/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * RemoteFX Codec Library - RLGR

 *

 * Copyright 2011 Vic Lee

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

/**

 * This implementation of RLGR refers to

 * [MS-RDPRFX] 3.1.8.1.7.3 RLGR1/RLGR3 Pseudocode

 */

#include <freerdp/config.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <winpr/assert.h>

#include <winpr/cast.h>

#include <winpr/crt.h>

#include <winpr/print.h>

#include <winpr/sysinfo.h>

#include <winpr/bitstream.h>

#include <winpr/intrin.h>

#include "rfx_bitstream.h"

#include "rfx_rlgr.h"

/* Constants used in RLGR1/RLGR3 algorithm */

#define KPMAX (80) /* max value for kp or krp */

#define LSGR (3)   /* shift count to convert kp to k */

#define UP_GR (4)  /* increase in kp after a zero run in RL mode */

#define DN_GR (6)  /* decrease in kp after a nonzero symbol in RL mode */

#define UQ_GR (3)  /* increase in kp after nonzero symbol in GR mode */

#define DQ_GR (3)  /* decrease in kp after zero symbol in GR mode */

/* Returns the least number of bits required to represent a given value */

#define GetMinBits(_val, _nbits) \

  do                           \

  {                            \

    UINT32 _v = (_val);      \

    (_nbits) = 0;            \

    while (_v)               \

    {                        \

      _v >>= 1;            \

      (_nbits)++;          \

    }                        \

  } while (0)

/*

 * Update the passed parameter and clamp it to the range [0, KPMAX]

 * Return the value of parameter right-shifted by LSGR

 */

static inline uint32_t UpdateParam(uint32_t* param, int32_t deltaP)

{

  WINPR_ASSERT(param);

  if (deltaP < 0)

  {

    const uint32_t udeltaP = WINPR_ASSERTING_INT_CAST(uint32_t, -deltaP);

    if (udeltaP > *param)

      *param = 0;

    else

      *param -= udeltaP;

  }

  else

    *param += WINPR_ASSERTING_INT_CAST(uint32_t, deltaP);

  if ((*param) > KPMAX)

    (*param) = KPMAX;

  return (*param) >> LSGR;

}

static BOOL g_LZCNT = FALSE;

static INIT_ONCE rfx_rlgr_init_once = INIT_ONCE_STATIC_INIT;

static BOOL CALLBACK rfx_rlgr_init(PINIT_ONCE once, PVOID param, PVOID* context)

{

  WINPR_UNUSED(once);

  WINPR_UNUSED(param);

  WINPR_UNUSED(context);

  g_LZCNT = IsProcessorFeaturePresentEx(PF_EX_LZCNT);

  return TRUE;

}

static inline UINT32 lzcnt_s(UINT32 x)

{

  if (!x)

    return 32;

  if (!g_LZCNT)

  {

    UINT32 y = 0;

    UINT32 n = 32;

    y = x >> 16;

    if (y != 0)

    {

      WINPR_ASSERT(n >= 16);

      n = n - 16;

      x = y;

    }

    y = x >> 8;

    if (y != 0)

    {

      WINPR_ASSERT(n >= 8);

      n = n - 8;

      x = y;

    }

    y = x >> 4;

    if (y != 0)

    {

      WINPR_ASSERT(n >= 4);

      n = n - 4;

      x = y;

    }

    y = x >> 2;

    if (y != 0)

    {

      WINPR_ASSERT(n >= 2);

      n = n - 2;

      x = y;

    }

    y = x >> 1;

    if (y != 0)

    {

      WINPR_ASSERT(n >= 2);

      return n - 2;

    }

    WINPR_ASSERT(n >= x);

    return n - x;

  }

  return __lzcnt(x);

}

int rfx_rlgr_decode(RLGR_MODE mode, const BYTE* WINPR_RESTRICT pSrcData, UINT32 SrcSize,

                    INT16* WINPR_RESTRICT pDstData, UINT32 rDstSize)

{

  uint32_t vk = 0;

  size_t run = 0;

  size_t cnt = 0;

  size_t size = 0;

  size_t offset = 0;

  INT16 mag = 0;

  UINT32 k = 0;

  UINT32 kp = 0;

  UINT32 kr = 0;

