help with pasm subroutines

pilot0315

I have been trying to get the math from the book to work as a subroutine as advertised. Tried several combinations and I cannot get them to work. Would someone please look at this as a second set of eyes.
Thanks.

It appears that it should be simple. I have a incrementing count program working but these will not work.

Again thanks

Ariba

You still don't stop the cog at the end of the code. And you call the writer-subroutine at a point that never shoud be reached (between the subroutines).

Also the unnecessary "mov x_var, temp_var" lines are still there. This will confuse a reader of your tutorial.

Here is your 2 subroutine code with better indentions and the above issues corrected. I also renamed the temp_var to varptr, because that describes it better.

{{Multiplication based on the propeller manual page 380}}

CON
   _clkmode = xtal1 + pll16x
   '_xinfreq = 6_250_000   'MY BOARD AT 1OOMHZ  DIFFERENT CRYSTAL
   _xinfreq = 5_000_000  'QUICKSTART 80 MHZ  NORMAL CRYSTAL

var
   'Spin variables
   long x             'we pass this address in par at cognew
   long y
   long product
   
obj
   pst : "parallax serial terminal"

pub main
   x := 3
   y := 9
   pst.start(115000)
   waitcnt(clkfreq*5 +cnt)      'hold five sec to open the
   'serial terminal and enable it
   cognew(@asm,@x)              'start cog at the first variable address
   waitcnt(clkfreq*2 +cnt)      'give pasm time to do the work
   
   pst.str(string("product:"))  'show a string on terminal
   pst.dec(product~)            'show decimal value of product on terminal
   pst.newline
     

dat
'
asm                  org

                     mov varptr, par            'move par to the local varptr (points to x-var)
                     rdlong x_var, varptr       'read in the x value from Spin vars
                     add varptr, #4             'incr varptr to next long which is the y-var address
                     rdlong y_var, varptr       'read in the y value
                     add varptr, #4             'inc varptr to the product variable address

                     call #multiply             'multiply x with y
                     call #writer               'and write result to product var

                     cogid   t                  'stop the cog
                     cogstop t

' Subroutines

multiply             shl x_var,#16              'get multiplicand into x[31..16]
                     mov t,#16                  'ready for 16 multiplier bits
                     shr y_var,#1 wc            'get initial multiplier bit into c
:loop          if_c  add y_var,x_var wc         'if bit set, add multiplicand to product
                     rcr y_var,#1 wc            'put next multiplier in c, shift prod.
                     djnz t,#:loop              'loop until done                     
multiply_ret         ret                        'return with product in y[31..0] 'this would be a subroutine
                     
writer               wrlong y_var, varptr       'write the product from y[31..0] to the
writer_ret           ret                        'product variable for the top object


varptr               res   1                    'reserve space for cogregisters
x_var                res   1
y_var                res   1
t                    res   1

Andy

pilot0315

Thanks for the help in cleaning it up. I will look at your suggestions. I will study it to see what I missed.

pilot0315

BTW I get the cogid and cogstop to not leave the cog open.