--- /dev/null
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+ /*-*************************************
+ * Dependencies
+ ***************************************/
+#include "zstd_compress_literals.h"
+
+
+/* **************************************************************
+* Debug Traces
+****************************************************************/
+#if DEBUGLEVEL >= 2
+
+static size_t showHexa(const void* src, size_t srcSize)
+{
+ const BYTE* const ip = (const BYTE*)src;
+ size_t u;
+ for (u=0; u<srcSize; u++) {
+ RAWLOG(5, " %02X", ip[u]); (void)ip;
+ }
+ RAWLOG(5, " \n");
+ return srcSize;
+}
+
+#endif
+
+
+/* **************************************************************
+* Literals compression - special cases
+****************************************************************/
+size_t ZSTD_noCompressLiterals (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
+{
+ BYTE* const ostart = (BYTE*)dst;
+ U32 const flSize = 1 + (srcSize>31) + (srcSize>4095);
+
+ DEBUGLOG(5, "ZSTD_noCompressLiterals: srcSize=%zu, dstCapacity=%zu", srcSize, dstCapacity);
+
+ RETURN_ERROR_IF(srcSize + flSize > dstCapacity, dstSize_tooSmall, "");
+
+ switch(flSize)
+ {
+ case 1: /* 2 - 1 - 5 */
+ ostart[0] = (BYTE)((U32)set_basic + (srcSize<<3));
+ break;
+ case 2: /* 2 - 2 - 12 */
+ MEM_writeLE16(ostart, (U16)((U32)set_basic + (1<<2) + (srcSize<<4)));
+ break;
+ case 3: /* 2 - 2 - 20 */
+ MEM_writeLE32(ostart, (U32)((U32)set_basic + (3<<2) + (srcSize<<4)));
+ break;
+ default: /* not necessary : flSize is {1,2,3} */
+ assert(0);
+ }
+
+ ZSTD_memcpy(ostart + flSize, src, srcSize);
+ DEBUGLOG(5, "Raw (uncompressed) literals: %u -> %u", (U32)srcSize, (U32)(srcSize + flSize));
+ return srcSize + flSize;
+}
+
+static int allBytesIdentical(const void* src, size_t srcSize)
+{
+ assert(srcSize >= 1);
+ assert(src != NULL);
+ { const BYTE b = ((const BYTE*)src)[0];
+ size_t p;
+ for (p=1; p<srcSize; p++) {
+ if (((const BYTE*)src)[p] != b) return 0;
+ }
+ return 1;
+ }
+}
+
+size_t ZSTD_compressRleLiteralsBlock (void* dst, size_t dstCapacity, const void* src, size_t srcSize)
+{
+ BYTE* const ostart = (BYTE*)dst;
+ U32 const flSize = 1 + (srcSize>31) + (srcSize>4095);
+
+ assert(dstCapacity >= 4); (void)dstCapacity;
+ assert(allBytesIdentical(src, srcSize));
+
+ switch(flSize)
+ {
+ case 1: /* 2 - 1 - 5 */
+ ostart[0] = (BYTE)((U32)set_rle + (srcSize<<3));
+ break;
+ case 2: /* 2 - 2 - 12 */
+ MEM_writeLE16(ostart, (U16)((U32)set_rle + (1<<2) + (srcSize<<4)));
+ break;
+ case 3: /* 2 - 2 - 20 */
+ MEM_writeLE32(ostart, (U32)((U32)set_rle + (3<<2) + (srcSize<<4)));
+ break;
+ default: /* not necessary : flSize is {1,2,3} */
+ assert(0);
+ }
+
+ ostart[flSize] = *(const BYTE*)src;
+ DEBUGLOG(5, "RLE : Repeated Literal (%02X: %u times) -> %u bytes encoded", ((const BYTE*)src)[0], (U32)srcSize, (U32)flSize + 1);
+ return flSize+1;
+}
+
+/* ZSTD_minLiteralsToCompress() :
+ * returns minimal amount of literals
+ * for literal compression to even be attempted.
+ * Minimum is made tighter as compression strategy increases.
