39 lines
838 B
ArmAsm
39 lines
838 B
ArmAsm
;------------------------------------------------------------------------------
|
|
; beep
|
|
;
|
|
; Beeps the speaker
|
|
; DE sets duration
|
|
;------------------------------------------------------------------------------
|
|
beep:
|
|
push AF
|
|
push DE
|
|
di
|
|
beep_loop:
|
|
LD A,0x08
|
|
OUT (CS_PIO_AD), A
|
|
CALL beep_pause
|
|
LD A,0x00
|
|
OUT (CS_PIO_AD), A
|
|
CALL beep_pause
|
|
DEC DE
|
|
ld A,D
|
|
or E
|
|
jr NZ, beep_loop
|
|
pop de
|
|
pop af
|
|
ei
|
|
ret
|
|
|
|
beep_pause:
|
|
PUSH BC
|
|
_beep_pause_l1:
|
|
;NEG ; 8 T-states
|
|
;NEG ; 8 T-states
|
|
NEG ; 8 T-states
|
|
NEG ; 8 T-states
|
|
DEC BC ; 6 T-states
|
|
LD A,C ; 9 T-states
|
|
OR B ; 4 T-states
|
|
JP NZ,_beep_pause_l1 ; 10 T-states
|
|
POP BC
|
|
RET ; Pause complete, RETurn
|