From 0591a01c5a02b46c56c31b4314b3dc41ecca266a Mon Sep 17 00:00:00 2001
From: fatcookies <michael_jackson@live.co.uk>
Date: Thu, 16 Jan 2020 21:58:02 +0000
Subject: [PATCH] Reduced stack usage in showBootLogoIfavailable(). Introduced
 new function OLED::drawAreaSwapped() for drawing images where the octets are
 reveresed endianess in 16-bit words.

---
 workspace/TS100/Core/Inc/OLED.hpp |  2 ++
 workspace/TS100/Core/Src/OLED.cpp | 38 +++++++++++++++++++++++++++++++
 workspace/TS100/Core/Src/main.cpp | 34 ++++++++++-----------------
 3 files changed, 52 insertions(+), 22 deletions(-)

diff --git a/workspace/TS100/Core/Inc/OLED.hpp b/workspace/TS100/Core/Inc/OLED.hpp
index 2ceacb21..381fd9f0 100644
--- a/workspace/TS100/Core/Inc/OLED.hpp
+++ b/workspace/TS100/Core/Inc/OLED.hpp
@@ -92,6 +92,8 @@ public:
 	static void drawSymbol(uint8_t symbolID);//Used for drawing symbols of a predictable width
 	static void drawArea(int16_t x, int8_t y, uint8_t wide, uint8_t height,
 			const uint8_t* ptr); //Draw an area, but y must be aligned on 0/8 offset
+	static void drawAreaSwapped(int16_t x, int8_t y, uint8_t wide, uint8_t height,
+			const uint8_t* ptr); //Draw an area, but y must be aligned on 0/8 offset
 	static void fillArea(int16_t x, int8_t y, uint8_t wide, uint8_t height,
 			const uint8_t value); //Fill an area, but y must be aligned on 0/8 offset
 	static void drawFilledRect(uint8_t x0, uint8_t y0, uint8_t x1, uint8_t y1,
diff --git a/workspace/TS100/Core/Src/OLED.cpp b/workspace/TS100/Core/Src/OLED.cpp
index 7506dd50..ebcd880a 100644
--- a/workspace/TS100/Core/Src/OLED.cpp
+++ b/workspace/TS100/Core/Src/OLED.cpp
@@ -262,6 +262,44 @@ void OLED::drawArea(int16_t x, int8_t y, uint8_t wide, uint8_t height,
 		}
 	}
 }
+
+// Draw an area, but y must be aligned on 0/8 offset
+// For data which has octets swapped in a 16-bit word.
+void OLED::drawAreaSwapped(int16_t x, int8_t y, uint8_t wide, uint8_t height,
+		const uint8_t *ptr) {
+	// Splat this from x->x+wide in two strides
+	if (x <= -wide)
+		return;  // cutoffleft
+	if (x > 96)
+		return;      // cutoff right
+
+	uint8_t visibleStart = 0;
+	uint8_t visibleEnd = wide;
+
+	// trimming to draw partials
+	if (x < 0) {
+		visibleStart -= x;  // subtract negative value == add absolute value
+	}
+	if (x + wide > 96) {
+		visibleEnd = 96 - x;
+	}
+
+	if (y == 0) {
+		// Splat first line of data
+		for (uint8_t xx = visibleStart; xx < visibleEnd; xx+=2) {
+			firstStripPtr[xx + x] = ptr[xx + 1];
+			firstStripPtr[xx + x + 1] = ptr[xx];
+		}
+	}
+	if (y == 8 || height == 16) {
+		// Splat the second line
+		for (uint8_t xx = visibleStart; xx < visibleEnd; xx+=2) {
+			secondStripPtr[x + xx] = ptr[xx + 1 + (height == 16 ? wide : 0)];
+			secondStripPtr[x + xx + 1] = ptr[xx + (height == 16 ? wide : 0)];
+		}
+	}
+}
+
 void OLED::fillArea(int16_t x, int8_t y, uint8_t wide, uint8_t height,
 		const uint8_t value) {
 	// Splat this from x->x+wide in two strides
diff --git a/workspace/TS100/Core/Src/main.cpp b/workspace/TS100/Core/Src/main.cpp
index 9bbbfec8..e59cd503 100644
--- a/workspace/TS100/Core/Src/main.cpp
+++ b/workspace/TS100/Core/Src/main.cpp
@@ -283,31 +283,21 @@ void startMOVTask(void const *argument __unused) {
 #define FLASH_LOGOADDR \
   (0x8000000 | 0xF800) /*second last page of flash set aside for logo image*/
 
+/* The header value is (0xAA,0x55,0xF0,0x0D) but is stored in little endian 16
+ * bits words on the flash */
+const uint8_t LOGO_HEADER_VALUE[] = {0x55, 0xAA, 0x0D, 0xF0};
+
 bool showBootLogoIfavailable() {
-	// check if the header is there (0xAA,0x55,0xF0,0x0D)
-	// If so display logo
-	// TODO REDUCE STACK ON THIS ONE, USE DRAWING IN THE READ LOOP
-	uint16_t temp[98];
+    uint8_t *header = (uint8_t*) (FLASH_LOGOADDR);
 
-	for (uint8_t i = 0; i < (98); i++) {
-		temp[i] = *(uint16_t*) (FLASH_LOGOADDR + (i * 2));
-	}
-	uint8_t temp8[98 * 2];
-	for (uint8_t i = 0; i < 98; i++) {
-		temp8[i * 2] = temp[i] >> 8;
-		temp8[i * 2 + 1] = temp[i] & 0xFF;
-	}
+	// check if the header is correct. 
+    for(int i = 0; i < 4; i++) {
+        if(header[i] != LOGO_HEADER_VALUE[i]) {
+            return false;
+        }
+    }
 
-	if (temp8[0] != 0xAA)
-		return false;
-	if (temp8[1] != 0x55)
-		return false;
-	if (temp8[2] != 0xF0)
-		return false;
-	if (temp8[3] != 0x0D)
-		return false;
-
-	OLED::drawArea(0, 0, 96, 16, (uint8_t*) (temp8 + 4));
+	OLED::drawAreaSwapped(0, 0, 96, 16, (uint8_t*) (FLASH_LOGOADDR + 4));
 	OLED::refresh();
 	return true;
 }