  UINT32 krp = 0;

  UINT16 code = 0;

  UINT32 sign = 0;

  UINT32 nIdx = 0;

  UINT32 val1 = 0;

  UINT32 val2 = 0;

  INT16* pOutput = nullptr;

  wBitStream* bs = nullptr;

  wBitStream s_bs = WINPR_C_ARRAY_INIT;

  const SSIZE_T DstSize = rDstSize;

  if (!InitOnceExecuteOnce(&rfx_rlgr_init_once, rfx_rlgr_init, nullptr, nullptr))

    return -1;

  k = 1;

  kp = k << LSGR;

  kr = 1;

  krp = kr << LSGR;

  if ((mode != RLGR1) && (mode != RLGR3))

    mode = RLGR1;

  if (!pSrcData || !SrcSize)

    return -1;

  if (!pDstData || !DstSize)

    return -1;

  pOutput = pDstData;

  bs = &s_bs;

  BitStream_Attach(bs, pSrcData, SrcSize);

  BitStream_Fetch(bs);

  while ((BitStream_GetRemainingLength(bs) > 0) && ((pOutput - pDstData) < DstSize))

  {

    if (k)

    {

      /* Run-Length (RL) Mode */

      run = 0;

      /* count number of leading 0s */

      cnt = lzcnt_s(bs->accumulator);

      size_t nbits = BitStream_GetRemainingLength(bs);

      if (cnt > nbits)

        cnt = WINPR_ASSERTING_INT_CAST(uint32_t, nbits);

      vk = WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      while ((cnt == 32) && (BitStream_GetRemainingLength(bs) > 0))

      {

        BitStream_Shift32(bs);

        cnt = lzcnt_s(bs->accumulator);

        nbits = BitStream_GetRemainingLength(bs);

        if (cnt > nbits)

          cnt = nbits;

        WINPR_ASSERT(cnt + vk <= UINT32_MAX);

        vk += WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      }

      BitStream_Shift(bs, (vk % 32));

      if (BitStream_GetRemainingLength(bs) < 1)

        break;

      BitStream_Shift(bs, 1);

      while (vk--)

      {

        const UINT32 add = (1 << k); /* add (1 << k) to run length */

        run += add;

        /* update k, kp params */

        kp += UP_GR;

        if (kp > KPMAX)

          kp = KPMAX;

        k = kp >> LSGR;

      }

      /* next k bits contain run length remainder */

      if (BitStream_GetRemainingLength(bs) < k)

        break;

      bs->mask = ((1 << k) - 1);

      run += ((bs->accumulator >> (32 - k)) & bs->mask);

      BitStream_Shift(bs, k);

      /* read sign bit */

      if (BitStream_GetRemainingLength(bs) < 1)

        break;

      sign = (bs->accumulator & 0x80000000) ? 1 : 0;

      BitStream_Shift(bs, 1);

      /* count number of leading 1s */

      cnt = lzcnt_s(~(bs->accumulator));

      nbits = BitStream_GetRemainingLength(bs);

      if (cnt > nbits)

        cnt = nbits;

      vk = WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      while ((cnt == 32) && (BitStream_GetRemainingLength(bs) > 0))

      {

        BitStream_Shift32(bs);

        cnt = lzcnt_s(~(bs->accumulator));

        nbits = BitStream_GetRemainingLength(bs);

        if (cnt > nbits)

          cnt = nbits;

        WINPR_ASSERT(cnt + vk <= UINT32_MAX);

        vk += WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      }

      BitStream_Shift(bs, (vk % 32));

      if (BitStream_GetRemainingLength(bs) < 1)

        break;

      BitStream_Shift(bs, 1);

      /* next kr bits contain code remainder */

      if (BitStream_GetRemainingLength(bs) < kr)

        break;

      bs->mask = ((1 << kr) - 1);

      if (kr > 0)

        code = (UINT16)((bs->accumulator >> (32 - kr)) & bs->mask);

      else

        code = 0;

      BitStream_Shift(bs, kr);

      /* add (vk << kr) to code */

      code |= (vk << kr);

      if (!vk)

      {

        /* update kr, krp params */

        if (krp > 2)

          krp -= 2;

        else

          krp = 0;

        kr = krp >> LSGR;

      }

      else if (vk != 1)

