- Bump CMake minimum to 3.13 (required for target_link_directories)
- Move find_package(PkgConfig) to Unix-only block (Windows uses bundled libmodbus)
- Fix printf format UB: cast iAddr to unsigned int for %X specifier
- Allow RTU slave address 0 when -Q quirk is enabled
- Apply consistent quirk logic to TCP mode for symmetry

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Added bounds checking to prevent iCount from overflowing when parsing
large ranges, which could lead to heap buffer overflow via insufficient
calloc allocation.

Changes:
- Check range size with long long arithmetic before adding to iCount
- Check iCount bounds before incrementing
- Fix signed/unsigned comparison warning in mb_delay

Cherry-picked from Jules: 8f639d0
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Replace unsafe pointer casting (which violates C strict aliasing rules)
with memcpy and bitwise operations to safely swap 16-bit halves of
32-bit values.

This ensures correct behavior across different optimization levels
and compilers, avoiding undefined behavior.

Cherry-picked from Jules: a6472ec
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

The mb_delay function contained a dead code path that called sleep(-1)
when d == ULONG_MAX. This is problematic because:
- sleep() takes unsigned int, causing UINT_MAX seconds (~136 years) sleep
- The input d is derived from iPollRate (>= 100) or constant 20, never -1

Changes:
- Remove the dead code path entirely
- Use nanosleep unconditionally on Unix-like systems
- Mark mb_delay as static (internal linkage)

Cherry-picked from Jules: 1c4863c
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Avoid redundant modbus_set_slave() calls by checking if the current
slave address matches the target before setting it. This reduces
unnecessary I/O overhead when polling a single slave repeatedly.

Cherry-picked from Jules: b37345e
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Replace direct exit/cleanup in signal handler with a volatile flag that
is checked in the main loop. This follows best practices for async-signal
safety:

- Add g_bExitSignal volatile sig_atomic_t flag
- Check flag at loop entry and inner loops
- Suppress spurious error messages when interrupted by signal
- Signal handler now only sets the flag

This prevents undefined behavior from calling non-async-signal-safe
functions (like modbus_close, free, printf) in signal handlers.

Cherry-picked from Jules: fd2744a
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Add typedef to prevent ISO C warning about empty translation unit
when MBPOLL_GPIO_RTS is not defined (file becomes effectively empty).

Partial cherry-pick from Jules: a7109f0
(mb_delay cast fix superseded by sleep refactor in bd7c742)

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

The function was declared but never implemented or used in the codebase.
Removing dead code improves maintainability.

Cherry-picked from Jules: 82d3e16 (PR #2)
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Add comprehensive test suite for serial port configuration functions:
- sSerialFlowToStr: flow control type conversion
- sSerialDataBitsToStr: data bits conversion
- sSerialStopBitsToStr: stop bits conversion
- sSerialParityToStr: parity conversion

Test infrastructure:
- tests/test_serial.c: All serial function tests
- tests/CMakeLists.txt: CTest integration
- BUILD_TESTING option in main CMakeLists.txt

Based on Jules AI contributions from PRs #10, #11, #14, #15
Reviewed by: Gemini Code Assist

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Replaces the N+1 read pattern with batched Modbus requests for contiguous addresses.
Supports up to 125 registers or 2000 bits per request, significantly reducing transaction overhead.
Ensures alignment by using a `uint16_t` buffer.
Verified with `unit-test-server` for correctness and performance.
Rebased on origin/master to incorporate latest changes.

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

Replaces the N+1 read pattern with batched Modbus requests for contiguous addresses.
Supports up to 125 registers or 2000 bits per request, significantly reducing transaction overhead.
Ensures alignment by using a `uint16_t` buffer.
Verified with `unit-test-server` for correctness and performance.
Rebased on origin/master to incorporate latest changes and resolved conflicts.

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

Replaces the N+1 read pattern with batched Modbus requests for contiguous addresses.
Supports up to 125 registers or 2000 bits per request, significantly reducing transaction overhead.
Ensures alignment by using a `uint16_t` buffer.
Verified with `unit-test-server` for correctness and performance.
Rebased on v1.5.3 as requested.

