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island-story/src/oam.s

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Move player on input
3 years ago
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  1. INCLUDE "hardware.inc"
  2. 

  3. SECTION "OAM Mirror", WRAM0, ALIGN[8]
  4. 

  5. _OAM:: ds 40 * 4
  6. _OAM_end:
  7. 

  8. SECTION "OAM DMA routine", ROM0
  9. 

  10. ; Initialize OAM

  11. OAM_Init::
  12.     ; Clear internal OAM

  13.     ld hl, _OAM
  14.     xor a
  15.     ld c, _OAM_end - _OAM
  16.     call memset
  17. 

  18.     ; Copy DMA transfer routine to HRAM

  19.     ld hl, waitForDMA
  20.     ld bc, DMA_Start
  21.     ld d, waitForDMA_end - waitForDMA
  22.     call memcpy
  23. 

  24.     ret
  25. 

  26. waitForDMA:
  27.     ld [rDMA], a
  28.     ld a, 40
  29. .wait:
  30.     dec a
  31.     jr nz, .wait
  32.     ret
  33. waitForDMA_end:
  34. 

  35. SECTION "OAM DMA", HRAM
  36. 

  37. DMA_Start::
  38.     ds waitForDMA_end - waitForDMA