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Updates to calling C

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This commit is contained in:
alpine9000
2016-03-16 20:25:15 +11:00
parent 68c54c01d2
commit 9e2888bc84
4 changed files with 15 additions and 10 deletions
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021.calling_c/init.s
+9 -8
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@@ -19,14 +19,15 @@ Init:
jsr PokeBitplanePointers
endif
;; void PokeBitplanePointers(unsigned short* copper, unsigned char* bitplanes, unsigned offset, unsigned numBitplanes, unsigned screenWidthBytes)
move.l #SCREEN_WIDTH_BYTES,-(sp)
move.l #SCREEN_BIT_DEPTH,-(sp)
move.l #0,-(sp)
pea bitplanes
pea copperList
jsr _PokeBitplanePointers
add.l #20,sp
;; Make a call to a C function with the following prototype:
;; void PokeBitplanePointers(unsigned short* copper, unsigned char* bitplanes, unsigned offset, unsigned numBitplanes, unsigned screenWidthBytes)
move.l #SCREEN_WIDTH_BYTES,-(sp) ; arguments are pushed onto the stack...
move.l #SCREEN_BIT_DEPTH,-(sp) ; in reverse order
move.l #0,-(sp) ; offset == 0
pea bitplanes ; make sure you push the address...
pea copperList ; of variables, not the value
jsr _PokeBitplanePointers ; C adds an _ to all global symbols
add.l #20,sp ; Need to pop the arguments from the stack
;; set up playfield
move.w #(RASTER_Y_START<<8)|RASTER_X_START,DIWSTRT(a6)