      {

        /* update kr, krp params */

        krp += vk;

        if (krp > KPMAX)

          krp = KPMAX;

        kr = krp >> LSGR;

      }

      /* update k, kp params */

      if (kp > DN_GR)

        kp -= DN_GR;

      else

        kp = 0;

      k = kp >> LSGR;

      /* compute magnitude from code */

      if (sign)

        mag = WINPR_ASSERTING_INT_CAST(int16_t, (code + 1)) * -1;

      else

        mag = WINPR_ASSERTING_INT_CAST(int16_t, code + 1);

      /* write to output stream */

      offset = WINPR_ASSERTING_INT_CAST(size_t, (pOutput)-pDstData);

      size = run;

      if ((offset + size) > rDstSize)

        size = WINPR_ASSERTING_INT_CAST(size_t, DstSize) - offset;

      if (size)

      {

        ZeroMemory(pOutput, size * sizeof(INT16));

        pOutput += size;

      }

      if ((pOutput - pDstData) < DstSize)

      {

        *pOutput = mag;

        pOutput++;

      }

    }

    else

    {

      /* Golomb-Rice (GR) Mode */

      /* count number of leading 1s */

      cnt = lzcnt_s(~(bs->accumulator));

      size_t nbits = BitStream_GetRemainingLength(bs);

      if (cnt > nbits)

        cnt = nbits;

      vk = WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      while ((cnt == 32) && (BitStream_GetRemainingLength(bs) > 0))

      {

        BitStream_Shift32(bs);

        cnt = lzcnt_s(~(bs->accumulator));

        nbits = BitStream_GetRemainingLength(bs);

        if (cnt > nbits)

          cnt = nbits;

        WINPR_ASSERT(cnt + vk <= UINT32_MAX);

        vk += WINPR_ASSERTING_INT_CAST(uint32_t, cnt);

      }

      BitStream_Shift(bs, (vk % 32));

      if (BitStream_GetRemainingLength(bs) < 1)

        break;

      BitStream_Shift(bs, 1);

      /* next kr bits contain code remainder */

      if (BitStream_GetRemainingLength(bs) < kr)

        break;

      bs->mask = ((1 << kr) - 1);

      if (kr > 0)

        code = (UINT16)((bs->accumulator >> (32 - kr)) & bs->mask);

      else

        code = 0;

      BitStream_Shift(bs, kr);

      /* add (vk << kr) to code */

      code |= (vk << kr);

      if (!vk)

      {

        /* update kr, krp params */

        if (krp > 2)

          krp -= 2;

        else

          krp = 0;

        kr = (krp >> LSGR) & UINT32_MAX;

      }

      else if (vk != 1)

      {

        /* update kr, krp params */

        krp += vk;

        if (krp > KPMAX)

          krp = KPMAX;

        kr = krp >> LSGR;

      }

      if (mode == RLGR1) /* RLGR1 */

      {

        if (!code)

        {

          /* update k, kp params */

          kp += UQ_GR;

          if (kp > KPMAX)

            kp = KPMAX;

          k = kp >> LSGR;

          mag = 0;

        }

        else

        {

          /* update k, kp params */

          if (kp > DQ_GR)

            kp -= DQ_GR;

          else

            kp = 0;

          k = kp >> LSGR;

          /*

           * code = 2 * mag - sign

           * sign + code = 2 * mag

           */

          if (code & 1)

            mag = WINPR_ASSERTING_INT_CAST(INT16, (code + 1) >> 1) * -1;

          else

            mag = WINPR_ASSERTING_INT_CAST(INT16, code >> 1);

        }

        if ((pOutput - pDstData) < DstSize)

        {

          *pOutput = mag;

          pOutput++;

        }

      }

      else if (mode == RLGR3) /* RLGR3 */

      {

        nIdx = 0;

        if (code)

        {

          mag = WINPR_ASSERTING_INT_CAST(int16_t, code);

          nIdx = 32 - lzcnt_s(WINPR_ASSERTING_INT_CAST(uint32_t, mag));

        }

        if (BitStream_GetRemainingLength(bs) < nIdx)

          break;

        bs->mask = ((1 << nIdx) - 1);

        if (nIdx > 0)

          val1 = ((bs->accumulator >> (32 - nIdx)) & bs->mask);

        else

          val1 = 0;

