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LCD12864

 
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georpo



Joined: 18 Nov 2008
Posts: 141
Location: Athens, Greece.

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LCD12864
PostPosted: Wed May 02, 2018 2:27 am     Reply with quote

Hello,

I am making my custom library to set/clear pixel on a 128*64 LCD with ST7920.

I got it working but I have this in my code:

Code:

   if       (px==0 || px==8  || px==16 || px==24 || px==32 || px==40 || px==48 || px==56 || px==64 || px==72 || px==80 || px==88 || px==96 || px==104 || px==112 || px==120) Pix=128;
   else if (px==1 || px==9  || px==17 || px==25 || px==33 || px==41 || px==49 || px==57 || px==65 || px==73 || px==81 || px==89 || px==97 || px==105 || px==113 || px==121) Pix=64;
   else if (px==2 || px==10 || px==18 || px==26 || px==34 || px==42 || px==50 || px==58 || px==66 || px==74 || px==82 || px==90 || px==98 || px==106 || px==114 || px==122) Pix=32;
   else if (px==3 || px==11 || px==19 || px==27 || px==35 || px==43 || px==51 || px==59 || px==67 || px==75 || px==73 || px==91 || px==99 || px==107 || px==115 || px==123) Pix=16;
   else if (px==4 || px==12 || px==20 || px==28 || px==36 || px==44 || px==52 || px==60 || px==68 || px==76 || px==84 || px==92 || px==100 || px==108 || px==116 || px==124) Pix=8;
   else if (px==5 || px==13 || px==21 || px==29 || px==37 || px==45 || px==53 || px==61 || px==69 || px==77 || px==85 || px==93 || px==101 || px==109 || px==117 || px==125) Pix=4;
   else if (px==6 || px==14 || px==22 || px==30 || px==38 || px==46 || px==54 || px==62 || px==70 || px==78 || px==86 || px==94 || px==102 || px==110 || px==118 || px==126) Pix=2;
   else if (px==7 || px==15 || px==23 || px==31 || px==39 || px==47 || px==55 || px==63 || px==71 || px==79 || px==87 || px==95 || px==103 || px==111 || px==119 || px==127) Pix=1;


Is there a better/more efficient way to do this?

Thanks!
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George.
Ttelmah



Joined: 11 Mar 2010
Posts: 13536

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PostPosted: Wed May 02, 2018 2:42 am     Reply with quote

Code:

   int8 temp;
   const pxval[]={128,64,32,16,8,4,2,1};

   temp=px%8;
   Pix=pxval[temp];


I think that should give the right values.
georpo



Joined: 18 Nov 2008
Posts: 141
Location: Athens, Greece.

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PostPosted: Wed May 02, 2018 3:18 am     Reply with quote

It works Shocked

I have no idea how but it works!

thanks a lot Ttelmah!

Just noticed that your trick saved me 14% of ROM Neutral
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George.


Last edited by georpo on Wed May 02, 2018 3:31 am; edited 1 time in total
georpo



Joined: 18 Nov 2008
Posts: 141
Location: Athens, Greece.

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PostPosted: Wed May 02, 2018 3:25 am     Reply with quote

BTW, in some other part of my "setpixel" code:

Code:

   if(px<8) X=0;                  //0-7            
   else if((px>7) && (px<16)) X=1;      //8-15
   else if((px>15) && (px<24)) X=2;   //16-23
   else if((px>23) && (px<32)) X=3;   //24-31
   else if((px>31) && (px<40)) X=4;   //32-39
   else if((px>39) && (px<48)) X=5;   //40-47
   else if((px>47) && (px<56)) X=6;   //48-55
   else if((px>55) && (px<64)) X=7;   //56-63   
   else if((px>63) && (px<72)) X=8;   //64-71
   else if((px>71) && (px<80)) X=9;   //72-79
   else if((px>79) && (px<88)) X=10;   //80-87
   else if((px>87) && (px<96)) X=11;   //88-95
   else if((px>95) && (px<104)) X=12;   //96-103
   else if((px>103) && (px<112)) X=13;   //104-111
   else if((px>111) && (px<120)) X=14;   //112-119
   else if((px>119) && (px<128)) X=15;   //120-127


The above decides in which X offset the pixel belongs to.
Is there any magic here? Rolling Eyes
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George.
temtronic



Joined: 01 Jul 2010
Posts: 6251
Location: Greensville,Ontario

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PostPosted: Wed May 02, 2018 4:55 am     Reply with quote

It's early for me but
this...
else if((px>7) && (px<16)) X=1; //8-15

could be simplified to
else if(px<16)) X=1; //8-15

providing the IFs are in the correct order
something like this...
if(px<8) X=0; //0-7
else if(px<16)) X=1; //8-15
else if(px<24)) X=2; //16-23
else if(px<32)) X=3; //24-31
...
should work fine
when I look at it is says
if px<8 x becomes 0 and leave else then if px<16 x become 2.....

The other option would be to use the 'SWITCH...' statement. Actually you should code both and see what compiles,dump the listing(programname.lst file) to see It may be the SWITCH method produces smaller,faster code which means less ROM space and faster execution.
georpo



Joined: 18 Nov 2008
Posts: 141
Location: Athens, Greece.

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PostPosted: Wed May 02, 2018 5:15 am     Reply with quote

I get the point.

Thanks a million!
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George.
temtronic



Joined: 01 Jul 2010
Posts: 6251
Location: Greensville,Ontario

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PostPosted: Wed May 02, 2018 5:37 am     Reply with quote

great cause I'm still sleepy over here in canada......
always amazes me the WORLDWIDE appeal of PICs !
ohpa
Ttelmah



Joined: 11 Mar 2010
Posts: 13536

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PostPosted: Wed May 02, 2018 7:03 am     Reply with quote

georpo wrote:
It works Shocked

I have no idea how but it works!

thanks a lot Ttelmah!

Just noticed that your trick saved me 14% of ROM Neutral


OK lets go through it....

Code:


   int8 temp;
   const pxval[]={128,64,32,16,8,4,2,1};

   temp=px%8;
//Now this gives the remainder from dividing by 8. so just 1 to 7
//'1' for the first line of your tests, '2' for the next, etc. etc..

   Pix=pxval[temp];
//This gives '128' for '1', '64' for '2' etc..

Smile
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