dreyndev/JD2022-TU1
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
JD2022-TU1/main/extern/Camcam/LIBS/Input/Jpeg/Jidctint.c

599 lines
22 KiB
C
Raw Blame History

/*$T Jidctint.c GC! 1.097 02/16/01 13:42:10 */
/*$6
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
*/
/*
* jidctint.c Copyright (C) 1991-1994, 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 slow-but-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 an
* algorithm described in C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical
* Fast 1-D DCT Algorithms with 11 Multiplications", Proc. Int'l. Conf. on
* Acoustics, Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991. The
* primary algorithm described there uses 11 multiplies and 29 adds. We use their
* alternate method with 12 multiplies and 32 adds. The advantage of this method
* is that no data path contains more than one multiplication; this allows a very
* simple and accurate implementation in scaled fixed-point arithmetic, with a
* minimal number of shifts.
*/
#define JPEG_INTERNALS
#include "JINCLUDE.H"
#include "JPEGLIB.H"
#include "JDCT.H" /* Private declarations for DCT subsystem */
#ifdef DCT_ISLOW_SUPPORTED
/* This module is specialized to the case DCTSIZE = 8. */
#if DCTSIZE != 8
Sorry, this code only copes with 8 x8 DCTs. /* deliberate syntax err */
#endif
/*
* The poop on this scaling stuff is as follows: Each 1-D IDCT step produces
* outputs which are a factor of sqrt(N) larger than the true IDCT outputs. The
* final outputs are therefore a factor of N larger than desired; since N=8 this
* can be cured by a simple right shift at the end of the algorithm. The advantage
* of this arrangement is that we save two multiplications per 1-D IDCT, because
* the y0 and y4 inputs need not be divided by sqrt(N). We have to do addition and
* subtraction of the integer inputs, which is no problem, and multiplication by
* fractional constants, which is a problem to do in integer arithmetic. We
* multiply all the constants by CONST_SCALE and convert them to integer constants
* (thus retaining CONST_BITS bits of precision in the constants). After doing a
* multiplication we have to divide the product by CONST_SCALE, with proper
* rounding, to produce the correct output. This division can be done cheaply as a
* right shift of CONST_BITS bits. We postpone shifting as long as possible so
* that partial sums can be added together with full fractional precision. The
* outputs of the first pass are scaled up by PASS1_BITS bits so that they are
* represented to better-than-integral precision. These outputs require
* BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word with the
* recommended scaling. (To scale up 12-bit sample data further, an intermediate
* INT32 array would be needed.) To avoid overflow of the 32-bit intermediate
* results in pass 2, we must have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <=
* 26. Error analysis shows that the values given below are the most effective.
*/
#if BITS_IN_JSAMPLE == 8
#define CONST_BITS 13
#define PASS1_BITS 2
#else
#define CONST_BITS 13
#define PASS1_BITS 1 /* lose a little precision to avoid overflow */
#endif
/*
* 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...)
