In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Zoot wrote:

Because the second number in the function declaration is the number of parameters expected to be passed: 1.

MyFunc FUNC  return bytes, minimum number of parameters, maximum number of parameters

If you are expecting to pass different numbers of bytes (sometimes a word, sometimes a word and a byte, etc), then you either need to parse and decide what to do based on __PARAMCNT (in your function itself):

MyFunc FUNC 2, 1, 3

FUNC MyFunc
   IF __PARAMCNT = 1 THEN ' only one byte? clear MSB of wparam12 and clear param3
       __PARAM2 = 0
       __PARAM3 = 0
   ELSEIF __PARAMCNT = 2 THEN
        __PARAM3 = 0
   ENDIF
   tmpW1 = __WPARAM12
   tmpB3 = __PARAM3
   ' do stuff
   RETURN tmpW1
   ENDFUNC




--- OR ----

 you need to force the function call to "promote" values to Words, even if you pass a byte, e.g.

MyFunc FUNC 2, 3, 3, Word, Byte

would be a function that returns two bytes (__WPARAM12) and expects 3 bytes as a Word and a Byte. The cool thing is even if your value for the Word parameter is <256, SX/B will clear the upper byte of the parameter word. So....

FUNC MyFunc

     tmpW1 = __WPARAM12
     tmpB3 = __PARAM3
     ' do some stuff
     RETURN tmpW1

     ENDFUNC

If I do this:

   someWord = MyFunc, 1, 10

then param1 = 1
param2 = 0
param3 = 10


If I do this:

   someWord = MyFunc, 2000, 10

then param1 = 2000 & $FF
param2 = 2000 >> 8
param3 = 10

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