/**
* @brief Collision handler for 'search ROM' procedure.
* @details You can find algorithm details in APPNOTE 187
* "1-Wire Search Algorithm" from Maxim
*
* @param[in,out] sr pointer to the @p onewire_search_rom_t helper structure
*/
static uint8_t collision_handler(onewire_search_rom_t *sr) {
uint8_t bit;
switch(sr->reg.search_iter) {
case ONEWIRE_SEARCH_ROM_NEXT:
if ((int)sr->reg.rombit < sr->last_zero_branch) {
bit = extract_path_bit(sr->prev_path, sr->reg.rombit);
if (0 == bit) {
sr->prev_zero_branch = sr->reg.rombit;
sr->reg.result = ONEWIRE_SEARCH_ROM_SUCCESS;
}
store_bit(sr, bit);
return bit;
}
else if ((int)sr->reg.rombit == sr->last_zero_branch) {
sr->last_zero_branch = sr->prev_zero_branch;
store_bit(sr, 1);
return 1;
}
else {
/* found next branch some levels deeper */
sr->prev_zero_branch = sr->last_zero_branch;
sr->last_zero_branch = sr->reg.rombit;
store_bit(sr, 0);
sr->reg.result = ONEWIRE_SEARCH_ROM_SUCCESS;
return 0;
}
break;
case ONEWIRE_SEARCH_ROM_FIRST:
/* always take 0-branch */
sr->prev_zero_branch = sr->last_zero_branch;
sr->last_zero_branch = sr->reg.rombit;
store_bit(sr, 0);
sr->reg.result = ONEWIRE_SEARCH_ROM_SUCCESS;
return 0;
break;
default:
osalSysHalt("Unhandled case");
return 0; /* warning supressor */
break;
}
}
int main(void)
{
// Allocate a bit vector no larger than MAX_BITS in size.
const size_t bit_vector_size = MAX_BITS / CHAR_BIT * sizeof(unsigned char);
unsigned char* bits = malloc(bit_vector_size);
if (!bits)
{
fprintf(stderr, "unable to allocate %lu bytes: %s\n",
bit_vector_size, strerror(errno));
exit(EXIT_FAILURE);
}
for (int pass = 0; pass < 2; pass++)
{
memset(bits, 0, MAX_BITS / CHAR_BIT);
int offset = (pass == 0) ? 0 : -(MAX_BITS / CHAR_BIT);
char buffer[BUFSIZ];
while (fgets(buffer, sizeof(buffer), stdin) != NULL)
{
int n = atoi(buffer);
if (pass == 0 && n < MAX_BITS)
store_bit(n, bits, offset);
else if (pass == 1 && n >= MAX_BITS)
store_bit(n, bits, offset);
}
for (int i = (pass == 0) ? 0 : MAX_BITS, j = (pass == 0) ? MAX_BITS : MAX_VALUE; i < j; i++)
{
int byte = (i / CHAR_BIT) + offset;
int bit = i % CHAR_BIT;
if (bits[byte] & 1 << bit)
{
fprintf(stdout, "%07d\n", i);
}
}
}
free(bits);
return 0;
}
/**
* @brief 1-wire search ROM callback.
* @note Must be called from PWM's ISR.
*
* @param[in] pwmp pointer to the @p PWMDriver object
* @param[in] owp pointer to the @p onewireDriver object
*
* @notapi
*/
static void ow_search_rom_cb(PWMDriver *pwmp, onewireDriver *owp) {
onewire_search_rom_t *sr = &owp->search_rom;
if (0 == sr->reg.bit_step) { /* read direct bit */
sr->reg.bit_buf |= ow_read_bit(owp);
sr->reg.bit_step++;
}
else if (1 == sr->reg.bit_step) { /* read complement bit */
sr->reg.bit_buf |= ow_read_bit(owp) << 1;
sr->reg.bit_step++;
switch(sr->reg.bit_buf){
case 0b11:
/* no one device on bus or any other fail happened */
sr->reg.result = ONEWIRE_SEARCH_ROM_ERROR;
goto THE_END;
break;
case 0b01:
/* all slaves have 1 in this position */
store_bit(sr, 1);
ow_write_bit_I(owp, 1);
break;
case 0b10:
/* all slaves have 0 in this position */
store_bit(sr, 0);
ow_write_bit_I(owp, 0);
break;
case 0b00:
/* collision */
sr->reg.single_device = false;
ow_write_bit_I(owp, collision_handler(sr));
break;
}
}
else { /* start next step */
#if !ONEWIRE_SYNTH_SEARCH_TEST
ow_write_bit_I(owp, 1);
#endif
sr->reg.bit_step = 0;
sr->reg.bit_buf = 0;
}
/* one ROM successfully discovered */
if (64 == sr->reg.rombit) {
sr->reg.devices_found++;
sr->reg.search_iter = ONEWIRE_SEARCH_ROM_NEXT;
if (true == sr->reg.single_device)
sr->reg.result = ONEWIRE_SEARCH_ROM_LAST;
goto THE_END;
}
return; /* next search bit iteration */
THE_END:
#if ONEWIRE_SYNTH_SEARCH_TEST
(void)pwmp;
return;
#else
osalSysLockFromISR();
pwmDisableChannelI(pwmp, owp->config->master_channel);
pwmDisableChannelI(pwmp, owp->config->sample_channel);
osalThreadResumeI(&(owp)->thread, MSG_OK);
osalSysUnlockFromISR();
#endif
}
