From: Toni Wilen <twilen@winuae.net>
Date: Wed, 7 Jun 2017 17:39:54 +0000 (+0300)
Subject: Sound filter + FPU side-effect quick workaround.
X-Git-Tag: 3500~14
X-Git-Url: https://git.unchartedbackwaters.co.uk/w/?a=commitdiff_plain;h=4636893baf8a56674dfd7206773f3911beb94c2b;p=francis%2Fwinuae.git

Sound filter + FPU side-effect quick workaround.
---

diff --git a/audio.cpp b/audio.cpp
index bcbbc015..2f3a8b8f 100644
--- a/audio.cpp
+++ b/audio.cpp
@@ -401,7 +401,7 @@ static int filter (int input, struct filter_state *fs)
 
 	case FILTER_MODEL_A500:
 		fs->rc1 = a500e_filter1_a0 * input + (1 - a500e_filter1_a0) * fs->rc1 + DENORMAL_OFFSET;
-		fs->rc2 = a500e_filter2_a0 * fs->rc1 + (1-a500e_filter2_a0) * fs->rc2;
+		fs->rc2 = a500e_filter2_a0 * fs->rc1 + (1 - a500e_filter2_a0) * fs->rc2;
 		normal_output = fs->rc2;
 
 		fs->rc3 = filter_a0 * normal_output + (1 - filter_a0) * fs->rc3;
@@ -1747,6 +1747,8 @@ static int sound_prefs_changed (void)
 	return 0;
 }
 
+double softfloat_tan(double v);
+
 /* This computes the 1st order low-pass filter term b0.
 * The a1 term is 1.0 - b0. The center frequency marks the -3 dB point. */
 #ifndef M_PI
@@ -1763,8 +1765,9 @@ static float rc_calculate_a0 (int sample_rate, int cutoff_freq)
 	/* Compensate for the bilinear transformation. This allows us to specify the
 	* stop frequency more exactly, but the filter becomes less steep further
 	* from stopband. */
-	omega = tan (omega / 2) * 2;
-	return 1 / (1 + 1 / omega);
+	omega = softfloat_tan (omega / 2.0) * 2.0;
+	float out = 1.0 / (1.0 + 1.0 / omega);
+	return out;
 }
 
 void check_prefs_changed_audio (void)
@@ -1881,6 +1884,7 @@ void set_audio (void)
 	a500e_filter1_a0 = rc_calculate_a0 (currprefs.sound_freq, 6200);
 	a500e_filter2_a0 = rc_calculate_a0 (currprefs.sound_freq, 20000);
 	filter_a0 = rc_calculate_a0 (currprefs.sound_freq, 7000);
+	memset (sound_filter_state, 0, sizeof sound_filter_state);
 	led_filter_audio ();
 
 	/* Select the right interpolation method.  */
diff --git a/fpp_native.cpp b/fpp_native.cpp
index 143b5b88..39f13f7a 100644
--- a/fpp_native.cpp
+++ b/fpp_native.cpp
@@ -1275,3 +1275,20 @@ void fp_init_native(void)
 	fpp_tst = fp_tst;
 	fpp_move = fp_move;
 }
+
+double softfloat_tan(double v)
+{
+	struct float_status f = { 0 };
+	uae_u32 w1, w2;
+	fpdata fpd = { 0 };
+
+	fpd.fp = v;
+	set_floatx80_rounding_precision(80, &f);
+	set_float_rounding_mode(float_round_to_zero, &f);
+	fp_from_double(&fpd, &w1, &w2);
+	floatx80 fv = float64_to_floatx80(((uae_u64)w1 << 32) | w2, &fs);
+	fv = floatx80_tan(fv, &fs);
+	float64 f64 = floatx80_to_float64(fv, &fs);
+	fp_to_double(&fpd, f64 >> 32, (uae_u32)f64);
+	return fpd.fp;
+}