shithub: pokecrystal

ref: 91e89a29a20d075ffbdd3a2f75b507c8202b1dce
dir: /common/copy2.asm/

CopyBytes: ; 0x3026
; copy bc bytes from hl to de
	inc b  ; we bail the moment b hits 0, so include the last run
	inc c  ; same thing; include last byte
	jr .HandleLoop
.CopyByte
	ld a, [hli]
	ld [de], a
	inc de
.HandleLoop
	dec c
	jr nz, .CopyByte
	dec b
	jr nz, .CopyByte
	ret

SwapBytes: ; 0x3034
; swap bc bytes between hl and de
.Loop
	; stash [hl] away on the stack
	ld a, [hl]
	push af

	; copy a byte from [de] to [hl]
	ld a, [de]
	ld [hli], a

	; retrieve the previous value of [hl]; put it in [de]
	pop af
	ld [de], a
	inc de

	; handle loop stuff
	dec bc
	ld a, b
	or c
	jr nz, .Loop
	ret

ByteFill: ; 0x3041
; fill bc bytes with the value of a, starting at hl
	inc b  ; we bail the moment b hits 0, so include the last run
	inc c  ; same thing; include last byte
	jr .HandleLoop
.PutByte
	ld [hli], a
.HandleLoop
	dec c
	jr nz, .PutByte
	dec b
	jr nz, .PutByte
	ret

GetFarByte: ; 0x304d
; retrieve a single byte from a:hl, and return it in a.
	; bankswitch to new bank
	ld [hBuffer], a
	ld a, [hROMBank]
	push af
	ld a, [hBuffer]
	rst Bankswitch

	; get byte from new bank
	ld a, [hl]
	ld [hBuffer], a

	; bankswitch to previous bank
	pop af
	rst Bankswitch

	; return retrieved value in a
	ld a, [hBuffer]
	ret

GetFarHalfword: ; 0x305d
; retrieve a halfword from a:hl, and return it in hl.
	; bankswitch to new bank
	ld [hBuffer], a
	ld a, [hROMBank]
	push af
	ld a, [hBuffer]
	rst Bankswitch

	; get halfword from new bank, put it in hl
	ld a, [hli]
	ld h, [hl]
	ld l, a

	; bankswitch to previous bank and return
	pop af
	rst Bankswitch
	ret
; 0x306b

FarCopyWRAM: ; 306b
	ld [hBuffer], a
	ld a, [rSVBK]
	push af
	ld a, [hBuffer]
	ld [rSVBK], a
	call CopyBytes
	pop af
	ld [rSVBK], a
	ret
; 307b

GetFarWRAMByte: ; 307b
	ld [hBuffer], a
	ld a, [rSVBK]
	push af
	ld a, [hBuffer]
	ld [rSVBK], a
	ld a, [hl]
	ld [hBuffer], a
	pop af
	ld [rSVBK], a
	ld a, [hBuffer]
	ret
; 308d

GetFarWRAMWord: ; 308d
	ld [hBuffer], a
	ld a, [rSVBK]
	push af
	ld a, [hBuffer]
	ld [rSVBK], a
	ld a, [hli]
	ld h, [hl]
	ld l, a
	pop af
	ld [rSVBK], a
	ret
; 309d