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<html><!-- Created using the cpp_pretty_printer from the dlib C++ library. See http://dlib.net for updates. --><head><title>dlib C++ Library - jidctfst.c</title></head><body bgcolor='white'><pre>
<font color='#009900'>/*
* jidctfst.c
*
* Copyright (C) 1994-1998, Thomas G. Lane.
* 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 fast, not so accurate integer implementation of the
* inverse DCT (Discrete Cosine Transform). In the IJG code, this routine
* must also perform dequantization of the input coefficients.
*
* 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 &amp; Mitchell
* JPEG textbook (see REFERENCES section in file README). The following code
* is based directly on figure 4-8 in P&amp;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&amp;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 fixed-point math,
* accuracy is lost due to imprecise representation of the scaled
* quantization values. The smaller the quantization table entry, the less
* precise the scaled value, so this implementation does worse with high-
* quality-setting files than with low-quality ones.
*/</font>
<font color='#0000FF'>#define</font> JPEG_INTERNALS
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='jinclude.h.html'>jinclude.h</a>"
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='jpeglib.h.html'>jpeglib.h</a>"
<font color='#0000FF'>#include</font> "<a style='text-decoration:none' href='jdct.h.html'>jdct.h</a>" <font color='#009900'>/* Private declarations for DCT subsystem */</font>
<font color='#0000FF'>#ifdef</font> DCT_IFAST_SUPPORTED
<font color='#009900'>/*
* This module is specialized to the case DCTSIZE = 8.
*/</font>
<font color='#0000FF'>#if</font> DCTSIZE <font color='#5555FF'>!</font><font color='#5555FF'>=</font> <font color='#979000'>8</font>
Sorry, <font color='#0000FF'>this</font> code only copes with <font color='#979000'>8</font>x8 DCTs. <font color='#009900'>/* deliberate syntax err */</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* Scaling decisions are generally the same as in the LL&amp;M algorithm;
* see jidctint.c for more details. However, we choose to descale
* (right shift) multiplication products as soon as they are formed,
* rather than carrying additional fractional bits into subsequent additions.
* This compromises accuracy slightly, but it lets us save a few shifts.
* More importantly, 16-bit arithmetic is then adequate (for 8-bit samples)
* everywhere except in the multiplications proper; this saves a good deal
* of work on 16-bit-int machines.
*
* The dequantized coefficients are not integers because the AA&amp;N scaling
* factors have been incorporated. We represent them scaled up by PASS1_BITS,
* so that the first and second IDCT rounds have the same input scaling.
* For 8-bit JSAMPLEs, we choose IFAST_SCALE_BITS = PASS1_BITS so as to
* avoid a descaling shift; this compromises accuracy rather drastically
* for small quantization table entries, but it saves a lot of shifts.
* For 12-bit JSAMPLEs, there's no hope of using 16x16 multiplies anyway,
* so we use a much larger scaling factor to preserve accuracy.
*
* A final compromise is to represent the multiplicative constants to only
* 8 fractional bits, rather than 13. This saves some shifting work on some
* machines, and may also reduce the cost of multiplication (since there
* are fewer one-bits in the constants).
*/</font>
<font color='#0000FF'>#if</font> BITS_IN_JSAMPLE <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> CONST_BITS <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> PASS1_BITS <font color='#979000'>2</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> CONST_BITS <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> PASS1_BITS <font color='#979000'>1</font> <font color='#009900'>/* lose a little precision to avoid overflow */</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus
* causing a lot of useless floating-point operations at run time.
* To get around this we use the following pre-calculated constants.
* If you change CONST_BITS you may want to add appropriate values.
* (With a reasonable C compiler, you can just rely on the FIX() macro...)
