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The Independent JPEG Group's JPEG software v9b

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This commit is contained in:
Guido Vollbeding
2016-01-17 00:00:00 +00:00
committed by DRC
parent fc11193e7a
commit a560e4b423
53 changed files with 7614 additions and 5008 deletions
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51
jidctflt.c
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@@ -2,7 +2,7 @@
* jidctflt.c
*
* Copyright (C) 1994-1998, Thomas G. Lane.
* Modified 2010 by Guido Vollbeding.
* Modified 2010-2015 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.
*
@@ -63,6 +63,8 @@
/*
* Perform dequantization and inverse DCT on one block of coefficients.
*
* cK represents cos(K*pi/16).
*/
GLOBAL(void)
@@ -77,7 +79,7 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
FLOAT_MULT_TYPE * quantptr;
FAST_FLOAT * wsptr;
JSAMPROW outptr;
JSAMPLE *range_limit = cinfo->sample_range_limit;
JSAMPLE *range_limit = IDCT_range_limit(cinfo);
int ctr;
FAST_FLOAT workspace[DCTSIZE2]; /* buffers data between passes */
@@ -95,14 +97,14 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
* 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;
@@ -111,13 +113,13 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
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]);
@@ -135,7 +137,7 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
tmp3 = tmp10 - tmp13;
tmp1 = tmp11 + tmp12;
tmp2 = tmp11 - tmp12;
/* Odd part */
tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]);
@@ -172,7 +174,7 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
quantptr++;
wsptr++;
}
/* Pass 2: process rows from work array, store into output array. */
wsptr = workspace;
@@ -183,16 +185,17 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
* 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);
/* Prepare range-limit and float->int conversion */
z5 = wsptr[0] + (((FAST_FLOAT) RANGE_CENTER) + ((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;
tmp12 = (wsptr[2] - wsptr[6]) *
((FAST_FLOAT) 1.414213562) - tmp13; /* 2*c4 */
tmp0 = tmp10 + tmp13;
tmp3 = tmp10 - tmp13;
@@ -206,28 +209,28 @@ jpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr,
z11 = wsptr[1] + wsptr[7];
z12 = wsptr[1] - wsptr[7];
tmp7 = z11 + z13;
tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562);
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;
tmp6 = tmp12 - tmp7; /* phase 2 */
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];
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 */
}
}