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/*
* Output extender
*
* Copyright (c) 2013 Michael Buesch <m@bues.ch>
*
* 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 2 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "ioext.h"
struct ioext_context ioext_ctx;
/* Write the I/O-extender state out to the hardware
* shift register.
*/
void ioext_commit(void)
{
struct ioext_context *ctx = &ioext_ctx;
uint8_t chip;
/* For each chip. */
for (chip = 0; chip < EXTOUT_NR_CHIPS; chip++) {
/* Write the new state to the shift register,
* if it did not change.
*/
if (ctx->states[chip] != ctx->old_states[chip]) {
ctx->old_states[chip] = ctx->states[chip];
pcf8574_write(&ctx->chips[chip],
ctx->states[chip]);
}
}
}
/* Initialize the I/O-extender.
* This also initializes the shift register.
* If "all_ones" is true, all state bits are initialized to 1.
*/
void ioext_init(bool all_ones)
{
struct ioext_context *ctx = &ioext_ctx;
uint8_t chip;
/* Reset data structures. */
memset(ctx, 0, sizeof(*ctx));
if (all_ones) {
memset(ctx->states, 0xFF, sizeof(ctx->states));
memset(ctx->old_states, 0xFF, sizeof(ctx->states));
}
/* Initialize the shift register. */
for (chip = 0; chip < EXTOUT_NR_CHIPS; chip++)
pcf8574_init(&ctx->chips[chip], chip, 1, all_ones);
}
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