Reducing PROGMEM and RAM Usage - Revision history

Filmote: /* Tips for Reducing RAM */

2024-08-14T12:03:51Z

Tips for Reducing RAM

← Older revision		Revision as of 12:03, 14 August 2024
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	}</pre>		}</pre>

	** That small modification will save us thousands of bytes!		* That small modification will save us thousands of bytes!
	* Use https://godbolt.org/z/8vhWqj8KE (pre-configured with correct settings) to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.		* Use https://godbolt.org/z/8vhWqj8KE (pre-configured with correct settings) to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.
	* Use <code>arduboy.boot();</code> and <code>arduboy.safeMode();</code> instead of <code>arduboy.begin();</code>. <code>arduboy.systemButtons();</code> and <code>arduboy.waitNoButtons();</code> can also be added for convenience (turning on and off sound at bootup). Note that this will get rid of the scrolling logo.		* Use <code>arduboy.boot();</code> and <code>arduboy.safeMode();</code> instead of <code>arduboy.begin();</code>. <code>arduboy.systemButtons();</code> and <code>arduboy.waitNoButtons();</code> can also be added for convenience (turning on and off sound at bootup). Note that this will get rid of the scrolling logo.
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	== Tips for Reducing RAM ==		== Tips for Reducing RAM ==

	* Put PROGMEM on arrays/data that will not change. Note you will have to use <code>pgm_read_byte(&array[index])</code> or some variant of it .
	* Declare variables <code>constexpr</code> if they do not change.		* Declare variables <code>constexpr</code> if they do not change.
	* Put string literals in PROGMEM by surrounding them with the <code>F("string literal here")</code> macro. Pharap's [https://github.com/Pharap/FlashStringHelperDemo FlashStringHelper] library is very helpful when dealing with strings in PROGMEM.		* Put string literals in PROGMEM by surrounding them with the <code>F("string literal here")</code> macro. Pharap's [https://github.com/Pharap/FlashStringHelperDemo FlashStringHelper] library is very helpful when dealing with strings in PROGMEM.
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	== Storing and Retrieving Static Numerical Data ==		== Storing and Retrieving Static Numerical Data ==



	Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is purely static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.		Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is purely static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.

Filmote: /* Storing and Retrieving Static Numerical Data */

2024-08-11T02:54:51Z

Storing and Retrieving Static Numerical Data

← Older revision		Revision as of 02:54, 11 August 2024
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	Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.
			Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is purely static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.

	A simple example is shown below:		A simple example is shown below:

Filmote: /* Storing and Retrieving Static Data */

2024-08-11T02:54:31Z

Storing and Retrieving Static Data

← Older revision		Revision as of 02:54, 11 August 2024
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	* Pack variables into bits as much as possible. For example, instead of using an array of 8 bools, use 1 byte with each bit representing a bool. Reading and writing bits can be done with <code>bitRead(number, bit)</code> and <code>bitWrite(number, bit, value)</code>.		* Pack variables into bits as much as possible. For example, instead of using an array of 8 bools, use 1 byte with each bit representing a bool. Reading and writing bits can be done with <code>bitRead(number, bit)</code> and <code>bitWrite(number, bit, value)</code>.

	== Storing and Retrieving Static Data ==		== Storing and Retrieving Static Numerical Data ==

Filmote: /* Storing and Retrieving Static Data */

2024-08-11T02:53:47Z

Storing and Retrieving Static Data

← Older revision		Revision as of 02:53, 11 August 2024
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	** In our example, there are a huge amount of float functions that are taking up a lot of space.		** In our example, there are a huge amount of float functions that are taking up a lot of space.
	** How can we fix this? In our source code, we can change x from a float to a uint8_t:		** How can we fix this? In our source code, we can change x from a float to a uint8_t:
	<pre>		<pre>#include <Arduboy2.h>
	#include <Arduboy2.h>

	Arduboy2 arduboy;		Arduboy2 arduboy;