*/
#if CONST_BITS == 13
#define FIX_0_298631336 ((INT32) 2446) /* FIX(0.298631336) */
#define FIX_0_390180644 ((INT32) 3196) /* FIX(0.390180644) */
#define FIX_0_541196100 ((INT32) 4433) /* FIX(0.541196100) */
#define FIX_0_765366865 ((INT32) 6270) /* FIX(0.765366865) */
#define FIX_0_899976223 ((INT32) 7373) /* FIX(0.899976223) */
#define FIX_1_175875602 ((INT32) 9633) /* FIX(1.175875602) */
#define FIX_1_501321110 ((INT32) 12299) /* FIX(1.501321110) */
#define FIX_1_847759065 ((INT32) 15137) /* FIX(1.847759065) */
#define FIX_1_961570560 ((INT32) 16069) /* FIX(1.961570560) */
#define FIX_2_053119869 ((INT32) 16819) /* FIX(2.053119869) */
#define FIX_2_562915447 ((INT32) 20995) /* FIX(2.562915447) */
#define FIX_3_072711026 ((INT32) 25172) /* FIX(3.072711026) */
#else
#define FIX_0_298631336 FIX(0.298631336)
#define FIX_0_390180644 FIX(0.390180644)
#define FIX_0_541196100 FIX(0.541196100)
#define FIX_0_765366865 FIX(0.765366865)
#define FIX_0_899976223 FIX(0.899976223)
#define FIX_1_175875602 FIX(1.175875602)
#define FIX_1_501321110 FIX(1.501321110)
#define FIX_1_847759065 FIX(1.847759065)
#define FIX_1_961570560 FIX(1.961570560)
#define FIX_2_053119869 FIX(2.053119869)
#define FIX_2_562915447 FIX(2.562915447)
#define FIX_3_072711026 FIX(3.072711026)
#endif
/*
* Multiply an INT32 variable by an INT32 constant to yield an INT32 result. For
* 8-bit samples with the recommended scaling, all the variable and constant
* values involved are no more than 16 bits wide, so a 16x16->32 bit multiply can
* be used instead of a full 32x32 multiply. For 12-bit samples, a full 32-bit
* multiplication will be needed.
*/
#if BITS_IN_JSAMPLE == 8
#define MULTIPLY(var, const) MULTIPLY16C16(var, const)
#else
#define MULTIPLY(var, const) ((var) * (const))
#endif
/*
=======================================================================================================================
Dequantize a coefficient by multiplying it by the multiplier-table entry; produce an int result. In this module,
both inputs and result are 16 bits or less, so either int or short multiply will work.
=======================================================================================================================
*/
#define DEQUANTIZE(coef, quantval) (((ISLOW_MULT_TYPE) (coef)) * (quantval))
/* Perform dequantization and inverse DCT on one block of coefficients. */
#if defined(PSX2_TARGET) && !defined(_DEBUG)
void fct11(int *pi_tmp0, int *pi_tmp1);
/* special for !!**?<3F>!! de code warrior */
/*
=======================================================================================================================
=======================================================================================================================
*/
void Jade_jpeg_idct_islow
(
j_decompress_ptr _pst_cinfo,
Jade_jpeg_component_info *_pst_compptr,
short *_ps_coef_block,
unsigned char **_ppuc_output_buf,
unsigned int _ui_output_col
)
{
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
int i_tmp0, i_tmp1, i_tmp2, i_tmp3;
int i_tmp10, i_tmp11, i_tmp12, i_tmp13;
int i_z1, i_z2, i_z3, i_z4, i_z5;
short *ps_inptr;
int *pi_quantptr;
int *pi_wsptr;
unsigned char *puc_outptr;
unsigned char *puc_range_limit;
int i_ctr;
int ai_workspace[64];
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