*/</font>
<font color='#0000FF'>#if</font> CONST_BITS <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> FIX_1_082392200 <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>INT32<font face='Lucida Console'>)</font> <font color='#979000'>277</font><font face='Lucida Console'>)</font> <font color='#009900'>/* FIX(1.082392200) */</font>
<font color='#0000FF'>#define</font> FIX_1_414213562 <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>INT32<font face='Lucida Console'>)</font> <font color='#979000'>362</font><font face='Lucida Console'>)</font> <font color='#009900'>/* FIX(1.414213562) */</font>
<font color='#0000FF'>#define</font> FIX_1_847759065 <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>INT32<font face='Lucida Console'>)</font> <font color='#979000'>473</font><font face='Lucida Console'>)</font> <font color='#009900'>/* FIX(1.847759065) */</font>
<font color='#0000FF'>#define</font> FIX_2_613125930 <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>INT32<font face='Lucida Console'>)</font> <font color='#979000'>669</font><font face='Lucida Console'>)</font> <font color='#009900'>/* FIX(2.613125930) */</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> FIX_1_082392200 FIX<font face='Lucida Console'>(</font><font color='#979000'>1.082392200</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#define</font> FIX_1_414213562 FIX<font face='Lucida Console'>(</font><font color='#979000'>1.414213562</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#define</font> FIX_1_847759065 FIX<font face='Lucida Console'>(</font><font color='#979000'>1.847759065</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#define</font> FIX_2_613125930 FIX<font face='Lucida Console'>(</font><font color='#979000'>2.613125930</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* We can gain a little more speed, with a further compromise in accuracy,
* by omitting the addition in a descaling shift. This yields an incorrectly
* rounded result half the time...
*/</font>
<font color='#0000FF'>#ifndef</font> USE_ACCURATE_ROUNDING
<font color='#0000FF'>#undef</font> DESCALE
<font color='#0000FF'>#define</font> DESCALE<font face='Lucida Console'>(</font>x,n<font face='Lucida Console'>)</font> RIGHT_SHIFT<font face='Lucida Console'>(</font>x, n<font face='Lucida Console'>)</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* Multiply a DCTELEM variable by an INT32 constant, and immediately
* descale to yield a DCTELEM result.
*/</font>
<font color='#0000FF'>#define</font> MULTIPLY<font face='Lucida Console'>(</font>var,<font color='#0000FF'>const</font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> DESCALE<font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>var<font face='Lucida Console'>)</font> <font color='#5555FF'>*</font> <font face='Lucida Console'>(</font><font color='#0000FF'>const</font><font face='Lucida Console'>)</font>, CONST_BITS<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#009900'>/* Dequantize a coefficient by multiplying it by the multiplier-table
* entry; produce a DCTELEM result. For 8-bit data a 16x16-&gt;16
* multiplication will do. For 12-bit data, the multiplier table is
* declared INT32, so a 32-bit multiply will be used.
*/</font>
<font color='#0000FF'>#if</font> BITS_IN_JSAMPLE <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> DEQUANTIZE<font face='Lucida Console'>(</font>coef,quantval<font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>IFAST_MULT_TYPE<font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>coef<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'>*</font> <font face='Lucida Console'>(</font>quantval<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> DEQUANTIZE<font face='Lucida Console'>(</font>coef,quantval<font face='Lucida Console'>)</font> \
<b><a name='DESCALE'></a>DESCALE</b><font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>coef<font face='Lucida Console'>)</font><font color='#5555FF'>*</font><font face='Lucida Console'>(</font>quantval<font face='Lucida Console'>)</font>, IFAST_SCALE_BITS<font color='#5555FF'>-</font>PASS1_BITS<font face='Lucida Console'>)</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* Like DESCALE, but applies to a DCTELEM and produces an int.
* We assume that int right shift is unsigned if INT32 right shift is.
