# Build
## Platform requirements
* Requires [zlib](http://zlib.net) or a zlib-compatible library
* Integers must be two's complement.
* Fixed width integer types up to `(u)int32_t`
* `CHAR_BIT` must equal 8.
* `size_t` must be unsigned.
* `size_t` and `int` must be at least 32-bit, 16-bit platforms are not
supported.
* Floating point support and math functions
## CMake
```bash
mkdir cbuild
cd cbuild
cmake .. # Don't forget to set optimization level!
make
make install
```
## Meson
```bash
meson build --buildtype=release # Default is debug
cd build
ninja
ninja install
```
## Embedding the source code
The source files `spng.c`/`spng.h` can be embedded in a project without
any configuration, SSE2 intrinsics are enabled by default on x86.
## Build options
| (auto) | (auto) | `SPNG_STATIC` | | Controls symbol visibility on Windows |
| enable_opt | ENABLE_OPT | `SPNG_DISABLE_OPT` | ON | Compile with optimizations |
| | | `SPNG_SSE=<1-4>` | 1 | SSE version target for x86 (ignored on non-x86) |
| static_zlib | | | OFF | Link zlib statically |
| use_miniz | | `SPNG_USE_MINIZ` | OFF | Compile using miniz, disables some features |
| (auto) | | `SPNG_ENABLE_TARGET_CLONES` | | Use target_clones() to optimize (GCC + glibc only) |
| dev_build | | | OFF | Enable the testsuite, requires libpng |
| benchmarks | | | OFF | Enable benchmarks, requires Git LFS |
| oss_fuzz | | | OFF | Enable regression tests with OSS-Fuzz corpora |
Valid values for `SPNG_SSE`:
* 1 - SSE2
* 2 - same as above
* 3 - SSSE3
* 4 - SSE4.1
Currently only SSE2 optimizations are tested.
The source code alone can be built without any compiler flags,
compiler-specific macros are used to omit the need for options
such as `-msse2`, `-mssse3`.
## miniz
[miniz](https://github.com/richgel999/miniz) is a single source file replacement for zlib,
linking against miniz allows libspng to be embedded into a project with just
four files: `spng.c`, `miniz.c` and their headers.
For building with miniz add the `SPNG_USE_MINIZ` compiler option,
this handles some minor differences in the API.
Performance is mostly identical, slightly better in some cases
compared to stock zlib.
## Profile-guided optimization
[Profile-guided optimization (PGO)](https://clang.llvm.org/docs/UsersManual.html#profile-guided-optimization)
improves performance by up to 10%.
```bash
# Run in root directory
git clone https://github.com/libspng/benchmark_images.git
cd build
meson configure -Dbuildtype=release --default-library both -Db_pgo=generate
ninja
./example ../benchmark_images/medium_rgb8.png
./example ../benchmark_images/medium_rgba8.png
./example ../benchmark_images/large_palette.png
meson configure -Db_pgo=use
ninja
ninja install
```
## Documentation
Documentation is built with [mkdocs](https://www.mkdocs.org/):
```bash
# Run in root directory
mkdocs build
```