -111,11 +111,14 @@ biquad_gen(biquad *bq, int type, double fc, double gain, double bw, double fs) {
 	if (type == 2) bqi = highpass(cw, a_pass);
 
 	double a0r = 1/bqi.a0;
-	bq->b0 = a0r * bqi.b0;
-	bq->b1 = a0r * bqi.b1;
-	bq->b2 = a0r * bqi.b2;
-	bq->a1 = -a0r * bqi.a1;
-	bq->a2 = -a0r * bqi.a2;
+
+	return (biquad) {
+		.b0 = a0r * bqi.b0,
+		.b1 = a0r * bqi.b1,
+		.b2 = a0r * bqi.b2,
+		.a1 = -a0r * bqi.a1,
+		.a2 = -a0r * bqi.a2
+	};
 }
 
 bq_t
diff --git a/crap_util.h b/crap_util.h
index 12df2c2..fe13c2c 100644
--- a/crap_util.h
+++ b/crap_util.h
@@ -23,6 +23,8 @@
 
 /* http://musicdsp.org/showone.php?id=51 */
 /* http://musicdsp.org/files/denormal.pdf */
+/* this is pretty gross;
+ * it's too easy to define BIQUAD_DOUBLE in one file and not another */
 #ifdef BIQUAD_DOUBLE
 typedef double bq_t;
 #define IS_DENORMAL(f) (((*(uint64_t *)&f)&0x7FF0000000000000)==0)
@@ -51,8 +53,8 @@ highpass(double cw, double g);
 biquad_interim
 orfanidi(double w0, double Gf, double g);
 
-void
-biquad_gen(biquad *bq, int type, double fc, double gain, double bw, double fs);
+biquad
+biquad_gen(int type, double fc, double gain, double bw, double fs);
 
 bq_t
 biquad_run(biquad *bq, bq_t x);
diff --git a/design.c b/design.c
new file mode 100644
index 0000000..1e89cd4
--- /dev/null
+++ b/design.c
@@ -0,0 +1,28 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <math.h>
+#include <errno.h>
+
+#include "crap_util.h"
+
+void
+usage() {
+	fputs("usage: design SAMPLERATE TYPE CENTERFREQ GAIN BANDWIDTH\n", stderr);
+	exit(1);
+}
+
+int
+main(int argc, char **argv) {
+	if (argc != 6) usage();
+	double tv[5];
+	for (int i = 1; i <= 5; i++) {
+		tv[i - 1]=strtold(argv[i], NULL);
+		if (errno) {
+			fprintf(stderr, "arg #%i failed to convert to double\n", i);
+			exit(1);
+		}
+	}
+	biquad bq = biquad_gen((int) tv[1], tv[2], tv[3], tv[4], tv[0]);
+	printf("b0 %+.18f\nb1 %+.18f\nb2 %+.18f\na1 %+.18f\na2 %+.18f\n",bq.b0,bq.b1,bq.b2,bq.a1,bq.a2);
+	return 0;
+}