        BitStream_Shift(bs, nIdx);

        val2 = code - val1;

        if (val1 && val2)

        {

          /* update k, kp params */

          if (kp > 2 * DQ_GR)

            kp -= (2 * DQ_GR);

          else

            kp = 0;

          k = kp >> LSGR;

        }

        else if (!val1 && !val2)

        {

          /* update k, kp params */

          kp += (2 * UQ_GR);

          if (kp > KPMAX)

            kp = KPMAX;

          k = kp >> LSGR;

        }

        if (val1 & 1)

          mag = WINPR_ASSERTING_INT_CAST(int16_t, (val1 + 1) >> 1) * -1;

        else

          mag = WINPR_ASSERTING_INT_CAST(int16_t, val1 >> 1);

        if ((pOutput - pDstData) < DstSize)

        {

          *pOutput = mag;

          pOutput++;

        }

        if (val2 & 1)

          mag = WINPR_ASSERTING_INT_CAST(int16_t, (val2 + 1) >> 1) * -1;

        else

          mag = WINPR_ASSERTING_INT_CAST(int16_t, val2 >> 1);

        if ((pOutput - pDstData) < DstSize)

        {

          *pOutput = WINPR_ASSERTING_INT_CAST(int16_t, mag);

          pOutput++;

        }

      }

    }

  }

  offset = WINPR_ASSERTING_INT_CAST(size_t, (pOutput - pDstData));

  if (offset < rDstSize)

  {

    size = WINPR_ASSERTING_INT_CAST(size_t, DstSize) - offset;

    ZeroMemory(pOutput, size * 2);

    pOutput += size;

  }

  offset = WINPR_ASSERTING_INT_CAST(size_t, (pOutput - pDstData));

  if ((DstSize < 0) || (offset != (size_t)DstSize))

    return -1;

  return 1;

}

/* Returns the next coefficient (a signed int) to encode, from the input stream */

#define GetNextInput(_n)    \

  do                      \

  {                       \

    if (data_size > 0)  \

    {                   \

      (_n) = *data++; \

      data_size--;    \

    }                   \

    else                \

    {                   \

      (_n) = 0;       \

    }                   \

  } while (0)

/* Emit bitPattern to the output bitstream */

#define OutputBits(numBits, bitPattern) rfx_bitstream_put_bits(bs, bitPattern, numBits)

/* Emit a bit (0 or 1), count number of times, to the output bitstream */

static inline void OutputBit(RFX_BITSTREAM* bs, uint32_t count, UINT8 bit)

{

  UINT16 _b = ((bit) ? 0xFFFF : 0);

  const uint32_t rem = count % 16;

  for (uint32_t x = 0; x < count - rem; x += 16)

    rfx_bitstream_put_bits(bs, _b, 16);

  if (rem > 0)

    rfx_bitstream_put_bits(bs, _b, rem);

}

/* Converts the input value to (2 * abs(input) - sign(input)), where sign(input) = (input < 0 ? 1 :

 * 0) and returns it */

static inline UINT32 Get2MagSign(INT32 input)

{

  if (input >= 0)

    return WINPR_ASSERTING_INT_CAST(UINT32, 2 * input);

  return WINPR_ASSERTING_INT_CAST(UINT32, -2 * input - 1);

}

/* Outputs the Golomb/Rice encoding of a non-negative integer */

#define CodeGR(krp, val) rfx_rlgr_code_gr(bs, krp, val)

static void rfx_rlgr_code_gr(RFX_BITSTREAM* bs, uint32_t* krp, UINT32 val)

{

  uint32_t kr = *krp >> LSGR;

  /* unary part of GR code */

  const uint32_t vk = val >> kr;

  OutputBit(bs, vk, 1);

  OutputBit(bs, 1, 0);

  /* remainder part of GR code, if needed */

  if (kr)

  {

    OutputBits(kr, val & ((1 << kr) - 1));

  }

  /* update krp, only if it is not equal to 1 */

  if (vk == 0)

  {

    (void)UpdateParam(krp, -2);

  }

  else if (vk > 1)

  {

    (void)UpdateParam(krp, WINPR_CXX_COMPAT_CAST(int32_t, vk));

