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| author | Kirill Volinsky <mataes2007@gmail.com> | 2012-05-18 22:10:43 +0000 | 
|---|---|---|
| committer | Kirill Volinsky <mataes2007@gmail.com> | 2012-05-18 22:10:43 +0000 | 
| commit | 725f68b6808a8a30778f58223fac75386f082785 (patch) | |
| tree | ccba410760749d45139e5e78fd5e08f416ade1a0 /plugins/FreeImage/Source/LibJPEG/jidctflt.c | |
| parent | f920ef497f3299ae24fe783ce03bdd93b419f764 (diff) | |
plugins folders renaming
git-svn-id: http://svn.miranda-ng.org/main/trunk@61 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c
Diffstat (limited to 'plugins/FreeImage/Source/LibJPEG/jidctflt.c')
| -rw-r--r-- | plugins/FreeImage/Source/LibJPEG/jidctflt.c | 235 | 
1 files changed, 235 insertions, 0 deletions
diff --git a/plugins/FreeImage/Source/LibJPEG/jidctflt.c b/plugins/FreeImage/Source/LibJPEG/jidctflt.c new file mode 100644 index 0000000000..f399600c89 --- /dev/null +++ b/plugins/FreeImage/Source/LibJPEG/jidctflt.c @@ -0,0 +1,235 @@ +/*
 + * jidctflt.c
 + *
 + * Copyright (C) 1994-1998, Thomas G. Lane.
 + * Modified 2010 by Guido Vollbeding.
 + * This file is part of the Independent JPEG Group's software.
 + * For conditions of distribution and use, see the accompanying README file.
 + *
 + * This file contains a floating-point implementation of the
 + * inverse DCT (Discrete Cosine Transform).  In the IJG code, this routine
 + * must also perform dequantization of the input coefficients.
 + *
 + * This implementation should be more accurate than either of the integer
 + * IDCT implementations.  However, it may not give the same results on all
 + * machines because of differences in roundoff behavior.  Speed will depend
 + * on the hardware's floating point capacity.
 + *
 + * A 2-D IDCT can be done by 1-D IDCT on each column followed by 1-D IDCT
 + * on each row (or vice versa, but it's more convenient to emit a row at
 + * a time).  Direct algorithms are also available, but they are much more
 + * complex and seem not to be any faster when reduced to code.
 + *
 + * This implementation is based on Arai, Agui, and Nakajima's algorithm for
 + * scaled DCT.  Their original paper (Trans. IEICE E-71(11):1095) is in
 + * Japanese, but the algorithm is described in the Pennebaker & Mitchell
 + * JPEG textbook (see REFERENCES section in file README).  The following code
 + * is based directly on figure 4-8 in P&M.
 + * While an 8-point DCT cannot be done in less than 11 multiplies, it is
 + * possible to arrange the computation so that many of the multiplies are
 + * simple scalings of the final outputs.  These multiplies can then be
 + * folded into the multiplications or divisions by the JPEG quantization
 + * table entries.  The AA&N method leaves only 5 multiplies and 29 adds
 + * to be done in the DCT itself.
 + * The primary disadvantage of this method is that with a fixed-point
 + * implementation, accuracy is lost due to imprecise representation of the
 + * scaled quantization values.  However, that problem does not arise if
 + * we use floating point arithmetic.
 + */
 +
 +#define JPEG_INTERNALS
 +#include "jinclude.h"
 +#include "jpeglib.h"
 +#include "jdct.h"		/* Private declarations for DCT subsystem */
 +
 +#ifdef DCT_FLOAT_SUPPORTED
 +
 +
 +/*
 + * This module is specialized to the case DCTSIZE = 8.
 + */
 +
 +#if DCTSIZE != 8
 +  Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */
 +#endif
 +
 +
 +/* Dequantize a coefficient by multiplying it by the multiplier-table
 + * entry; produce a float result.
