mirror of
https://github.com/id-Software/DOOM-3-BFG.git
synced 2024-12-11 13:11:47 +00:00
397 lines
15 KiB
C++
397 lines
15 KiB
C++
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/*
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* jidctred.c
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*
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* Copyright (C) 1994, Thomas G. Lane.
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* This file is part of the Independent JPEG Group's software.
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* For conditions of distribution and use, see the accompanying README file.
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*
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* This file contains inverse-DCT routines that produce reduced-size output:
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* either 4x4, 2x2, or 1x1 pixels from an 8x8 DCT block.
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*
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* The implementation is based on the Loeffler, Ligtenberg and Moschytz (LL&M)
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* algorithm used in jidctint.c. We simply replace each 8-to-8 1-D IDCT step
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* with an 8-to-4 step that produces the four averages of two adjacent outputs
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* (or an 8-to-2 step producing two averages of four outputs, for 2x2 output).
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* These steps were derived by computing the corresponding values at the end
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* of the normal LL&M code, then simplifying as much as possible.
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*
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* 1x1 is trivial: just take the DC coefficient divided by 8.
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*
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* See jidctint.c for additional comments.
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*/
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#define JPEG_INTERNALS
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#include "jinclude.h"
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#include "jpeglib.h"
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#include "jdct.h" /* Private declarations for DCT subsystem */
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#ifdef IDCT_SCALING_SUPPORTED
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/*
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* This module is specialized to the case DCTSIZE = 8.
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*/
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#if DCTSIZE != 8
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Sorry, this code only copes with 8 x8 DCTs. /* deliberate syntax err */
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#endif
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/* Scaling is the same as in jidctint.c. */
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#if BITS_IN_JSAMPLE == 8
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#define CONST_BITS 13
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#define PASS1_BITS 2
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#else
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#define CONST_BITS 13
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#define PASS1_BITS 1 /* lose a little precision to avoid overflow */
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#endif
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/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
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* causing a lot of useless floating-point operations at run time.
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* To get around this we use the following pre-calculated constants.
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* If you change CONST_BITS you may want to add appropriate values.
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* (With a reasonable C compiler, you can just rely on the FIX() macro...)
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*/
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#if CONST_BITS == 13
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#define FIX_0_211164243 ( (INT32) 1730 ) /* FIX(0.211164243) */
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#define FIX_0_509795579 ( (INT32) 4176 ) /* FIX(0.509795579) */
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#define FIX_0_601344887 ( (INT32) 4926 ) /* FIX(0.601344887) */
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#define FIX_0_720959822 ( (INT32) 5906 ) /* FIX(0.720959822) */
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#define FIX_0_765366865 ( (INT32) 6270 ) /* FIX(0.765366865) */
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#define FIX_0_850430095 ( (INT32) 6967 ) /* FIX(0.850430095) */
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#define FIX_0_899976223 ( (INT32) 7373 ) /* FIX(0.899976223) */
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#define FIX_1_061594337 ( (INT32) 8697 ) /* FIX(1.061594337) */
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#define FIX_1_272758580 ( (INT32) 10426 ) /* FIX(1.272758580) */
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#define FIX_1_451774981 ( (INT32) 11893 ) /* FIX(1.451774981) */
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#define FIX_1_847759065 ( (INT32) 15137 ) /* FIX(1.847759065) */
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#define FIX_2_172734803 ( (INT32) 17799 ) /* FIX(2.172734803) */
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#define FIX_2_562915447 ( (INT32) 20995 ) /* FIX(2.562915447) */
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#define FIX_3_624509785 ( (INT32) 29692 ) /* FIX(3.624509785) */
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#else
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#define FIX_0_211164243 FIX( 0.211164243 )
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#define FIX_0_509795579 FIX( 0.509795579 )
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#define FIX_0_601344887 FIX( 0.601344887 )
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#define FIX_0_720959822 FIX( 0.720959822 )
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#define FIX_0_765366865 FIX( 0.765366865 )
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#define FIX_0_850430095 FIX( 0.850430095 )
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#define FIX_0_899976223 FIX( 0.899976223 )
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#define FIX_1_061594337 FIX( 1.061594337 )
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#define FIX_1_272758580 FIX( 1.272758580 )
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#define FIX_1_451774981 FIX( 1.451774981 )
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#define FIX_1_847759065 FIX( 1.847759065 )
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#define FIX_2_172734803 FIX( 2.172734803 )
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#define FIX_2_562915447 FIX( 2.562915447 )
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#define FIX_3_624509785 FIX( 3.624509785 )
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#endif
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/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result.
