[code-utils] adding helper macro OT_ARRAY_LENGTH() (#2743)

This commit adds helper macro `OT_ARRAY_LENGTH()` to get the number
of elements in an array.

src/cli/cli.cpp

@@ -393,7 +393,7 @@ otError Interpreter::ParseUnsignedLong(char *argv, unsigned long &value)
 
 void Interpreter::ProcessHelp(int argc, char *argv[])
 {
-    for (unsigned int i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (unsigned int i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         mServer->OutputFormat("%s\r\n", sCommands[i].mName);
     }
@@ -3443,7 +3443,7 @@ void Interpreter::ProcessLine(char *aBuf, uint16_t aBufLength, Server &aServer)
         mServer->OutputFormat("under diagnostics mode, execute 'diag stop' before running any other commands.\r\n"));
 #endif
 
-    for (i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         if (strcmp(cmd, sCommands[i].mName) == 0)
         {
@@ -3454,7 +3454,7 @@ void Interpreter::ProcessLine(char *aBuf, uint16_t aBufLength, Server &aServer)
 
     // Check user defined commands if built-in command
     // has not been found
-    if (i == sizeof(sCommands) / sizeof(sCommands[0]))
+    if (i == OT_ARRAY_LENGTH(sCommands))
     {
         for (i = 0; i < mUserCommandsLength; i++)
         {
@@ -3494,14 +3494,13 @@ void Interpreter::HandleNetifStateChanged(uint32_t aFlags)
     VerifyOrExit((aFlags & OT_CHANGED_THREAD_NETDATA) != 0);
 
 #ifndef OTDLL
-    otIp6SlaacUpdate(mInstance, mSlaacAddresses, sizeof(mSlaacAddresses) / sizeof(mSlaacAddresses[0]),
-                     otIp6CreateRandomIid, NULL);
+    otIp6SlaacUpdate(mInstance, mSlaacAddresses, OT_ARRAY_LENGTH(mSlaacAddresses), otIp6CreateRandomIid, NULL);
 #if OPENTHREAD_ENABLE_DHCP6_SERVER
     otDhcp6ServerUpdate(mInstance);
 #endif // OPENTHREAD_ENABLE_DHCP6_SERVER
 
 #if OPENTHREAD_ENABLE_DHCP6_CLIENT
-    otDhcp6ClientUpdate(mInstance, mDhcpAddresses, sizeof(mDhcpAddresses) / sizeof(mDhcpAddresses[0]), NULL);
+    otDhcp6ClientUpdate(mInstance, mDhcpAddresses, OT_ARRAY_LENGTH(mDhcpAddresses), NULL);
 #endif // OPENTHREAD_ENABLE_DHCP6_CLIENT
 #endif
 

src/cli/cli_dataset.cpp

@@ -199,7 +199,7 @@ otError Dataset::Process(otInstance *aInstance, int argc, char *argv[], Server &
         ExitNow(error = Print(sDataset));
     }
 
-    for (unsigned int i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (unsigned int i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         if (strcmp(argv[0], sCommands[i].mName) == 0)
         {
@@ -214,7 +214,7 @@ exit:
 
 otError Dataset::ProcessHelp(otInstance *aInstance, int argc, char *argv[])
 {
-    for (unsigned int i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (unsigned int i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         sServer->OutputFormat("%s\r\n", sCommands[i].mName);
     }

src/cli/cli_udp_example.cpp

@@ -56,7 +56,7 @@ UdpExample::UdpExample(Interpreter &aInterpreter)
 
 otError UdpExample::ProcessHelp(int argc, char *argv[])
 {
-    for (unsigned int i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (unsigned int i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         mInterpreter.mServer->OutputFormat("%s\r\n", sCommands[i].mName);
     }
@@ -180,7 +180,7 @@ otError UdpExample::Process(int argc, char *argv[])
 {
     otError error = OT_ERROR_PARSE;
 
-    for (size_t i = 0; i < sizeof(sCommands) / sizeof(sCommands[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(sCommands); i++)
     {
         if (strcmp(argv[0], sCommands[i].mName) == 0)
         {

src/core/common/code_utils.hpp

@@ -38,6 +38,16 @@
 
 #include "utils/wrap_stdbool.h"
 
+/**
+ * This macro calculates the number of elements in an array.
+ *
+ * @param[in] aArray  Name of the array variable.
+ *
+ * @returns Number of elements in the array.
+ *
+ */
+#define OT_ARRAY_LENGTH(aArray) (sizeof(aArray) / sizeof(aArray[0]))
+
 // Calculates the aligned variable size.
 #define otALIGNED_VAR_SIZE(size, align_type) (((size) + (sizeof(align_type) - 1)) / sizeof(align_type))
 

src/core/meshcop/commissioner.cpp

@@ -156,7 +156,7 @@ otError Commissioner::SendCommissionerSet(void)
     steeringData.Init();
     steeringData.Clear();
 
