cscg22-gearboy

CSCG 2022 Challenge 'Gearboy'
git clone https://git.sinitax.com/sinitax/cscg22-gearboy
Log | Files | Refs | sfeed.txt

vmemcpy.s (932B)

      1        .include        "global.s"
      2
      3        .title  "VRAM utilities"
      4        .module VRAMUtils
      5        .area   _HOME
      6
      7; void vmemcpy (unsigned int dst, const void *src, unsigned int size) __z88dk_callee __preserves_regs(iyh,iyl);
      8_set_data::
      9_vmemcpy::
     10        pop de          ; pop ret address
     11        pop hl          ; dst
     12        
     13        DISABLE_VBLANK_COPY
     14
     15        VDP_WRITE_CMD h, l
     16        
     17        pop hl          ; src
     18        pop bc          ; size
     19        
     20        ld a, b         ; HI(size)
     21        ld b, c         ; LO(size)
     22        
     23        ld c, #.VDP_DATA
     24
     25        rlc b
     26        rrc b           ; check b is zero
     27        jr  z, 2$ 
     281$:
     29        outi
     30        jp  nz, 1$      ; 10 = 26 (VRAM safe)
     312$:
     32        inc a
     33        jp  4$          
     343$:
     35        outi
     36        jp  nz, 3$      ; 10 = 26 (VRAM safe)
     374$:
     38        dec a
     39        jp  nz, 3$
     40
     41        ENABLE_VBLANK_COPY
     42
     43        ld h, d
     44        ld l, e
     45        jp (hl)