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public bufinit
public ff_empty,ff_get,ff_full,ff_put
public ff_puth,ff_cnt,ff_gech
public fifolst
extrn msg.sm,hwl2phy
maclib z180reg.inc
maclib config.inc
;--------------------------------------------------------------------
dseg
fifolst:
rept 4
dw 0
endm
;--------------------------------------------------------------------
dseg
bufinit:
ld (ix+o.in_idx),0 ;reset pointers (empty fifo)
ld (ix+o.out_idx),0
ld a,(ix+o.id)
ld hl,fifolst
ld e,a
ld d,0
add hl,de
add hl,de
push ix
pop de
cp 4
jr nc,bfi_skip
ld (hl),e
inc hl
ld (hl),d
bfi_skip:
ex de,hl
call hwl2phy ;get phys. address of fifo
ld c,a
ld a,(ix+o.id) ;fifo id
or a ;test if fifo 0
ret z
cp 4
ret nc
; TODO: move to better place
ld b,a
push bc ;c: bank-addr, b: ignored
push hl ;address
ld c,0
push bc ;c: function, b:subf
ld b,5
ld h,c
ld l,c
add hl,sp
call msg.sm
pop hl
pop hl
pop hl
ret
;--------------------------------------------------------------
; Check if characters in fifo
; Fifo is empty, if output index and input index are the same
ff_empty:
ld a,(ix+o.in_idx) ;
sub (ix+o.out_idx) ;
ret z
or 0ffh
ret
;--------------------------------------------------------------
; get character from fifo
; destroys hl,b
;
; return:
; c,a: next character
ff_get:
push ix
pop hl
ld c,(ix+o.out_idx) ;
ld b,0
add hl,bc
ld a,c
bg.wait:
cp (ix+o.in_idx) ;
jr z,bg.wait
inc a
and (ix+o.mask)
ld c,(hl)
ld (ix+o.out_idx),a
ld a,c
ret
;--------------------------------------------------------------
; get character and ramaining count from fifo
; halt cpu, while buffer is empty
; destroys hl
;
; return:
; c,a: next character
; b: number of charachters in fifo
ff_gech:
push ix
pop hl
ld c,(ix+o.out_idx) ;
ld b,0
add hl,bc
gech.wait:
ld a,(ix+o.in_idx) ;
sub c
jr nz,gech.cont
halt
jr gech.wait
gech.cont:
and (ix+o.mask) ;
dec a
ld b,a
ld a,c
inc a
and (ix+o.mask)
ld c,(hl)
ld (ix+o.out_idx),a
ld a,c
ret
;--------------------------------------------------------------
; Check if room in fifo
; buffer is full, if output index is one behind input index
;
; return
; a = 0 and z if buffer full
; a = ff and nz if buffer not full
ff_full:
ld a,(ix+o.in_idx) ;
inc a ;
and (ix+o.mask) ;
sub (ix+o.out_idx) ;
ret z
or 0ffh
ret
;--------------------------------------------------------------
; put character in c in buffer
; destroys bc
ff_put:
push ix ;
ex (sp),hl ; get buffer start address
ld a,c ;
ld c,(ix+o.in_idx) ; add input index
ld b,0 ;
add hl,bc ;
ld (hl),a ; one place is allways free
pop hl ; restore hl
ld a,c ; bump input index
inc a ;
and (ix+o.mask) ;
bp.wait: ; do
cp (ix+o.out_idx) ;
jr z,bp.wait ; while new input idx == ouput idx
ld (ix+o.in_idx),a ;
ret ;
;--------------------------------------------------------------
; put character in c in buffer
; halt cpu, while buffer is is full
; destroys bc
ff_puth:
push ix ;
ex (sp),hl ; get buffer start address
ld a,c ;
ld c,(ix+o.in_idx) ; add input index
ld b,0 ;
add hl,bc ;
ld (hl),a ; one place is allways free
pop hl ; restore hl
ld a,c ; bump input index
inc a ;
and (ix+o.mask) ;
jr $+3
bph.wait: ; do
halt ; halt cpu
cp (ix+o.out_idx) ;
jr z,bph.wait ; while new input idx == ouput idx
ld (ix+o.in_idx),a ;
ret ;
;--------------------------------------------------------------
; Return number of characters in fifo
;
ff_cnt:
ld a,(ix+o.in_idx) ;
sub (ix+o.out_idx) ;
and (ix+o.mask) ;
ret
;--------------------------------------------------------------
end
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