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         if (!mJoiners[i].mValid)
         {
@@ -187,7 +187,7 @@ exit:
 
 void Commissioner::ClearJoiners(void)
 {
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         mJoiners[i].mValid = false;
     }
@@ -204,7 +204,7 @@ otError Commissioner::AddJoiner(const Mac::ExtAddress *aEui64, const char *aPSKd
     VerifyOrExit(strlen(aPSKd) <= Dtls::kPskMaxLength, error = OT_ERROR_INVALID_ARGS);
     RemoveJoiner(aEui64, 0); // remove immediately
 
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         if (mJoiners[i].mValid)
         {
@@ -259,7 +259,7 @@ otError Commissioner::RemoveJoiner(const Mac::ExtAddress *aEui64, uint32_t aDela
 
     VerifyOrExit(mState == OT_COMMISSIONER_STATE_ACTIVE, error = OT_ERROR_INVALID_STATE);
 
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         if (!mJoiners[i].mValid)
         {
@@ -366,7 +366,7 @@ void Commissioner::HandleJoinerExpirationTimer(void)
     uint32_t now = TimerMilli::GetNow();
 
     // Remove Joiners.
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         if (!mJoiners[i].mValid)
         {
@@ -389,7 +389,7 @@ void Commissioner::UpdateJoinerExpirationTimer(void)
     uint32_t nextTimeout = 0xffffffff;
 
     // Check if timer should be set for next Joiner.
-    for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
     {
         {
             if (!mJoiners[i].mValid)
@@ -821,7 +821,7 @@ void Commissioner::HandleRelayReceive(Coap::Header &aHeader, Message &aMessage,
         memcpy(mJoinerIid, joinerIid.GetIid(), sizeof(mJoinerIid));
         mJoinerIid[0] ^= 0x2;
 
-        for (size_t i = 0; i < sizeof(mJoiners) / sizeof(mJoiners[0]); i++)
+        for (size_t i = 0; i < OT_ARRAY_LENGTH(mJoiners); i++)
         {
             if (!mJoiners[i].mValid)
             {

src/core/net/netif.cpp

@@ -88,13 +88,13 @@ Netif::Netif(Instance &aInstance, int8_t aInterfaceId)
     , mMulticastPromiscuous(false)
     , mNext(NULL)
 {
-    for (size_t i = 0; i < sizeof(mExtUnicastAddresses) / sizeof(mExtUnicastAddresses[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mExtUnicastAddresses); i++)
     {
         // To mark the address as unused/available, set the `mNext` to point back to itself.
         mExtUnicastAddresses[i].mNext = &mExtUnicastAddresses[i];
     }
 
-    for (size_t i = 0; i < sizeof(mExtMulticastAddresses) / sizeof(mExtMulticastAddresses[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mExtMulticastAddresses); i++)
     {
         // To mark the address as unused/available, set the `mNext` to point back to itself.
         mExtMulticastAddresses[i].mNext = &mExtMulticastAddresses[i];
@@ -240,7 +240,7 @@ exit:
 otError Netif::GetNextExternalMulticast(uint8_t &aIterator, Address &aAddress)
 {
     otError                error = OT_ERROR_NOT_FOUND;
-    size_t                 num   = sizeof(mExtMulticastAddresses) / sizeof(mExtMulticastAddresses[0]);
+    size_t                 num   = OT_ARRAY_LENGTH(mExtMulticastAddresses);
     NetifMulticastAddress *entry;
 
     VerifyOrExit(aIterator < num);
@@ -267,7 +267,7 @@ otError Netif::SubscribeExternalMulticast(const Address &aAddress)
 {
     otError                error = OT_ERROR_NONE;
     NetifMulticastAddress *entry;
-    size_t                 num = sizeof(mExtMulticastAddresses) / sizeof(mExtMulticastAddresses[0]);
+    size_t                 num = OT_ARRAY_LENGTH(mExtMulticastAddresses);
 
     if (IsMulticastSubscribed(aAddress))
     {
@@ -301,7 +301,7 @@ otError Netif::UnsubscribeExternalMulticast(const Address &aAddress)
     otError                error = OT_ERROR_NONE;
     NetifMulticastAddress *entry;
     NetifMulticastAddress *last = NULL;
-    size_t                 num  = sizeof(mExtMulticastAddresses) / sizeof(mExtMulticastAddresses[0]);
+    size_t                 num  = OT_ARRAY_LENGTH(mExtMulticastAddresses);
 