	-- float x;		// float x; << try to avoid floats

	++ uint8_t x;		uint8_t x;

	void setup() {		void setup() {
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	arduboy.display();		arduboy.display();

	}		}</pre>
	</pre>

	** That small modification will save us thousands of bytes!		** That small modification will save us thousands of bytes!
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	A simple example is shown below:		A simple example is shown below:

	<pre>		<pre>const uint8_t numbers[] PROGMEM = { 1, 2, 3, 4, 5 };
	const uint8_t numbers[] PROGMEM = { 1, 2, 3, 4, 5 };

	uint8_t aNumber = 0;		uint8_t aNumber = 0;
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	Serial.println(aNumber);		Serial.println(aNumber);

	}		}</pre>
	</pre>

	~~The <code>pgm_read_byte()</code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html pgmspace] library.~~

	library. This library includes numerous functions for reading other data:		The <code>pgm_read_byte()</code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html pgmspace] library. This library includes numerous functions for reading other data:

	To read a <code>uint8_t</code> ~~use~~ <code>pgm_read_byte(address)</code>		* read a <code>uint8_t</code> using <code>pgm_read_byte(address)</code>
	To read a <code>uint16_t</code> ~~use~~ <code>pgm_read_word(address)</code>		* read a <code>uint16_t</code> using <code>pgm_read_word(address)</code>
	To read a <code>uint32_t</code> ~~use~~ <code>pgm_read_dword(address)</code>		* read a <code>uint32_t</code> using <code>pgm_read_dword(address)</code>
	To read a <code>float</code> ~~use~~ <code>pgm_read_float(address)</code>		* read a <code>float</code> using <code>pgm_read_float(address)</code>

	Data can be copied from PROGMEM into a structure in a single action, as shown below. This approach alleviates the need to copy each element of the room data (width, height and player position) individually.		Data can be copied from PROGMEM into a structure in a single action, as shown below. This approach alleviates the need to copy each element of the room data (width, height and player position) individually.

	<pre>		<pre>struct Room {
	struct Room {
	uint8_t roomWidth;		uint8_t roomWidth;
	uint8_t roomHeight;		uint8_t roomHeight;
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	void loadRoom(uint8_t index) {		void loadRoom(uint8_t index) {
	memcpy_P(&currentRoom, &rooms[index], sizeof(Room));		memcpy_P(&currentRoom, &rooms[index], sizeof(Room));
	}		}</pre>
	</pre>

Filmote: /* Storing and Retrieving Static Data */

2024-08-11T02:51:33Z

Storing and Retrieving Static Data

← Older revision		Revision as of 02:51, 11 August 2024
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	</pre>		</pre>

	The <code>pgm_read_byte()</code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html ~~here~~].		The <code>pgm_read_byte()</code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html pgmspace] library.

	library. This library includes numerous functions for reading other data:		library. This library includes numerous functions for reading other data:
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	Data can be copied from PROGMEM into a structure in a single action, as shown below. This approach alleviates the need to copy each element of the room data (width, height and player position) individually.		Data can be copied from PROGMEM into a structure in a single action, as shown below. This approach alleviates the need to copy each element of the room data (width, height and player position) individually.

			<pre>
	struct Room {		struct Room {

	uint8_t roomWidth;		uint8_t roomWidth;

	uint8_t roomHeight;		uint8_t roomHeight;

	uint8_t playerX;		uint8_t playerX;

	uint8_t playerY;		uint8_t playerY;

	};		};

	constexpr Room rooms[] PROGMEM {		constexpr Room rooms[] PROGMEM {

	16, 16, 3, 3, // Room 1		16, 16, 3, 3, // Room 1

	32, 32, 5, 6, // Room 2		32, 32, 5, 6, // Room 2

	...		...

