From ef24cdc7dee3c56876c7d9bb9ceaa703d33a6a2e Mon Sep 17 00:00:00 2001
From: SirSydom <com@sirsydom.de>
Date: Sat, 19 Feb 2022 23:18:39 +0100
Subject: [PATCH] #175 added a binary search for address and assoc table can be
 enabled by defining USE_BINSEARCH

---
 src/knx/address_table_object.cpp     | 39 +++++++++++++++++++++++++++-
 src/knx/association_table_object.cpp | 24 +++++++++++++++++
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/src/knx/address_table_object.cpp b/src/knx/address_table_object.cpp
index 689580c..5c90b40 100644
--- a/src/knx/address_table_object.cpp
+++ b/src/knx/address_table_object.cpp
@@ -36,9 +36,28 @@ uint16_t AddressTableObject::getGroupAddress(uint16_t tsap)
 uint16_t AddressTableObject::getTsap(uint16_t addr)
 {
     uint16_t size = entryCount();
+    #ifdef USE_BINSEARCH
+    addr = htons(addr);
+
+    uint16_t low,high,i;
+    low = 0;
+    high = size-1;
+
+    while(low <= high)
+    {
+        i = (low+high)/2;
+        if (_groupAddresses[i] == addr)
+            return i;
+        if(addr < _groupAddresses[i])
+            high = i - 1;
+        else
+            low = i + 1 ;
+    }
+    #else
     for (uint16_t i = 1; i <= size; i++)
         if (ntohs(_groupAddresses[i]) == addr)
             return i;
+    #endif
     return 0;
 }
 
@@ -58,10 +77,28 @@ const uint8_t* AddressTableObject::restore(const uint8_t* buffer)
 bool AddressTableObject::contains(uint16_t addr)
 {
     uint16_t size = entryCount();
+    #ifdef USE_BINSEARCH
+    addr = htons(addr);
+
+    uint16_t low,high,i;
+    low = 0;
+    high = size-1;
+
+    while(low <= high)
+    {
+        i = (low+high)/2;
+        if (_groupAddresses[i] == addr)
+            return true;
+        if(addr < _groupAddresses[i])
+            high = i - 1;
+        else
+            low = i + 1 ;
+    }
+    #else
     for (uint16_t i = 1; i <= size; i++)
         if (ntohs(_groupAddresses[i]) == addr)
             return true;
-
+    #endif
     return false;
 }
 
diff --git a/src/knx/association_table_object.cpp b/src/knx/association_table_object.cpp
index 0880fc7..b1d8c56 100644
--- a/src/knx/association_table_object.cpp
+++ b/src/knx/association_table_object.cpp
@@ -50,11 +50,35 @@ const uint8_t* AssociationTableObject::restore(const uint8_t* buffer)
 int32_t AssociationTableObject::translateAsap(uint16_t asap)
 {
     uint16_t entries = entryCount();
+    #ifdef USE_BINSEARCH
+    uint16_t low,high,i;
+    low = 0;
+    high = entries-1;
+
+    while(low <= high)
+    {
+        i = (low+high)/2;
+        uint16_t asap_i = getASAP(i);
+        if (asap_i == asap)
+        {
+             // as the binary search does not hit the first element in a list with identical items,
+             // search downwards to return the first occurence in the table
+            while(getASAP(--i) == asap)
+                ;
+            return getASAP(i+1);
+        }
+        if(asap_i < asap)
+            high = i - 1;
+        else
+            low = i + 1 ;
+    }
+    #else
     for (uint16_t i = 0; i < entries; i++)
     {
         if (getASAP(i) == asap)
             return getTSAP(i);
     }
+    #endif
     return -1;
 }