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|
; Beeper engine
; Copyright (C) 2021 by Juan J. Martinez <jjm@usebox.net>
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in
; all copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
; THE SOFTWARE.
;
.globl _beeper_init
.globl _beeper_queue
.globl _beeper_play
_beeper_init::
di
ld (sfx_data), hl
xor a
ld (sfx_type), a
ei
ret
_beeper_queue::
di
ld a, l
call queue_next
ei
ret
queue_next:
ld (sfx_type), a
or a
ret z
dec a
ld hl, (sfx_data)
ld c, l
ld b, h
ld h, #0
ld l, a
ld d, h
ld e, l
add hl, hl
add hl, hl
add hl, de
add hl, bc
ld de, #sfx_type
ld bc, #5
ldir
ret
_beeper_play::
ld a, (sfx_type)
or a
ret z
dec a
jr z, tone
dec a
; shouldn't happen!
ret nz
; noise
ld a, (sfx_freq)
ld d, a
ld b, #0
noise_loop:
call rnd
and #0x10
; FIXME: border ?
out (0xfe), a
ld c, d
noise_freq_loop:
dec b
jr z, noise_done
dec c
jr nz, noise_freq_loop
jr noise_loop
tone:
ld a, (sfx_freq)
ld d, a
xor a
ld b, a
tone_loop:
; FIXME: border ?
out (0xfe), a
xor #0x10
ld c, d
freq_loop:
dec b
jr z, tone_done
dec c
jr nz, freq_loop
jr tone_loop
tone_done:
noise_done:
ld a, (sfx_next)
ld hl, #sfx_frames
dec (hl)
jr z, queue_next
; freq change (slide)
ld a, (sfx_freq_chg)
add d
ld (sfx_freq), a
ret
rnd:
ld hl, #0xf3a1
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 (rnd + 1), hl
ret
sfx_type: .ds 1
sfx_frames: .ds 1
sfx_freq: .ds 1
sfx_freq_chg: .ds 1
sfx_next: .ds 1
sfx_data: .ds 2
|