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* For 8-bit samples with the recommended scaling, all the variable
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* and constant values involved are no more than 16 bits wide, so a
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* 16x16->32 bit multiply can be used instead of a full 32x32 multiply.
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* For 12-bit samples, a full 32-bit multiplication will be needed.
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*/
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#if BITS_IN_JSAMPLE == 8
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#define MULTIPLY( var, const ) MULTIPLY16C16( var, const )
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#else
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#define MULTIPLY( var, const ) ( ( var ) * ( const ) )
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#endif
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/* Dequantize a coefficient by multiplying it by the multiplier-table
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* entry; produce an int result. In this module, both inputs and result
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* are 16 bits or less, so either int or short multiply will work.
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*/
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#define DEQUANTIZE( coef, quantval ) ( ( (ISLOW_MULT_TYPE) ( coef ) ) * ( quantval ) )
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/*
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* Perform dequantization and inverse DCT on one block of coefficients,
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* producing a reduced-size 4x4 output block.
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*/
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GLOBAL void
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jpeg_idct_4x4( j_decompress_ptr cinfo, jpeg_component_info * compptr,
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JCOEFPTR coef_block,
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JSAMPARRAY output_buf, JDIMENSION output_col ) {
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INT32 tmp0, tmp2, tmp10, tmp12;
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INT32 z1, z2, z3, z4;
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JCOEFPTR inptr;
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ISLOW_MULT_TYPE * quantptr;
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int * wsptr;
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JSAMPROW outptr;
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JSAMPLE * range_limit = IDCT_range_limit( cinfo );
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int ctr;
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int workspace[DCTSIZE * 4];/* buffers data between passes */
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SHIFT_TEMPS
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/* Pass 1: process columns from input, store into work array. */
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inptr = coef_block;
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quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;
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wsptr = workspace;
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for ( ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr-- ) {
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/* Don't bother to process column 4, because second pass won't use it */
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if ( ctr == DCTSIZE - 4 ) {
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continue;
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}
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if ( ( inptr[DCTSIZE * 1] | inptr[DCTSIZE * 2] | inptr[DCTSIZE * 3] |
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inptr[DCTSIZE * 5] | inptr[DCTSIZE * 6] | inptr[DCTSIZE * 7] ) == 0 ) {
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/* AC terms all zero; we need not examine term 4 for 4x4 output */
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int dcval = DEQUANTIZE( inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0] ) << PASS1_BITS;
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wsptr[DCTSIZE * 0] = dcval;
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wsptr[DCTSIZE * 1] = dcval;
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wsptr[DCTSIZE * 2] = dcval;
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wsptr[DCTSIZE * 3] = dcval;
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continue;
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}
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/* Even part */
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tmp0 = DEQUANTIZE( inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0] );
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tmp0 <<= ( CONST_BITS + 1 );
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z2 = DEQUANTIZE( inptr[DCTSIZE * 2], quantptr[DCTSIZE * 2] );
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z3 = DEQUANTIZE( inptr[DCTSIZE * 6], quantptr[DCTSIZE * 6] );
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tmp2 = MULTIPLY( z2, FIX_1_847759065 ) + MULTIPLY( z3, -FIX_0_765366865 );
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tmp10 = tmp0 + tmp2;
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tmp12 = tmp0 - tmp2;
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/* Odd part */
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z1 = DEQUANTIZE( inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7] );
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z2 = DEQUANTIZE( inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5] );
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z3 = DEQUANTIZE( inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3] );
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z4 = DEQUANTIZE( inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1] );
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tmp0 = MULTIPLY( z1, -FIX_0_211164243 )/* sqrt(2) * (c3-c1) */
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+ MULTIPLY( z2, FIX_1_451774981 )/* sqrt(2) * (c3+c7) */