*/</font>
<font color='#0000FF'>#ifdef</font> RIGHT_SHIFT_IS_UNSIGNED
<font color='#0000FF'>#define</font> ISHIFT_TEMPS DCTELEM ishift_temp;
<font color='#0000FF'>#if</font> BITS_IN_JSAMPLE <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>8</font>
<font color='#0000FF'>#define</font> DCTELEMBITS <font color='#979000'>16</font> <font color='#009900'>/* DCTELEM may be 16 or 32 bits */</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> DCTELEMBITS <font color='#979000'>32</font> <font color='#009900'>/* DCTELEM must be 32 bits */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#define</font> IRIGHT_SHIFT<font face='Lucida Console'>(</font>x,shft<font face='Lucida Console'>)</font> \
<font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>ishift_temp <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>x<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'>&lt;</font> <font color='#979000'>0</font> ? \
<font face='Lucida Console'>(</font>ishift_temp <font color='#5555FF'>&gt;</font><font color='#5555FF'>&gt;</font> <font face='Lucida Console'>(</font>shft<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'>|</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>~<font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> <font color='#979000'>0</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font face='Lucida Console'>(</font>DCTELEMBITS<font color='#5555FF'>-</font><font face='Lucida Console'>(</font>shft<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font> : \
<font face='Lucida Console'>(</font>ishift_temp <font color='#5555FF'>&gt;</font><font color='#5555FF'>&gt;</font> <font face='Lucida Console'>(</font>shft<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> ISHIFT_TEMPS
<font color='#0000FF'>#define</font> IRIGHT_SHIFT<font face='Lucida Console'>(</font>x,shft<font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>x<font face='Lucida Console'>)</font> <font color='#5555FF'>&gt;</font><font color='#5555FF'>&gt;</font> <font face='Lucida Console'>(</font>shft<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> USE_ACCURATE_ROUNDING
<font color='#0000FF'>#define</font> IDESCALE<font face='Lucida Console'>(</font>x,n<font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> IRIGHT_SHIFT<font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>x<font face='Lucida Console'>)</font> <font color='#5555FF'>+</font> <font face='Lucida Console'>(</font><font color='#979000'>1</font> <font color='#5555FF'>&lt;</font><font color='#5555FF'>&lt;</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>n<font face='Lucida Console'>)</font><font color='#5555FF'>-</font><font color='#979000'>1</font><font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>, n<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#else</font>
<font color='#0000FF'>#define</font> IDESCALE<font face='Lucida Console'>(</font>x,n<font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> IRIGHT_SHIFT<font face='Lucida Console'>(</font>x, n<font face='Lucida Console'>)</font><font face='Lucida Console'>)</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/*
* Perform dequantization and inverse DCT on one block of coefficients.
*/</font>
GLOBAL<font face='Lucida Console'>(</font><font color='#0000FF'><u>void</u></font><font face='Lucida Console'>)</font>
jpeg_idct_ifast <font face='Lucida Console'>(</font>j_decompress_ptr cinfo, jpeg_component_info <font color='#5555FF'>*</font> compptr,
JCOEFPTR coef_block,
JSAMPARRAY output_buf, JDIMENSION output_col<font face='Lucida Console'>)</font>
<b>{</b>
DCTELEM tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
DCTELEM tmp10, tmp11, tmp12, tmp13;
DCTELEM z5, z10, z11, z12, z13;
JCOEFPTR inptr;
IFAST_MULT_TYPE <font color='#5555FF'>*</font> quantptr;
<font color='#0000FF'><u>int</u></font> <font color='#5555FF'>*</font> wsptr;
JSAMPROW outptr;
JSAMPLE <font color='#5555FF'>*</font>range_limit <font color='#5555FF'>=</font> <font color='#BB00BB'>IDCT_range_limit</font><font face='Lucida Console'>(</font>cinfo<font face='Lucida Console'>)</font>;
<font color='#0000FF'><u>int</u></font> ctr;
<font color='#0000FF'><u>int</u></font> workspace[DCTSIZE2]; <font color='#009900'>/* buffers data between passes */</font>
SHIFT_TEMPS <font color='#009900'>/* for DESCALE */</font>
ISHIFT_TEMPS <font color='#009900'>/* for IDESCALE */</font>
<font color='#009900'>/* Pass 1: process columns from input, store into work array. */</font>
inptr <font color='#5555FF'>=</font> coef_block;
quantptr <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>IFAST_MULT_TYPE <font color='#5555FF'>*</font><font face='Lucida Console'>)</font> compptr<font color='#5555FF'>-</font><font color='#5555FF'>&gt;</font>dct_table;
wsptr <font color='#5555FF'>=</font> workspace;
<font color='#0000FF'>for</font> <font face='Lucida Console'>(</font>ctr <font color='#5555FF'>=</font> DCTSIZE; ctr <font color='#5555FF'>&gt;</font> <font color='#979000'>0</font>; ctr<font color='#5555FF'>-</font><font color='#5555FF'>-</font><font face='Lucida Console'>)</font> <b>{</b>
<font color='#009900'>/* 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.