     for (entry = mMulticastAddresses; entry; entry = entry->GetNext())
     {
@@ -338,7 +338,7 @@ exit:
 
 void Netif::UnsubscribeAllExternalMulticastAddresses(void)
 {
-    size_t num = sizeof(mExtMulticastAddresses) / sizeof(mExtMulticastAddresses[0]);
+    size_t num = OT_ARRAY_LENGTH(mExtMulticastAddresses);
 
     for (NetifMulticastAddress *entry = &mExtMulticastAddresses[0]; num > 0; num--, entry++)
     {
@@ -408,7 +408,7 @@ otError Netif::AddExternalUnicastAddress(const NetifUnicastAddress &aAddress)
 {
     otError              error = OT_ERROR_NONE;
     NetifUnicastAddress *entry;
-    size_t               num = sizeof(mExtUnicastAddresses) / sizeof(mExtUnicastAddresses[0]);
+    size_t               num = OT_ARRAY_LENGTH(mExtUnicastAddresses);
 
     VerifyOrExit(!aAddress.GetAddress().IsLinkLocal(), error = OT_ERROR_INVALID_ARGS);
 
@@ -454,7 +454,7 @@ otError Netif::RemoveExternalUnicastAddress(const Address &aAddress)
     otError              error = OT_ERROR_NONE;
     NetifUnicastAddress *entry;
     NetifUnicastAddress *last = NULL;
-    size_t               num  = sizeof(mExtUnicastAddresses) / sizeof(mExtUnicastAddresses[0]);
+    size_t               num  = OT_ARRAY_LENGTH(mExtUnicastAddresses);
 
     for (entry = mUnicastAddresses; entry; entry = entry->GetNext())
     {
@@ -491,7 +491,7 @@ exit:
 
 void Netif::RemoveAllExternalUnicastAddresses(void)
 {
-    size_t num = sizeof(mExtUnicastAddresses) / sizeof(mExtUnicastAddresses[0]);
+    size_t num = OT_ARRAY_LENGTH(mExtUnicastAddresses);
 
     for (NetifUnicastAddress *entry = &mExtUnicastAddresses[0]; num > 0; num--, entry++)
     {

src/core/thread/mle.cpp

@@ -138,7 +138,7 @@ Mle::Mle(Instance &aInstance)
 #if OPENTHREAD_ENABLE_SERVICE
 
     // Service Alocs
-    for (size_t i = 0; i < sizeof(mServiceAlocs) / sizeof(mServiceAlocs[0]); i++)
+    for (size_t i = 0; i < OT_ARRAY_LENGTH(mServiceAlocs); i++)
     {
         memset(&mServiceAlocs[i], 0, sizeof(mServiceAlocs[i]));
 
@@ -774,7 +774,7 @@ otError Mle::SetMeshLocalPrefix(const uint8_t *aMeshLocalPrefix)
 
 #if OPENTHREAD_ENABLE_SERVICE
 
-    for (uint8_t i = 0; i < sizeof(mServiceAlocs) / sizeof(mServiceAlocs[0]); i++)
+    for (uint8_t i = 0; i < OT_ARRAY_LENGTH(mServiceAlocs); i++)
     {
         if (HostSwap16(mServiceAlocs[i].GetAddress().mFields.m16[7]) != Mac::kShortAddrInvalid)
         {
@@ -1387,7 +1387,7 @@ void Mle::UpdateServiceAlocs(void)
     int                   i                  = 0;
     NetworkData::Leader & leaderData         = netif.GetNetworkDataLeader();
     otNetworkDataIterator serviceIterator    = OT_NETWORK_DATA_ITERATOR_INIT;
-    int                   serviceAlocsLength = sizeof(mServiceAlocs) / sizeof(mServiceAlocs[0]);
+    int                   serviceAlocsLength = OT_ARRAY_LENGTH(mServiceAlocs);
 
     VerifyOrExit(mRole != OT_DEVICE_ROLE_DISABLED);
 

src/ncp/changed_props_set.cpp

@@ -28,6 +28,8 @@
 
 #include "changed_props_set.hpp"
 
