headphones/firmware/code/i2s.pio

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; Copyright 2022 Colin Lam, Ploopy Corporation
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
.program i2s_read
.side_set 2
set x, 30 side 0b00
left_channel:
in pins, 1 side 0b11
jmp x-- left_channel side 0b10
in pins, 1 side 0b11
set x, 30 side 0b10
right_channel:
in pins, 1 side 0b01
jmp x--, right_channel side 0b00
in pins, 1 side 0b01
.program i2s_write
.side_set 2
set x, 30 side 0b01
left_channel:
out pins, 1 side 0b10
jmp x-- left_channel side 0b11
out pins, 1 side 0b10
set x, 30 side 0b11
right_channel:
out pins, 1 side 0b00
jmp x--, right_channel side 0b01
out pins, 1 side 0b00