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+ MULTIPLY( z3, -FIX_2_172734803 )/* sqrt(2) * (-c1-c5) */
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+ MULTIPLY( z4, FIX_1_061594337 );/* sqrt(2) * (c5+c7) */
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tmp2 = MULTIPLY( z1, -FIX_0_509795579 )/* sqrt(2) * (c7-c5) */
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+ MULTIPLY( z2, -FIX_0_601344887 )/* sqrt(2) * (c5-c1) */
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+ MULTIPLY( z3, FIX_0_899976223 )/* sqrt(2) * (c3-c7) */
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+ MULTIPLY( z4, FIX_2_562915447 );/* sqrt(2) * (c1+c3) */
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/* Final output stage */
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wsptr[DCTSIZE * 0] = (int) DESCALE( tmp10 + tmp2, CONST_BITS - PASS1_BITS + 1 );
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wsptr[DCTSIZE * 3] = (int) DESCALE( tmp10 - tmp2, CONST_BITS - PASS1_BITS + 1 );
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wsptr[DCTSIZE * 1] = (int) DESCALE( tmp12 + tmp0, CONST_BITS - PASS1_BITS + 1 );
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wsptr[DCTSIZE * 2] = (int) DESCALE( tmp12 - tmp0, CONST_BITS - PASS1_BITS + 1 );
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}
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/* Pass 2: process 4 rows from work array, store into output array. */
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wsptr = workspace;
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for ( ctr = 0; ctr < 4; ctr++ ) {
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outptr = output_buf[ctr] + output_col;
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/* It's not clear whether a zero row test is worthwhile here ... */
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#ifndef NO_ZERO_ROW_TEST
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if ( ( wsptr[1] | wsptr[2] | wsptr[3] | wsptr[5] | wsptr[6] |
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wsptr[7] ) == 0 ) {
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/* AC terms all zero */
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JSAMPLE dcval = range_limit[(int) DESCALE( (INT32) wsptr[0], PASS1_BITS + 3 )
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& RANGE_MASK];
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outptr[0] = dcval;
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outptr[1] = dcval;
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outptr[2] = dcval;
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outptr[3] = dcval;
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wsptr += DCTSIZE;/* advance pointer to next row */
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continue;
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}
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#endif
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/* Even part */
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tmp0 = ( (INT32) wsptr[0] ) << ( CONST_BITS + 1 );
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tmp2 = MULTIPLY( (INT32) wsptr[2], FIX_1_847759065 )
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+ MULTIPLY( (INT32) wsptr[6], -FIX_0_765366865 );
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tmp10 = tmp0 + tmp2;
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tmp12 = tmp0 - tmp2;
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/* Odd part */
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z1 = (INT32) wsptr[7];
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z2 = (INT32) wsptr[5];
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z3 = (INT32) wsptr[3];
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z4 = (INT32) wsptr[1];
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tmp0 = MULTIPLY( z1, -FIX_0_211164243 )/* sqrt(2) * (c3-c1) */
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+ MULTIPLY( z2, FIX_1_451774981 )/* sqrt(2) * (c3+c7) */
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+ MULTIPLY( z3, -FIX_2_172734803 )/* sqrt(2) * (-c1-c5) */
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+ MULTIPLY( z4, FIX_1_061594337 );/* sqrt(2) * (c5+c7) */
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tmp2 = MULTIPLY( z1, -FIX_0_509795579 )/* sqrt(2) * (c7-c5) */
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+ MULTIPLY( z2, -FIX_0_601344887 )/* sqrt(2) * (c5-c1) */
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+ MULTIPLY( z3, FIX_0_899976223 )/* sqrt(2) * (c3-c7) */
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+ MULTIPLY( z4, FIX_2_562915447 );/* sqrt(2) * (c1+c3) */
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/* Final output stage */
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outptr[0] = range_limit[(int) DESCALE( tmp10 + tmp2,
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CONST_BITS + PASS1_BITS + 3 + 1 )
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& RANGE_MASK];
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outptr[3] = range_limit[(int) DESCALE( tmp10 - tmp2,
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CONST_BITS + PASS1_BITS + 3 + 1 )
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& RANGE_MASK];
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outptr[1] = range_limit[(int) DESCALE( tmp12 + tmp0,
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CONST_BITS + PASS1_BITS + 3 + 1 )
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& RANGE_MASK];
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outptr[2] = range_limit[(int) DESCALE( tmp12 - tmp0,
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CONST_BITS + PASS1_BITS + 3 + 1 )
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& RANGE_MASK];
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wsptr += DCTSIZE; /* advance pointer to next row */
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}
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}
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/*
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* Perform dequantization and inverse DCT on one block of coefficients,
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* producing a reduced-size 2x2 output block.
