From 6264eb876d5a33b1be7f4bb42701bbc0774d3e94 Mon Sep 17 00:00:00 2001
From: DhiaZ <dhia.zerrari@outlook.com>
Date: Sat, 13 Aug 2022 00:40:34 +0100
Subject: [PATCH] Reimplemented LCD_DelayMS in T32 assembly

---
 .cproject                          | 11 ++++++++++-
 .settings/language.settings.xml    |  4 ++--
 LCD_LIBRARY/Includes/lcd_hd44780.h |  2 +-
 LCD_LIBRARY/Sources/lcd_hd44780.c  | 24 ++++++++++++++++++------
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/.cproject b/.cproject
index 5ca759f..a850dbd 100644
--- a/.cproject
+++ b/.cproject
@@ -57,6 +57,7 @@
 									<listOptionValue builtIn="false" value="&quot;${workspace_loc:/${ProjName}/USER}&quot;"/>
 									<listOptionValue builtIn="false" value="&quot;${workspace_loc:/${ProjName}/LCD_LIBRARY/Includes}&quot;"/>
 								</option>
+								<option id="ilg.gnuarmeclipse.managedbuild.cross.option.c.compiler.asmlisting.1172722941" name="Generate assembler listing (-Wa,-adhlns=&quot;$@.lst&quot;)" superClass="ilg.gnuarmeclipse.managedbuild.cross.option.c.compiler.asmlisting" useByScannerDiscovery="false" value="true" valueType="boolean"/>
 								<inputType id="ilg.gnuarmeclipse.managedbuild.cross.tool.c.compiler.input.520716099" superClass="ilg.gnuarmeclipse.managedbuild.cross.tool.c.compiler.input"/>
 							</tool>
 							<tool id="ilg.gnuarmeclipse.managedbuild.cross.tool.cpp.compiler.1550483362" name="Cross ARM C++ Compiler" superClass="ilg.gnuarmeclipse.managedbuild.cross.tool.cpp.compiler"/>
@@ -209,6 +210,14 @@
 		</scannerConfigBuildInfo>
 	</storageModule>
 	<storageModule moduleId="org.eclipse.cdt.core.LanguageSettingsProviders"/>
-	<storageModule moduleId="refreshScope"/>
+	<storageModule moduleId="refreshScope" versionNumber="2">
+		<configuration configurationName="Debug">
+			<resource resourceType="PROJECT" workspacePath="/nano_4k_1602_lcd"/>
+		</configuration>
+		<configuration configurationName="Release">
+			<resource resourceType="PROJECT" workspacePath="/nano_4k_1602_lcd"/>
+		</configuration>
+	</storageModule>
 	<storageModule moduleId="org.eclipse.cdt.make.core.buildtargets"/>
+	<storageModule moduleId="org.eclipse.cdt.internal.ui.text.commentOwnerProjectMappings"/>
 </cproject>
diff --git a/.settings/language.settings.xml b/.settings/language.settings.xml
index 4a66895..93b17ca 100644
--- a/.settings/language.settings.xml
+++ b/.settings/language.settings.xml
@@ -5,7 +5,7 @@
 			<provider copy-of="extension" id="org.eclipse.cdt.ui.UserLanguageSettingsProvider"/>
 			<provider-reference id="org.eclipse.cdt.core.ReferencedProjectsLanguageSettingsProvider" ref="shared-provider"/>
 			<provider-reference id="org.eclipse.cdt.managedbuilder.core.MBSLanguageSettingsProvider" ref="shared-provider"/>
-			<provider class="org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector" console="false" env-hash="380660608850552377" id="ilg.gnuarmeclipse.managedbuild.cross.GCCBuiltinSpecsDetector" keep-relative-paths="false" name="CDT ARM Cross GCC Built-in Compiler Settings " parameter="${COMMAND} ${FLAGS} ${cross_toolchain_flags} -E -P -v -dD &quot;${INPUTS}&quot;" prefer-non-shared="true">
+			<provider class="org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector" console="false" env-hash="-553365652118462094" id="ilg.gnuarmeclipse.managedbuild.cross.GCCBuiltinSpecsDetector" keep-relative-paths="false" name="CDT ARM Cross GCC Built-in Compiler Settings " parameter="${COMMAND} ${FLAGS} ${cross_toolchain_flags} -E -P -v -dD &quot;${INPUTS}&quot;" prefer-non-shared="true">
 				<language-scope id="org.eclipse.cdt.core.gcc"/>
 				<language-scope id="org.eclipse.cdt.core.g++"/>
 			</provider>
@@ -16,7 +16,7 @@
 			<provider copy-of="extension" id="org.eclipse.cdt.ui.UserLanguageSettingsProvider"/>
 			<provider-reference id="org.eclipse.cdt.core.ReferencedProjectsLanguageSettingsProvider" ref="shared-provider"/>
 			<provider-reference id="org.eclipse.cdt.managedbuilder.core.MBSLanguageSettingsProvider" ref="shared-provider"/>
-			<provider class="org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector" console="false" env-hash="357097478580585823" id="ilg.gnuarmeclipse.managedbuild.cross.GCCBuiltinSpecsDetector" keep-relative-paths="false" name="CDT ARM Cross GCC Built-in Compiler Settings " parameter="${COMMAND} ${FLAGS} ${cross_toolchain_flags} -E -P -v -dD &quot;${INPUTS}&quot;" prefer-non-shared="true">
+			<provider class="org.eclipse.cdt.managedbuilder.language.settings.providers.GCCBuiltinSpecsDetector" console="false" env-hash="-576928782388428648" id="ilg.gnuarmeclipse.managedbuild.cross.GCCBuiltinSpecsDetector" keep-relative-paths="false" name="CDT ARM Cross GCC Built-in Compiler Settings " parameter="${COMMAND} ${FLAGS} ${cross_toolchain_flags} -E -P -v -dD &quot;${INPUTS}&quot;" prefer-non-shared="true">
 				<language-scope id="org.eclipse.cdt.core.gcc"/>
 				<language-scope id="org.eclipse.cdt.core.g++"/>
 			</provider>
diff --git a/LCD_LIBRARY/Includes/lcd_hd44780.h b/LCD_LIBRARY/Includes/lcd_hd44780.h
index feb3ce6..efa8a46 100644
--- a/LCD_LIBRARY/Includes/lcd_hd44780.h
+++ b/LCD_LIBRARY/Includes/lcd_hd44780.h
@@ -52,7 +52,7 @@ void LCD_WriteChar(char c);
 void LCD_WriteString(char *string);
 void LCD_WriteByteToNibbleBus(int byte);
 void LCD_GPIOInit();
-void LCD_DelayMS(__IO uint32_t delay_ms);
+void LCD_DelayMS(volatile uint32_t delay_ms);
 
