libastcenc

This is a build2 package for the ARM astc-encoder C library. It provides Adaptive Scalable Texture Compression (ASTC) encoding and decoding via the public C API in <astcenc.h>.

Usage

To start using libastcenc in your project, add the following depends value to your manifest, adjusting the version constraint as appropriate:

depends: libastcenc ^5.7.0

Then import the library in your buildfile:

import libs = libastcenc%lib{astcenc}

Include the public header as:

#include <astcenc.h>

Importable targets

This package provides the following importable targets:

lib{astcenc}

The core encoder/decoder library (static and shared variants). The astcenc command-line tool is a separate package.

Configuration variables

[string] config.libastcenc.isa ?= <target baseline>

SIMD backend. One of none, native, sse2, sse41, avx2, neon, sve128, sve256 (upstream ASTCENC_ISA_*).

The default is a portable production baseline for the target CPU: sse2 on x86_64, neon on little-endian aarch64 / arm64, none otherwise (including big-endian targets). Override with native for host-tuned codegen (-march=native on non-MSVC), or with a fixed ISA such as avx2.

Upstream SIMD backends are little-endian only. A big-endian build must use none (or native, which follows the compiler). Combining an explicit SIMD ISA with a big-endian target is rejected.

[bool] config.libastcenc.decompress_only ?= false

Build a decompress-only library (ASTCENC_DECOMPRESS_ONLY).

[bool] config.libastcenc.invariance ?= true

Floating-point invariance (upstream ASTCENC_INVARIANCE).

[bool] config.libastcenc.x86_gathers ?= true

Use native x86 gathers for the avx2 backend (upstream ASTCENC_X86_GATHERS). Ignored for every other ISA.

[uint64] config.libastcenc.block_max_texels ?= 0

Limit supported ASTC block sizes (ASTCENC_BLOCK_MAX_TEXELS). 0 keeps the header default of 216 (all 2D and 3D sizes). Use 144 to drop 3D 6x6x6 and shrink compressor tables.

[bool, null] config.libastcenc.big_endian ?= [null]

Big-endian target (ASTCENC_BIG_ENDIAN). The default is auto-detected from the compiler/target via the HAVE_BIGENDIAN autoconf check. Set true or false to override. The define is applied only for isa=none, matching upstream.