rfx_dwt.c

 
#include <freerdp/config.h>
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include "rfx_dwt.h"
 
static INLINE void rfx_dwt_2d_decode_block(INT16* WINPR_RESTRICT buffer, INT16* WINPR_RESTRICT idwt,
                                           size_t subband_width)
{
  const size_t total_width = subband_width << 1;
 
  /* Inverse DWT in horizontal direction, results in 2 sub-bands in L, H order in tmp buffer idwt.
   */
  /* The 4 sub-bands are stored in HL(0), LH(1), HH(2), LL(3) order. */
  /* The lower part L uses LL(3) and HL(0). */
  /* The higher part H uses LH(1) and HH(2). */
 
  const INT16* ll = buffer + subband_width * subband_width * 3;
  const INT16* hl = buffer;
  INT16* l_dst = idwt;
 
  const INT16* lh = buffer + subband_width * subband_width;
  const INT16* hh = buffer + subband_width * subband_width * 2;
  INT16* h_dst = idwt + subband_width * subband_width * 2;
 
  for (size_t y = 0; y < subband_width; y++)
  {
    /* Even coefficients */
    l_dst[0] = ll[0] - ((hl[0] + hl[0] + 1) >> 1);
    h_dst[0] = lh[0] - ((hh[0] + hh[0] + 1) >> 1);
    for (size_t n = 1; n < subband_width; n++)
    {
      const size_t x = n << 1;
      l_dst[x] = ll[n] - ((hl[n - 1] + hl[n] + 1) >> 1);
      h_dst[x] = lh[n] - ((hh[n - 1] + hh[n] + 1) >> 1);
    }
 
    /* Odd coefficients */
    size_t n = 0;
    for (; n < subband_width - 1; n++)
    {
      const size_t x = n << 1;
      l_dst[x + 1] = (hl[n] << 1) + ((l_dst[x] + l_dst[x + 2]) >> 1);
      h_dst[x + 1] = (hh[n] << 1) + ((h_dst[x] + h_dst[x + 2]) >> 1);
    }
 
    const size_t x = n << 1;
    l_dst[x + 1] = (hl[n] << 1) + (l_dst[x]);
    h_dst[x + 1] = (hh[n] << 1) + (h_dst[x]);
 
    ll += subband_width;
    hl += subband_width;
    l_dst += total_width;
 
    lh += subband_width;
    hh += subband_width;
    h_dst += total_width;
  }
 
  /* Inverse DWT in vertical direction, results are stored in original buffer. */
  for (size_t x = 0; x < total_width; x++)
  {
    const INT16* l = idwt + x;
    const INT16* h = idwt + x + subband_width * total_width;
    INT16* dst = buffer + x;
 
    *dst = *l - ((*h * 2 + 1) >> 1);
 
    for (size_t n = 1; n < subband_width; n++)
    {
      l += total_width;
      h += total_width;
 
      /* Even coefficients */
      dst[2 * total_width] = *l - ((*(h - total_width) + *h + 1) >> 1);
 
      /* Odd coefficients */
      dst[total_width] = (*(h - total_width) << 1) + ((*dst + dst[2 * total_width]) >> 1);
 
      dst += 2 * total_width;
    }
 
    dst[total_width] = (*h << 1) + ((*dst * 2) >> 1);
  }
}
 
void rfx_dwt_2d_decode(INT16* WINPR_RESTRICT buffer, INT16* WINPR_RESTRICT dwt_buffer)
{
  WINPR_ASSERT(buffer);
  WINPR_ASSERT(dwt_buffer);
 
  rfx_dwt_2d_decode_block(&buffer[3840], dwt_buffer, 8);
  rfx_dwt_2d_decode_block(&buffer[3072], dwt_buffer, 16);
  rfx_dwt_2d_decode_block(&buffer[0], dwt_buffer, 32);
}
 
static void rfx_dwt_2d_encode_block(INT16* WINPR_RESTRICT buffer, INT16* WINPR_RESTRICT dwt,
                                    UINT32 subband_width)
{
  INT16* src = NULL;
  INT16* l = NULL;
  INT16* h = NULL;
  INT16* l_src = NULL;
  INT16* h_src = NULL;
  INT16* hl = NULL;
  INT16* lh = NULL;
  INT16* hh = NULL;
  INT16* ll = NULL;
 
  const UINT32 total_width = subband_width << 1;
 
  /* DWT in vertical direction, results in 2 sub-bands in L, H order in tmp buffer dwt. */
  for (UINT32 x = 0; x < total_width; x++)
  {
    for (UINT32 n = 0; n < subband_width; n++)
    {
      UINT32 y = n << 1;
      l = dwt + 1ULL * n * total_width + x;
      h = l + 1ULL * subband_width * total_width;
      src = buffer + 1ULL * y * total_width + x;
 
      /* H */
      *h = (src[total_width] -
            ((src[0] + src[n < subband_width - 1 ? 2 * total_width : 0]) >> 1)) >>
           1;
 
      /* L */
      *l = src[0] + (n == 0 ? *h : (*(h - total_width) + *h) >> 1);
    }
  }
 
  /* DWT in horizontal direction, results in 4 sub-bands in HL(0), LH(1), HH(2), LL(3) order,
   * stored in original buffer. */
  /* The lower part L generates LL(3) and HL(0). */
  /* The higher part H generates LH(1) and HH(2). */
 
  ll = buffer + 3ULL * subband_width * subband_width;
  hl = buffer;
  l_src = dwt;
 
  lh = buffer + 1ULL * subband_width * subband_width;
  hh = buffer + 2ULL * subband_width * subband_width;
  h_src = dwt + 2ULL * subband_width * subband_width;
 
  for (size_t y = 0; y < subband_width; y++)
  {
    /* L */
    for (UINT32 n = 0; n < subband_width; n++)
    {
      UINT32 x = n << 1;
 
      /* HL */
      hl[n] =
          (l_src[x + 1] - ((l_src[x] + l_src[n < subband_width - 1 ? x + 2 : x]) >> 1)) >> 1;
      /* LL */
      ll[n] = l_src[x] + (n == 0 ? hl[n] : (hl[n - 1] + hl[n]) >> 1);
    }
 
    /* H */
    for (UINT32 n = 0; n < subband_width; n++)
    {
      UINT32 x = n << 1;
 
      /* HH */
      hh[n] =
          (h_src[x + 1] - ((h_src[x] + h_src[n < subband_width - 1 ? x + 2 : x]) >> 1)) >> 1;
      /* LH */
      lh[n] = h_src[x] + (n == 0 ? hh[n] : (hh[n - 1] + hh[n]) >> 1);
    }
 
    ll += subband_width;
    hl += subband_width;
    l_src += total_width;
 
    lh += subband_width;
    hh += subband_width;
    h_src += total_width;
  }
}
 
void rfx_dwt_2d_encode(INT16* WINPR_RESTRICT buffer, INT16* WINPR_RESTRICT dwt_buffer)
{
  WINPR_ASSERT(buffer);
  WINPR_ASSERT(dwt_buffer);
 
  rfx_dwt_2d_encode_block(&buffer[0], dwt_buffer, 32);
  rfx_dwt_2d_encode_block(&buffer[3072], dwt_buffer, 16);
  rfx_dwt_2d_encode_block(&buffer[3840], dwt_buffer, 8);
}