+#include "common/code_utils.hpp"
+
 namespace ot {
 namespace Ncp {
 
@@ -87,7 +89,7 @@ const ChangedPropsSet::Entry ChangedPropsSet::mSupportedProps[] =
 
 uint8_t ChangedPropsSet::GetNumEntries(void) const
 {
-    return (sizeof(mSupportedProps) / sizeof(mSupportedProps[0]));
+    return OT_ARRAY_LENGTH(mSupportedProps);
 }
 
 void ChangedPropsSet::Add(spinel_prop_key_t aPropKey, spinel_status_t aStatus)

src/ncp/ncp_base.cpp

@@ -1305,39 +1305,22 @@ NcpBase::PropertyHandler NcpBase::FindPropertyHandler(spinel_prop_key_t aKey, co
 
 NcpBase::PropertyHandler NcpBase::FindGetPropertyHandler(spinel_prop_key_t aKey)
 {
-    return FindPropertyHandler(
-               aKey,
-               mGetPropertyHandlerTable,
-               sizeof(mGetPropertyHandlerTable) / sizeof(mGetPropertyHandlerTable[0])
-           );
-
+    return FindPropertyHandler(aKey, mGetPropertyHandlerTable, OT_ARRAY_LENGTH(mGetPropertyHandlerTable));
 }
 
 NcpBase::PropertyHandler NcpBase::FindSetPropertyHandler(spinel_prop_key_t aKey)
 {
-    return FindPropertyHandler(
-               aKey,
-               mSetPropertyHandlerTable,
-               sizeof(mSetPropertyHandlerTable) / sizeof(mSetPropertyHandlerTable[0])
-           );
+    return FindPropertyHandler(aKey, mSetPropertyHandlerTable, OT_ARRAY_LENGTH(mSetPropertyHandlerTable));
 }
 
 NcpBase::PropertyHandler NcpBase::FindInsertPropertyHandler(spinel_prop_key_t aKey)
 {
-   return FindPropertyHandler(
-               aKey,
-               mInsertPropertyHandlerTable,
-               sizeof(mInsertPropertyHandlerTable) / sizeof(mInsertPropertyHandlerTable[0])
-           );
+   return FindPropertyHandler(aKey, mInsertPropertyHandlerTable, OT_ARRAY_LENGTH(mInsertPropertyHandlerTable));
 }
 
 NcpBase::PropertyHandler NcpBase::FindRemovePropertyHandler(spinel_prop_key_t aKey)
 {
-    return FindPropertyHandler(
-               aKey,
-               mRemovePropertyHandlerTable,
-               sizeof(mRemovePropertyHandlerTable) / sizeof(mRemovePropertyHandlerTable[0])
-           );
+    return FindPropertyHandler(aKey, mRemovePropertyHandlerTable, OT_ARRAY_LENGTH(mRemovePropertyHandlerTable));
 }
 
 // Returns `true` and updates the `aError` on success.

src/ncp/ncp_base_mtd.cpp

@@ -3010,7 +3010,7 @@ void NcpBase::ProcessThreadChangedFlags(void)
 
     // Convert OT_CHANGED flags to corresponding NCP property update.
 
-    for (unsigned i = 0; i < sizeof(kFlags) / sizeof(kFlags[0]); i++)
+    for (unsigned i = 0; i < OT_ARRAY_LENGTH(kFlags); i++)
     {
         uint32_t threadFlag = kFlags[i].mThreadFlag;
 

tests/unit/test_child.cpp

@@ -32,6 +32,7 @@
 #include <openthread/openthread.h>
 
 #include "test_util.h"
+#include "common/code_utils.hpp"
 #include "common/instance.hpp"
 #include "thread/topology.hpp"
 
@@ -132,7 +133,7 @@ void TestChildIp6Address(void)
 
     numAddresses++;
 
-    for (uint8_t index = 0; index < static_cast<uint8_t>(sizeof(ip6Addresses) / sizeof(ip6Addresses[0])); index++)
+    for (uint8_t index = 0; index < static_cast<uint8_t>(OT_ARRAY_LENGTH(ip6Addresses)); index++)
     {
         VerifyOrQuit(numAddresses < kMaxChildIp6Addresses, "Too many IPv6 addresses in the unit test");
         SuccessOrQuit(addresses[numAddresses++].FromString(ip6Addresses[index]),

tests/unit/test_child_table.cpp

@@ -32,6 +32,7 @@
 #include <openthread/openthread.h>
 
 #include "test_util.h"
+#include "common/code_utils.hpp"
 #include "common/instance.hpp"
 #include "thread/child_table.hpp"
 
@@ -109,7 +110,7 @@ void VerifyChildTableContent(ChildTable &aTable, uint8_t aChildListLength, const
 {
     printf("Test ChildTable with %d entries", aChildListLength);
 
