SMW RNG

Original 6502 code:
-------------------
GetRand:
PHY
LDY #$01
JSR TickRandom
DEY
JSR TickRandom
PLY
RTL

TickRandom:
LDA $148B
ASL
ASL
SEC
ADC $148B
STA $148B
ASL $148C
LDA #$20
BIT $148C
BCC Label1
BEQ Label3
BNE Label2
Label1: BNE Label3
Label2: INC $148C
Label3: LDA $148C
EOR $148B
STA $148D,Y
RTL

Converted GBz80 code: (with help of GBDev Discord)
--------------------------------------------------
Random_:
        ld bc,wRandomState+3
        call TickRandom
        dec bc
        jp TickRandom

TickRandom:
        ld hl,wRandomState
        ld a,(hl)
        add a,a
        add a,a
        scf
        adc a,(hl)
        ld (hli),a
        sla (hl)
        bit 5,(hl)
        jr nc,.one
        jr z,.three
        jr nz,.two
.one    jr nz,.three
.two    inc (hl)
.three  ld a,(hld)
        xor (hl)
        ld h,b ; ld16 hl,bc
        ld l,c
        ld (hl),a
        ret