parent
a81190c2e1
commit
0e378b6547
GPG Key ID:
2C5FD5035250423D
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//
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// Created by MightyPork on 2018/02/01.
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//
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#include "platform.h" |
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#include "_ow_checksum.h" |
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static inline uint8_t crc8_bits(uint8_t data) |
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{ |
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uint8_t crc = 0; |
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if(data & 1) crc ^= 0x5e; |
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if(data & 2) crc ^= 0xbc; |
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if(data & 4) crc ^= 0x61; |
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if(data & 8) crc ^= 0xc2; |
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if(data & 0x10) crc ^= 0x9d; |
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if(data & 0x20) crc ^= 0x23; |
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if(data & 0x40) crc ^= 0x46; |
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if(data & 0x80) crc ^= 0x8c; |
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return crc; |
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} |
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static uint8_t crc8_add(uint8_t cksum, uint8_t byte) |
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{ |
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return crc8_bits(byte ^ cksum); |
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} |
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uint8_t ow_checksum(const uint8_t *buff, uint16_t len) |
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{ |
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uint8_t cksum = 0; |
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for(uint16_t i = 0; i < len; i++) { |
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cksum = crc8_add(cksum, buff[i]); |
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} |
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return cksum; |
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} |
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//
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// Created by MightyPork on 2018/02/01.
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//
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#ifndef GEX_F072_OW_CHECKSUM_H |
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#define GEX_F072_OW_CHECKSUM_H |
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#include <stdint.h> |
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/**
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* Compute a 1-wire type checksum. |
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* If the buffer includes the checksum, the result should be 0. |
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* |
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* (this function may be used externally, or you can delete the implementation |
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* from the c file if another implementation is already available) |
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* |
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* @param[in] buf - buffer of bytes to verify |
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* @param[in] len - buffer length |
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* @return checksum |
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*/ |
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uint8_t ow_checksum(const uint8_t *buf, uint16_t len); |
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#endif //GEX_F072_OW_CHECKSUM_H
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//
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// Created by MightyPork on 2018/02/01.
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//
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#ifndef GEX_F072_OW_LOW_LEVEL_H |
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#define GEX_F072_OW_LOW_LEVEL_H |
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#include "platform.h" |
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#include "unit_base.h" |
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#include "_ow_low_level.h" |
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/**
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* Reset the 1-wire bus |
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*/ |
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bool ow_reset(Unit *unit); |
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/**
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* Write a bit to the 1-wire bus |
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*/ |
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void ow_write_bit(Unit *unit, bool bit); |
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/**
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* Read a bit from the 1-wire bus |
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*/ |
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bool ow_read_bit(Unit *unit); |
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/**
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* Write a byte to the 1-wire bus |
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*/ |
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void ow_write_u8(Unit *unit, uint8_t byte); |
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/**
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* Write a halfword to the 1-wire bus |
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*/ |
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void ow_write_u16(Unit *unit, uint16_t halfword); |
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/**
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* Write a word to the 1-wire bus |
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*/ |
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void ow_write_u32(Unit *unit, uint32_t word); |
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/**
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* Write a doubleword to the 1-wire bus |
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*/ |
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void ow_write_u64(Unit *unit, uint64_t dword); |
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/**
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* Read a byte form the 1-wire bus |
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*/ |
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uint8_t ow_read_u8(Unit *unit); |
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/**
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* Read a halfword form the 1-wire bus |
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*/ |
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uint16_t ow_read_u16(Unit *unit); |
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/**
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* Read a word form the 1-wire bus |
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*/ |
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uint32_t ow_read_u32(Unit *unit); |
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/**
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* Read a doubleword form the 1-wire bus |
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*/ |
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uint64_t ow_read_u64(Unit *unit); |
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#endif //GEX_F072_OW_LOW_LEVEL_H
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//
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// Created by MightyPork on 2018/02/01.