puc_range_limit = ((_pst_cinfo)->sample_range_limit + 128);
ps_inptr = _ps_coef_block;
pi_quantptr = (int *) _pst_compptr->dct_table;
pi_wsptr = ai_workspace;
for(i_ctr = 8; i_ctr > 0; i_ctr--)
{
if
(
(
ps_inptr[8 * 1] |
ps_inptr[8 * 2] |
ps_inptr[8 * 3] |
ps_inptr[8 * 4] |
ps_inptr[8 * 5] |
ps_inptr[8 * 6] |
ps_inptr[8 * 7]
) == 0
)
{
/*~~~~~~~~*/
int i_dcval;
/*~~~~~~~~*/
i_dcval = (((int) (ps_inptr[8 * 0])) * (pi_quantptr[8 * 0])) << 2;
pi_wsptr[8 * 0] = i_dcval;
pi_wsptr[8 * 1] = i_dcval;
pi_wsptr[8 * 2] = i_dcval;
pi_wsptr[8 * 3] = i_dcval;
pi_wsptr[8 * 4] = i_dcval;
pi_wsptr[8 * 5] = i_dcval;
pi_wsptr[8 * 6] = i_dcval;
pi_wsptr[8 * 7] = i_dcval;
ps_inptr++;
pi_quantptr++;
pi_wsptr++;
}
else
{
i_z2 = (((int) (ps_inptr[8 * 2])) * (pi_quantptr[8 * 2]));
i_z3 = (((int) (ps_inptr[8 * 6])) * (pi_quantptr[8 * 6]));
i_z1 = ((i_z2 + i_z3) * (((int) 4433)));
i_tmp2 = i_z1 + ((i_z3) * (-((int) 15137)));
i_tmp3 = i_z1 + ((i_z2) * (((int) 6270)));
fct11(&i_tmp0, &i_tmp1);
i_z2 = (((int) (ps_inptr[8 * 0])) * (pi_quantptr[8 * 0]));
i_z3 = (((int) (ps_inptr[8 * 4])) * (pi_quantptr[8 * 4]));
i_tmp0 = (i_z2 + i_z3) << 13;
i_tmp1 = (i_z2 - i_z3) << 13;
i_tmp10 = i_tmp0 + i_tmp3;
i_tmp13 = i_tmp0 - i_tmp3;
i_tmp11 = i_tmp1 + i_tmp2;
i_tmp12 = i_tmp1 - i_tmp2;
i_tmp0 = (((int) (ps_inptr[8 * 7])) * (pi_quantptr[8 * 7]));
i_tmp1 = (((int) (ps_inptr[8 * 5])) * (pi_quantptr[8 * 5]));
i_tmp2 = (((int) (ps_inptr[8 * 3])) * (pi_quantptr[8 * 3]));
i_tmp3 = (((int) (ps_inptr[8 * 1])) * (pi_quantptr[8 * 1]));
i_z1 = i_tmp0 + i_tmp3;
i_z2 = i_tmp1 + i_tmp2;
i_z3 = i_tmp0 + i_tmp2;
i_z4 = i_tmp1 + i_tmp3;
i_z5 = ((i_z3 + i_z4) * (((int) 9633)));
i_tmp0 = ((i_tmp0) * (((int) 2446)));
i_tmp1 = ((i_tmp1) * (((int) 16819)));
i_tmp2 = ((i_tmp2) * (((int) 25172)));
i_tmp3 = ((i_tmp3) * (((int) 12299)));
i_z1 = ((i_z1) * (-((int) 7373)));
i_z2 = ((i_z2) * (-((int) 20995)));
i_z3 = ((i_z3) * (-((int) 16069)));
i_z4 = ((i_z4) * (-((int) 3196)));
i_z3 += i_z5;
i_z4 += i_z5;
i_tmp0 += i_z1 + i_z3;
i_tmp1 += i_z2 + i_z4;
i_tmp2 += i_z2 + i_z3;
i_tmp3 += i_z1 + i_z4;
pi_wsptr[8 * 0] = (int) (((i_tmp10 + i_tmp3) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 7] = (int) (((i_tmp10 - i_tmp3) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 1] = (int) (((i_tmp11 + i_tmp2) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 6] = (int) (((i_tmp11 - i_tmp2) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 2] = (int) (((i_tmp12 + i_tmp1) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 5] = (int) (((i_tmp12 - i_tmp1) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 3] = (int) (((i_tmp13 + i_tmp0) + (((int) 1) << 10)) >> 11);
pi_wsptr[8 * 4] = (int) (((i_tmp13 - i_tmp0) + (((int) 1) << 10)) >> 11);
ps_inptr++;
pi_quantptr++;
pi_wsptr++;
}
}
pi_wsptr = ai_workspace;
for(i_ctr = 0; i_ctr < 8; i_ctr++)
{
puc_outptr = _ppuc_output_buf[i_ctr] + _ui_output_col;
if((pi_wsptr[1] | pi_wsptr[2] | pi_wsptr[3] | pi_wsptr[4] | pi_wsptr[5] | pi_wsptr[6] | pi_wsptr[7]) == 0)
{
/*~~~~~~~~~~~~~~~~~~~~~*/
unsigned char uc_dcval;
/*~~~~~~~~~~~~~~~~~~~~~*/
uc_dcval = puc_range_limit[(int) ((((int) pi_wsptr[0]) + (((int) 1) << ((2 + 3) - 1))) >> (2 + 3)) & 1023];
puc_outptr[0] = uc_dcval;
puc_outptr[1] = uc_dcval;
puc_outptr[2] = uc_dcval;
