Memory Manager Architecture#

High-Level Architecture Diagram#

The following diagram presents the high-level architecture of the Memory Manager components.

Core Components#

The Memory Manager includes six main components that work together to provide comprehensive memory management capabilities:

Dynamic Allocation System#

• File: sl_memory_manager.c

• Purpose: Provides malloc/free/calloc/realloc functionality with advanced features

• Key Features:

  • First-fit allocation algorithm with block splitting

  • Long-term (LT) vs short-term (ST) allocation strategies

  • Configurable alignment (1-512 bytes, power-of-2)

  • Thread-safe operation with critical sections

  • Heap fragmentation reduction through LT/ST allocation

Memory Pool System#

• File: sl_memory_manager_pool.c

• Purpose: Fixed-size block allocation for deterministic memory management

• Key Features:

  • Guaranteed allocation quotas

  • More robust against unexpected allocation failures

  • Static or dynamic pool handle management

  • Deterministic allocation/deallocation timing

Dynamic Reservation System#

• File: sl_memory_manager_dynamic_reservation.c

• Purpose: Special construct for reserving blocks from short-term heap section

• Key Features:

  • Block reservation with specific alignment

  • Reservation handle management

  • Different usage pattern from dynamic allocation API

Memory Region Management#

• File: sl_memory_manager_region.c

• Purpose: Provides heap and stack region information

• Key Features:

  • Stack region size and location queries

  • Heap region size and location queries

Retargeting System#

• File: sl_memory_manager_retarget.c

• Purpose: Redirects standard C library functions to Memory Manager

• Key Features:

  • malloc/free/calloc/realloc retargeting

  • Linker wrap functionality for GCC and IAR

• Implementation Details:

  • Linker Wrapping: Uses GCC --wrap and IAR $Sub$$ mechanisms to intercept standard library calls

  • Function Mapping: Maps malloc/free/calloc/realloc to Memory Manager equivalents

  • Toolchain Support: Supports both GCC and IAR toolchains with appropriate wrapping mechanisms

  • Reentrant Support: Handles reentrant versions of memory functions for multi-threaded environments

C++ Support#

• File: sl_memory_manager_cpp.cpp

• Purpose: C++ operator overloading for new/delete

• Key Features:

  • Standard C++ new/delete operator overloading

  • Exception handling integration

  • Multiple allocation variants

• Implementation Details:

  • Operator Overloading: Overloads new, new[], delete, and delete[] operators

  • Exception Safety: Integrates with C++ exception handling mechanisms

  • Multiple Variants: Supports different allocation variants (sized, aligned, etc.)

  • Resource Acquisition Is Initialization (RAII) Integration: Enables automatic memory management through C++ RAII patterns (i.e., resources are properly released when they are no longer needed)

  • Standard Compliance: Follows C++ standard requirements for operator overloading

Internal Architecture and Design Rationale#

Memory Layout Strategy#

The Memory Manager implements a sophisticated memory layout strategy to minimize fragmentation:

Dual-End Allocation Model:

• Long-term allocations start from the heap beginning and grow upward

• Short-term allocations start from the heap end and grow downward

• Free space exists between the two allocation regions

• Fragmentation reduction is achieved by grouping similar lifetime allocations

Allocation Algorithm Details#

First-Fit with Block Splitting:

• Search Strategy: Traverse the implicit block list starting from the start of the heap (long-term allocations) or from the end of the heap (short-term allocations)

• Block Selection: Choose the first block that can satisfy the request

• Splitting Logic: If free block is significantly larger than requested, create a new free block with the surplus

• Minimum Size: Respects SL_MEMORY_MANAGER_BLOCK_ALLOCATION_MIN_SIZE to prevent excessive fragmentation

• Alignment Handling: Ensures proper alignment while minimizing waste

Free Operation with Merging:

• Adjacent Block Detection: Scan for physically adjacent free blocks

• Merge Strategy: Combine adjacent free blocks to reduce fragmentation

• List Updates: Update long-term and/or short-term free block head pointers to reflect merged blocks

• Metadata Cleanup: Reset metadata for merged blocks

Thread Safety Implementation#

Critical Section Strategy:

• Global Mutex: Single critical section protects all heap operations

• Interrupt Disable: Brief interrupt disable during critical operations

• RTOS Integration: Compatible with RTOS task switching

• ISR Considerations: Documented latency warnings for interrupt context usage

Dependencies#

The Memory Manager integrates with multiple platform components and hardware interfaces:

Hardware Dependencies#

Software Dependencies#

Development Tool Dependencies#

• Simplicity Studio: IDE integration for configuration, debugging, and memory usage analysis

• Universal Configurator: Configuration interface for memory management settings and optimization parameters

• Linker Configuration: Automatic linker wrap options for standard C library function retargeting

• Memory Analysis Tools: Integration with platform debugging tools for heap monitoring and fragmentation analysis