view contrib/python-zstandard/zstd/common/entropy_common.c @ 51929:93d872a06132 default tip

typing: add type annotations to the dirstate classes

The basic procedure here was to use `merge-pyi` to merge the `git/dirstate.pyi`
file in (after renaming the interface class to match), cleaning up the import
statement mess, and then repeating the procedure for `mercurial/dirstate.pyi`.
Surprisingly, git's dirstate had more hints inferred in its *.pyi file.

After that, it was a manual examination of each method in the interface, and how
they were implemented in the core and git classes to verify what was inferred by
pytype, and fill in the missing gaps.  Since this involved jumping around
between three different files, I applied the same type info to all three at the
same time.  Complex types I rolled up into type aliases in the interface module,
and used that as needed.  That way if it changes, there's one place to edit.

There are some hints still missing, and some documentation that doesn't match
the signatures.  They should all be marked with TODOs.  There are also a bunch
of methods on the core class that aren't on the Protocol class that seem like
maybe they should be (like `set_tracked()`).  There are even more methods
missing from the git class.  But that's a project for another time.

/*
   Common functions of New Generation Entropy library
   Copyright (C) 2016, Yann Collet.

   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:

       * Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
       * Redistributions in binary form must reproduce the above
   copyright notice, this list of conditions and the following disclaimer
   in the documentation and/or other materials provided with the
   distribution.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

    You can contact the author at :
    - FSE+HUF source repository : https://github.com/Cyan4973/FiniteStateEntropy
    - Public forum : https://groups.google.com/forum/#!forum/lz4c
*************************************************************************** */

/* *************************************
*  Dependencies
***************************************/
#include "mem.h"
#include "error_private.h"       /* ERR_*, ERROR */
#define FSE_STATIC_LINKING_ONLY  /* FSE_MIN_TABLELOG */
#include "fse.h"
#define HUF_STATIC_LINKING_ONLY  /* HUF_TABLELOG_ABSOLUTEMAX */
#include "huf.h"


/*===   Version   ===*/
unsigned FSE_versionNumber(void) { return FSE_VERSION_NUMBER; }


/*===   Error Management   ===*/
unsigned FSE_isError(size_t code) { return ERR_isError(code); }
const char* FSE_getErrorName(size_t code) { return ERR_getErrorName(code); }

unsigned HUF_isError(size_t code) { return ERR_isError(code); }
const char* HUF_getErrorName(size_t code) { return ERR_getErrorName(code); }


/*-**************************************************************
*  FSE NCount encoding-decoding
****************************************************************/
size_t FSE_readNCount (short* normalizedCounter, unsigned* maxSVPtr, unsigned* tableLogPtr,
                 const void* headerBuffer, size_t hbSize)
{
    const BYTE* const istart = (const BYTE*) headerBuffer;
    const BYTE* const iend = istart + hbSize;
    const BYTE* ip = istart;
    int nbBits;
    int remaining;
    int threshold;
    U32 bitStream;
    int bitCount;
    unsigned charnum = 0;
    int previous0 = 0;

    if (hbSize < 4) {
        /* This function only works when hbSize >= 4 */
        char buffer[4];
        memset(buffer, 0, sizeof(buffer));
        memcpy(buffer, headerBuffer, hbSize);
        {   size_t const countSize = FSE_readNCount(normalizedCounter, maxSVPtr, tableLogPtr,
                                                    buffer, sizeof(buffer));
            if (FSE_isError(countSize)) return countSize;
            if (countSize > hbSize) return ERROR(corruption_detected);
            return countSize;
    }   }
    assert(hbSize >= 4);

    /* init */
    memset(normalizedCounter, 0, (*maxSVPtr+1) * sizeof(normalizedCounter[0]));   /* all symbols not present in NCount have a frequency of 0 */
    bitStream = MEM_readLE32(ip);
    nbBits = (bitStream & 0xF) + FSE_MIN_TABLELOG;   /* extract tableLog */
    if (nbBits > FSE_TABLELOG_ABSOLUTE_MAX) return ERROR(tableLog_tooLarge);
    bitStream >>= 4;
    bitCount = 4;
    *tableLogPtr = nbBits;
    remaining = (1<<nbBits)+1;
    threshold = 1<<nbBits;
    nbBits++;

