; ---------------------------------------------------------------- input
; The keyboard read directly (interrupts stay off: the engine pops weights
; off the stack pointer), the beeper, and the dice.

; scan: A = the key held (0: none). The shifts are passed over, so CAPS
; SHIFT with 6 or 7 (the cursor keys) reads as 6 or 7.
scan:   push de
        ld hl,KEYTAB
        ld bc,$fefe
.r:     in a,(c)
        cpl
        and $1f
        ld e,5
.b:     rra
        jr nc,.n
        ld d,a
        ld a,(hl)
        or a
        jr nz,.got
        ld a,d
.n:     inc hl
        dec e
        jr nz,.b
        rlc b
        jr c,.r
        xor a
.got:   pop de
        ret

; getk: getkey, the keys it will take (for KSET) in A.
getk:   ld (KSET),a

; getkey: A = the next key pressed (after the last is let go). The time
; waited stirs the dice. I is not returned: it shows or hides the pip
; counts. KWAIT is 1 while it waits; KSET is left at K_ANY.
getkey: call scan
        or a
        jr nz,getkey
        ld b,20
        call pause
        ld a,1
        ld (KWAIT),a
.w:     ld hl,(SEED)
        inc hl
        ld a,h
        or l
        jr nz,.s
        inc hl
.s:     ld (SEED),hl
        call scan
        or a
        jr z,.w
        push af
        xor a
        ld (KWAIT),a
        call click
        pop af
        ; I, anywhere: the pip counts shown or hidden
        cp 'I'
        jr z,.pips
        push af
        xor a                   ; K_ANY
        ld (KSET),a
        pop af
        ret
.pips:  ld a,(PIPOFF)
        xor 1
        ld (PIPOFF),a
        ld a,(UP)
        or a
        call nz,drawpips
        jr getkey

KEYTAB: db 0,'Z','X','C','V'
        db 'A','S','D','F','G'
        db 'Q','W','E','R','T'
        db '1','2','3','4','5'
        db '0','9','8','7','6'
        db 'P','O','I','U','Y'
        db 13,'L','K','J','H'
        db ' ',0,'M','N','B'

; yesno: carry for Y, not for N; A = the keys' set (K_TAKE or K_AGAIN).
yesno:  push af
        call getk
        pop bc
        cp 'Y'
        scf
        ret z
        cp 'N'
        ld a,b
        jr nz,yesno
        or a
        ret

; pause: B fiftieths of a second, about.
pause:  push bc
        ld bc,2600
.l:     dec bc
        ld a,b
        or c
        jr nz,.l
        pop bc
        djnz pause
        ret

; tone: B cycles of a square wave, C its half period.
tone:   ld a,$10
.l:     out ($fe),a
        ld e,c
.d:     dec e
        jr nz,.d
        xor $10
        djnz .l
        xor a
        out ($fe),a
        ret

click:  ld bc,$0660
        jr tone

; tune: HL -> pairs of half period and cycles, ended by 0.
tune:   ld c,(hl)
        inc hl
        ld a,c
        or a
        ret z
        ld b,(hl)
        inc hl
        push hl
        call tone
        pop hl
        jr tune

; rand: A = a random byte (xorshift).
rand:   ld hl,(SEED)
        ld a,h
        rra
        ld a,l
        rra
        xor h
        ld h,a
        ld a,l
        rra
        ld a,h
        rra
        xor l
        ld l,a
        xor h
        ld h,a
        ld (SEED),hl
        ret

; rand6: A = a die, 1 to 6.
rand6:  call rand
        and 7
        cp 6
        jr nc,rand6
        inc a
        ret

; roll: the dice rolled for SHOWN, rattling.
roll:   ld b,7
.r:     push bc
        call rand6
        ld (DIE1),a
        call rand6
        ld (DIE2),a
        call drawdice
        call rand
        and $3f
        or $20
        ld c,a
        ld b,4
        call tone
        ld b,3
        call pause
        pop bc
        djnz .r
        ; shown larger first, but the opening roll's (one die each)
        ld a,(SHOWN)
        cp 3
        jr z,setdice
        ld a,(DIE1)
        ld b,a
        ld a,(DIE2)
        cp b
        jr c,setdice
        jr z,setdice
        ld (DIE1),a
        ld a,b
        ld (DIE2),a
; setdice: DHI >= DLO from DIE1, DIE2, larger first for the engine.
setdice:
        ld a,(DIE1)
        ld b,a
        ld a,(DIE2)
        cp b
        jr c,.lo
        ld (DHI),a
        ld a,b
        ld (DLO),a
        ret
.lo:    ld (DLO),a
        ld a,b
        ld (DHI),a
        ret

T_WIN:  db $50,40,$40,50,$30,60,$28,120,0
T_LOSE: db $30,40,$40,40,$60,40,$80,80,0
T_DBL:  db $30,30,$28,30,$30,30,$28,60,0