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

Replaces the N+1 read pattern with batched Modbus requests for contiguous addresses.
Supports up to 125 registers or 2000 bits per request, significantly reducing transaction overhead.
Ensures alignment by using a `uint16_t` buffer.
Respects recent signal handling improvements (`g_bExitSignal`).
Verified with `unit-test-server` for correctness and performance.
Rebased on v1.5.3 (bbc029b).

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

Optimizes Modbus polling with batched reads for contiguous addresses:
- Batches up to 125 registers or 2000 bits per request
- Uses uint16_t buffer for proper alignment
- Reduces transaction overhead significantly
- Preserves all v1.5.3 improvements (signal handler, security fixes)

Includes benchmark.sh for performance testing.

Merged from: origin/batch-reads-optimization-14003233585538614312
Original PR: #22 by google-labs-jules[bot]

Co-Authored-By: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

- Moved `xMbPollContext` and enums to `src/mbpoll.h`.
- Created `src/chipio.h` and `src/chipio.c` for ChipIO specific logic.
- Defined `xChipIoContext` to encapsulate ChipIO state.
- Updated `src/mbpoll.c` to use the new module.
- Exposed necessary helper functions from `mbpoll.c` in `mbpoll.h`.
- Updated `CMakeLists.txt` to include `src/chipio.c`.
- Fixed `-Wsign-compare` warning in `mb_delay`.
- Cleaned up duplicate `_GNU_SOURCE` definitions.

This change addresses the TODO to separate the ChipIO part, improving maintainability and reducing the size of `mbpoll.c`. Re-based on v1.5.3.

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

Verified compatibility with v1.5.3 base branch. The `iGetIntList` refactor and tests function correctly. Minor cleanup in `CMakeLists.txt` to avoid duplicate test inclusion.

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

- Remove duplicate enum definitions in mbpoll.c (already in mbpoll.h)
- Fix variable redeclaration in parse_args
- Add src/utils.c and src/chipio.c to CMakeLists.txt
- Update mbpoll.h to include utils.h
- Add modbus_get_slave mock to tests/include/modbus.h

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Extracted lSwapLong and fSwapFloat from src/mbpoll.c to src/utils.c.
- Updated functions to accept endianness flag instead of relying on global state.
- Implemented swapping using memcpy to avoid strict aliasing violations.
- Added src/utils.h header.
- Added tests/test_utils.c with unit tests covering identity, swap, and negative scenarios.
- Updated CMakeLists.txt to include new sources, enable testing, and make libmodbus optional (allowing tests to run without it).

Co-authored-by: zknpr <96851588+zknpr@users.noreply.github.com>

- Resolved merge conflicts in mbpoll.c
- Updated lSwapLong/fSwapFloat calls to use explicit endianness
- Added _GNU_SOURCE to chipio.c for strcasestr
- Added overflow check for integer list allocation in utils.c

- Add integer overflow protection in batch buffer calculations
- Add overflow checks in vAllocate for size calculations
- Add strtol/strtod range validation (errno + bounds checks)
- Add NULL check for modbus context in vCleanup
- Add weak vFailureExit implementation in utils.c for standalone compilation
- Enable unit tests in CI for Linux, macOS, and Windows
- Fix .gitignore to allow .github directory

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

- Added `release-*` to push trigger branches.
- Added `v*.*.*` tags to push trigger.

This ensures CI runs for release branches and tagged releases, addressing the issue where tests existed but weren't automatically validated on pushes to these refs.

- src/chipio.c: Use standard <string.h> instead of <strings.h> for Windows compatibility. Map strcasecmp to _stricmp on Windows. Wrap _GNU_SOURCE definition.
- src/mbpoll.c: Wrap _GNU_SOURCE definition to avoid redefinition warnings.
- src/utils.c: Conditionally exclude vFailureExit when SKIP_FAILURE_EXIT is defined to avoid linker errors with test mocks.
- tests/CMakeLists.txt: Define SKIP_FAILURE_EXIT for test_utils target to prevent multiple definition errors.

MSVC does not support -Wno-pedantic, which caused a build error. This flag is now applied only when NOT MSVC.

- Define SKIP_FAILURE_EXIT for mbpoll target to prevent src/utils.c from defining vFailureExit.
- This resolves LNK2005 error as mbpoll.c already provides the definition.