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*/
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GLOBAL void
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jpeg_idct_2x2( j_decompress_ptr cinfo, jpeg_component_info * compptr,
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JCOEFPTR coef_block,
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JSAMPARRAY output_buf, JDIMENSION output_col ) {
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INT32 tmp0, tmp10, z1;
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JCOEFPTR inptr;
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ISLOW_MULT_TYPE * quantptr;
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int * wsptr;
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JSAMPROW outptr;
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JSAMPLE * range_limit = IDCT_range_limit( cinfo );
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int ctr;
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int workspace[DCTSIZE * 2];/* buffers data between passes */
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SHIFT_TEMPS
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/* Pass 1: process columns from input, store into work array. */
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inptr = coef_block;
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quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;
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wsptr = workspace;
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for ( ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr-- ) {
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/* Don't bother to process columns 2,4,6 */
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if ( ( ctr == DCTSIZE - 2 ) || ( ctr == DCTSIZE - 4 ) || ( ctr == DCTSIZE - 6 ) ) {
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continue;
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}
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if ( ( inptr[DCTSIZE * 1] | inptr[DCTSIZE * 3] |
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inptr[DCTSIZE * 5] | inptr[DCTSIZE * 7] ) == 0 ) {
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/* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */
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int dcval = DEQUANTIZE( inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0] ) << PASS1_BITS;
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wsptr[DCTSIZE * 0] = dcval;
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wsptr[DCTSIZE * 1] = dcval;
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continue;
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}
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/* Even part */
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z1 = DEQUANTIZE( inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0] );
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tmp10 = z1 << ( CONST_BITS + 2 );
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/* Odd part */
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z1 = DEQUANTIZE( inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7] );
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tmp0 = MULTIPLY( z1, -FIX_0_720959822 );/* sqrt(2) * (c7-c5+c3-c1) */
|
||
|
|