	};		};

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	void loadRoom(uint8_t index) {		void loadRoom(uint8_t index) {

	memcpy_P(&currentRoom, &rooms[index], sizeof(Room));		memcpy_P(&currentRoom, &rooms[index], sizeof(Room));

	}		}
			</pre>

Filmote: /* Storing and Retrieving Static Data */

2024-08-11T02:50:27Z

Storing and Retrieving Static Data

← Older revision		Revision as of 02:50, 11 August 2024
Line 81:		Line 81:
	</pre>		</pre>

	The <code>pgm_read_byte()<code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html here].		The <code>pgm_read_byte()</code> function is provided by the [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html here].

	library. This library includes numerous functions for reading other data:		library. This library includes numerous functions for reading other data:

Filmote: /* Storing and Retrieving Static Data from PROGMEM */

2024-08-11T02:50:10Z

Storing and Retrieving Static Data from PROGMEM

← Older revision		Revision as of 02:50, 11 August 2024
Line 60:		Line 60:
	* Pack variables into bits as much as possible. For example, instead of using an array of 8 bools, use 1 byte with each bit representing a bool. Reading and writing bits can be done with <code>bitRead(number, bit)</code> and <code>bitWrite(number, bit, value)</code>.		* Pack variables into bits as much as possible. For example, instead of using an array of 8 bools, use 1 byte with each bit representing a bool. Reading and writing bits can be done with <code>bitRead(number, bit)</code> and <code>bitWrite(number, bit, value)</code>.

	== Storing and Retrieving Static Data ~~from PROGMEM~~ ==		== Storing and Retrieving Static Data ==


	Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.		Declaring an array of static data takes up both RAM and PROGMEM on the Arduboy as the data needs to be stored in the program and copied into RAM as the program starts. If the data is static, you can remove the need to store the data in RAM and minimise the PROGMEM usage by using the <code>PROGMEM</code> keyword on the array and the helper functions to retrieve the data.

Filmote at 02:49, 11 August 2024

2024-08-11T02:49:31Z

@@ Line 54: / Line 54: @@
 == Tips for Reducing RAM ==
-* Put PROGMEM on arrays/data that will not change. Note you will have to use <code>pgm_read_byte(&array[index])</code> or some variant of it (see documentation [https://www.nongnu.org/avr-libc/user-manual/group__avr__pgmspace.html here]).
+* Put PROGMEM on arrays/data that will not change. Note you will have to use <code>pgm_read_byte(&array[index])</code> or some variant of it .
 * Declare variables <code>constexpr</code> if they do not change.
 * Put string literals in PROGMEM by surrounding them with the <code>F("string literal here")</code> macro. Pharap's [https://github.com/Pharap/FlashStringHelperDemo FlashStringHelper] library is very helpful when dealing with strings in PROGMEM.
 * Use locals instead of globals when possible. Locals are stored on the stack and exist only in a scope, while globals are stored for the entire lifetime of the program.
 * Pack variables into bits as much as possible. For example, instead of using an array of 8 bools, use 1 byte with each bit representing a bool. Reading and writing bits can be done with <code>bitRead(number, bit)</code> and <code>bitWrite(number, bit, value)</code>.

Sublinear: Fix link to Compiler Explorer

2024-07-20T01:55:06Z

Fix link to Compiler Explorer

← Older revision		Revision as of 01:55, 20 July 2024
Line 41:		Line 41:

