test program for floating point issues on c128

c128floatproblem.asm

@@ -0,0 +1,48 @@
+
+; this program adds 2 floats 1.2345 + 4.4444 and prints the result 5.67879
+; it works fine on C64 and CX16 but fails to add the right number on C128
+; I think it has something to do with the banking on the C128
+; because several rom fp routines mention "value in bank 1"
+; but I don't know what this means and why the program as given doesn't work
+
+.cpu  '6502'
+
+* = $1300       ; sys 4864
+
+P8ZP_SCRATCH_W1 = 251    ; free zp word
+CHROUT = $ffd2
+
+; c128:
+MOVFM = $af63
+FADD = $af18
+FOUT = $af06
+
+;cx16:
+;MOVFM = $fe42
+;FADD = $fe12
+;FOUT = $fe7b
+
+;c64:
+;MOVFM = $bba2
+;FADD = $b867
+;FOUT = $bddd
+
+            lda  #<f1
+            ldy  #>f1
+            jsr  MOVFM       ; load FAC1
+            lda  #<f2
+            ldy  #>f2
+            jsr  FADD        ; add mem float to FAC1     DOESN'T WORK ON C128!?
+            jsr  FOUT        ; convert to string
+            sta  P8ZP_SCRATCH_W1
+            sty  P8ZP_SCRATCH_W1+1
+            ldy  #0
+_printloop  lda  (P8ZP_SCRATCH_W1),y
+            beq  _done
+            jsr  CHROUT
+            iny
+            bne  _printloop
+_done       jmp  _done
+
+f1	.byte  $81, $1e, $04, $18, $93  ; float 1.2345
+f2	.byte  $83, $0e, $38, $86, $59  ; float 4.4444