-    for (uint8_t k = 0; k < sizeof(kAllFilters) / sizeof(kAllFilters[0]); k++)
+    for (uint8_t k = 0; k < OT_ARRAY_LENGTH(kAllFilters); k++)
     {
         ChildTable::StateFilter filter = kAllFilters[k];
 
@@ -296,7 +297,7 @@ void TestChildTable(void)
         },
     };
 
-    const uint8_t testListLength = sizeof(testChildList) / sizeof(testChildList[0]);
+    const uint8_t testListLength = OT_ARRAY_LENGTH(testChildList);
 
     uint8_t testNumAllowedChildren = 2;
 
@@ -314,7 +315,7 @@ void TestChildTable(void)
     VerifyOrQuit(table->GetMaxChildrenAllowed() == table->GetMaxChildren(),
                  "GetMaxChildrenAllowed() initial value is incorrect ");
 
-    for (uint8_t i = 0; i < sizeof(kAllFilters) / sizeof(kAllFilters[0]); i++)
+    for (uint8_t i = 0; i < OT_ARRAY_LENGTH(kAllFilters); i++)
     {
         ChildTable::StateFilter filter = kAllFilters[i];
 

tests/unit/test_link_quality.cpp

@@ -28,6 +28,7 @@
 
 #include <openthread/openthread.h>
 
+#include "common/code_utils.hpp"
 #include "thread/link_quality.hpp"
 #include "utils/wrap_string.h"
 
@@ -427,7 +428,7 @@ void TestSuccessRateTracker(void)
 
     // Adding success/failure at different rates and checking the RateTracker rate for every sample
 
-    for (uint16_t testRound = 0; testRound < sizeof(kWeightLimit) / sizeof(kWeightLimit[0]) * 2; testRound++)
+    for (uint16_t testRound = 0; testRound < OT_ARRAY_LENGTH(kWeightLimit) * 2; testRound++)
     {
         uint16_t weightLimit;
         bool     reverseLogic;

tests/unit/test_mac_frame.cpp

@@ -28,6 +28,7 @@
 
 #include <openthread/openthread.h>
 
+#include "common/code_utils.hpp"
 #include "common/debug.hpp"
 #include "mac/mac.hpp"
 #include "mac/mac_frame.hpp"
@@ -68,7 +69,7 @@ void TestMacHeader(void)
          Mac::Frame::kSecMic32 | Mac::Frame::kKeyIdMode2, 19},
     };
 
-    for (unsigned i = 0; i < sizeof(tests) / sizeof(tests[0]); i++)
+    for (unsigned i = 0; i < OT_ARRAY_LENGTH(tests); i++)
     {
         uint8_t    psdu[Mac::Frame::kMTU];
         Mac::Frame frame;

tests/unit/test_network_data.cpp

@@ -28,6 +28,7 @@
 
 #include <openthread/config.h>
 
+#include "common/code_utils.hpp"
 #include "common/instance.hpp"
 #include "thread/network_data_local.hpp"
 
@@ -108,7 +109,7 @@ void TestNetworkDataIterator(void)
         printf("\nTest #1: Network data 1");
         printf("\n-------------------------------------------------");
 
-        for (uint8_t i = 0; i < sizeof(routes) / sizeof(routes[0]); i++)
+        for (uint8_t i = 0; i < OT_ARRAY_LENGTH(routes); i++)
         {
             SuccessOrQuit(netData.GetNextExternalRoute(&iter, &config), "GetNextExternalRoute() failed\n");
             PrintExternalRouteConfig(config);
@@ -158,7 +159,7 @@ void TestNetworkDataIterator(void)
         printf("\nTest #2: Network data 2");
         printf("\n-------------------------------------------------");
 
-        for (uint8_t i = 0; i < sizeof(routes) / sizeof(routes[0]); i++)
+        for (uint8_t i = 0; i < OT_ARRAY_LENGTH(routes); i++)
         {
             SuccessOrQuit(netData.GetNextExternalRoute(&iter, &config), "GetNextExternalRoute() failed\n");
             PrintExternalRouteConfig(config);

tests/unit/test_timer.cpp

@@ -28,6 +28,7 @@
 
 #include "test_platform.h"
 
+#include "common/code_utils.hpp"
 #include "common/debug.hpp"
 #include "common/instance.hpp"
 #include "common/timer.hpp"
@@ -550,7 +551,7 @@ int TestTenTimers(void)
 
     size_t i;
 
-    for (i = 0; i < sizeof(kTimeShift) / sizeof(kTimeShift[0]); i++)
+    for (i = 0; i < OT_ARRAY_LENGTH(kTimeShift); i++)
     {
         TenTimers(kTimeShift[i]);
     }