home, macros: disassemble text-related functions and add text fn macros

Signed-off-by: Tauwasser <Tauwasser@tauwasser.eu>

1 files changed, 105 insertions, 0 deletions

diff --git a/home/print_bcd.asm b/home/print_bcd.asm
new file mode 100644
index 0000000..fa8d825
--- /dev/null
+++ b/home/print_bcd.asm
@@ -0,0 +1,105 @@
+INCLUDE "constants.asm"
+
+SECTION "BCD Finalize", ROM0[$33a3]
+
+PrintLetterDelay:: ; 33a3 (0:33a3)
+	ld a, [wce5f]
+	bit 4, a
+	ret nz
+	ld a, [wTextBoxFlags]
+	bit 1, a
+	ret z
+	push hl
+	push de
+	push bc
+	ld a, [wTextBoxFlags]
+	bit 0, a
+	jr z, .waitOneFrame
+	ld a, [wce5f]
+	and $07
+	jr .initFrameCnt
+.waitOneFrame
+	ld a, $01
+.initFrameCnt
+	ld [wVBlankJoyFrameCounter], a
+.checkButtons
+	call GetJoypad
+	ldh a, [hJoyState]
+.checkAButton
+	bit 0, a ; is the A button pressed?
+	jr z, .checkBButton
+	jr .endWait
+.checkBButton
+	bit 1, a ; is the B button pressed?
+	jr z, .buttonsNotPressed
+.endWait
+	call DelayFrame
+	jr .done
+.buttonsNotPressed ; if neither A nor B is pressed
+	ld a, [wVBlankJoyFrameCounter]
+	and a
+	jr nz, .checkButtons
+.done
+	pop bc
+	pop de
+	pop hl
+	ret
+; 0x33e3
+
+SECTION "BCD Functions", ROM0[$3ab2]
+
+; function to print a BCD (Binary-coded decimal) number
+; de = address of BCD number
+; hl = destination address
+; c = flags and length
+; bit 7: if set, do not print leading zeroes
+;        if unset, print leading zeroes
+; bit 6: if set, left-align the string (do not pad empty digits with spaces)
+;        if unset, right-align the string
+; bits 0-5: length of BCD number in bytes
+; Note that bits 5 and 7 are modified during execution. The above reflects
+; their meaning at the beginning of the functions's execution.
+PrintBCDNumber:: ; 3ab2 (0:3ab2)
+	ld b, c  ; save flags in b
+	res 7, c
+	res 6, c ; c now holds the length
+.loop
+	ld a, [de]
+	swap a
+	call PrintBCDDigit
+	ld a, [de]
+	call PrintBCDDigit
+	inc de
+	dec c
+	jr nz, .loop
+	bit 7, b      ; were any non-zero digits printed?
+	jr z, .done
+.numberEqualsZero ; if every digit of the BCD number is zero
+	bit 6, b
+	jr nz, .skipRightAlignmentAdjustment
+	dec hl                    ; if the string is right-aligned, it needs
+.skipRightAlignmentAdjustment ;to be moved back one space
+	ld [hl], "０"
+	call PrintLetterDelay
+	inc hl
+.done
+	ret
+
+PrintBCDDigit:: ; 3ad5 (0:3ad5)
+	and $0f
+	and a
+	jr z, .zeroDigit
+	res 7, b           ; unset 7 to indicate that a nonzero
+.outputDigit           ; digit has been reached
+	add "０"
+	ld [hli], a
+	jp PrintLetterDelay
+.zeroDigit
+	bit 7, b           ; either printing leading zeroes or 
+	jr z, .outputDigit ; already reached a nonzero digit?
+	bit 6, b
+	ret nz             ; left-align, don't pad with space
+	ld a, "　"
+	ld [hli], a
+	ret
+; 0x3aed
\ No newline at end of file