Readability enhancements in heap_1.c (#1074)

* Remove that Heap_1.c unnecessary judgment and code logic * Remove useless alignment calculations and increase heap usage size * Revert "Remove useless alignment calculations and increase heap usage size" This reverts commit 7832a4bc118661676c4aaa377e412c35ec0b728c. * Readability improvements Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com> --------- Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com> Co-authored-by: huangly <huangly@milesight.com> Co-authored-by: Gaurav Aggarwal <aggarg@amazon.com>

Author: 3 people

portable/MemMang/heap_1.c

@@ -51,7 +51,15 @@
 #endif
 
 /* A few bytes might be lost to byte aligning the heap start address. */
-#define configADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
+#define configADJUSTED_HEAP_SIZE ( configTOTAL_HEAP_SIZE - portBYTE_ALIGNMENT )
+
+/* Max value that fits in a size_t type. */
+#define heapSIZE_MAX ( ~( ( size_t ) 0 ) )
+
+/* Check if adding a and b will result in overflow. */
+#define heapADD_WILL_OVERFLOW( a, b ) ( ( a ) > ( heapSIZE_MAX - ( b ) ) )
+
+/*-----------------------------------------------------------*/
 
 /* Allocate the memory for the heap. */
 #if ( configAPPLICATION_ALLOCATED_HEAP == 1 )
@@ -76,12 +84,16 @@ void * pvPortMalloc( size_t xWantedSize )
  /* Ensure that blocks are always aligned. */
  #if ( portBYTE_ALIGNMENT != 1 )
  {
- if( xWantedSize & portBYTE_ALIGNMENT_MASK )
+ size_t xAdditionalRequiredSize;
+
+ if( ( xWantedSize & portBYTE_ALIGNMENT_MASK ) != 0x00 )
  {
- /* Byte alignment required. Check for overflow. */
- if( ( xWantedSize + ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) ) ) > xWantedSize )
+ /* Byte alignment required. */
+ xAdditionalRequiredSize = portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK );
+
+ if( heapADD_WILL_OVERFLOW( xWantedSize, xAdditionalRequiredSize ) == 0 )
  {
- xWantedSize += ( portBYTE_ALIGNMENT - ( xWantedSize & portBYTE_ALIGNMENT_MASK ) );
+ xWantedSize += xAdditionalRequiredSize;
  }
  else
  {
@@ -96,13 +108,14 @@ void * pvPortMalloc( size_t xWantedSize )
  if( pucAlignedHeap == NULL )
  {
  /* Ensure the heap starts on a correctly aligned boundary. */
- pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) & ucHeap[ portBYTE_ALIGNMENT - 1 ] ) & ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );
+ pucAlignedHeap = ( uint8_t * ) ( ( ( portPOINTER_SIZE_TYPE ) &( ucHeap[ portBYTE_ALIGNMENT - 1 ] ) ) &
+ ( ~( ( portPOINTER_SIZE_TYPE ) portBYTE_ALIGNMENT_MASK ) ) );
  }
 
- /* Check there is enough room left for the allocation and. */
- if( ( xWantedSize > 0 ) && /* valid size */
- ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) &&
- ( ( xNextFreeByte + xWantedSize ) > xNextFreeByte ) ) /* Check for overflow. */
+ /* Check there is enough room left for the allocation. */
+ if( ( xWantedSize > 0 ) &&
+ ( heapADD_WILL_OVERFLOW( xNextFreeByte, xWantedSize ) == 0 ) &&
+ ( ( xNextFreeByte + xWantedSize ) < configADJUSTED_HEAP_SIZE ) )
  {
  /* Return the next free byte then increment the index past this
  * block. */