1 files changed, 217 insertions, 0 deletions
diff --git a/home/print_num.asm b/home/print_num.asm
new file mode 100644
index 00000000..5155977b
--- /dev/null
+++ b/home/print_num.asm
@@ -0,0 +1,217 @@
+PrintNumber::
+; Print the c-digit, b-byte value at de.
+; Allows 2 to 7 digits. For 1-digit numbers, add
+; the value to char "0" instead of calling PrintNumber.
+; Flags LEADING_ZEROES and LEFT_ALIGN can be given
+; in bits 7 and 6 of b respectively.
+	push bc
+	xor a
+	ld [hPastLeadingZeros], a
+	ld [hNumToPrint], a
+	ld [hNumToPrint + 1], a
+	ld a, b
+	and $f
+	cp 1
+	jr z, .byte
+	cp 2
+	jr z, .word
+.long
+	ld a, [de]
+	ld [hNumToPrint], a
+	inc de
+	ld a, [de]
+	ld [hNumToPrint + 1], a
+	inc de
+	ld a, [de]
+	ld [hNumToPrint + 2], a
+	jr .start
+
+.word
+	ld a, [de]
+	ld [hNumToPrint + 1], a
+	inc de
+	ld a, [de]
+	ld [hNumToPrint + 2], a
+	jr .start
+
+.byte
+	ld a, [de]
+	ld [hNumToPrint + 2], a
+
+.start
+	push de
+
+	ld d, b
+	ld a, c
+	ld b, a
+	xor a
+	ld c, a
+	ld a, b
+
+	cp 2
+	jr z, .tens
+	cp 3
+	jr z, .hundreds
+	cp 4
+	jr z, .thousands
+	cp 5
+	jr z, .ten_thousands
+	cp 6
+	jr z, .hundred_thousands
+
+print_digit: macro
+
+if (\1) / $10000
+	ld a, \1 / $10000 % $100
+else	xor a
+endc
+	ld [hPowerOf10 + 0], a
+
+if (\1) / $100
+	ld a, \1 / $100   % $100
+else	xor a
+endc
+	ld [hPowerOf10 + 1], a
+
+	ld a, \1 / $1     % $100
+	ld [hPowerOf10 + 2], a
+
+	call .PrintDigit
+	call .NextDigit
+endm
+
+.millions          print_digit 1000000
+.hundred_thousands print_digit 100000
+.ten_thousands     print_digit 10000
+.thousands         print_digit 1000
+.hundreds          print_digit 100
+
+.tens
+	ld c, 0
+	ld a, [hNumToPrint + 2]
+.mod
+	cp 10
+	jr c, .ok
+	sub 10
+	inc c
+	jr .mod
+.ok
+
+	ld b, a
+	ld a, [hPastLeadingZeros]
+	or c
+	ld [hPastLeadingZeros], a
+	jr nz, .past
+	call .PrintLeadingZero
+	jr .next
+.past
+	ld a, "0"
+	add c
+	ld [hl], a
+.next
+
+	call .NextDigit
+.ones
+	ld a, "0"
+	add b
+	ld [hli], a
+	pop de
+	dec de
+	pop bc
+	ret
+
+.PrintDigit:
+; Divide by the current decimal place.
+; Print the quotient, and keep the modulus.
+	ld c, 0
+.loop
+	ld a, [hPowerOf10]
+	ld b, a
+	ld a, [hNumToPrint]
+	ld [hSavedNumToPrint], a
+	cp b
+	jr c, .underflow0
+	sub b
+	ld [hNumToPrint], a
+	ld a, [hPowerOf10 + 1]
+	ld b, a
+	ld a, [hNumToPrint + 1]
+	ld [hSavedNumToPrint + 1], a
+	cp b
+	jr nc, .noborrow1
+
+	ld a, [hNumToPrint]
+	or 0
+	jr z, .underflow1
+	dec a
+	ld [hNumToPrint], a
+	ld a, [hNumToPrint + 1]
+.noborrow1
+
+	sub b
+	ld [hNumToPrint + 1], a
+	ld a, [hPowerOf10 + 2]
+	ld b, a
+	ld a, [hNumToPrint + 2]
+	ld [hSavedNumToPrint + 2], a
+	cp b
+	jr nc, .noborrow2
+
+	ld a, [hNumToPrint + 1]
+	and a
+	jr nz, .borrowed
+
+	ld a, [hNumToPrint]
+	and a
+	jr z, .underflow2
+	dec a
+	ld [hNumToPrint], a
+	xor a
+.borrowed
+
+	dec a
+	ld [hNumToPrint + 1], a
+	ld a, [hNumToPrint + 2]
+.noborrow2
+	sub b
+	ld [hNumToPrint + 2], a
+	inc c
+	jr .loop
+
+.underflow2
+	ld a, [hSavedNumToPrint + 1]
+	ld [hNumToPrint + 1], a
+.underflow1
+	ld a, [hSavedNumToPrint]
+	ld [hNumToPrint], a
+.underflow0
+	ld a, [hPastLeadingZeros]
+	or c
+	jr z, .PrintLeadingZero
+
+	ld a, "0"
+	add c
+	ld [hl], a
+	ld [hPastLeadingZeros], a
+	ret
+
+.PrintLeadingZero:
+	bit BIT_LEADING_ZEROES, d
+	ret z
+	ld [hl], "0"
+	ret
+
+.NextDigit:
+; Increment unless the number is left-aligned,
+; leading zeroes are not printed, and no digits
+; have been printed yet.
+	bit BIT_LEADING_ZEROES, d
+	jr nz, .inc
+	bit BIT_LEFT_ALIGN, d
+	jr z, .inc
+	ld a, [hPastLeadingZeros]
+	and a
+	ret z
+.inc
+	inc hl
+	ret