Add NES building and adapt example functions

LibMultiSpacc/neslib/splitxy.s

@@ -0,0 +1,81 @@
+
+.importzp TEMP, PPU_CTRL_VAR, PPU_CTRL_VAR1, SCROLL_X1, SCROLL_Y1
+.import popax
+.include "nes.inc"
+.include "zpvars.inc"
+.export _splitxy
+
+;;void __fastcall__ splitxy(unsigned int x,unsigned int y);
+
+WRITE1=TEMP+1
+WRITE2=TEMP+2
+
+_splitxy:
+
+   ; Extract SCROLL_Y1, SCROLL_X1, WRITE1 from parameters.
+
+   sta <TEMP
+
+   txa
+   bne @1
+   lda <TEMP
+   cmp #240
+   bcs @1
+   sta <SCROLL_Y1
+   lda #0
+   sta <TEMP
+   beq @2   ;bra
+
+@1:
+   sec
+   lda <TEMP
+   sbc #240
+   sta <SCROLL_Y1
+   lda #8               ;; Bit 3
+   sta <TEMP
+@2:
+
+   jsr popax
+   sta <SCROLL_X1
+   txa
+   and #$01
+   asl a
+   asl a                ;; Bit 2
+   ora <TEMP               ;; From Y
+   sta <WRITE1            ;; Store!
+
+   ; Calculate WRITE2 = ((Y & $F8) << 2) | (X >> 3)
+
+   lda <SCROLL_Y1
+   and #$F8
+   asl a
+   asl a
+   sta <TEMP             ;; TEMP = (Y & $F8) << 2
+   lda <SCROLL_X1
+   lsr a
+   lsr a
+   lsr a                ;; A = (X >> 3)
+   ora <TEMP             ;; A = (X >> 3) | ((Y & $F8) << 2)
+   sta <WRITE2            ;; Store!
+
+   ; Wait for sprite 0 hit
+
+@3:
+   bit PPU_STATUS
+   bvs @3
+@4:
+   bit PPU_STATUS
+   bvc @4
+
+   ; Set scroll value
+   lda PPU_STATUS
+   lda <WRITE1
+   sta PPU_ADDR
+   lda <SCROLL_Y1
+   sta PPU_SCROLL
+   lda <SCROLL_X1
+   ldx <WRITE2
+   sta PPU_SCROLL
+   stx PPU_ADDR
+   
+   rts