From 75456894774ea27d1e17d28c98a9a68584cde933 Mon Sep 17 00:00:00 2001
From: Connor Olding <cloningdonor@gmail.com>
Date: Tue, 11 Feb 2014 03:00:41 -0800
Subject: [PATCH] tube: fix oversampling

the original cascade was missing a first-order filter entirely!
N is incremented so the cascade is only second-order filters
which allows minimal changes to the code.

additionally the output sample is from the last
zero-padding for a slightly better phase response.
---
 README.md   |  3 +--
 crap/tube.h | 33 +++++++++++++++++----------------
 2 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/README.md b/README.md
index a1b0559..09868ba 100644
--- a/README.md
+++ b/README.md
@@ -37,8 +37,6 @@ white noise generator. loud, full-range, 0dBFS. don't say i didn't warn you.
 __crap\_tube (0x50F7BA11)__
 
 static waveshaper with 4x oversampling, sounds kinda like a tube i guess?
-be aware that its oversampling currently boosts top-most frequencies by
-~2dB before attenuating.
 
 ### crap delay test
 
@@ -60,6 +58,7 @@ other targets:
 
 ## TODO
 
+* spaces-in-paths support in Makefile
 * rename plugins (fix capitalization consistency and such)
 * reduce input/output buffers on biquads (shared)
 * ease up on the preprocessor ifs
diff --git a/crap/tube.h b/crap/tube.h
index 7005911..741878e 100644
--- a/crap/tube.h
+++ b/crap/tube.h
@@ -11,7 +11,7 @@
 #define COPYRIGHT "MIT"
 #define PARAMETERS 2
 
-#define HIST_SIZE_2 (2 + 2*10)
+#define HIST_SIZE_2 (2 + 2*11)
 #define HIST_SIZE   (HIST_SIZE_2*2)
 
 typedef struct {
@@ -67,21 +67,22 @@ static double
 oversample(double h[HIST_SIZE_2], double x)
 {
 	/* designed with <https://coewww.rutgers.edu/~orfanidi/hpeq/>
-	fs = 44100; OS = 4; Gs = -120; f2 = 18248/fs/OS; f2s = 22050/fs/OS;
-	N = hpeqord(-Inf,0,Gs,-6,2*pi*f2s,2*pi*f2,2) % 20.9971490662433
+	fs = 44100; OS = 4; Gs = -120; f2 = 18544/fs/OS; f2s = 22050/fs/OS;
+	N = hpeqord(-Inf,0,Gs,-6,2*pi*f2s,2*pi*f2,2) % 21.9986847697467
 	*/
 	double y;
-	LOWPASS(0, +0.65855672,-0.92949215,-1.56012668,+0.94774797);
-	LOWPASS(1, +0.61716958,-0.85685555,-1.47099672,+0.84848033);
-	LOWPASS(2, +0.56959704,-0.76263107,-1.37527450,+0.75183750);
-	LOWPASS(3, +0.51503506,-0.64652564,-1.27052746,+0.65407194);
-	LOWPASS(4, +0.45328074,-0.50918096,-1.15569311,+0.55307363);
-	LOWPASS(5, +0.38524858,-0.35361043,-1.03185791,+0.44874463);
-	LOWPASS(6, +0.31367929,-0.18703461,-0.90341296,+0.34373693);
-	LOWPASS(7, +0.24382090,-0.02260789,-0.77918770,+0.24422161);
-	LOWPASS(8, +0.18353302,+0.12028336,-0.67260228,+0.15995168);
-	LOWPASS(9, +0.14205849,+0.21898074,-0.59952639,+0.10262410);
-	BQSHIFT(10);
+	LOWPASS( 0,+0.68211844,-0.96291784,-1.54972173,+0.95104078);
+	LOWPASS( 1,+0.64259794,-0.89367078,-1.46615406,+0.85767914);
+	LOWPASS( 2,+0.59754712,-0.80432534,-1.37570293,+0.76647184);
+	LOWPASS( 3,+0.54606830,-0.69425498,-1.27603271,+0.67391434);
+	LOWPASS( 4,+0.48770451,-0.56343052,-1.16582052,+0.57779902);
+	LOWPASS( 5,+0.42283783,-0.41357065,-1.04538942,+0.47749444);
+	LOWPASS( 6,+0.35328311,-0.24971266,-0.91771844,+0.37457200);
+	LOWPASS( 7,+0.28296589,-0.08195448,-0.78962026,+0.27359756);
+	LOWPASS( 8,+0.21832227,+0.07351444,-0.67243388,+0.18259286);
+	LOWPASS( 9,+0.16778186,+0.19566401,-0.58109077,+0.11231849);
+	LOWPASS(10,+0.13979560,+0.26348229,-0.53059324,+0.07366673);
+	BQSHIFT(11);
 	return y;
 }
 
@@ -101,10 +102,10 @@ process_os(personal *data, double x, int right)
 	#define doit(SAMP) \
 	oversample(h1, process_one(4*oversample(h0, SAMP), \
 	    smooth(&data->drive), smooth(&data->wet)))
-	y = doit(x);
-	    doit(0);
+	    doit(x);
 	    doit(0);
 	    doit(0);
+	y = doit(0);
 	#undef doit
 
 	return y;