 + */
 +
 +#define DEQUANTIZE(coef,quantval)  (((FAST_FLOAT) (coef)) * (quantval))
 +
 +
 +/*
 + * Perform dequantization and inverse DCT on one block of coefficients.
 + */
 +
 +GLOBAL(void)
 +jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
 +		 JCOEFPTR coef_block,
 +		 JSAMPARRAY output_buf, JDIMENSION output_col)
 +{
 +  FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
 +  FAST_FLOAT tmp10, tmp11, tmp12, tmp13;
 +  FAST_FLOAT z5, z10, z11, z12, z13;
 +  JCOEFPTR inptr;
 +  FLOAT_MULT_TYPE * quantptr;
 +  FAST_FLOAT * wsptr;
 +  JSAMPROW outptr;
 +  JSAMPLE *range_limit = cinfo->sample_range_limit;
 +  int ctr;
 +  FAST_FLOAT workspace[DCTSIZE2]; /* buffers data between passes */
 +
 +  /* Pass 1: process columns from input, store into work array. */
 +
 +  inptr = coef_block;
 +  quantptr = (FLOAT_MULT_TYPE *) compptr->dct_table;
 +  wsptr = workspace;
 +  for (ctr = DCTSIZE; ctr > 0; ctr--) {
 +    /* Due to quantization, we will usually find that many of the input
 +     * coefficients are zero, especially the AC terms.  We can exploit this
 +     * by short-circuiting the IDCT calculation for any column in which all
 +     * the AC terms are zero.  In that case each output is equal to the
 +     * DC coefficient (with scale factor as needed).
 +     * With typical images and quantization tables, half or more of the
 +     * column DCT calculations can be simplified this way.
 +     */
 +    
 +    if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 &&
 +	inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 &&
 +	inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 &&
 +	inptr[DCTSIZE*7] == 0) {
 +      /* AC terms all zero */
 +      FAST_FLOAT dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
 +      
 +      wsptr[DCTSIZE*0] = dcval;
 +      wsptr[DCTSIZE*1] = dcval;
 +      wsptr[DCTSIZE*2] = dcval;
 +      wsptr[DCTSIZE*3] = dcval;
 +      wsptr[DCTSIZE*4] = dcval;
 +      wsptr[DCTSIZE*5] = dcval;
 +      wsptr[DCTSIZE*6] = dcval;
 +      wsptr[DCTSIZE*7] = dcval;
 +      
 +      inptr++;			/* advance pointers to next column */
 +      quantptr++;
 +      wsptr++;
 +      continue;
 +    }
 +    
 +    /* Even part */
 +
 +    tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]);
 +    tmp1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]);
 +    tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]);
 +    tmp3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]);
 +
 +    tmp10 = tmp0 + tmp2;	/* phase 3 */
 +    tmp11 = tmp0 - tmp2;
 +
 +    tmp13 = tmp1 + tmp3;	/* phases 5-3 */
 +    tmp12 = (tmp1 - tmp3) * ((FAST_FLOAT) 1.414213562) - tmp13; /* 2*c4 */
 +
 +    tmp0 = tmp10 + tmp13;	/* phase 2 */
 +    tmp3 = tmp10 - tmp13;
 +    tmp1 = tmp11 + tmp12;
 +    tmp2 = tmp11 - tmp12;
 +    
 +    /* Odd part */
 +
 +    tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);
 +    tmp5 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]);
 +    tmp6 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]);
 +    tmp7 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]);
 +
 +    z13 = tmp6 + tmp5;		/* phase 6 */
