cscg22-gearboy

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

scroll.s (1203B)

      1        .include        "global.s"
      2
      3        .title  "console utilities"
      4        .module ConsoleUtils
      5
      6        .globl  .curx, .cury
      7
      8        .area   _HOME
      9
     10.scroll_viewport::
     11        DISABLE_VBLANK_COPY     ; switch OFF copy shadow SAT
     12        ld hl, #(.VDP_TILEMAP + ((.SCREEN_Y_OFS + 1) * .VDP_MAP_WIDTH * 2))
     13
     14        ld bc, #((.SCREEN_HEIGHT - 1) * .VDP_MAP_WIDTH * 2)
     15        inc b
     16        inc c
     17        jr 1$
     182$:
     19        res 6, h
     20        WRITE_VDP_CMD_HL
     21        nop
     22        nop
     23        in a, (.VDP_DATA)
     24        ld e, a
     25
     26        ld a, l
     27        sub #(.VDP_MAP_WIDTH * 2)
     28        ld l, a
     29        ld a, h
     30        sbc #0
     31        ld h, a
     32
     33        set 6, h
     34        WRITE_VDP_CMD_HL
     35        nop
     36        ld a, e
     37        out (.VDP_DATA), a
     38
     39        ld a, #((.VDP_MAP_WIDTH * 2) + 1)
     40        add l
     41        ld l, a
     42        adc h
     43        sub l
     44        ld h, a
     45
     461$:
     47        dec c
     48        jr nz, 2$
     49        djnz 2$ 
     50
     51        ld hl, #(.VDP_TILEMAP + ((.SCREEN_Y_OFS + .SCREEN_HEIGHT - 1) * .VDP_MAP_WIDTH * 2))
     52        WRITE_VDP_CMD_HL
     53
     54        ld hl, #.SPACE
     55        ld b, #.VDP_MAP_WIDTH
     563$:
     57        WRITE_VDP_DATA_HL
     58        djnz 3$
     59
     60        ENABLE_VBLANK_COPY         ; switch ON copy shadow SAT
     61        ret