+ */
+static size_t
+ZSTD_minLiteralsToCompress(ZSTD_strategy strategy, HUF_repeat huf_repeat)
+{
+ assert((int)strategy >= 0);
+ assert((int)strategy <= 9);
+ /* btultra2 : min 8 bytes;
+ * then 2x larger for each successive compression strategy
+ * max threshold 64 bytes */
+ { int const shift = MIN(9-(int)strategy, 3);
+ size_t const mintc = (huf_repeat == HUF_repeat_valid) ? 6 : (size_t)8 << shift;
+ DEBUGLOG(7, "minLiteralsToCompress = %zu", mintc);
+ return mintc;
+ }
+}
+
+size_t ZSTD_compressLiterals (
+ void* dst, size_t dstCapacity,
+ const void* src, size_t srcSize,
+ void* entropyWorkspace, size_t entropyWorkspaceSize,
+ const ZSTD_hufCTables_t* prevHuf,
+ ZSTD_hufCTables_t* nextHuf,
+ ZSTD_strategy strategy,
+ int disableLiteralCompression,
+ int suspectUncompressible,
+ int bmi2)
+{
+ size_t const lhSize = 3 + (srcSize >= 1 KB) + (srcSize >= 16 KB);
+ BYTE* const ostart = (BYTE*)dst;
+ U32 singleStream = srcSize < 256;
+ symbolEncodingType_e hType = set_compressed;
+ size_t cLitSize;
+
+ DEBUGLOG(5,"ZSTD_compressLiterals (disableLiteralCompression=%i, srcSize=%u, dstCapacity=%zu)",
+ disableLiteralCompression, (U32)srcSize, dstCapacity);
+
+ DEBUGLOG(6, "Completed literals listing (%zu bytes)", showHexa(src, srcSize));
+
+ /* Prepare nextEntropy assuming reusing the existing table */
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+
+ if (disableLiteralCompression)
+ return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+
+ /* if too small, don't even attempt compression (speed opt) */
+ if (srcSize < ZSTD_minLiteralsToCompress(strategy, prevHuf->repeatMode))
+ return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+
+ RETURN_ERROR_IF(dstCapacity < lhSize+1, dstSize_tooSmall, "not enough space for compression");
+ { HUF_repeat repeat = prevHuf->repeatMode;
+ int const flags = 0
+ | (bmi2 ? HUF_flags_bmi2 : 0)
+ | (strategy < ZSTD_lazy && srcSize <= 1024 ? HUF_flags_preferRepeat : 0)
+ | (strategy >= HUF_OPTIMAL_DEPTH_THRESHOLD ? HUF_flags_optimalDepth : 0)
+ | (suspectUncompressible ? HUF_flags_suspectUncompressible : 0);
+
+ typedef size_t (*huf_compress_f)(void*, size_t, const void*, size_t, unsigned, unsigned, void*, size_t, HUF_CElt*, HUF_repeat*, int);
+ huf_compress_f huf_compress;
+ if (repeat == HUF_repeat_valid && lhSize == 3) singleStream = 1;
+ huf_compress = singleStream ? HUF_compress1X_repeat : HUF_compress4X_repeat;
+ cLitSize = huf_compress(ostart+lhSize, dstCapacity-lhSize,
+ src, srcSize,
+ HUF_SYMBOLVALUE_MAX, LitHufLog,
+ entropyWorkspace, entropyWorkspaceSize,
+ (HUF_CElt*)nextHuf->CTable,
+ &repeat, flags);
+ DEBUGLOG(5, "%zu literals compressed into %zu bytes (before header)", srcSize, cLitSize);
+ if (repeat != HUF_repeat_none) {
+ /* reused the existing table */
+ DEBUGLOG(5, "reusing statistics from previous huffman block");
+ hType = set_repeat;
+ }
+ }
+
+ { size_t const minGain = ZSTD_minGain(srcSize, strategy);
+ if ((cLitSize==0) || (cLitSize >= srcSize - minGain) || ERR_isError(cLitSize)) {
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+ return ZSTD_noCompressLiterals(dst, dstCapacity, src, srcSize);
+ } }
+ if (cLitSize==1) {
+ /* A return value of 1 signals that the alphabet consists of a single symbol.
+ * However, in some rare circumstances, it could be the compressed size (a single byte).
+ * For that outcome to have a chance to happen, it's necessary that `srcSize < 8`.
+ * (it's also necessary to not generate statistics).
+ * Therefore, in such a case, actively check that all bytes are identical. */
+ if ((srcSize >= 8) || allBytesIdentical(src, srcSize)) {
+ ZSTD_memcpy(nextHuf, prevHuf, sizeof(*prevHuf));
+ return ZSTD_compressRleLiteralsBlock(dst, dstCapacity, src, srcSize);
+ } }
+
+ if (hType == set_compressed) {
+ /* using a newly constructed table */
+ nextHuf->repeatMode = HUF_repeat_check;
+ }
+
+ /* Build header */
+ switch(lhSize)
+ {
+ case 3: /* 2 - 2 - 10 - 10 */
+ if (!singleStream) assert(srcSize >= MIN_LITERALS_FOR_4_STREAMS);
+ { U32 const lhc = hType + ((U32)(!singleStream) << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<14);
+ MEM_writeLE24(ostart, lhc);
+ break;
+ }
+ case 4: /* 2 - 2 - 14 - 14 */
+ assert(srcSize >= MIN_LITERALS_FOR_4_STREAMS);
+ { U32 const lhc = hType + (2 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<18);
+ MEM_writeLE32(ostart, lhc);
+ break;
+ }
+ case 5: /* 2 - 2 - 18 - 18 */
+ assert(srcSize >= MIN_LITERALS_FOR_4_STREAMS);
+ { U32 const lhc = hType + (3 << 2) + ((U32)srcSize<<4) + ((U32)cLitSize<<22);
+ MEM_writeLE32(ostart, lhc);
+ ostart[4] = (BYTE)(cLitSize >> 10);
+ break;
+ }
+ default: /* not possible : lhSize is {3,4,5} */
+ assert(0);
+ }
+ DEBUGLOG(5, "Compressed literals: %u -> %u", (U32)srcSize, (U32)(lhSize+cLitSize));
+ return lhSize+cLitSize;
+}
notaz.gp2x.de / pcsx_rearmed.git / blobdiff