From d5f20c45b9dc8e5fb85a19add41baa934cffe3e1 Mon Sep 17 00:00:00 2001
From: Brumi-2021 <ea3hqj@gmail.com>
Date: Tue, 2 May 2023 17:19:23 +0200
Subject: [PATCH] Adding 16 bit LFSR , to Noise Signal Generator App

---
 firmware/application/apps/ui_siggen.hpp | 36 +++++++++++++------------
 firmware/baseband/proc_siggen.cpp       | 15 +++++++++--
 firmware/baseband/proc_siggen.hpp       |  7 +++--
 3 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/firmware/application/apps/ui_siggen.hpp b/firmware/application/apps/ui_siggen.hpp
index 58ed49b88..bb5b76e03 100644
--- a/firmware/application/apps/ui_siggen.hpp
+++ b/firmware/application/apps/ui_siggen.hpp
@@ -48,29 +48,30 @@ private:
 	void update_tone();
 	void on_tx_progress(const uint32_t progress, const bool done);
 	
-	const std::string shape_strings[9] = {
-		"CW          ",
-		"Sine        ",
-		"Triangle    ",
-		"Saw up      ",
-		"Saw down    ",
-		"Square      ",
-		"Noise n20Khz",
-		"Noise n10khz",
-		"Noise n5khz "
+	const std::string shape_strings[10] = {
+		"CW-no mod",
+		"Sine     ",
+		"Triangle ",
+		"Saw up   ",
+		"Saw down ",
+		"Square        ",
+		"Noise 8-nx20Khz",	// using 8 bits LFSR register, 6 order polynomial feedback.
+		"Noise 8-nx10khz",	// using 8 bits LFSR register, 7 order polynomial feedback.
+		"Noise 8 -nx5khz ",	// using 8 bits LFSR register, 8 order polynomial feedback.
+		"Noise 16-nx1khz"	// using 16 bits LFSR register, 16 order polynomial feedback.
 	};
 	
 	bool auto_update { false };
 	
 	Labels labels {
-		{ { 6 * 8, 4 + 10 }, "Shape:", Color::light_grey() },
-		{ { 7 * 8, 7 * 8 }, "Tone:      Hz", Color::light_grey() },
+		{ { 3 * 8, 4 + 10 }, "Shape:", Color::light_grey() },
+		{ { 6 * 8, 7 * 8 }, "Tone:      Hz", Color::light_grey() },
 		{ { 22 * 8, 15 * 8 + 4 }, "s.", Color::light_grey() },
 		{ { 8 * 8, 20 * 8 }, "Modulation: FM", Color::light_grey() }
 	};
 	
 	ImageOptionsField options_shape {
-		{ 13 * 8, 4, 32, 32 },
+		{ 10 * 8, 4, 32, 32 },
 		Color::white(),
 		Color::black(),
 		{
@@ -82,12 +83,13 @@ private:
 			{ &bitmap_sig_square, 5 },
 			{ &bitmap_sig_noise, 6 },
 			{ &bitmap_sig_noise, 7 },
-			{ &bitmap_sig_noise, 8 }
+			{ &bitmap_sig_noise, 8 },
+			{ &bitmap_sig_noise, 9 }
 		}
 	};
 	
 	Text text_shape {
-		{ 18 * 8, 4 + 10, 8 * 8, 16 },
+		{ 15 * 8, 4 + 10, 8 * 8, 16 },
 		""
 	};
 	
@@ -98,12 +100,12 @@ private:
 	};
 	
 	Button button_update {
-		{ 6 * 8, 10 * 8, 8 * 8, 3 * 8 },
+		{ 5 * 8, 10 * 8, 8 * 8, 3 * 8 },
 		"Update"
 	};
 	
 	Checkbox checkbox_auto {
-		{ 16 * 8, 10 * 8 },
+		{ 15 * 8, 10 * 8 },
 		4,
 		"Auto"
 	};
diff --git a/firmware/baseband/proc_siggen.cpp b/firmware/baseband/proc_siggen.cpp
index 2fdc55456..714f51202 100644
--- a/firmware/baseband/proc_siggen.cpp
+++ b/firmware/baseband/proc_siggen.cpp
@@ -75,6 +75,17 @@ void SigGenProcessor::execute(const buffer_c8_t& buffer) {
 				bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 4))  & 1;	
         		lfsr = (lfsr >> 1) | (bit << 7);
            		sample = lfsr;
+			} else if (tone_shape == 9) { // 16 bits LFSR .taps: 16, 15, 13, 4 ;feedback polynomial: x^16 + x^15 + x^13 + x^4 + 1
+				// Periode 65535= 2^n-1, harmonics every < 1Khz  , quite continuous .  
+				if (counter == 0) {
+					bit_16 = ((lfsr_16 >> 0) ^ (lfsr_16 >> 1) ^ (lfsr_16 >> 3) ^ (lfsr_16 >> 4) ^ (lfsr_16 >> 12) & 1);
+        			lfsr_16 = (lfsr_16 >> 1) | (bit_16 << 15);
+					sample = (lfsr_16 & 0x00FF);
+					counter++;
+				} else {		// counter == 1 , no need to shift the register again, just use the top 8 bits.
+					// sample = ((lfsr_16 & 0XFF00) >> 8);   // it becomes less continuous the spectrum. Better skip it .
+					counter = 0;	
+				}
 			} 
 
 			if (tone_shape < 6) 	{
@@ -114,8 +125,8 @@ void SigGenProcessor::on_message(const Message* const msg) {
 			fm_delta = message.bw * (0xFFFFFFULL / 1536000);
 			tone_shape = message.shape;
 			
-			// lfsr = 0x54DF0119;
-			 lfsr = seed_value ;  
+			 lfsr = seed_value ;  		// init lfsr 8 bits.
+			 lfsr_16 = seed_value_16;	// init lfsr 16 bits.
 
 			configured = true;
 			break;
diff --git a/firmware/baseband/proc_siggen.hpp b/firmware/baseband/proc_siggen.hpp
index c4adcd8ba..84c6b896c 100644
--- a/firmware/baseband/proc_siggen.hpp
+++ b/firmware/baseband/proc_siggen.hpp
@@ -44,9 +44,12 @@ private:
     bool auto_off { };
 	int32_t phase { 0 }, sphase { 0 }, delta { 0 }; 	// they may have sign .
 	int8_t  sample { 0 }, re { 0 }, im { 0 };			// they may have sign .
-    uint8_t seed_value = {0x56};   						// seed : any nonzero start state will work. 
+    uint8_t seed_value = {0x56};   						// seed 8 bits lfsr  : any nonzero start state will work. 
+	uint16_t seed_value_16 = {0xACE1};					// seed 16 bits lfsr : any nonzero start state will work. 
 	uint8_t lfsr { }, bit { };  						// bit must be 8-bit to allow bit<<7 later in the code */
-	
+	uint16_t lfsr_16 { }, bit_16 { }; 					// bit must be 8-bit to allow bit<<7 later in the code */
+	uint8_t counter {0};
+
 	TXProgressMessage txprogress_message { };
 };