[Coco] lbsr and rts

[Wayne Campbell]

I may be missing something, but I thought calls to subroutines required a rts instruction. In Basic09, there has to be a RETURN statement for any given GOSUB, but not necessarily one-for-one. I can, for example, have a series of subroutine calls, where there are multiple entry points for the subroutine, and one RETURN statement, like:

code
GOSUB 20
more code
GOSUB 30
more code
END

20 code
more code
30 even more code
still more code
RETURN

It will not generate any errors, and as long as the code is written correctly, it will work.

I have found, in the assembly code generated by disasm, that there are labels in the declarations (all those fcb's) that are being addressed in the code using lbsr op codes. Yet, there is no rts instruction anywhere in those fcb's. Can someone explain how this works? An example is:

* The L010A label is addressed twice in the program code.
L010A    fcb   $9D
         fcb   $1E 
         fcb   $04 
* The L010D label is addressed ten times in the program code.
L010D    fcb   $9D
         fcb   $1E 
         fcb   $02 

this series continues until:

L013A    fcb   $9D 
         fcb   $2A *
         fcb   $00 
         fcb   $00 
         fcb   $72 r
         fcb   $02 

In the code, the following statements address these labels:

Both occurrences of the L010A label, and one of the L010D labels, occur in this routine:
L08F8    ldx   $02,s
         lda   #$80
         lbsr  L010A
         bne   L090F
         lbsr  L010D
         beq   L0915
         leax  $03,x
         lda   #$20
         lbsr  L010A
         beq   L0915

I just don't understand.

Wayne