*/</font>
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>1</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>2</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>3</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>4</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>5</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>6</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>7</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font><font face='Lucida Console'>)</font> <b>{</b>
<font color='#009900'>/* AC terms all zero */</font>
<font color='#0000FF'><u>int</u></font> dcval <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>]<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>1</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>2</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>3</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>4</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>5</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>6</font>] <font color='#5555FF'>=</font> dcval;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>7</font>] <font color='#5555FF'>=</font> dcval;
inptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>; <font color='#009900'>/* advance pointers to next column */</font>
quantptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>;
wsptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>;
<font color='#0000FF'>continue</font>;
<b>}</b>
<font color='#009900'>/* Even part */</font>
tmp0 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>]<font face='Lucida Console'>)</font>;
tmp1 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>2</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>2</font>]<font face='Lucida Console'>)</font>;
tmp2 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>4</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>4</font>]<font face='Lucida Console'>)</font>;
tmp3 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>6</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>6</font>]<font face='Lucida Console'>)</font>;
tmp10 <font color='#5555FF'>=</font> tmp0 <font color='#5555FF'>+</font> tmp2; <font color='#009900'>/* phase 3 */</font>
tmp11 <font color='#5555FF'>=</font> tmp0 <font color='#5555FF'>-</font> tmp2;
tmp13 <font color='#5555FF'>=</font> tmp1 <font color='#5555FF'>+</font> tmp3; <font color='#009900'>/* phases 5-3 */</font>
tmp12 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>tmp1 <font color='#5555FF'>-</font> tmp3, FIX_1_414213562<font face='Lucida Console'>)</font> <font color='#5555FF'>-</font> tmp13; <font color='#009900'>/* 2*c4 */</font>
tmp0 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>+</font> tmp13; <font color='#009900'>/* phase 2 */</font>
tmp3 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>-</font> tmp13;
tmp1 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>+</font> tmp12;
tmp2 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>-</font> tmp12;
<font color='#009900'>/* Odd part */</font>
tmp4 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>1</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>1</font>]<font face='Lucida Console'>)</font>;
tmp5 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>3</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>3</font>]<font face='Lucida Console'>)</font>;
tmp6 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>5</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>5</font>]<font face='Lucida Console'>)</font>;
tmp7 <font color='#5555FF'>=</font> <font color='#BB00BB'>DEQUANTIZE</font><font face='Lucida Console'>(</font>inptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>7</font>], quantptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>7</font>]<font face='Lucida Console'>)</font>;
z13 <font color='#5555FF'>=</font> tmp6 <font color='#5555FF'>+</font> tmp5; <font color='#009900'>/* phase 6 */</font>
z10 <font color='#5555FF'>=</font> tmp6 <font color='#5555FF'>-</font> tmp5;
z11 <font color='#5555FF'>=</font> tmp4 <font color='#5555FF'>+</font> tmp7;
z12 <font color='#5555FF'>=</font> tmp4 <font color='#5555FF'>-</font> tmp7;
tmp7 <font color='#5555FF'>=</font> z11 <font color='#5555FF'>+</font> z13; <font color='#009900'>/* phase 5 */</font>
tmp11 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z11 <font color='#5555FF'>-</font> z13, FIX_1_414213562<font face='Lucida Console'>)</font>; <font color='#009900'>/* 2*c4 */</font>
z5 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z10 <font color='#5555FF'>+</font> z12, FIX_1_847759065<font face='Lucida Console'>)</font>; <font color='#009900'>/* 2*c2 */</font>
tmp10 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z12, FIX_1_082392200<font face='Lucida Console'>)</font> <font color='#5555FF'>-</font> z5; <font color='#009900'>/* 2*(c2-c6) */</font>