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//
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#include "platform.h" |
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#include "unit_1wire.h" |
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#define OW_INTERNAL |
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#include "_ow_search.h" |
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#include "_ow_internal.h" |
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#include "_ow_low_level.h" |
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#include "_ow_checksum.h" |
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#include "_ow_commands.h" |
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void ow_search_init(Unit *unit, uint8_t command, bool test_checksums) |
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{ |
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if (unit->driver != &UNIT_1WIRE) |
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trap("Wrong unit type - %s", unit->driver->name); |
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assert_param(command == OW_ROM_SEARCH || command == OW_ROM_ALM_SEARCH); |
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struct priv *priv = unit->data; |
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struct ow_search_state *state = &priv->searchState; |
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state->prev_last_fork = 64; |
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memset(state->prev_code, 0, 8); |
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state->status = OW_SEARCH_MORE; |
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state->command = command; |
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state->first = true; |
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state->test_checksums = test_checksums; |
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} |
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uint16_t ow_search_run(Unit *unit, ow_romcode_t *codes, uint16_t capacity) |
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{ |
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if (unit->driver != &UNIT_1WIRE) |
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trap("Wrong unit type - %s", unit->driver->name); |
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assert_param(codes); |
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struct priv *priv = unit->data; |
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struct ow_search_state *state = &priv->searchState; |
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if (state->status != OW_SEARCH_MORE) return 0; |
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uint16_t found_devices = 0; |
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while (found_devices < capacity) { |
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uint8_t index = 0; |
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ow_romcode_t code = {}; |
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int8_t last_fork = -1; |
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// Start a new transaction. Devices respond to reset
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if (!ow_reset(unit)) { |
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state->status = OW_SEARCH_FAILED; |
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goto done; |
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} |
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// Send the search command (SEARCH_ROM, SEARCH_ALARM)
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ow_write_u8(unit, state->command); |
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uint8_t *code_byte = &code[0]; |
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bool p, n; |
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while (index != 64) { |
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// Read a bit and its complement
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p = ow_read_bit(unit); |
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n = ow_read_bit(unit); |
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if (!p && !n) { |
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// A fork: there are devices on the bus with different bit value
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// (the bus is open-drain, in both cases one device pulls it low)
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if ((found_devices > 0 || !state->first) && index < state->prev_last_fork) { |
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// earlier than the last fork, take the same turn as before
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p = ow_code_getbit(state->prev_code, index); |
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if (!p) last_fork = index; // remember for future runs, 1 not explored yet
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} |
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else if (index == state->prev_last_fork) { |
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p = 1; // both forks are now exhausted
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} |
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else { // a new fork
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last_fork = index; |
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} |
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} |
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else if (p && n) { |
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// No devices left connected - this doesn't normally happen
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state->status = OW_SEARCH_FAILED; |
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goto done; |
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} |
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// All devices have a matching bit here, or it was resolved in a fork
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if (p) *code_byte |= (1 << (index & 7)); |
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ow_write_bit(unit, p); |
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index++; |
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if((index & 7) == 0) { |
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code_byte++; |
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} |
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} |
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memcpy(state->prev_code, code, 8); |
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if (!state->test_checksums || 0 == ow_checksum(code, 8)) { |
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// Record a found address
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memcpy(codes[found_devices], code, 8); |
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found_devices++; |
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} |
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// Stop condition
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if (last_fork == -1) { |
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state->status = OW_SEARCH_DONE; |
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goto done; |
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} |
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state->prev_last_fork = last_fork; |
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} |
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done: |
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state->first = false; |
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return found_devices; |
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} |
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@ -0,0 +1,81 @@ |
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//
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// Created by MightyPork on 2018/02/01.
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//
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#ifndef GEX_F072_OW_SEARCH_H |
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#define GEX_F072_OW_SEARCH_H |
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#ifndef OW_INTERNAL |
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#error bad include! |
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#endif |
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#include <stdint.h> |
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#include <stdbool.h> |
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#include "unit_base.h" |
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// --------------------------------------------------------------------------------------
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/**
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* Data type holding a romcode |
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*/ |
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typedef uint8_t ow_romcode_t[8]; |
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/**
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* Get a single bit from a romcode |
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*/ |
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#define ow_code_getbit(code, index) (bool)((code)[(index) >> 3] & (1 << ((index) & 7))) |
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/**
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* Convert to unsigned 64-bit integer |
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* (works only on little-endian systems - eg. OK on x86/x86_64, not on PowerPC) |
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*/ |
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#define ow_romcode_to_u64(code) (*((uint64_t *) (void *)(code))) |
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/**
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* States of the search algorithm |
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*/ |
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enum ow_search_result { |
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OW_SEARCH_DONE = 0, |
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OW_SEARCH_MORE = 1, |
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OW_SEARCH_FAILED = 2, |
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}; |
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/**
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* Internal state of the search algorithm. |
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* Check status to see if more remain to be read or an error occurred. |
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*/ |
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struct ow_search_state { |
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int8_t prev_last_fork; |
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ow_romcode_t prev_code; |
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uint8_t command; |
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enum ow_search_result status; |
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bool first; |
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bool test_checksums; |
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}; |
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/**
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* Init the search algorithm state structure |
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* |
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* @param[out] state - inited struct |
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* @param[in] command - command to send for requesting the search (e.g. SEARCH_ROM) |
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* @param[in] test_checksums - verify checksums of all read romcodes |
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*/ |
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void ow_search_init(Unit *unit, uint8_t command, bool test_checksums); |
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/**
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* Perform a search of the 1-wire bus, with a state struct pre-inited |
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* using ow_search_init(). |
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* |
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* Romcodes are stored in the provided array in a numerically ascending order. |
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* |
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* This function may be called repeatedly to retrieve more addresses than could fit |
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* in the address buffer. |
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* |
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* @param[in,out] state - search state, used for multiple calls with limited buffer size |
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* @param[out] codes - buffer for found romcodes |
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* @param[in] capacity - buffer capacity |
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* @return number of romcodes found. Search status is stored in state->status |
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*/ |
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uint16_t ow_search_run(Unit *unit, ow_romcode_t *codes, uint16_t capacity); |
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#endif //GEX_F072_OW_SEARCH_H
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