  }

}

int rfx_rlgr_encode(RLGR_MODE mode, const INT16* WINPR_RESTRICT data, UINT32 data_size,

                    BYTE* WINPR_RESTRICT buffer, UINT32 buffer_size)

{

  uint32_t k = 0;

  uint32_t kp = 0;

  uint32_t krp = 0;

  RFX_BITSTREAM* bs = nullptr;

  if (!(bs = (RFX_BITSTREAM*)winpr_aligned_calloc(1, sizeof(RFX_BITSTREAM), 32)))

    return 0;

  rfx_bitstream_attach(bs, buffer, buffer_size);

  /* initialize the parameters */

  k = 1;

  kp = 1 << LSGR;

  krp = 1 << LSGR;

  /* process all the input coefficients */

  while (data_size > 0)

  {

    int input = 0;

    if (k)

    {

      uint32_t numZeros = 0;

      uint32_t runmax = 0;

      BYTE sign = 0;

      /* RUN-LENGTH MODE */

      /* collect the run of zeros in the input stream */

      numZeros = 0;

      GetNextInput(input);

      while (input == 0 && data_size > 0)

      {

        numZeros++;

        GetNextInput(input);

      }

      // emit output zeros

      runmax = 1 << k;

      while (numZeros >= runmax)

      {

        OutputBit(bs, 1, 0); /* output a zero bit */

        numZeros -= runmax;

        k = UpdateParam(&kp, UP_GR); /* update kp, k */

        runmax = 1 << k;

      }

      /* output a 1 to terminate runs */

      OutputBit(bs, 1, 1);

      /* output the remaining run length using k bits */

      OutputBits(k, numZeros);

      /* note: when we reach here and the last byte being encoded is 0, we still

         need to output the last two bits, otherwise mstsc will crash */

      /* encode the nonzero value using GR coding */

      const UINT32 mag =

          (UINT32)(input < 0 ? -input : input); /* absolute value of input coefficient */

      sign = (input < 0 ? 1 : 0);         /* sign of input coefficient */

      OutputBit(bs, 1, sign);          /* output the sign bit */

      CodeGR(&krp, mag ? mag - 1 : 0); /* output GR code for (mag - 1) */

      k = UpdateParam(&kp, -DN_GR);

    }

    else

    {

      /* GOLOMB-RICE MODE */

      if (mode == RLGR1)

      {

        UINT32 twoMs = 0;

        /* RLGR1 variant */

        /* convert input to (2*magnitude - sign), encode using GR code */

        GetNextInput(input);

        twoMs = Get2MagSign(input);

        CodeGR(&krp, twoMs);

        /* update k, kp */

        /* NOTE: as of Aug 2011, the algorithm is still wrongly documented

           and the update direction is reversed */

        if (twoMs)

        {

          k = UpdateParam(&kp, -DQ_GR);

        }

        else

        {

          k = UpdateParam(&kp, UQ_GR);

        }

      }

      else /* mode == RLGR3 */

      {

        UINT32 twoMs1 = 0;

        UINT32 twoMs2 = 0;

        UINT32 sum2Ms = 0;

        UINT32 nIdx = 0;

        /* RLGR3 variant */

        /* convert the next two input values to (2*magnitude - sign) and */

        /* encode their sum using GR code */

        GetNextInput(input);

        twoMs1 = Get2MagSign(input);

        GetNextInput(input);

        twoMs2 = Get2MagSign(input);

        sum2Ms = twoMs1 + twoMs2;

        CodeGR(&krp, sum2Ms);

        /* encode binary representation of the first input (twoMs1). */

        GetMinBits(sum2Ms, nIdx);

        OutputBits(nIdx, twoMs1);

        /* update k,kp for the two input values */

        if (twoMs1 && twoMs2)

        {

          k = UpdateParam(&kp, -2 * DQ_GR);

        }

        else if (!twoMs1 && !twoMs2)

        {

          k = UpdateParam(&kp, 2 * UQ_GR);

        }

      }

    }

  }

  rfx_bitstream_flush(bs);

  uint32_t processed_size = rfx_bitstream_get_processed_bytes(bs);

  winpr_aligned_free(bs);

  return WINPR_ASSERTING_INT_CAST(int, processed_size);

}