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Diffstat (limited to 'plugins/FreeImage/Source/LibJPEG/jfdctflt.c')
| -rw-r--r-- | plugins/FreeImage/Source/LibJPEG/jfdctflt.c | 174 | 
1 files changed, 174 insertions, 0 deletions
diff --git a/plugins/FreeImage/Source/LibJPEG/jfdctflt.c b/plugins/FreeImage/Source/LibJPEG/jfdctflt.c new file mode 100644 index 0000000000..3c1b174801 --- /dev/null +++ b/plugins/FreeImage/Source/LibJPEG/jfdctflt.c @@ -0,0 +1,174 @@ +/*
 + * jfdctflt.c
 + *
 + * Copyright (C) 1994-1996, Thomas G. Lane.
 + * Modified 2003-2009 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
 + * forward DCT (Discrete Cosine Transform).
 + *
 + * This implementation should be more accurate than either of the integer
 + * DCT 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 DCT can be done by 1-D DCT on each row followed by 1-D DCT
 + * on each column.  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
 +
 +
 +/*
 + * Perform the forward DCT on one block of samples.
 + */
 +
 +GLOBAL(void)
 +jpeg_fdct_float (FAST_FLOAT * data, JSAMPARRAY sample_data, JDIMENSION start_col)
 +{
 +  FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
 +  FAST_FLOAT tmp10, tmp11, tmp12, tmp13;
 +  FAST_FLOAT z1, z2, z3, z4, z5, z11, z13;
 +  FAST_FLOAT *dataptr;
 +  JSAMPROW elemptr;
 +  int ctr;
 +
 +  /* Pass 1: process rows. */
 +
 +  dataptr = data;
 +  for (ctr = 0; ctr < DCTSIZE; ctr++) {
 +    elemptr = sample_data[ctr] + start_col;
 +
 +    /* Load data into workspace */
 +    tmp0 = (FAST_FLOAT) (GETJSAMPLE(elemptr[0]) + GETJSAMPLE(elemptr[7]));
 +    tmp7 = (FAST_FLOAT) (GETJSAMPLE(elemptr[0]) - GETJSAMPLE(elemptr[7]));
 +    tmp1 = (FAST_FLOAT) (GETJSAMPLE(elemptr[1]) + GETJSAMPLE(elemptr[6]));
 +    tmp6 = (FAST_FLOAT) (GETJSAMPLE(elemptr[1]) - GETJSAMPLE(elemptr[6]));
 +    tmp2 = (FAST_FLOAT) (GETJSAMPLE(elemptr[2]) + GETJSAMPLE(elemptr[5]));
 +    tmp5 = (FAST_FLOAT) (GETJSAMPLE(elemptr[2]) - GETJSAMPLE(elemptr[5]));
 +    tmp3 = (FAST_FLOAT) (GETJSAMPLE(elemptr[3]) + GETJSAMPLE(elemptr[4]));
 +    tmp4 = (FAST_FLOAT) (GETJSAMPLE(elemptr[3]) - GETJSAMPLE(elemptr[4]));
 +
 +    /* Even part */
 +
 +    tmp10 = tmp0 + tmp3;	/* phase 2 */
 +    tmp13 = tmp0 - tmp3;
 +    tmp11 = tmp1 + tmp2;
 +    tmp12 = tmp1 - tmp2;
 +
 +    /* Apply unsigned->signed conversion */
 +    dataptr[0] = tmp10 + tmp11 - 8 * CENTERJSAMPLE; /* phase 3 */
 +    dataptr[4] = tmp10 - tmp11;
 +
 +    z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */
 +    dataptr[2] = tmp13 + z1;	/* phase 5 */
 +    dataptr[6] = tmp13 - z1;
 +
 +    /* Odd part */
 +
 +    tmp10 = tmp4 + tmp5;	/* phase 2 */
 +    tmp11 = tmp5 + tmp6;
 +    tmp12 = tmp6 + tmp7;
 +
 +    /* The rotator is modified from fig 4-8 to avoid extra negations. */
 +    z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */
 +    z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */
 +    z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */
 +    z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */
 +
 +    z11 = tmp7 + z3;		/* phase 5 */
 +    z13 = tmp7 - z3;
 +
 +    dataptr[5] = z13 + z2;	/* phase 6 */
 +    dataptr[3] = z13 - z2;
 +    dataptr[1] = z11 + z4;
 +    dataptr[7] = z11 - z4;
 +
 +    dataptr += DCTSIZE;		/* advance pointer to next row */
 +  }
 +
 +  /* Pass 2: process columns. */
 +
 +  dataptr = data;
 +  for (ctr = DCTSIZE-1; ctr >= 0; ctr--) {
 +    tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7];
 +    tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7];
 +    tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6];
 +    tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6];
 +    tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5];
 +    tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5];
 +    tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4];
 +    tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4];
 +
 +    /* Even part */
 +
 +    tmp10 = tmp0 + tmp3;	/* phase 2 */
 +    tmp13 = tmp0 - tmp3;
 +    tmp11 = tmp1 + tmp2;
 +    tmp12 = tmp1 - tmp2;
 +
 +    dataptr[DCTSIZE*0] = tmp10 + tmp11; /* phase 3 */
 +    dataptr[DCTSIZE*4] = tmp10 - tmp11;
 +
 +    z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */
 +    dataptr[DCTSIZE*2] = tmp13 + z1; /* phase 5 */
 +    dataptr[DCTSIZE*6] = tmp13 - z1;
 +
 +    /* Odd part */
 +
 +    tmp10 = tmp4 + tmp5;	/* phase 2 */
 +    tmp11 = tmp5 + tmp6;
 +    tmp12 = tmp6 + tmp7;
 +
 +    /* The rotator is modified from fig 4-8 to avoid extra negations. */
 +    z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */
 +    z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */
 +    z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */
 +    z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */
 +
 +    z11 = tmp7 + z3;		/* phase 5 */
 +    z13 = tmp7 - z3;
 +
 +    dataptr[DCTSIZE*5] = z13 + z2; /* phase 6 */
 +    dataptr[DCTSIZE*3] = z13 - z2;
 +    dataptr[DCTSIZE*1] = z11 + z4;
 +    dataptr[DCTSIZE*7] = z11 - z4;
 +
 +    dataptr++;			/* advance pointer to next column */
 +  }
 +}
 +
 +#endif /* DCT_FLOAT_SUPPORTED */
  | 