puc_outptr[3] = uc_dcval;
puc_outptr[4] = uc_dcval;
puc_outptr[5] = uc_dcval;
puc_outptr[6] = uc_dcval;
puc_outptr[7] = uc_dcval;
pi_wsptr += 8;
}
else
{
i_z2 = (int) pi_wsptr[2];
i_z3 = (int) pi_wsptr[6];
i_z1 = ((i_z2 + i_z3) * (((int) 4433)));
i_tmp2 = i_z1 + ((i_z3) * (-((int) 15137)));
i_tmp3 = i_z1 + ((i_z2) * (((int) 6270)));
fct11(&i_tmp0, &i_tmp1);
i_tmp0 = ((int) pi_wsptr[0] + (int) pi_wsptr[4]) << 13;
i_tmp1 = ((int) pi_wsptr[0] - (int) pi_wsptr[4]) << 13;
i_tmp10 = i_tmp0 + i_tmp3;
i_tmp13 = i_tmp0 - i_tmp3;
i_tmp11 = i_tmp1 + i_tmp2;
i_tmp12 = i_tmp1 - i_tmp2;
i_tmp0 = (int) pi_wsptr[7];
i_tmp1 = (int) pi_wsptr[5];
i_tmp2 = (int) pi_wsptr[3];
i_tmp3 = (int) pi_wsptr[1];
i_z1 = i_tmp0 + i_tmp3;
i_z2 = i_tmp1 + i_tmp2;
i_z3 = i_tmp0 + i_tmp2;
i_z4 = i_tmp1 + i_tmp3;
i_z5 = ((i_z3 + i_z4) * (((int) 9633)));
i_tmp0 = ((i_tmp0) * (((int) 2446)));
i_tmp1 = ((i_tmp1) * (((int) 16819)));
i_tmp2 = ((i_tmp2) * (((int) 25172)));
i_tmp3 = ((i_tmp3) * (((int) 12299)));
i_z1 = ((i_z1) * (-((int) 7373)));
i_z2 = ((i_z2) * (-((int) 20995)));
i_z3 = ((i_z3) * (-((int) 16069)));
i_z4 = ((i_z4) * (-((int) 3196)));
i_z3 += i_z5;
i_z4 += i_z5;
i_tmp0 += i_z1 + i_z3;
i_tmp1 += i_z2 + i_z4;
i_tmp2 += i_z2 + i_z3;
i_tmp3 += i_z1 + i_z4;
puc_outptr[0] = puc_range_limit[(int) (((i_tmp10 + i_tmp3) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[7] = puc_range_limit[(int) (((i_tmp10 - i_tmp3) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[1] = puc_range_limit[(int) (((i_tmp11 + i_tmp2) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[6] = puc_range_limit[(int) (((i_tmp11 - i_tmp2) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[2] = puc_range_limit[(int) (((i_tmp12 + i_tmp1) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[5] = puc_range_limit[(int) (((i_tmp12 - i_tmp1) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[3] = puc_range_limit[(int) (((i_tmp13 + i_tmp0) + (((int) 1) << 17)) >> 18) & 1023];
puc_outptr[4] = puc_range_limit[(int) (((i_tmp13 - i_tmp0) + (((int) 1) << 17)) >> 18) & 1023];
pi_wsptr += 8;
}
}
}
/*
=======================================================================================================================
=======================================================================================================================
*/
void fct11(int *pi_tmp0, int *pi_tmp1)
{
}
#else
/*
=======================================================================================================================
=======================================================================================================================
*/
GLOBAL void Jade_jpeg_idct_islow
(
j_decompress_ptr cinfo,
Jade_jpeg_component_info *compptr,
JCOEFPTR coef_block,
JSAMPARRAY output_buf,
JDIMENSION output_col
)
{
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
INT32 tmp0, tmp1, tmp2, tmp3;
INT32 tmp10, tmp11, tmp12, tmp13;
INT32 z1, z2, z3, z4, z5;
JCOEFPTR inptr;
ISLOW_MULT_TYPE *quantptr;
int *wsptr;
JSAMPROW outptr;
JSAMPLE *range_limit;
int ctr;
int workspace[DCTSIZE2]; /* buffers data between passes */
SHIFT_TEMPS
/*
* Pass 1: process columns from input, store into work array. <20>
* Note results are scaled up by sqrt(8) compared to a true IDCT; <20>
* furthermore, we scale the results by 2**PASS1_BITS.