    while ((remaining>1) & (charnum<=*maxSVPtr)) {
        if (previous0) {
            unsigned n0 = charnum;
            while ((bitStream & 0xFFFF) == 0xFFFF) {
                n0 += 24;
                if (ip < iend-5) {
                    ip += 2;
                    bitStream = MEM_readLE32(ip) >> bitCount;
                } else {
                    bitStream >>= 16;
                    bitCount   += 16;
            }   }
            while ((bitStream & 3) == 3) {
                n0 += 3;
                bitStream >>= 2;
                bitCount += 2;
            }
            n0 += bitStream & 3;
            bitCount += 2;
            if (n0 > *maxSVPtr) return ERROR(maxSymbolValue_tooSmall);
            while (charnum < n0) normalizedCounter[charnum++] = 0;
            if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
                assert((bitCount >> 3) <= 3); /* For first condition to work */
                ip += bitCount>>3;
                bitCount &= 7;
                bitStream = MEM_readLE32(ip) >> bitCount;
            } else {
                bitStream >>= 2;
        }   }
        {   int const max = (2*threshold-1) - remaining;
            int count;

            if ((bitStream & (threshold-1)) < (U32)max) {
                count = bitStream & (threshold-1);
                bitCount += nbBits-1;
            } else {
                count = bitStream & (2*threshold-1);
                if (count >= threshold) count -= max;
                bitCount += nbBits;
            }

            count--;   /* extra accuracy */
            remaining -= count < 0 ? -count : count;   /* -1 means +1 */
            normalizedCounter[charnum++] = (short)count;
            previous0 = !count;
            while (remaining < threshold) {
                nbBits--;
                threshold >>= 1;
            }

            if ((ip <= iend-7) || (ip + (bitCount>>3) <= iend-4)) {
                ip += bitCount>>3;
                bitCount &= 7;
            } else {
                bitCount -= (int)(8 * (iend - 4 - ip));
                ip = iend - 4;
            }
            bitStream = MEM_readLE32(ip) >> (bitCount & 31);
    }   }   /* while ((remaining>1) & (charnum<=*maxSVPtr)) */
    if (remaining != 1) return ERROR(corruption_detected);
    if (bitCount > 32) return ERROR(corruption_detected);
    *maxSVPtr = charnum-1;

    ip += (bitCount+7)>>3;
    return ip-istart;
}


/*! HUF_readStats() :
    Read compact Huffman tree, saved by HUF_writeCTable().
    `huffWeight` is destination buffer.
    `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32.
    @return : size read from `src` , or an error Code .
    Note : Needed by HUF_readCTable() and HUF_readDTableX?() .
*/
size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats,
                     U32* nbSymbolsPtr, U32* tableLogPtr,
                     const void* src, size_t srcSize)
{
    U32 weightTotal;
    const BYTE* ip = (const BYTE*) src;
    size_t iSize;
    size_t oSize;

    if (!srcSize) return ERROR(srcSize_wrong);
    iSize = ip[0];
    /* memset(huffWeight, 0, hwSize);   *//* is not necessary, even though some analyzer complain ... */

    if (iSize >= 128) {  /* special header */
        oSize = iSize - 127;
        iSize = ((oSize+1)/2);
        if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
        if (oSize >= hwSize) return ERROR(corruption_detected);
        ip += 1;
        {   U32 n;
            for (n=0; n<oSize; n+=2) {
                huffWeight[n]   = ip[n/2] >> 4;
                huffWeight[n+1] = ip[n/2] & 15;
    }   }   }
    else  {   /* header compressed with FSE (normal case) */
        FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(6)];  /* 6 is max possible tableLog for HUF header (maybe even 5, to be tested) */
        if (iSize+1 > srcSize) return ERROR(srcSize_wrong);
        oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 6);   /* max (hwSize-1) values decoded, as last one is implied */
        if (FSE_isError(oSize)) return oSize;
    }

    /* collect weight stats */
    memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32));
    weightTotal = 0;
    {   U32 n; for (n=0; n<oSize; n++) {
            if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected);
            rankStats[huffWeight[n]]++;
            weightTotal += (1 << huffWeight[n]) >> 1;
    }   }
    if (weightTotal == 0) return ERROR(corruption_detected);

    /* get last non-null symbol weight (implied, total must be 2^n) */
    {   U32 const tableLog = BIT_highbit32(weightTotal) + 1;
        if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected);
        *tableLogPtr = tableLog;
        /* determine last weight */
        {   U32 const total = 1 << tableLog;
            U32 const rest = total - weightTotal;
            U32 const verif = 1 << BIT_highbit32(rest);
            U32 const lastWeight = BIT_highbit32(rest) + 1;
            if (verif != rest) return ERROR(corruption_detected);    /* last value must be a clean power of 2 */
            huffWeight[oSize] = (BYTE)lastWeight;
            rankStats[lastWeight]++;
    }   }

    /* check tree construction validity */
    if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected);   /* by construction : at least 2 elts of rank 1, must be even */

    /* results */
    *nbSymbolsPtr = (U32)(oSize+1);
    return iSize+1;
}