Gosub to a variable ?
Don Moore
Posts: 4
I'm very new to programming in for the BS2 and have run into a problem. I'm trying to use the GOSUB command but instead of an "address label" I'm trying to get it to read the value of a variable as the address label, and I'm getting an error. "Expected a label"
I'm trying to use it to look up a value to draw with a 7 LED display POV wheel.
I know there's an easier way to do it but the concept is below:
If I can't do it this way, is there a way to pipe my LOOKUP output into the GOSUB command directly instead of a variable (like is done with the OUTH after the lookup for a 7-seg LED)?
Thank you in advance.
~Don
I'm trying to use it to look up a value to draw with a 7 LED display POV wheel.
I know there's an easier way to do it but the concept is below:
If I can't do it this way, is there a way to pipe my LOOKUP output into the GOSUB command directly instead of a variable (like is done with the OUTH after the lookup for a 7-seg LED)?
Thank you in advance.
~Don
displaychar VAR Byte ' Letter to be drawn
DO
FOR counter = 0 TO 6
LOOKUP counter, [noparse][[/noparse] "A", "B", "C", "D", "E", "F", "G" ], displaychar ' I'm just using this as test data. Later it will be READ from a DATA string, which I'll want to be able to edit for various messages.
GOSUB [color=#990000][b]displaychar[/b][/color]
PAUSE 10
NEXT
LOOP
A:
OUTH = %0011111
OUTH = %0100100
OUTH = %1000100
OUTH = %0100100
OUTH = %0011111
RETURN
.
.
.
G:
OUTH = %0111110
OUTH = %1000001
OUTH = %1001001
OUTH = %1001001
OUTH = %0111010
RETURN
Comments
Check out the ON... GOSUB function...
Syntax: ON Offset GOTO Address1, Address2, ...AddressN
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Beau Schwabe
IC Layout Engineer
Parallax, Inc.
Whatever you GOSUB to should be a section of code that eventually executes a RETURN instruction to continue just after your original GOSUB.
GOSUB is like a little side trip for your program. Your program uses GOSUB to take a little side trip, then returns to where it left off, to continue the main journey.
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· -- Carl, nn5i
Change your FOR/NEXT loop to look like this....
FOR counter = 0 TO 6 ON counter GOSUB A, B, C, D, E, F, G PAUSE 10 NEXT▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe
IC Layout Engineer
Parallax, Inc.
I understand that.. but what I'm trying to do is something to the sort of...
MyMessage DATA "This message will be displayed 0" <<--- I want to be able to change this without reworking the entire program
index VAR byte
DO UNTIL displaychar = 0
READ MyMessage + index, displaychar
Gosub displaychar
index = index + 1
loop
And I'm using GOSUB because I may have to jump to the letter E for example several times for my message...
I didn't want to have to hardcode a bunch of GOSUB <address> manually every time I changed the displayed message.
BEAU:
Using the earlier suggestion, I could do a LOOKDOWN on the read "displaychar" to get an offset value (0-25 for A-Z) to use, then specify that on the {ON offset GOTO address1, address2....}. I just thought there might be a more direct approach.
I'll give it a shot to see what I can come up with.
Your new approach will work but it won't allow me to do content checking .. for example .. if the character is a "space" pause for 20ms instead of a GOSUB command. The ABCDE text is just something for me to get started with then build off of
I think I'll have to do your earlier suggestion. The second suggestion you made however, is interesting, and gives me a few ideas for later.
Thanks again.
Post Edited (Don Moore) : 11/9/2008 6:16:10 AM GMT
Ltr_A DATA %0011111, %0100100, %1000100, %0100100, %0011111 ... Ltr_G DATA %0111110, %1000001, %1001001. %1001001, %0111010 ... FOR counter = 0 to 6 ptr = counter * 5 + Ltr_A FOR i = ptr TO ptr + 4 READ i, char OUTH = char NEXT PAUSE 10 NEXTYour program will be more compact this way, as well.
-Phil