Hi Dean,

If its always 50% then just divide by 2, which is efficiently implemented by
a right shift by one bit. CCS-C should optimise it to a rotate right
operation.

int Val, Result;

Result = Val / 2;

if the percentages change then you will need to change that to multiply by
100 then divide by the percentage. Note - be careful you don't over run the
integer. You need to do the multiply first.

In CCS-C the "int" type by default is 8 bits. This is always compiler
dependant, if you want to make sure of the size your using try using int8,
int16 and int32 as the types.

So if you had a 8 bit number and you wanted to get an arbitrary percentage,
you would need to promote it to a 16 bit number so you don't overflow it

int8 Val, Result;
int8 Percent;
int16 temp;

temp = (int16) Val * 100;
temp = temp / Percent;
Result = (int8)temp;

the type in brackets is a cast to that type of the following identifier.

hope that helps,
Ash.

---
Ashley Roll
Digital Nemesis Pty Ltd
www.digitalnemesis.com
Mobile: +61 (0)417 705 718




> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of MATTHEWS, DEAN (D.)
> Sent: Thursday, 21 February 2002 7:15 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]:working out percentages
>
>
> Hello,
>
> I am using a PIC16f877 and CCs compiler.  Is there a maths
> function that will enable me to calculate 50% of an integer
> variable in a register and store the answer in another
> variable, or would I calculate it myself.
>
> Also is an integer 8 bit or 16 bit long.  some books say it
> is 8bit and others 16 bit.
>
> Dean Matthews
> Reliability Engineering
> Ford Engine Plant Bridgend
> Waterton industrial estate
> cf31 3pj
> South Wales, U.K
> Tel No: 0044(1656)672597
> Fax No: 0044(1656)672558
> Email: dmatth14@ford.com
> Room 25/118
> ` Please consider your environmental responsibility before
> printing this e-mail
>
>
> -----Original Message-----
> From: M. Adam Davis [mailto:adampic@UBASICS.COM]
> Sent: 31 January 2002 14:53
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]:16F877 and LCD
>
>
> Since there seems to be a good bit of interest in this, I'll see about
> modifying one of my current projects to portB instead of A.
>
> The code for the 'f877 with the LCD EN and RS on PORTA, and the data
> lines on PORTC is here:
> http://ubasics.com/adam/pic/node.c
>
> I don't know when I'll have time to modify it, but you can load it up.
>
> The first thing it does is sends "Micro Basics HAT" to the
> top line of a
> 16x2 LCD display (should be the top line of any display) then
> goes on to
> perform its basic duties (which in this case is measuring pulse length
> on two pins for a 2-axis acceleraometer).  To get it to do anything
> after that you'll need to rip out all the 'while(accel...)'
> statements.
>  At that point it'll start displaying 3 hex numbers on the bottom line
> of a 2 line LCD.
>
> If you are only using one line on your LCD, make sure you're
> initializing it correctly.  Check out the numerous website
> and tutorials
> on initializing alphanumeric LCD displays.  My initialization sets up
> the display for two lines, and while it shouldn't matter it
> sometimes can.
>
> -Adam
>
>
> Michael Pettersson wrote:
>
> >Hello All!
> >
> >I'm new with PIC and the 16F877 and have started testing the
> CC5Xfree from
> >http://www.bknd.com
> >
> >I have a project that I would like to start with but I need
> a LCD for this.
> >My first attampts was not succesful and now I need some help.
> >
> >Could anyone help me with a LCD 4 bit parallell test
> software with the
> >cc5xfree software and against the 16F877 micro?
> >
> >Thanks!
> >
> >Michael
> >
> >--
> >http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body
> >
> >
> >
> >
> >
>
> --
> http://www.piclist.com hint: To leave the PICList
> mailto:piclist-unsubscribe-request@mitvma.mit.edu
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads
>
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads