git.rot13.org Git - simavr/blob - simavr/sim/sim_twi.c

   1 /*
   2         sim_twi.c
   3
   4         Internal TWI/i2c slave/master subsystem
   5
   6         Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
   7
   8         This file is part of simavr.
   9
  10         simavr is free software: you can redistribute it and/or modify
  11         it under the terms of the GNU General Public License as published by
  12         the Free Software Foundation, either version 3 of the License, or
  13         (at your option) any later version.
  14
  15         simavr is distributed in the hope that it will be useful,
  16         but WITHOUT ANY WARRANTY; without even the implied warranty of
  17         MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18         GNU General Public License for more details.
  19
  20         You should have received a copy of the GNU General Public License
  21         along with simavr.  If not, see <http://www.gnu.org/licenses/>.
  22  */
  23
  24 #include <stdlib.h>
  25 #include "sim_twi.h"
  26
  27 void twi_bus_init(twi_bus_t * bus)
  28 {
  29 }
  30
  31 void twi_bus_attach(twi_bus_t * bus, twi_slave_t * slave)
  32 {
  33         twi_slave_detach(slave);
  34         slave->bus = bus;
  35         slave->next = bus->slave;
  36         bus->slave = slave;
  37 }
  38
  39 int twi_bus_start(twi_bus_t * bus, uint8_t address)
  40 {
  41         // if we already have a peer, check to see if it's
  42         // still matching, if so, skip the lookup
  43         if (bus->peer && twi_slave_match(bus->peer, address))
  44                 return bus->peer->start(bus->peer, address, 1);
  45
  46         bus->peer = NULL;
  47         twi_slave_t *s = bus->slave;
  48         while (s) {
  49                 if (twi_slave_match(s, address)) {
  50                         if (s->start(s, address, 0)) {
  51                                 bus->peer = s;
  52                                 s->byte_index = 0;
  53                                 return 1;
  54                         }
  55                 }
  56                 s = s->next;
  57         }
  58         return 0;
  59 }
  60
  61 void twi_bus_stop(twi_bus_t * bus)
  62 {
  63         if (bus->peer && bus->peer->stop)
  64                 bus->peer->stop(bus->peer);
  65         bus->peer = NULL;
  66 }
  67
  68 int twi_bus_write(twi_bus_t * bus, uint8_t data)
  69 {
  70         if (!bus->peer || !bus->peer->write)
  71                 return 0;
  72
  73         int res = bus->peer->write(bus->peer, data);
  74         if (bus->peer)
  75                 bus->peer->byte_index++;
  76         return res;
  77 }
  78
  79 uint8_t twi_bus_read(twi_bus_t * bus)
  80 {
  81         if (!bus->peer || !bus->peer->read)
  82                 return 0;
  83
  84         uint8_t res = bus->peer->read(bus->peer);
  85         if (bus->peer)
  86                 bus->peer->byte_index++;
  87         return res;
  88 }
  89
  90 void twi_slave_init(twi_slave_t * slave, void * param)
  91 {
  92         slave->param = param;
  93 }
  94
  95 void twi_slave_detach(twi_slave_t * slave)
  96 {
  97         if (!slave || !slave->bus)
  98                 return;
  99         twi_slave_t *s = slave->bus->slave;
 100         while (s) {
 101                 if (s->next == slave) {
 102                         // clear that, too
 103                         if (slave->bus->peer == slave)
 104                                 slave->bus->peer = NULL;
 105
 106                         s->next = slave->next;
 107                         slave->next = NULL;
 108                         slave->bus = NULL;
 109                         return;
 110                 }
 111                 s = s->next;
 112         }
 113 }
 114
 115 int twi_slave_match(twi_slave_t * slave, uint8_t address)
 116 {
 117         if (slave->has_address)
 118                 return slave->has_address(slave, address);
 119         return (address & ~1) == (slave->address & ~1);
 120 }
 121