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Project:
1		Project:
2		; hl is Z, de is Y, bc is X
3		; assume hl is stricly positive
4		; 265 bytes, +-600 TStates depending the input
5		add hl, hl
6		; return if neg
7		ret c
8		ld a, h
9		or a
10		jr z, _scale_up
11		_scale_down_loop:
12		srl a
13		rr l
14		sra d
15		rr e
16		sra b
17		rr c
18		or a
19		jp nz, _scale_down_loop
20		_scale_up:
21		; l, e, c are significant
22		ld a, l
23		or a
24		ret z
25		cp 98
26		jp z, _no_bissect
27		jr nc, _scale_done
28		_scale_up_loop:
29		sla e
30		sla c
31		add a, a
32		cp 98
33		jp c, _scale_up_loop
34		_scale_done:
35		rra
36		ld l, a
37		; l=Z, e=X, c=Y
38		xor a
39		; set a to 0 and reset carry flag
40		ld h, a
41		ld d, a
42		ld b, a
43		; first optimized iters (h,d,b are 0)
44		gBissectFirstIter:
45		ld a, l
46		rra
47		cp 49
48		; calculate midpoint and classify
49		jr nc, $+16
50		; store to h
51		ld h, a
52		ld a, e
53		inc a
54		sra a
55		ld d, a
56		ld a, c
57		inc a
58		sra a
59		ld b, a
60		jp $+10
61		; store it to l
62		ld l, a
63		inc e
64		sra e
65		inc c
66		sra c
67		; the bissection macro, unrolled to gain speed (and because we need all register)
68		#macro gBissectIter()
69		ld a, l
70		add a, h
71		rra
72		cp 49
73		; calculate midpoint and classify
74		jr nc, $+18
75		; store to h
76		ld h, a
77		ld a, e
78		inc a
79		add a, d
80		sra a
81		ld d, a
82		ld a, c
83		inc a
84		add a, b
85		sra a
86		ld b, a
87		jp $+16
88		; store it to l
89		ld l, a
90		ld a, e
91		inc a
92		add a, d
93		sra a
94		ld e, a
95		ld a, c
96		inc a
97		add a, b
98		sra a
99		ld c, a
100		#endmacro
101		; 4 more iters to match precision
102		gBissectIter()
103		gBissectIter()
104		gBissectIter()
105		gBissectIter()
106		; finish:
107		ld a, e
108		add a, d
109	-	; note : rra works because both d and e are either positive (no carry) or negative (carry set)
109	+	; note : sra must be used...
110		sra a
111		adc a, 48
112		; or whatever
113		ld (gScreenX), a
114		ld a, c
115		add a, b
116		sra a
117		ld c, a
118		ld a, 32
119		sbc a, c
120		ld (gScreenY), a
121		ret
122		_no_bissect:
123		ld a, e
124		add a, 48
125		ld (gScreenX), a
126		ld a, 32
127		sub c
128		ld (gScreenY), a
129		ret