z1 = DEQUANTIZE( inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5] );
|
||
|
|
tmp0 += MULTIPLY( z1, FIX_0_850430095 );/* sqrt(2) * (-c1+c3+c5+c7) */
|
||
|
|
z1 = DEQUANTIZE( inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3] );
|
||
|
|
tmp0 += MULTIPLY( z1, -FIX_1_272758580 );/* sqrt(2) * (-c1+c3-c5-c7) */
|
||
|
|
z1 = DEQUANTIZE( inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1] );
|
||
|
|
tmp0 += MULTIPLY( z1, FIX_3_624509785 );/* sqrt(2) * (c1+c3+c5+c7) */
|
||
|
|
|
||
|
|
/* Final output stage */
|
||
|
|
|
||
|
|
wsptr[DCTSIZE * 0] = (int) DESCALE( tmp10 + tmp0, CONST_BITS - PASS1_BITS + 2 );
|
||
|
|
wsptr[DCTSIZE * 1] = (int) DESCALE( tmp10 - tmp0, CONST_BITS - PASS1_BITS + 2 );
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Pass 2: process 2 rows from work array, store into output array. */
|
||
|
|
|
||
|
|
wsptr = workspace;
|
||
|
|
for ( ctr = 0; ctr < 2; ctr++ ) {
|
||
|
|
outptr = output_buf[ctr] + output_col;
|
||
|
|
/* It's not clear whether a zero row test is worthwhile here ... */
|
||
|
|
|
||
|
|
#ifndef NO_ZERO_ROW_TEST
|
||
|
|
if ( ( wsptr[1] | wsptr[3] | wsptr[5] | wsptr[7] ) == 0 ) {
|
||
|
|
/* AC terms all zero */
|
||
|
|
JSAMPLE dcval = range_limit[(int) DESCALE( (INT32) wsptr[0], PASS1_BITS + 3 )
|
||
|
|
& RANGE_MASK];
|
||
|
|
|
||
|
|
outptr[0] = dcval;
|
||
|
|
outptr[1] = dcval;
|
||
|
|
|
||
|
|
wsptr += DCTSIZE;/* advance pointer to next row */
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* Even part */
|
||
|
|
|
||
|
|
tmp10 = ( (INT32) wsptr[0] ) << ( CONST_BITS + 2 );
|
||
|
|
|
||
|
|
/* Odd part */
|
||
|
|
|
||
|
|
tmp0 = MULTIPLY( (INT32) wsptr[7], -FIX_0_720959822 )/* sqrt(2) * (c7-c5+c3-c1) */
|
||
|
|
+ MULTIPLY( (INT32) wsptr[5], FIX_0_850430095 )/* sqrt(2) * (-c1+c3+c5+c7) */
|
||
|
|
+ MULTIPLY( (INT32) wsptr[3], -FIX_1_272758580 )/* sqrt(2) * (-c1+c3-c5-c7) */
|
||
|
|
+ MULTIPLY( (INT32) wsptr[1], FIX_3_624509785 );/* sqrt(2) * (c1+c3+c5+c7) */
|
||
|
|
|
||
|
|
/* Final output stage */
|
||
|
|
|
||
|
|
outptr[0] = range_limit[(int) DESCALE( tmp10 + tmp0,
|
||
|
|
CONST_BITS + PASS1_BITS + 3 + 2 )
|
||
|
|
& RANGE_MASK];
|
||
|
|
outptr[1] = range_limit[(int) DESCALE( tmp10 - tmp0,
|
||
|
|
CONST_BITS + PASS1_BITS + 3 + 2 )
|
||
|
|
& RANGE_MASK];
|
||
|
|
|
||
|
|
wsptr += DCTSIZE; /* advance pointer to next row */
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Perform dequantization and inverse DCT on one block of coefficients,
|
||
|
|
* producing a reduced-size 1x1 output block.
|
||
|
|
*/
|
||
|
|
|
||
|
|
GLOBAL void
|
||
|
|
jpeg_idct_1x1( j_decompress_ptr cinfo, jpeg_component_info * compptr,
|
||
|
|
JCOEFPTR coef_block,
|
||
|
|
JSAMPARRAY output_buf, JDIMENSION output_col ) {
|
||
|
|
int dcval;
|
||
|
|
ISLOW_MULT_TYPE * quantptr;
|
||
|
|
JSAMPLE * range_limit = IDCT_range_limit( cinfo );
|
||
|
|
SHIFT_TEMPS
|
||
|
|
|
||
|
|
/* We hardly need an inverse DCT routine for this: just take the
|
||
|
|
* average pixel value, which is one-eighth of the DC coefficient.
|
||
|
|
*/
|
||
|
|
quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table;
|
||
|
|
dcval = DEQUANTIZE( coef_block[0], quantptr[0] );
|
||
|
|
dcval = (int) DESCALE( (INT32) dcval, 3 );
|
||
|
|
|
||
|
|
output_buf[0][output_col] = range_limit[dcval & RANGE_MASK];
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif /* IDCT_SCALING_SUPPORTED */
|