 +    z10 = tmp6 - tmp5;
 +    z11 = tmp4 + tmp7;
 +    z12 = tmp4 - tmp7;
 +
 +    tmp7 = z11 + z13;		/* phase 5 */
 +    tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562); /* 2*c4 */
 +
 +    z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */
 +    tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */
 +    tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */
 +
 +    tmp6 = tmp12 - tmp7;	/* phase 2 */
 +    tmp5 = tmp11 - tmp6;
 +    tmp4 = tmp10 - tmp5;
 +
 +    wsptr[DCTSIZE*0] = tmp0 + tmp7;
 +    wsptr[DCTSIZE*7] = tmp0 - tmp7;
 +    wsptr[DCTSIZE*1] = tmp1 + tmp6;
 +    wsptr[DCTSIZE*6] = tmp1 - tmp6;
 +    wsptr[DCTSIZE*2] = tmp2 + tmp5;
 +    wsptr[DCTSIZE*5] = tmp2 - tmp5;
 +    wsptr[DCTSIZE*3] = tmp3 + tmp4;
 +    wsptr[DCTSIZE*4] = tmp3 - tmp4;
 +
 +    inptr++;			/* advance pointers to next column */
 +    quantptr++;
 +    wsptr++;
 +  }
 +  
 +  /* Pass 2: process rows from work array, store into output array. */
 +
 +  wsptr = workspace;
 +  for (ctr = 0; ctr < DCTSIZE; ctr++) {
 +    outptr = output_buf[ctr] + output_col;
 +    /* Rows of zeroes can be exploited in the same way as we did with columns.
 +     * However, the column calculation has created many nonzero AC terms, so
 +     * the simplification applies less often (typically 5% to 10% of the time).
 +     * And testing floats for zero is relatively expensive, so we don't bother.
 +     */
 +    
 +    /* Even part */
 +
 +    /* Apply signed->unsigned and prepare float->int conversion */
 +    z5 = wsptr[0] + ((FAST_FLOAT) CENTERJSAMPLE + (FAST_FLOAT) 0.5);
 +    tmp10 = z5 + wsptr[4];
 +    tmp11 = z5 - wsptr[4];
 +
 +    tmp13 = wsptr[2] + wsptr[6];
 +    tmp12 = (wsptr[2] - wsptr[6]) * ((FAST_FLOAT) 1.414213562) - tmp13;
 +
 +    tmp0 = tmp10 + tmp13;
 +    tmp3 = tmp10 - tmp13;
 +    tmp1 = tmp11 + tmp12;
 +    tmp2 = tmp11 - tmp12;
 +
 +    /* Odd part */
 +
 +    z13 = wsptr[5] + wsptr[3];
 +    z10 = wsptr[5] - wsptr[3];
 +    z11 = wsptr[1] + wsptr[7];
 +    z12 = wsptr[1] - wsptr[7];
 +
 +    tmp7 = z11 + z13;
 +    tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562);
 +
 +    z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */
 +    tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */
 +    tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */
 +
 +    tmp6 = tmp12 - tmp7;
 +    tmp5 = tmp11 - tmp6;
 +    tmp4 = tmp10 - tmp5;
 +
 +    /* Final output stage: float->int conversion and range-limit */
 +
 +    outptr[0] = range_limit[((int) (tmp0 + tmp7)) & RANGE_MASK];
 +    outptr[7] = range_limit[((int) (tmp0 - tmp7)) & RANGE_MASK];
 +    outptr[1] = range_limit[((int) (tmp1 + tmp6)) & RANGE_MASK];
 +    outptr[6] = range_limit[((int) (tmp1 - tmp6)) & RANGE_MASK];
 +    outptr[2] = range_limit[((int) (tmp2 + tmp5)) & RANGE_MASK];
 +    outptr[5] = range_limit[((int) (tmp2 - tmp5)) & RANGE_MASK];
 +    outptr[3] = range_limit[((int) (tmp3 + tmp4)) & RANGE_MASK];
 +    outptr[4] = range_limit[((int) (tmp3 - tmp4)) & RANGE_MASK];
 +    
 +    wsptr += DCTSIZE;		/* advance pointer to next row */
 +  }
 +}
 +
 +#endif /* DCT_FLOAT_SUPPORTED */
  | 
