optimized and cleaned

main.c

@@ -10,30 +10,44 @@
 
 void main(void)
 {
+    // The search algorithm stores its internal state in a struct.
+
+    // This allows calling it repeatedly if there are more devices
+    // than could fit in the address buffer.
+
     struct ow_search_state search_state;
-    ow_search_init(&search_state, 0xFF); // the real onewire search command will go here when used with real hw
+    ow_search_init(&search_state, 0xF0); // SEARCH_ROM
 
-    ow_romcode_t addresses[4];
+    // Buffer for the found addresses - can have up to 65536 rows
+    // Keep in mind that each address uses 8 bytes
+    #define CODE_BUFFER_LEN 8
+    ow_romcode_t addresses[CODE_BUFFER_LEN];
 
-    int x=0;
+    // The algorithm stores its return value in the status field,
+    // we can loop until it becomes OW_SEARCH_DONE or OW_SEARCH_FAILED
     while (search_state.status == OW_SEARCH_MORE) {
-        uint16_t count = ow_search_run(&search_state, addresses, 4);
+        // Perform a run of the algorithm
+        uint16_t count = ow_search_run(&search_state, addresses, CODE_BUFFER_LEN);
+
+        // Do something with the found addresses
         printf("Found %d addresses, status %d\n", count, search_state.status);
-        for(int i=0; i<count; i++) {
+        for (int i = 0; i < count; i++) {
-            for(int j=0; j<8; j++) {
+            printf("> ");
+            for (int j = 0; j < 8; j++) {
                 printf("%02x ", addresses[i][j]);
             }
-            printf("\n");
+            uint64_t numeric = ow_romcode_to_u64(addresses[i]);
-            uint64_t numeric = *((uint64_t*)(void*)&addresses[i][0]);
+            printf(" (0x%016"PRIx64")\n", numeric);
-            printf("n = 0x%016"PRIx64"\n", numeric);
         }
         printf("\n");
-        if(++x > 10) break;
     }
 }
 
 // ------------ SIMULATOR ---------------
 
+// A simple 1-wire bus simulation following the real behavior of bus devices
+// in the search operation.
+
 struct owunit {
     ow_romcode_t romcode;
     bool selected;

ow_search.c

@@ -1,5 +1,6 @@
 //
 // Created by MightyPork on 2018/02/01.
+// MIT license
 //
 
 #include <stdlib.h>
@@ -12,14 +13,13 @@
 void ow_search_init(struct ow_search_state *state, uint8_t command)
 {
     state->prev_last_fork = 64;
-    memset(&state->prev_code[0], 0, 8);
+    memset(state->prev_code, 0, 8);
     state->status = OW_SEARCH_MORE;
     state->command = command;
     state->first = true;
 }
 
-uint16_t
+uint16_t ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capacity)
-ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capacity)
 {
     if (state->status != OW_SEARCH_MORE) return 0;
 
@@ -38,6 +38,8 @@ ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capac
         // Send the search command (SEARCH_ROM, SEARCH_ALARM)
         ow_write_u8(state->command);
 
+        uint8_t *code_byte = &code[0];
+
         bool p, n;
         while (index != 64) {
             // Read a bit and its complement
@@ -47,8 +49,7 @@ ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capac
             if (!p && !n) {
                 // A fork: there are devices on the bus with different bit value
                 // (the bus is open-drain, in both cases one device pulls it low)
-                if ((found_devices > 0 || !state->first) &&
+                if ((found_devices > 0 || !state->first) && index < state->prev_last_fork) {
-                    index < state->prev_last_fork) {
                     // earlier than the last fork, take the same turn as before
                     p = ow_code_getbit(state->prev_code, index);
                     if (!p) last_fork = index; // remember for future runs, 1 not explored yet
@@ -67,15 +68,18 @@ ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capac
             }
 
             // All devices have a matching bit here, or it was resolved in a fork
-            if (p) ow_code_setbit(code, index);
+            if (p) *code_byte |= (1 << (index & 7));
             ow_write_bit(p);
+
             index++;
+            if((index & 7) == 0) {
+                code_byte++;
+            }
         }
 
         // Record a found address
-        for (int i = 0; i < 8; i++) {
+        memcpy(state->prev_code, code, 8);
-            state->prev_code[i] = codes[found_devices][i] = code[i];
+        memcpy(codes[found_devices], code, 8);
-        }
         found_devices++;
 
         // Stop condition
@@ -86,7 +90,8 @@ ow_search_run(struct ow_search_state *state, ow_romcode_t *codes, uint16_t capac
 
         state->prev_last_fork = last_fork;
     }
-    done:
+
+done:
     state->first = false;
     return found_devices;
 }

ow_search.h

@@ -1,5 +1,6 @@
 //
-// Created by MightyPork on 2018/02/01.
+// Created by MightyPork on 2018/02/01
+// MIT license
 //
 
 #ifndef OW_SEARCH_H
@@ -39,13 +40,21 @@ extern bool ow_read_bit(void);
 
 // --------------------------------------------------------------------------------------
 
-/** Data type holding one romcode */
+/**
+ * Data type holding a romcode
+ */
 typedef uint8_t ow_romcode_t[8];
 
-/** Get a bit from a romcode */
+/**
-#define ow_code_getbit(code, index) (bool)((code)[(index) / 8] & (1 << ((index) % 8)))
+ * Get a single bit from a romcode
-/** Set a bit to 1 in a romcode */
+ */
-#define ow_code_setbit(code, index) ((code)[(index) / 8] |= (1 << ((index) % 8)))
+#define ow_code_getbit(code, index) (bool)((code)[(index) >> 3] & (1 << ((index) & 7)))
+
+/**
+ * Convert to unsigned 64-bit integer
+ * (works only on little-endian systems - eg. OK on x86/x86_64, not on PowerPC)
+ */
+#define ow_romcode_to_u64(code) (*((uint64_t *) (void *)(code)))
 
 /**
  * States of the search algorithm