Calculation Problem - value goes to zero after 65

[Darrel Taylor]

Ingvar,

OK, now we're getting silly, but I just can't resist.

Same thing as before, With Rounding, less code.

Dummy = Dec_speed * 9881
Dec_speed = R0 + R2.15 + Dec_speed

Saved 30 Words in the process.

OK, I'll quit now,
   Darrel

[Ingvar]

While were on the task of reducing and optimizing Toms code, i feel a strong urge to reduce .......

SSD4= (ssmax[18]>>4)
SSD3= (ssmax[18] & $f)
SSD2= (ssmax[17]>>4)
SSD1= (ssmax[17] & $f)

Then convert to Decimal:
Dec_speed=(ssd4*4096)+(ssd3*256)+(ssd2*16)+ssd1 ' convert to dec

..... into .....

Dec_speed.HighByte = ssmax[18]
Dec_speed.LowByte = ssmax[17]

...... thus saving time, codespace and ram ... you name it.

How about it Darrel, want a shot at it ;-)

[Darrel Taylor]

Good eye Ingvar,

I didn't even notice that he was Ripping them apart, just to re-assemble them back exactly like they were. That's a pretty big code savings.

And, here's my "Shot at it"

@Dec_Speed = _ssmax + 17
Dec_Speed   VAR  WORD  EXT

Zero Code.

Think we can reduce it even farther??

Darrel

[Dwayne]

Hello Darrell,,


Darrell>>Zero Code.

Think we can reduce it even farther?? <<


There goes the bankruptsy of Pkzip....

Dwayne

[Ingvar]

Ouch, i believe your "Shot at it" found it's target ..... sinking .... mayday. It's difficult to beat zero code, really difficult ...... sort of impossible.

However, i want to point out that if you change the value of "Dec_Speed" you infact change the values in the array(ssmax17&18). This makes it impossible to use for other tasks, not a problem in this application(i hope). I bet you know that but some people find it difficult to get their head around this.

Good job!

/Ingvar

[Darrel Taylor]

All true, I guess it's Bad Form to re-use variables like that.

So here it is. The End all, Be all solution to Tom's Knot to MPH conversion.

@Knots = _ssmax + 17
Knots    VAR  WORD  ext

Dec_speed = Knots * 9881
Dec_speed = R0 + R2.15 + Knots

That way it preserves the original Knots value and calculates Dec_speed from it.

Ok, now I really quit.

Darrel

[Heckler]

Darrel, Ingvar,

I hope you do not mind dusting off this OLD thread.

Quote by Ingvar... "I bet you know that but some people find it difficult to get their head around this."

Boy was he right... Very interesting but difficult to follow for a newbie.


I am also trying to convert knots and fractional knots to mph.h

Darrel could you please explain/elaborate on the code from your last post...

@Knots = _ssmax + 17
Knots VAR WORD ext

Dec_speed = Knots * 9881
Dec_speed = R0 + R2.15 + Knots

I thought that "@" usually proceeds "one line of assembly code"

As I read through this thread, I was not able to follow with much clarity.

In my gps program I end up with two variables containing integer knots and decimal knots.

If we assume the variables used are knots (whole knots) and knotsten (fractional knots) how would I apply your final code to provide mph.h?

Thanks much
Dwight