computing a 8 bit checksum in c++ -

-

i have following setup trying write custom file header. have fields described follows:

// assume these variables initialized. unsigned short x, y, z; unsigned int dl; unsigned int offset; // end assume  u_int8_t major_version = 0x31; u_int8_t minor_version = 0x30;  u_int_32_t data_offset = (u_int_32_t)offset;  u_int16_t size_x = (u_int16_t)x; u_int16_t size_y = (u_int16_t)y; u_int16_t size_z = (u_int16_t)z;  u_int_32_t data_size = (u_int_32_t)dl;

now, compute 8 bit header checksum fields starting major revision data_size variables. new , simple suffice current needs.

i'm not sure trying achieve, strictly answer question, 8-bit checksum computed as

sum_of_all_elements %255

simply put, add elements together, , sum % 255 checksum.
watch out overflows when doing addition (you can compute partial sums if run trouble).

on side note, 8-bit checksum not - won't distinguish cases , won't data recovery; that's why 16-bit checksum preferred.


Comments

Post a Comment

Popular posts from this blog

java - Plugin org.apache.maven.plugins:maven-install-plugin:2.4 or one of its dependencies could not be resolved -

-
i getting error message , further 1 here: failed read artifact descriptor org.apache.maven.plugins:maven-install-plugin:jar:2.4: even though when go .m2 repository path c:\users\a591024.m2\repository\org\apache\maven\plugins\maven-resources-plugin\2.4 the maven-resources-plugin-2.4.jar file there , maven-resources-plugin-2.4.pom there. have tried delete .m2 repository no luck. far maven not build project desperately need to. any ideas? it seems proxy issue please aad following in setting.xml grabbing lan setting , proxy information. <proxies> <proxy> <id>proxy</id> <active>true</active> <protocol>http</protocol> <host>hostname</host> <port>port</port> </proxy> </proxies> this frequent issue, please see below link well. plugin org.apache.maven.plugins:maven-clean-plugin:2.5 or 1 of dependencies not resolved maven: failed ret...
Read more

Round ImageView Android -

-
Image
i working on android application in doing rounded image view. working fine images, images 160x120 resolution shows oval shaped. code custom imageview given below, please me out here: public class roundimage extends drawable { private final bitmap mbitmap; private final paint mpaint; private final rectf mrectf; private final int mbitmapwidth; private final int mbitmapheight; public roundimage(bitmap bitmap) { mbitmap = bitmap; mrectf = new rectf(); mpaint = new paint(); mpaint.setantialias(true); mpaint.setdither(true); final bitmapshader shader = new bitmapshader(bitmap, shader.tilemode.clamp, shader.tilemode.clamp); mpaint.setshader(shader); mbitmapwidth = mbitmap.getwidth(); mbitmapheight = mbitmap.getheight(); } @override public void draw(canvas canvas) { canvas.drawoval(mrectf, mpaint); } @override protected void onboundschange(rect bound...
Read more

How can I utilize Yahoo Weather API in android -

-
Image
i want develop app using yahoo weather api android. want current , forecast weather details. i have tried different sources (e.g.: https://github.com/survivingwithandroid/weatherlib , getting error weatherlib api android , unable execute activity in android weatherlib ) , getting different errors m unable resplve. there can proper tutorial or guide! error: -17 08:50:48.961 3168-3168/com.survivingwithandroid.weather e/androidruntime﹕ fatal exception: main process: com.survivingwithandroid.weather, pid: 3168 java.lang.runtimeexception: unable start activity componentinfo{com.survivingwithandroid.weather/com.survivingwithandroid.weather.mainactivity}: java.lang.nullpointerexception: attempt invoke interface method 'boolean java.util.list.isempty()' on null object reference @ android.app.activitythread.performlaunchactivity(activitythread.java:2298) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2360) @ android.app.activi...
Read more