--- /dev/null
+/* ******************************************************************
+ * hist : Histogram functions
+ * part of Finite State Entropy project
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * You can contact the author at :
+ * - FSE source repository : https://github.com/Cyan4973/FiniteStateEntropy
+ * - Public forum : https://groups.google.com/forum/#!forum/lz4c
+ *
+ * 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 "../common/mem.h" /* U32, BYTE, etc. */
+#include "../common/debug.h" /* assert, DEBUGLOG */
+#include "../common/error_private.h" /* ERROR */
+#include "hist.h"
+
+
+/* --- Error management --- */
+unsigned HIST_isError(size_t code) { return ERR_isError(code); }
+
+/*-**************************************************************
+ * Histogram functions
+ ****************************************************************/
+unsigned HIST_count_simple(unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* src, size_t srcSize)
+{
+ const BYTE* ip = (const BYTE*)src;
+ const BYTE* const end = ip + srcSize;
+ unsigned maxSymbolValue = *maxSymbolValuePtr;
+ unsigned largestCount=0;
+
+ ZSTD_memset(count, 0, (maxSymbolValue+1) * sizeof(*count));
+ if (srcSize==0) { *maxSymbolValuePtr = 0; return 0; }
+
+ while (ip<end) {
+ assert(*ip <= maxSymbolValue);
+ count[*ip++]++;
+ }
+
+ while (!count[maxSymbolValue]) maxSymbolValue--;
+ *maxSymbolValuePtr = maxSymbolValue;
+
+ { U32 s;
+ for (s=0; s<=maxSymbolValue; s++)
+ if (count[s] > largestCount) largestCount = count[s];
+ }
+
+ return largestCount;
+}
+
+typedef enum { trustInput, checkMaxSymbolValue } HIST_checkInput_e;
+
+/* HIST_count_parallel_wksp() :
+ * store histogram into 4 intermediate tables, recombined at the end.
+ * this design makes better use of OoO cpus,
+ * and is noticeably faster when some values are heavily repeated.
+ * But it needs some additional workspace for intermediate tables.
+ * `workSpace` must be a U32 table of size >= HIST_WKSP_SIZE_U32.
+ * @return : largest histogram frequency,
+ * or an error code (notably when histogram's alphabet is larger than *maxSymbolValuePtr) */
+static size_t HIST_count_parallel_wksp(
+ unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* source, size_t sourceSize,
+ HIST_checkInput_e check,
+ U32* const workSpace)
+{
+ const BYTE* ip = (const BYTE*)source;
+ const BYTE* const iend = ip+sourceSize;
+ size_t const countSize = (*maxSymbolValuePtr + 1) * sizeof(*count);
+ unsigned max=0;
+ U32* const Counting1 = workSpace;
+ U32* const Counting2 = Counting1 + 256;
+ U32* const Counting3 = Counting2 + 256;
+ U32* const Counting4 = Counting3 + 256;
+
+ /* safety checks */
+ assert(*maxSymbolValuePtr <= 255);
+ if (!sourceSize) {
+ ZSTD_memset(count, 0, countSize);
+ *maxSymbolValuePtr = 0;
+ return 0;
+ }
+ ZSTD_memset(workSpace, 0, 4*256*sizeof(unsigned));
+
+ /* by stripes of 16 bytes */
+ { U32 cached = MEM_read32(ip); ip += 4;
+ while (ip < iend-15) {
+ U32 c = cached; cached = MEM_read32(ip); ip += 4;
+ Counting1[(BYTE) c ]++;
+ Counting2[(BYTE)(c>>8) ]++;
+ Counting3[(BYTE)(c>>16)]++;
+ Counting4[ c>>24 ]++;
+ c = cached; cached = MEM_read32(ip); ip += 4;
+ Counting1[(BYTE) c ]++;
+ Counting2[(BYTE)(c>>8) ]++;
