1 files changed, 143 insertions, 0 deletions
diff --git a/engine/multiply_divide.asm b/engine/multiply_divide.asm
new file mode 100755
index 00000000..4aa5fa26
--- /dev/null
+++ b/engine/multiply_divide.asm
@@ -0,0 +1,143 @@
+_Multiply: ; 37d41 (d:7d41)
+	ld a, $8
+	ld b, a
+	xor a
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	ld [$ff9b], a
+	ld [H_SAVEDNUMTOPRINT], a ; $ff9c
+	ld [$ff9d], a
+	ld [$ff9e], a
+.asm_37d4f
+	ld a, [H_REMAINDER] ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	srl a
+	ld [H_REMAINDER], a ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	jr nc, .asm_37d77
+	ld a, [$ff9e]
+	ld c, a
+	ld a, [$ff98]
+	add c
+	ld [$ff9e], a
+	ld a, [$ff9d]
+	ld c, a
+	ld a, [$ff97]
+	adc c
+	ld [$ff9d], a
+	ld a, [H_SAVEDNUMTOPRINT] ; $ff9c
+	ld c, a
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	adc c
+	ld [H_SAVEDNUMTOPRINT], a ; $ff9c
+	ld a, [$ff9b]
+	ld c, a
+	ld a, [H_DIVIDEND] ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	adc c
+	ld [$ff9b], a
+.asm_37d77
+	dec b
+	jr z, .asm_37d94
+	ld a, [$ff98]
+	sla a
+	ld [$ff98], a
+	ld a, [$ff97]
+	rl a
+	ld [$ff97], a
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	rl a
+	ld [H_NUMTOPRINT], a ; $ff96 (aliases: H_MULTIPLICAND)
+	ld a, [H_DIVIDEND] ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	rl a
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	jr .asm_37d4f
+.asm_37d94
+	ld a, [$ff9e]
+	ld [$ff98], a
+	ld a, [$ff9d]
+	ld [$ff97], a
+	ld a, [H_SAVEDNUMTOPRINT] ; $ff9c
+	ld [H_NUMTOPRINT], a ; $ff96 (aliases: H_MULTIPLICAND)
+	ld a, [$ff9b]
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	ret
+
+_Divide: ; 37da5 (d:7da5)
+	xor a
+	ld [$ff9a], a
+	ld [$ff9b], a
+	ld [H_SAVEDNUMTOPRINT], a ; $ff9c
+	ld [$ff9d], a
+	ld [$ff9e], a
+	ld a, $9
+	ld e, a
+.asm_37db3
+	ld a, [$ff9a]
+	ld c, a
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	sub c
+	ld d, a
+	ld a, [H_REMAINDER] ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	ld c, a
+	ld a, [H_DIVIDEND] ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	sbc c
+	jr c, .asm_37dce
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	ld a, d
+	ld [H_NUMTOPRINT], a ; $ff96 (aliases: H_MULTIPLICAND)
+	ld a, [$ff9e]
+	inc a
+	ld [$ff9e], a
+	jr .asm_37db3
+.asm_37dce
+	ld a, b
+	cp $1
+	jr z, .asm_37e18
+	ld a, [$ff9e]
+	sla a
+	ld [$ff9e], a
+	ld a, [$ff9d]
+	rl a
+	ld [$ff9d], a
+	ld a, [H_SAVEDNUMTOPRINT] ; $ff9c
+	rl a
+	ld [H_SAVEDNUMTOPRINT], a ; $ff9c
+	ld a, [$ff9b]
+	rl a
+	ld [$ff9b], a
+	dec e
+	jr nz, .asm_37e04
+	ld a, $8
+	ld e, a
+	ld a, [$ff9a]
+	ld [H_REMAINDER], a ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	xor a
+	ld [$ff9a], a
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	ld a, [$ff97]
+	ld [H_NUMTOPRINT], a ; $ff96 (aliases: H_MULTIPLICAND)
+	ld a, [$ff98]
+	ld [$ff97], a
+.asm_37e04
+	ld a, e
+	cp $1
+	jr nz, .asm_37e0a
+	dec b
+.asm_37e0a
+	ld a, [H_REMAINDER] ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	srl a
+	ld [H_REMAINDER], a ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	ld a, [$ff9a]
+	rr a
+	ld [$ff9a], a
+	jr .asm_37db3
+.asm_37e18
+	ld a, [H_NUMTOPRINT] ; $ff96 (aliases: H_MULTIPLICAND)
+	ld [H_REMAINDER], a ; $ff99 (aliases: H_DIVISOR, H_MULTIPLIER, H_POWEROFTEN)
+	ld a, [$ff9e]
+	ld [$ff98], a
+	ld a, [$ff9d]
+	ld [$ff97], a
+	ld a, [H_SAVEDNUMTOPRINT] ; $ff9c
+	ld [H_NUMTOPRINT], a ; $ff96 (aliases: H_MULTIPLICAND)
+	ld a, [$ff9b]
+	ld [H_DIVIDEND], a ; $ff95 (aliases: H_PRODUCT, H_PASTLEADINGZEROES, H_QUOTIENT)
+	ret