tmp12 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z10, <font color='#5555FF'>-</font> FIX_2_613125930<font face='Lucida Console'>)</font> <font color='#5555FF'>+</font> z5; <font color='#009900'>/* -2*(c2+c6) */</font>
tmp6 <font color='#5555FF'>=</font> tmp12 <font color='#5555FF'>-</font> tmp7; <font color='#009900'>/* phase 2 */</font>
tmp5 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>-</font> tmp6;
tmp4 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>+</font> tmp5;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>0</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp0 <font color='#5555FF'>+</font> tmp7<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>7</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp0 <font color='#5555FF'>-</font> tmp7<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>1</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp1 <font color='#5555FF'>+</font> tmp6<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>6</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp1 <font color='#5555FF'>-</font> tmp6<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>2</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp2 <font color='#5555FF'>+</font> tmp5<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>5</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp2 <font color='#5555FF'>-</font> tmp5<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>4</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp3 <font color='#5555FF'>+</font> tmp4<font face='Lucida Console'>)</font>;
wsptr[DCTSIZE<font color='#5555FF'>*</font><font color='#979000'>3</font>] <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font color='#0000FF'><u>int</u></font><font face='Lucida Console'>)</font> <font face='Lucida Console'>(</font>tmp3 <font color='#5555FF'>-</font> tmp4<font face='Lucida Console'>)</font>;
inptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>; <font color='#009900'>/* advance pointers to next column */</font>
quantptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>;
wsptr<font color='#5555FF'>+</font><font color='#5555FF'>+</font>;
<b>}</b>
<font color='#009900'>/* Pass 2: process rows from work array, store into output array. */</font>
<font color='#009900'>/* Note that we must descale the results by a factor of 8 == 2**3, */</font>
<font color='#009900'>/* and also undo the PASS1_BITS scaling. */</font>
wsptr <font color='#5555FF'>=</font> workspace;
<font color='#0000FF'>for</font> <font face='Lucida Console'>(</font>ctr <font color='#5555FF'>=</font> <font color='#979000'>0</font>; ctr <font color='#5555FF'>&lt;</font> DCTSIZE; ctr<font color='#5555FF'>+</font><font color='#5555FF'>+</font><font face='Lucida Console'>)</font> <b>{</b>
outptr <font color='#5555FF'>=</font> output_buf[ctr] <font color='#5555FF'>+</font> output_col;
<font color='#009900'>/* 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).
* On machines with very fast multiplication, it's possible that the
* test takes more time than it's worth. In that case this section
* may be commented out.
*/</font>
<font color='#0000FF'>#ifndef</font> NO_ZERO_ROW_TEST
<font color='#0000FF'>if</font> <font face='Lucida Console'>(</font>wsptr[<font color='#979000'>1</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> wsptr[<font color='#979000'>2</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> wsptr[<font color='#979000'>3</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> wsptr[<font color='#979000'>4</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font>
wsptr[<font color='#979000'>5</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> wsptr[<font color='#979000'>6</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font> <font color='#5555FF'>&amp;</font><font color='#5555FF'>&amp;</font> wsptr[<font color='#979000'>7</font>] <font color='#5555FF'>=</font><font color='#5555FF'>=</font> <font color='#979000'>0</font><font face='Lucida Console'>)</font> <b>{</b>
<font color='#009900'>/* AC terms all zero */</font>
JSAMPLE dcval <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>wsptr[<font color='#979000'>0</font>], PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>3</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>4</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>5</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>6</font>] <font color='#5555FF'>=</font> dcval;
outptr[<font color='#979000'>7</font>] <font color='#5555FF'>=</font> dcval;
wsptr <font color='#5555FF'>+</font><font color='#5555FF'>=</font> DCTSIZE; <font color='#009900'>/* advance pointer to next row */</font>
<font color='#0000FF'>continue</font>;
<b>}</b>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* Even part */</font>
tmp10 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>0</font>] <font color='#5555FF'>+</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>4</font>]<font face='Lucida Console'>)</font>;