*/
inptr;
/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
range_limit = IDCT_range_limit(cinfo);
inptr = coef_block;
quantptr = (ISLOW_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] |
inptr[DCTSIZE * 2] |
inptr[DCTSIZE * 3] |
inptr[DCTSIZE * 4] |
inptr[DCTSIZE * 5] |
inptr[DCTSIZE * 6] |
inptr[DCTSIZE * 7]
) == 0
)
{
/*~~~~~~*/
/* AC terms all zero */
int dcval;
/*~~~~~~*/
dcval = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]) << PASS1_BITS;
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: reverse the even part of the forward DCT. <20>
* The rotator is sqrt(2)*c(-6).
*/
z2 = DEQUANTIZE(inptr[DCTSIZE * 2], quantptr[DCTSIZE * 2]);
z3 = DEQUANTIZE(inptr[DCTSIZE * 6], quantptr[DCTSIZE * 6]);
z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065);
tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
z2 = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]);
z3 = DEQUANTIZE(inptr[DCTSIZE * 4], quantptr[DCTSIZE * 4]);
tmp0 = (z2 + z3) << CONST_BITS;
tmp1 = (z2 - z3) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
/*
* Odd part per figure 8; the matrix is unitary and hence its transpose is its
* inverse. i0..i3 are y7,y5,y3,y1 respectively.
*/
tmp0 = DEQUANTIZE(inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7]);
tmp1 = DEQUANTIZE(inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5]);
tmp2 = DEQUANTIZE(inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3]);
tmp3 = DEQUANTIZE(inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1]);
z1 = tmp0 + tmp3;
z2 = tmp1 + tmp2;
z3 = tmp0 + tmp2;
z4 = tmp1 + tmp3;
z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
tmp0 = MULTIPLY(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
tmp1 = MULTIPLY(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
tmp2 = MULTIPLY(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
tmp3 = MULTIPLY(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
z1 = MULTIPLY(z1, -FIX_0_899976223); /* sqrt(2) * (c7-c3) */
z2 = MULTIPLY(z2, -FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
z3 = MULTIPLY(z3, -FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
z4 = MULTIPLY(z4, -FIX_0_390180644); /* sqrt(2) * (c5-c3) */
z3 += z5;
z4 += z5;
tmp0 += z1 + z3;
tmp1 += z2 + z4;
tmp2 += z2 + z3;
tmp3 += z1 + z4;
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
wsptr[DCTSIZE * 0] = (int) DESCALE(tmp10 + tmp3, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 7] = (int) DESCALE(tmp10 - tmp3, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 1] = (int) DESCALE(tmp11 + tmp2, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 6] = (int) DESCALE(tmp11 - tmp2, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 2] = (int) DESCALE(tmp12 + tmp1, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 5] = (int) DESCALE(tmp12 - tmp1, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 3] = (int) DESCALE(tmp13 + tmp0, CONST_BITS - PASS1_BITS);
wsptr[DCTSIZE * 4] = (int) DESCALE(tmp13 - tmp0, CONST_BITS - PASS1_BITS);
inptr++; /* advance pointers to next column */
quantptr++;
wsptr++;
}
/*
* Pass 2: process rows from work array, store into output array. <20>
* Note that we must descale the results by a factor of 8 == 2**3, <20>
* and also undo the PASS1_BITS scaling.
