int bitbang_i2c_set(bitbang_i2c_interface *i2c, int line, int level) { int data; if (level != 0 && level != 1) { abort(); } if (line == BITBANG_I2C_SDA) { if (level == i2c->last_data) { return bitbang_i2c_nop(i2c); } i2c->last_data = level; if (i2c->last_clock == 0) { return bitbang_i2c_nop(i2c); } if (level == 0) { DPRINTF("START\n"); /* START condition. */ i2c->state = SENDING_BIT7; i2c->current_addr = -1; } else { /* STOP condition. */ bitbang_i2c_enter_stop(i2c); } return bitbang_i2c_ret(i2c, 1); } data = i2c->last_data; if (i2c->last_clock == level) { return bitbang_i2c_nop(i2c); } i2c->last_clock = level; if (level == 0) { /* State is set/read at the start of the clock pulse. release the data line at the end. */ return bitbang_i2c_ret(i2c, 1); } switch (i2c->state) { case STOPPED: case SENT_NACK: return bitbang_i2c_ret(i2c, 1); case SENDING_BIT7 ... SENDING_BIT0: i2c->buffer = (i2c->buffer << 1) | data; /* will end up in WAITING_FOR_ACK */ i2c->state++; return bitbang_i2c_ret(i2c, 1); case WAITING_FOR_ACK: if (i2c->current_addr < 0) { i2c->current_addr = i2c->buffer; DPRINTF("Address 0x%02x\n", i2c->current_addr); i2c_start_transfer(i2c->bus, i2c->current_addr >> 1, i2c->current_addr & 1); } else { DPRINTF("Sent 0x%02x\n", i2c->buffer); i2c_send(i2c->bus, i2c->buffer); } if (i2c->current_addr & 1) { i2c->state = RECEIVING_BIT7; } else { i2c->state = SENDING_BIT7; } return bitbang_i2c_ret(i2c, 0); case RECEIVING_BIT7: i2c->buffer = i2c_recv(i2c->bus); DPRINTF("RX byte 0x%02x\n", i2c->buffer); /* Fall through... */ case RECEIVING_BIT6 ... RECEIVING_BIT0: data = i2c->buffer >> 7; /* will end up in SENDING_ACK */ i2c->state++; i2c->buffer <<= 1; return bitbang_i2c_ret(i2c, data); case SENDING_ACK: i2c->state = RECEIVING_BIT7; if (data != 0) { DPRINTF("NACKED\n"); i2c->state = SENT_NACK; i2c_nack(i2c->bus); } else { DPRINTF("ACKED\n"); } return bitbang_i2c_ret(i2c, 1); } abort(); }