+ Counting3[(BYTE)(c>>16)]++;
+ Counting4[ c>>24 ]++;
+ c = cached; cached = MEM_read32(ip); ip += 4;
+ Counting1[(BYTE) c ]++;
+ Counting2[(BYTE)(c>>8) ]++;
+ Counting3[(BYTE)(c>>16)]++;
+ Counting4[ c>>24 ]++;
+ c = cached; cached = MEM_read32(ip); ip += 4;
+ Counting1[(BYTE) c ]++;
+ Counting2[(BYTE)(c>>8) ]++;
+ Counting3[(BYTE)(c>>16)]++;
+ Counting4[ c>>24 ]++;
+ }
+ ip-=4;
+ }
+
+ /* finish last symbols */
+ while (ip<iend) Counting1[*ip++]++;
+
+ { U32 s;
+ for (s=0; s<256; s++) {
+ Counting1[s] += Counting2[s] + Counting3[s] + Counting4[s];
+ if (Counting1[s] > max) max = Counting1[s];
+ } }
+
+ { unsigned maxSymbolValue = 255;
+ while (!Counting1[maxSymbolValue]) maxSymbolValue--;
+ if (check && maxSymbolValue > *maxSymbolValuePtr) return ERROR(maxSymbolValue_tooSmall);
+ *maxSymbolValuePtr = maxSymbolValue;
+ ZSTD_memmove(count, Counting1, countSize); /* in case count & Counting1 are overlapping */
+ }
+ return (size_t)max;
+}
+
+/* HIST_countFast_wksp() :
+ * Same as HIST_countFast(), but using an externally provided scratch buffer.
+ * `workSpace` is a writable buffer which must be 4-bytes aligned,
+ * `workSpaceSize` must be >= HIST_WKSP_SIZE
+ */
+size_t HIST_countFast_wksp(unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* source, size_t sourceSize,
+ void* workSpace, size_t workSpaceSize)
+{
+ if (sourceSize < 1500) /* heuristic threshold */
+ return HIST_count_simple(count, maxSymbolValuePtr, source, sourceSize);
+ if ((size_t)workSpace & 3) return ERROR(GENERIC); /* must be aligned on 4-bytes boundaries */
+ if (workSpaceSize < HIST_WKSP_SIZE) return ERROR(workSpace_tooSmall);
+ return HIST_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, trustInput, (U32*)workSpace);
+}
+
+/* HIST_count_wksp() :
+ * Same as HIST_count(), but using an externally provided scratch buffer.
+ * `workSpace` size must be table of >= HIST_WKSP_SIZE_U32 unsigned */
+size_t HIST_count_wksp(unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* source, size_t sourceSize,
+ void* workSpace, size_t workSpaceSize)
+{
+ if ((size_t)workSpace & 3) return ERROR(GENERIC); /* must be aligned on 4-bytes boundaries */
+ if (workSpaceSize < HIST_WKSP_SIZE) return ERROR(workSpace_tooSmall);
+ if (*maxSymbolValuePtr < 255)
+ return HIST_count_parallel_wksp(count, maxSymbolValuePtr, source, sourceSize, checkMaxSymbolValue, (U32*)workSpace);
+ *maxSymbolValuePtr = 255;
+ return HIST_countFast_wksp(count, maxSymbolValuePtr, source, sourceSize, workSpace, workSpaceSize);
+}
+
+#ifndef ZSTD_NO_UNUSED_FUNCTIONS
+/* fast variant (unsafe : won't check if src contains values beyond count[] limit) */
+size_t HIST_countFast(unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* source, size_t sourceSize)
+{
+ unsigned tmpCounters[HIST_WKSP_SIZE_U32];
+ return HIST_countFast_wksp(count, maxSymbolValuePtr, source, sourceSize, tmpCounters, sizeof(tmpCounters));
+}
+
+size_t HIST_count(unsigned* count, unsigned* maxSymbolValuePtr,
+ const void* src, size_t srcSize)
+{
+ unsigned tmpCounters[HIST_WKSP_SIZE_U32];
+ return HIST_count_wksp(count, maxSymbolValuePtr, src, srcSize, tmpCounters, sizeof(tmpCounters));
+}
+#endif
notaz.gp2x.de / pcsx_rearmed.git / blobdiff