 
 #endif /* __LCD_HD44780_H_ */
diff --git a/LCD_LIBRARY/Sources/lcd_hd44780.c b/LCD_LIBRARY/Sources/lcd_hd44780.c
index 4dd3513..770d0ca 100644
--- a/LCD_LIBRARY/Sources/lcd_hd44780.c
+++ b/LCD_LIBRARY/Sources/lcd_hd44780.c
@@ -9,6 +9,12 @@
 #include "gw1ns4c.h"
 #include "lcd_hd44780.h"
 #include "gpio_wrapper.h"
+/*----------------------------------------------------------------------------*/
+
+/* Definitions*/
+#define SYSCLK_MILLIS_RATIO (SystemCoreClock / 1000) //CPU cycles per millisecond
+#define DELAY_RATIO (SYSCLK_MILLIS_RATIO / 16) //asm delay loop takes about 16 clock cycles on average
+/*----------------------------------------------------------------------------*/
 
 /**
  * Performs the LCD function set
@@ -245,11 +251,17 @@ void LCD_WriteByteToNibbleBus(int byte)	{
 }
 
 /**
- * Waste CPU cycles for delay, weird name to avoid possible mixups
- * */
-void LCD_DelayMS(__IO uint32_t delay_ms) {
-	for (delay_ms = (SystemCoreClock >> 13) * delay_ms; delay_ms != 0;
-			delay_ms--)
-		;
+ * Waste CPU cycles for delay, it is NOT precise nor accurate so you should consider using hardware timers for precision
+ * Prefixed name to avoid possible conflicts
+ **/
+void LCD_DelayMS(volatile uint32_t milliseconds) {
+	//delay ratio = CPU cycles per millisecond / cycles needed to complete one asm loop (approx 16??)
+	uint32_t delayCycles = (milliseconds * DELAY_RATIO);
+
+	asm volatile (
+		"lcd_delay_loop_%=: subs %[delayReg], %[delayReg], #1\n\t" //sub does not modify flags, need subs
+		"bne lcd_delay_loop_%=\n\t"
+		: [delayReg] "+l"(delayCycles)
+	);
 }