	** That small modification will save us thousands of bytes!		** That small modification will save us thousands of bytes!
	* Use [https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,selection:(endColumn:2,endLineNumber:7,positionColumn:2,positionLineNumber:7,selectionStartColumn:2,selectionStartLineNumber:7,startColumn:2,startLineNumber:7),source:'//+Type+your+code+here,+or+load+an+example.%0A%23include+%3Cstdint.h%3E%0A%0Auint8_t+div_thousand(uint32_t+x)+%7B%0A%0A++++return+x+/+1024%3B%0A%7D'),l:'5',n:'1',o:'C%2B%2B+source+%231',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:avrg1410,filters:(b:'0',binary:'1',binaryObject:'1',commentOnly:'0',debugCalls:'1',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1',verboseDemangling:'0'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,libs:!(),options:'-O2+-mmcu%3Datmega32u4',overrides:!(),selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'+AVR+gcc+14.1.0+(Editor+%231)',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0')~~),l:'2',n:'0',o:'',t:'0')),version:4 Godbolt]~~ to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.		* Use https://godbolt.org/z/8vhWqj8KE (pre-configured with correct settings) to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.
	* Use <code>arduboy.boot();</code> and <code>arduboy.safeMode();</code> instead of <code>arduboy.begin();</code>. <code>arduboy.systemButtons();</code> and <code>arduboy.waitNoButtons();</code> can also be added for convenience (turning on and off sound at bootup). Note that this will get rid of the scrolling logo.		* Use <code>arduboy.boot();</code> and <code>arduboy.safeMode();</code> instead of <code>arduboy.begin();</code>. <code>arduboy.systemButtons();</code> and <code>arduboy.waitNoButtons();</code> can also be added for convenience (turning on and off sound at bootup). Note that this will get rid of the scrolling logo.
	* Use <code>Arduboy2Base</code> instead of <code>Arduboy2</code> if you don’t use text.		* Use <code>Arduboy2Base</code> instead of <code>Arduboy2</code> if you don’t use text.

Filmote: /* Tips for Reducing PROGMEM */

2024-07-14T05:25:01Z

Tips for Reducing PROGMEM

← Older revision		Revision as of 05:25, 14 July 2024
Line 23:		Line 23:

	arduboy.begin();		arduboy.begin();

	arduboy.setFrameRate(10);		arduboy.setFrameRate(10);

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	void loop() {		void loop() {

	if (!arduboy.nextFrame())		if (!arduboy.nextFrame()) return;

	return;

	arduboy.clear();		arduboy.clear();

	x++;		x++;

	arduboy.print(x / 10);		arduboy.print(x / 10);

	arduboy.display();		arduboy.display();

	}		}
	</pre>		</pre>

	** That small modification will save us thousands of bytes!		** That small modification will save us thousands of bytes!
	* Use [https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,selection:(endColumn:2,endLineNumber:7,positionColumn:2,positionLineNumber:7,selectionStartColumn:2,selectionStartLineNumber:7,startColumn:2,startLineNumber:7),source:'//+Type+your+code+here,+or+load+an+example.%0A%23include+%3Cstdint.h%3E%0A%0Auint8_t+div_thousand(uint32_t+x)+%7B%0A%0A++++return+x+/+1024%3B%0A%7D'),l:'5',n:'1',o:'C%2B%2B+source+%231',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:avrg1410,filters:(b:'0',binary:'1',binaryObject:'1',commentOnly:'0',debugCalls:'1',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1',verboseDemangling:'0'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,libs:!(),options:'-O2+-mmcu%3Datmega32u4',overrides:!(),selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'+AVR+gcc+14.1.0+(Editor+%231)',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4 Godbolt] to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.		* Use [https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,selection:(endColumn:2,endLineNumber:7,positionColumn:2,positionLineNumber:7,selectionStartColumn:2,selectionStartLineNumber:7,startColumn:2,startLineNumber:7),source:'//+Type+your+code+here,+or+load+an+example.%0A%23include+%3Cstdint.h%3E%0A%0Auint8_t+div_thousand(uint32_t+x)+%7B%0A%0A++++return+x+/+1024%3B%0A%7D'),l:'5',n:'1',o:'C%2B%2B+source+%231',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:avrg1410,filters:(b:'0',binary:'1',binaryObject:'1',commentOnly:'0',debugCalls:'1',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1',verboseDemangling:'0'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,libs:!(),options:'-O2+-mmcu%3Datmega32u4',overrides:!(),selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'+AVR+gcc+14.1.0+(Editor+%231)',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4 Godbolt] to see the assembly that the provided code will generate. You don't need to know assembly, the most important thing is if you see a function call to do an arithmetic operation, you may be able to avoid it. This is helpful to avoid division and mod, as discussed below.