1 files changed, 154 insertions, 0 deletions
diff --git a/engine/experience.asm b/engine/experience.asm
new file mode 100755
index 00000000..80177b50
--- /dev/null
+++ b/engine/experience.asm
@@ -0,0 +1,154 @@
+Func_58f43: ; 58f43 (16:4f43)
+	ld a, [$cf98]
+	ld [$d0b5], a
+	call GetMonHeader
+	ld d, $1
+.asm_58f4e
+	inc d
+	call CalcExperience
+	push hl
+	ld hl, $cfa8
+	ld a, [$ff98]
+	ld c, a
+	ld a, [hld]
+	sub c
+	ld a, [$ff97]
+	ld c, a
+	ld a, [hld]
+	sbc c
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	ld c, a
+	ld a, [hl]
+	sbc c
+	pop hl
+	jr nc, .asm_58f4e
+	dec d
+	ret
+
+; calculates the amount of experience needed for level d
+CalcExperience: ; 58f6a (16:4f6a)
+	ld a, [W_MONHGROWTHRATE]
+	add a
+	add a
+	ld c, a
+	ld b, $0
+	ld hl, GrowthRateTable
+	add hl, bc
+	call CalcDSquared
+	ld a, d
+	ld [H_MULTIPLIER], a ; $ff99
+	call Multiply
+	ld a, [hl]
+	and $f0
+	swap a
+	ld [H_MULTIPLIER], a ; $ff99
+	call Multiply
+	ld a, [hli]
+	and $f
+	ld [H_DIVISOR], a ; $ff99
+	ld b, $4
+	call Divide
+	ld a, [H_MULTIPLICAND] ; $ff96 (aliases: H_NUMTOPRINT)
+	push af
+	ld a, [H_MULTIPLICAND+1]
+	push af
+	ld a, [H_MULTIPLICAND+2]
+	push af
+	call CalcDSquared
+	ld a, [hl]
+	and $7f
+	ld [H_MULTIPLIER], a ; $ff99
+	call Multiply
+	ld a, [H_MULTIPLICAND] ; $ff96 (aliases: H_NUMTOPRINT)
+	push af
+	ld a, [H_MULTIPLICAND+1]
+	push af
+	ld a, [H_MULTIPLICAND+2]
+	push af
+	ld a, [hli]
+	push af
+	xor a
+	ld [H_MULTIPLICAND], a ; $ff96
+	ld [H_MULTIPLICAND+1], a
+	ld a, d
+	ld [H_MULTIPLICAND+2], a
+	ld a, [hli]
+	ld [H_MULTIPLIER], a
+	call Multiply
+	ld b, [hl]
+	ld a, [H_MULTIPLICAND+2]
+	sub b
+	ld [H_MULTIPLICAND+2], a
+	ld b, $0
+	ld a, [H_MULTIPLICAND+1]
+	sbc b
+	ld [H_MULTIPLICAND+1], a
+	ld a, [H_MULTIPLICAND] ; $ff96
+	sbc b
+	ld [H_MULTIPLICAND], a ; $ff96
+	pop af
+	and $80
+	jr nz, .subtractSquaredTerm ; check sign
+	pop bc
+	ld a, [H_MULTIPLICAND+2]
+	add b
+	ld [H_MULTIPLICAND+2], a
+	pop bc
+	ld a, [H_MULTIPLICAND+1]
+	adc b
+	ld [H_MULTIPLICAND+1], a
+	pop bc
+	ld a, [H_MULTIPLICAND]
+	adc b
+	ld [H_MULTIPLICAND], a
+	jr .addCubedTerm
+.subtractSquaredTerm
+	pop bc
+	ld a, [H_MULTIPLICAND+2]
+	sub b
+	ld [H_MULTIPLICAND+2], a
+	pop bc
+	ld a, [H_MULTIPLICAND+1]
+	sbc b
+	ld [H_MULTIPLICAND+1], a
+	pop bc
+	ld a, [H_MULTIPLICAND]
+	sbc b
+	ld [H_MULTIPLICAND], a
+.addCubedTerm
+	pop bc
+	ld a, [H_MULTIPLICAND+2]
+	add b
+	ld [H_MULTIPLICAND+2], a
+	pop bc
+	ld a, [H_MULTIPLICAND+1]
+	adc b
+	ld [H_MULTIPLICAND+1], a
+	pop bc
+	ld a, [H_MULTIPLICAND]
+	adc b
+	ld [H_MULTIPLICAND], a
+	ret
+
+; calculates d*d
+CalcDSquared: ; 59010 (16:5010)
+	xor a
+	ld [H_MULTIPLICAND], a ; $ff96 (aliases: H_NUMTOPRINT)
+	ld [H_MULTIPLICAND+1], a
+	ld a, d
+	ld [H_MULTIPLICAND+2], a
+	ld [H_MULTIPLIER], a ; $ff99 (aliases: H_DIVISOR, H_REMAINDER, H_POWEROFTEN)
+	jp Multiply
+
+; each entry has the following scheme:
+; %AAAABBBB %SCCCCCCC %DDDDDDDD %EEEEEEEE
+; resulting in
+;  (a*n^3)/b + sign*c*n^2 + d*n - e
+; where sign = -1 <=> S=1
+GrowthRateTable: ; 5901d (16:501d)
+	db $11,$00,$00,$00 ; medium fast      n^3
+	db $34,$0A,$00,$1E ; (unused?)    3/4 n^3 + 10 n^2         - 30
+	db $34,$14,$00,$46 ; (unused?)    3/4 n^3 + 20 n^2         - 70
+	db $65,$8F,$64,$8C ; medium slow: 6/5 n^3 - 15 n^2 + 100 n - 140
+	db $45,$00,$00,$00 ; fast:        4/5 n^3
+	db $54,$00,$00,$00 ; slow:        5/4 n^3