DrawNote:
    ld a, [wMutedChannels]
    ld b, a
    ld a, [wTmpCh]
    and a
    jr z, .skipshift
.shiftloop
    srl b
    dec a
    jr nz, .shiftloop
.skipshift
    srl b
    jp c, .nonote
    ld a, [wTmpCh]
    add a
    ld c, a
    ld b, 0
    ld hl, wC1Vol
    add hl, bc
    ld a, [hl]
    and a
    jr z, .nonote
; get the note from tone frequency
; e = ⌊96.5-12*log₂(k/Freq("C2")/(2048-[wCxFreq]))⌋
;   = ⌊96.5-12*(log₂(k/Freq("C2"))-log₂(2048-[wCxFreq]))⌋
; k = 131072 when wTmpCh != 2
; k =  65536 when wTmpCh =  2
; Freq("C2") is 65.4064Hz in A440
    ld hl, wC1Freq
    add hl, bc
    ld a, [hli]
    ld c, a
    ld b, [hl] ; [wCxFreq]
    ld a, 2048 % $100
    sub c
    ld l, a
    ld a, 2048 / $100
    sbc b
    ld h, a ; 2048-[wCxFreq]
    ld a, h
    and a
    ld a, l
    jr nz, .skip0check
    cp 1
    jr z, .logshiftdone
    jr c, .nonote
.skip0check
    ld bc, 0
    ld d, c
.logshiftloop
    srl h
    rr l
    rr c
    inc d
    ld a, h
    and a
    jr nz, .logshiftloop
    ld a, l
    cp 1
    jr nz, .logshiftloop
.logshiftdone
    ld hl, LogTable
    add hl, bc
    ld e, [hl] ; log₂(2048-[wCxFreq])
    ld a, [wTmpCh]
    cp 2
    ld hl, $af7 ; log₂(65536/Freq("C2"))
    jr z, .ch3
    ld hl, $bf7 ; log₂(131072/Freq("C2"))
.ch3
    ld a, l
    sub e
    ld l, a
    ld a, h
    sbc d
    ld h, a ; log₂(k/Freq("C2"))-log₂(2048-[wCxFreq])
    ld b, h
    ld c, l
    add hl, hl
    add hl, bc
    add hl, hl
    add hl, hl ; 12*(log₂(k/Freq("C2"))-log₂(2048-[wCxFreq]))
    ld b, h
    ld c, l ; 12*(log₂(k/Freq("C2"))-log₂(2048-[wCxFreq]))
    ld a, $80
    sub l
    ld a, $60 ; 96.5
    sbc h
    ld e, a ; ⌊96.5-12*(log₂(k/Freq("C2"))-log₂(2048-[wCxFreq]))⌋
    ld a, [wTmpCh]
    ld c, a
    ld b, 0
    ld hl, wChLastNotes
    add hl, bc
    add hl, bc
    add hl, bc
    ld a, e
    ld [hli], a
    srl a
    srl a
    and $fe
    ld [hli], a
    ld a, e
    and 7
    sla a
    ld [hli], a
    ret

.nonote
    ld a, [wTmpCh]
    ld c, a
    ld b, 0
    ld hl, wChLastNotes
    add hl, bc
    add hl, bc
    add hl, bc
    ld a, $ff
    ld [hli], a
    ld [hl], a
    ret

LogTable:
; ⌊log₂(1+(x/256))*256⌋
    db   0,   1,   2,   4,   5,   7,   8,   9,  11,  12,  14,  15,  16,  18,  19,  21
    db  22,  23,  25,  26,  27,  29,  30,  31,  33,  34,  35,  37,  38,  39,  40,  42
    db  43,  44,  46,  47,  48,  49,  51,  52,  53,  54,  56,  57,  58,  59,  61,  62
    db  63,  64,  65,  67,  68,  69,  70,  71,  73,  74,  75,  76,  77,  78,  80,  81
    db  82,  83,  84,  85,  87,  88,  89,  90,  91,  92,  93,  94,  96,  97,  98,  99
    db 100, 101, 102, 103, 104, 105, 106, 108, 109, 110, 111, 112, 113, 114, 115, 116
    db 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 131, 132, 133
    db 134, 135, 136, 137, 138, 139, 140, 140, 141, 142, 143, 144, 145, 146, 147, 148
    db 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 162, 163
    db 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 173, 174, 175, 176, 177, 178
    db 179, 180, 181, 181, 182, 183, 184, 185, 186, 187, 188, 188, 189, 190, 191, 192
    db 193, 194, 194, 195, 196, 197, 198, 199, 200, 200, 201, 202, 203, 204, 205, 205
    db 206, 207, 208, 209, 209, 210, 211, 212, 213, 214, 214, 215, 216, 217, 218, 218
    db 219, 220, 221, 222, 222, 223, 224, 225, 225, 226, 227, 228, 229, 229, 230, 231
    db 232, 232, 233, 234, 235, 235, 236, 237, 238, 239, 239, 240, 241, 242, 242, 243
    db 244, 245, 245, 246, 247, 247, 248, 249, 250, 250, 251, 252, 253, 253, 254, 255