From 6ef8f578817ee0134fd5867ca3b80590e3eb2368 Mon Sep 17 00:00:00 2001 From: skal Date: Thu, 14 May 2026 19:09:39 +0200 Subject: ans: order-0 rANS coder + WGSL asset compression Adds src/util/ans.{h,cc}, a per-chunk-adaptive order-0 rANS entropy coder. Decoder is always built; encoder is gated on ANS_ENABLE_ENCODER (tools only). Both sides take an optional 256-entry initial_counts table to seed the adaptive model. The per-chunk initial state is (1 << kBits). Higher initial states (e.g. with a signature packed into the upper bits) force a renorm-emit at iter 0 that the decoder never consumes, corrupting multi-chunk streams once stats become skewed. Asset pipeline: - AssetRecord gains 'compression' and 'uncompressed_size' fields. - asset_packer scans every WGSL file to build a corpus-wide byte histogram, then ANS-encodes each shader using that histogram as the seed. Histogram and accessor are emitted alongside the asset table. Round-trip verification runs at pack time for every compressed asset; failures fall back to uncompressed storage. - asset_manager decompresses on first GetAsset(), caches the heap-allocated buffer, and DropAsset / ReloadAssetsFromFile free it along with the procedural cache. - Disk-load (dev) builds are unchanged: WGSL paths stay as filenames. Tests: - src/tests/util/test_ans.cc: roundtrip variants (empty, single byte, single-symbol run, all-zeros, random uniform/skewed, repeated ASCII), seeded-vs-uniform compression, rejection of mismatched counts / corruption / truncation, PeekUncompressedSize. - 37/37 dev, 36/36 STRIP_ALL. Compression observed: WGSL shaders shrink to ~0.62-0.71x in the main workspace (81 of 105 assets qualify). Docs: - doc/ANS.md (new): algorithm, bitstream, API, asset pipeline integration, compression numbers, limitations, tests. - doc/ASSET_SYSTEM.md: new Compression section + updated technical guarantees for compressed assets. - doc/COMPLETED.md: May 2026 entry. - PROJECT_CONTEXT.md: Build status line mentions WGSL ANS compression. - CLAUDE.md, GEMINI.md: tier-3 build doc list includes ANS.md. --- src/util/asset_manager.cc | 44 ++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 40 insertions(+), 4 deletions(-) (limited to 'src/util/asset_manager.cc') diff --git a/src/util/asset_manager.cc b/src/util/asset_manager.cc index 26a82bf..264ddda 100644 --- a/src/util/asset_manager.cc +++ b/src/util/asset_manager.cc @@ -2,6 +2,7 @@ // It implements the generic asset retrieval logic with runtime caching. #include "util/asset_manager.h" +#include "util/ans.h" #include "util/asset_manager_utils.h" #include "util/check_return.h" #if defined(USE_TEST_ASSETS) @@ -114,6 +115,34 @@ const uint8_t* GetAsset(AssetId asset_id, size_t* out_size) { AssetRecord cached_record = source_record; + if (source_record.compression == AssetCompression::ANS_ASCII) { + // Decompress on first access. Buffer is null-terminated for C-string use. + const size_t uncomp = source_record.uncompressed_size; + uint8_t* buffer = new (std::nothrow) uint8_t[uncomp + 1]; + CHECK_RETURN_BEGIN(!buffer, nullptr) + if (out_size) *out_size = 0; + ERROR_MSG("Failed to allocate buffer for ANS-compressed asset id=%u", + index); + return nullptr; + CHECK_RETURN_END + size_t got = 0; + if (!ans::Decode(source_record.data, source_record.size, buffer, uncomp, + &got, GetAnsAsciiHistogram()) || + got != uncomp) { + delete[] buffer; + if (out_size) *out_size = 0; + ERROR_MSG("ANS decode failed for asset id=%u", index); + return nullptr; + } + buffer[uncomp] = 0; + cached_record.data = buffer; + cached_record.size = uncomp; + cached_record.uncompressed_size = uncomp; + g_asset_cache[index] = cached_record; + if (out_size) *out_size = uncomp; + return buffer; + } + if (source_record.type == AssetType::PROC || source_record.type == AssetType::PROC_GPU) { // Dynamically generate the asset @@ -224,6 +253,12 @@ void DropAsset(AssetId asset_id, const uint8_t* asset) { delete[] g_asset_cache[index].data; g_asset_cache[index] = {}; // Zero out the struct to force re-generation } + // Heap-allocated decompressed buffer (compression != NONE): cache owns it. + if (g_asset_cache[index].data == asset && + g_asset_cache[index].compression != AssetCompression::NONE) { + delete[] g_asset_cache[index].data; + g_asset_cache[index] = {}; + } #if !defined(STRIP_ALL) if (g_asset_cache[index].data == asset && (g_asset_cache[index].type == AssetType::SPEC || @@ -245,10 +280,11 @@ bool ReloadAssetsFromFile(const char* config_path) { // Clear cache to force reload for (size_t i = 0; i < (size_t)AssetId::ASSET_LAST_ID; ++i) { - if ((g_asset_cache[i].type == AssetType::PROC || - g_asset_cache[i].type == AssetType::PROC_GPU) && - g_asset_cache[i].data) { - delete[] g_asset_cache[i].data; + const AssetRecord& e = g_asset_cache[i]; + if (e.data && + (e.type == AssetType::PROC || e.type == AssetType::PROC_GPU || + e.compression != AssetCompression::NONE)) { + delete[] e.data; } g_asset_cache[i] = {}; } -- cgit v1.2.3