*/
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). 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.
*/
#ifndef NO_ZERO_ROW_TEST
if((wsptr[1] | wsptr[2] | wsptr[3] | wsptr[4] | wsptr[5] | wsptr[6] | wsptr[7]) == 0)
{
/*~~~~~~~~~~*/
/* AC terms all zero */
JSAMPLE dcval;
/*~~~~~~~~~~*/
dcval = range_limit[(int) DESCALE((INT32) wsptr[0], PASS1_BITS + 3) & RANGE_MASK];
outptr[0] = dcval;
outptr[1] = dcval;
outptr[2] = dcval;
outptr[3] = dcval;
outptr[4] = dcval;
outptr[5] = dcval;
outptr[6] = dcval;
outptr[7] = dcval;
wsptr += DCTSIZE; /* advance pointer to next row */
continue;
}
#endif
/*
* Even part: reverse the even part of the forward DCT. <20>
* The rotator is sqrt(2)*c(-6).
*/
z2 = (INT32) wsptr[2];
z3 = (INT32) wsptr[6];
z1 = MULTIPLY(z2 + z3, FIX_0_541196100);
tmp2 = z1 + MULTIPLY(z3, -FIX_1_847759065);
tmp3 = z1 + MULTIPLY(z2, FIX_0_765366865);
tmp0 = ((INT32) wsptr[0] + (INT32) wsptr[4]) << CONST_BITS;
tmp1 = ((INT32) wsptr[0] - (INT32) wsptr[4]) << CONST_BITS;
tmp10 = tmp0 + tmp3;
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
/*
* Odd part per figure 8; the matrix is unitary and hence its transpose is its
* inverse. i0..i3 are y7,y5,y3,y1 respectively.
*/
tmp0 = (INT32) wsptr[7];
tmp1 = (INT32) wsptr[5];
tmp2 = (INT32) wsptr[3];
tmp3 = (INT32) wsptr[1];
z1 = tmp0 + tmp3;
z2 = tmp1 + tmp2;
z3 = tmp0 + tmp2;
z4 = tmp1 + tmp3;
z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */
tmp0 = MULTIPLY(tmp0, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */
tmp1 = MULTIPLY(tmp1, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */
tmp2 = MULTIPLY(tmp2, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */
tmp3 = MULTIPLY(tmp3, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */
z1 = MULTIPLY(z1, -FIX_0_899976223); /* sqrt(2) * (c7-c3) */
z2 = MULTIPLY(z2, -FIX_2_562915447); /* sqrt(2) * (-c1-c3) */
z3 = MULTIPLY(z3, -FIX_1_961570560); /* sqrt(2) * (-c3-c5) */
z4 = MULTIPLY(z4, -FIX_0_390180644); /* sqrt(2) * (c5-c3) */
z3 += z5;
z4 += z5;
tmp0 += z1 + z3;
tmp1 += z2 + z4;
tmp2 += z2 + z3;
tmp3 += z1 + z4;
/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp3, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[7] = range_limit[(int) DESCALE(tmp10 - tmp3, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[1] = range_limit[(int) DESCALE(tmp11 + tmp2, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[6] = range_limit[(int) DESCALE(tmp11 - tmp2, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[2] = range_limit[(int) DESCALE(tmp12 + tmp1, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[5] = range_limit[(int) DESCALE(tmp12 - tmp1, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[3] = range_limit[(int) DESCALE(tmp13 + tmp0, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
outptr[4] = range_limit[(int) DESCALE(tmp13 - tmp0, CONST_BITS + PASS1_BITS + 3) & RANGE_MASK];
wsptr += DCTSIZE; /* advance pointer to next row */
}
}
#endif
#endif /* DCT_ISLOW_SUPPORTED */
Reference in a new issue View git blame Copy permalink