Determining variable length (number of digits) possible?

[mpgmike]

IF XVR > 999 THEN
[Work the first digit]
ENDIF ;If not, no action taken
IF XVR > 99 THEN
[Work the 2nd digit]
ENDIF ;If not, no action taken

[CuriousOne]

I'm doing a more featured custom decoder, which will display both letters and digits on max7219 7 segment display. It will also have custom decoder for digital values. The code is below:

FOURD=12345 'test value
dstart=2 'start segment
DLEN=2 'decode length

TEST: 'test digits
FOR x=DLEN TO 1 STEP -1
Z=FOURD DIG X+1	'EXTRACT VALUE
GOSUB FOURDEC
PAUSE 500
NEXT
GOTO TEST

FOURDEC:	'DIGIT DECODER
if Z=0 then Y=126
if Z=1 then Y=48
if z=2 then Y=109
if z=3 then Y=121
if z=4 then Y=51
if z=5 then Y=91
if z=6 then Y=95
if z=7 then Y=112
if z=8 then Y=127
if z=9 then Y=115
low load
shiftout datapin,clockpin,1,[x+DSTART-1, y]	'DISPLAY THE LETTER
high load
RETURN

This code works, but DLEN instead of cropping digits from the left, crops them from the right - say initial variable is "12345" and I want to display 2 digits from it, I'm getting "45" instead of "12", have no idea why. Same for start position - DSTART starts from rightmost position, instead of leftmost....

[CuriousOne]

FOURD=12345
FOURD=FOURD>>2 should return FOURD=123, right? but it returns 11419 !

[CuriousOne]

Forgot to mention, startup shift fixed:
shiftout datapin,clockpin,1,[X-DLEN+DSTART, y]

[mpgmike]

FOURD=12345
FOURD=FOURD>>2 should return FOURD=123, right? but it returns 11419 !

Not sure how that happened. First, you wouldn't get "123", as Right Shift 2 (>> 2) is the same as Divide by 4; in which case 12345 >> 2 = 3086 and not 11419.

Since you're dealing with a display, you may have to treat each place holder as a unique byte (perhaps value + $30 to convert it to ASCii); "12345" would be saved as $31, $32, $33, $34, $35 in an array. You can then shift your pointer 2 places to look at 123 by itself (as 3 individual bytes, of course).

[CuriousOne]

I've written a PC based converter, which deals with ASCII conversion. It generates PBP code for EEPROM.

[CuriousOne]

So back to shift.
How to trim one variable from left to right, to value of another variable?

say trim 12345 by 3 - mean, make 123 digits from it.

[HenrikOlsson]

12345 / 10 = 1234
12345 / 100 = 123
12345 / 1000 = 12
12345 / 10000 = 1

/Henrik.

[CuriousOne]

This requires too many IFs....
On spectrum we had X=LEFT(Y,Z)....