tmp11 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>0</font>] <font color='#5555FF'>-</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>4</font>]<font face='Lucida Console'>)</font>;
tmp13 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>2</font>] <font color='#5555FF'>+</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>6</font>]<font face='Lucida Console'>)</font>;
tmp12 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font><font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>2</font>] <font color='#5555FF'>-</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>6</font>], FIX_1_414213562<font face='Lucida Console'>)</font>
<font color='#5555FF'>-</font> tmp13;
tmp0 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>+</font> tmp13;
tmp3 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>-</font> tmp13;
tmp1 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>+</font> tmp12;
tmp2 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>-</font> tmp12;
<font color='#009900'>/* Odd part */</font>
z13 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>5</font>] <font color='#5555FF'>+</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>3</font>];
z10 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>5</font>] <font color='#5555FF'>-</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>3</font>];
z11 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>1</font>] <font color='#5555FF'>+</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>7</font>];
z12 <font color='#5555FF'>=</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>1</font>] <font color='#5555FF'>-</font> <font face='Lucida Console'>(</font>DCTELEM<font face='Lucida Console'>)</font> wsptr[<font color='#979000'>7</font>];
tmp7 <font color='#5555FF'>=</font> z11 <font color='#5555FF'>+</font> z13; <font color='#009900'>/* phase 5 */</font>
tmp11 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z11 <font color='#5555FF'>-</font> z13, FIX_1_414213562<font face='Lucida Console'>)</font>; <font color='#009900'>/* 2*c4 */</font>
z5 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z10 <font color='#5555FF'>+</font> z12, FIX_1_847759065<font face='Lucida Console'>)</font>; <font color='#009900'>/* 2*c2 */</font>
tmp10 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z12, FIX_1_082392200<font face='Lucida Console'>)</font> <font color='#5555FF'>-</font> z5; <font color='#009900'>/* 2*(c2-c6) */</font>
tmp12 <font color='#5555FF'>=</font> <font color='#BB00BB'>MULTIPLY</font><font face='Lucida Console'>(</font>z10, <font color='#5555FF'>-</font> FIX_2_613125930<font face='Lucida Console'>)</font> <font color='#5555FF'>+</font> z5; <font color='#009900'>/* -2*(c2+c6) */</font>
tmp6 <font color='#5555FF'>=</font> tmp12 <font color='#5555FF'>-</font> tmp7; <font color='#009900'>/* phase 2 */</font>
tmp5 <font color='#5555FF'>=</font> tmp11 <font color='#5555FF'>-</font> tmp6;
tmp4 <font color='#5555FF'>=</font> tmp10 <font color='#5555FF'>+</font> tmp5;
<font color='#009900'>/* Final output stage: scale down by a factor of 8 and range-limit */</font>
outptr[<font color='#979000'>0</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp0 <font color='#5555FF'>+</font> tmp7, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>7</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp0 <font color='#5555FF'>-</font> tmp7, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>1</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp1 <font color='#5555FF'>+</font> tmp6, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>6</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp1 <font color='#5555FF'>-</font> tmp6, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>2</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp2 <font color='#5555FF'>+</font> tmp5, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>5</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp2 <font color='#5555FF'>-</font> tmp5, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>4</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp3 <font color='#5555FF'>+</font> tmp4, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
outptr[<font color='#979000'>3</font>] <font color='#5555FF'>=</font> range_limit[<font color='#BB00BB'>IDESCALE</font><font face='Lucida Console'>(</font>tmp3 <font color='#5555FF'>-</font> tmp4, PASS1_BITS<font color='#5555FF'>+</font><font color='#979000'>3</font><font face='Lucida Console'>)</font>
<font color='#5555FF'>&amp;</font> RANGE_MASK];
wsptr <font color='#5555FF'>+</font><font color='#5555FF'>=</font> DCTSIZE; <font color='#009900'>/* advance pointer to next row */</font>
<b>}</b>
<b>}</b>
<font color='#0000FF'>#endif</font> <font color='#009900'>/* DCT_IFAST_SUPPORTED */</font>
</pre></body></html>