http://forums.leaflabs.com/topic.php?id=10136 A place to share, learn, and grow... en-US Fri, 22 Jan 2016 00:14:04 +0000 http://bbpress.org/?v=1.0.2 q http://forums.leaflabs.com/search.php http://forums.leaflabs.com/topic.php?id=10136#post-22065 Mon, 21 Jan 2013 14:06:58 +0000 pyrohaz 22065@http://forums.leaflabs.com/ <p>Thats really useful actually, all of my arrays are 64 pieces of data but by using size of, that eases things by a lot! Thanks for that :) </p> http://forums.leaflabs.com/topic.php?id=10136#post-22062 Mon, 21 Jan 2013 10:16:35 +0000 gbulmer 22062@http://forums.leaflabs.com/ <p>pyrohaz - I'd like to suggest a slightly more robust approach to copying memory.</p> <p>Instead of <code>memcpy(array1, array2, 128);</code><br /> do <code>memcpy(array1, array2, sizeof(array1));</code></p> <p><code>sizeof</code> is applied to the destination of the <code>memcpy</code>.</p> <p>Arduino (AVR, ATmega) and Maple (ARM, STM32) have different sizes for data types, for example <code>int</code>, so using a fixed value might not work when porting code. The compiler calculates <code>sizeof()</code> at compile time, and ensures the value is the actual size of the variable, which is more robust when porting code. <code>sizeof()</code> can be used in calculations, e.g. <code>sizeof(array1)-1</code></p> <p>NB, for folks who aren't familiar with sizeof; sizeof calculates the size of the value stored in the variable, sizeof does not calculate the size of object a variable may point at:<br /> <pre><code>char array1[130]; char *p = array1; char array2[130]; memcpy(p, array2, sizeof(p));</code></pre> <p>will only copy the size of a char pointer (4 bytes on STM32), and not the size of the array p is pointing to.<br /> <code>memcpy(p, array2, sizeof(*p));</code><br /> copies 1 byte. </p> http://forums.leaflabs.com/topic.php?id=10136#post-22061 Mon, 21 Jan 2013 09:25:36 +0000 pyrohaz 22061@http://forums.leaflabs.com/ <p>Heh! Brilliant, thats sorted it, I never needed to do that on arduino haha thanks a lot dude! :) </p> http://forums.leaflabs.com/topic.php?id=10136#post-22060 Mon, 21 Jan 2013 09:03:41 +0000 bubulindo 22060@http://forums.leaflabs.com/ <p>did you include string.h? </p> <p>This compiles for me: </p> <p>#include &lt;string.h&gt; &lt;------ THIS?? </p> <p>void setup(){}</p> <p>void loop(){</p> <p>char array1[130];<br /> char array2[130];</p> <p>memcpy(array1, array2, 128);<br /> } </p> http://forums.leaflabs.com/topic.php?id=10136#post-22059 Mon, 21 Jan 2013 07:36:21 +0000 pyrohaz 22059@http://forums.leaflabs.com/ <p>Hey,<br /> As you can probably tell from my questions, i'm porting from arduino to maple. So far so good!</p> <p>The only question, on my arduino, I can use the command memcpy to copy a 64 piece array from one section to another, for example:<br /> memcpy(array1, array2, 128);</p> <p>The small snippet of code above will copy array2 to array1.</p> <p>When I tried to write this code to my maple, it said that memcpy was not declared in this scope, the arduino IDE allows me to use this piece of code.</p> <p>What am I doing wrong?</p> <p>Thanks,<br /> Harris </p>