nest-open-source / manifest_repos / ffmpeg / 62cf23d89db2251203d6207e2261ddc5498167c6 / . / libavcodec / jfdctint_template.c

/* | |

* This file is part of the Independent JPEG Group's software. | |

* | |

* The authors make NO WARRANTY or representation, either express or implied, | |

* with respect to this software, its quality, accuracy, merchantability, or | |

* fitness for a particular purpose. This software is provided "AS IS", and | |

* you, its user, assume the entire risk as to its quality and accuracy. | |

* | |

* This software is copyright (C) 1991-1996, Thomas G. Lane. | |

* All Rights Reserved except as specified below. | |

* | |

* Permission is hereby granted to use, copy, modify, and distribute this | |

* software (or portions thereof) for any purpose, without fee, subject to | |

* these conditions: | |

* (1) If any part of the source code for this software is distributed, then | |

* this README file must be included, with this copyright and no-warranty | |

* notice unaltered; and any additions, deletions, or changes to the original | |

* files must be clearly indicated in accompanying documentation. | |

* (2) If only executable code is distributed, then the accompanying | |

* documentation must state that "this software is based in part on the work | |

* of the Independent JPEG Group". | |

* (3) Permission for use of this software is granted only if the user accepts | |

* full responsibility for any undesirable consequences; the authors accept | |

* NO LIABILITY for damages of any kind. | |

* | |

* These conditions apply to any software derived from or based on the IJG | |

* code, not just to the unmodified library. If you use our work, you ought | |

* to acknowledge us. | |

* | |

* Permission is NOT granted for the use of any IJG author's name or company | |

* name in advertising or publicity relating to this software or products | |

* derived from it. This software may be referred to only as "the Independent | |

* JPEG Group's software". | |

* | |

* We specifically permit and encourage the use of this software as the basis | |

* of commercial products, provided that all warranty or liability claims are | |

* assumed by the product vendor. | |

* | |

* This file contains a slow-but-accurate integer implementation of the | |

* forward DCT (Discrete Cosine Transform). | |

* | |

* A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT | |

* on each column. Direct algorithms are also available, but they are | |

* much more complex and seem not to be any faster when reduced to code. | |

* | |

* This implementation is based on 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. | |

*/ | |

/** | |

* @file | |

* Independent JPEG Group's slow & accurate dct. | |

*/ | |

#include "libavutil/common.h" | |

#include "dct.h" | |

#include "bit_depth_template.c" | |

#define DCTSIZE 8 | |

#define BITS_IN_JSAMPLE BIT_DEPTH | |

#define GLOBAL(x) x | |

#define RIGHT_SHIFT(x, n) ((x) >> (n)) | |

#define MULTIPLY16C16(var,const) ((var)*(const)) | |

#define DESCALE(x,n) RIGHT_SHIFT((x) + (1 << ((n) - 1)), n) | |

/* | |

* This module is specialized to the case DCTSIZE = 8. | |

*/ | |

#if DCTSIZE != 8 | |

#error "Sorry, this code only copes with 8x8 DCTs." | |

#endif | |

/* | |

* The poop on this scaling stuff is as follows: | |

* | |

* Each 1-D DCT step produces outputs which are a factor of sqrt(N) | |

* larger than the true DCT 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 DCT, | |

* because the y0 and y4 outputs need not be divided by sqrt(N). | |

* In the IJG code, this factor of 8 is removed by the quantization step | |

* (in jcdctmgr.c), NOT in this module. | |

* | |

* 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. (For 12-bit sample data, the intermediate | |

* array is int32_t anyway.) | |

* | |

* 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. | |

*/ | |

#undef CONST_BITS | |

#undef PASS1_BITS | |

#undef OUT_SHIFT | |

#if BITS_IN_JSAMPLE == 8 | |

#define CONST_BITS 13 | |

#define PASS1_BITS 4 /* set this to 2 if 16x16 multiplies are faster */ | |

#define OUT_SHIFT PASS1_BITS | |

#else | |

#define CONST_BITS 13 | |

#define PASS1_BITS 1 /* lose a little precision to avoid overflow */ | |

#define OUT_SHIFT (PASS1_BITS + 1) | |

#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_t) 2446) /* FIX(0.298631336) */ | |

#define FIX_0_390180644 ((int32_t) 3196) /* FIX(0.390180644) */ | |

#define FIX_0_541196100 ((int32_t) 4433) /* FIX(0.541196100) */ | |

#define FIX_0_765366865 ((int32_t) 6270) /* FIX(0.765366865) */ | |

#define FIX_0_899976223 ((int32_t) 7373) /* FIX(0.899976223) */ | |

#define FIX_1_175875602 ((int32_t) 9633) /* FIX(1.175875602) */ | |

#define FIX_1_501321110 ((int32_t) 12299) /* FIX(1.501321110) */ | |

#define FIX_1_847759065 ((int32_t) 15137) /* FIX(1.847759065) */ | |

#define FIX_1_961570560 ((int32_t) 16069) /* FIX(1.961570560) */ | |

#define FIX_2_053119869 ((int32_t) 16819) /* FIX(2.053119869) */ | |

#define FIX_2_562915447 ((int32_t) 20995) /* FIX(2.562915447) */ | |

#define FIX_3_072711026 ((int32_t) 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_t variable by an int32_t constant to yield an int32_t 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 && CONST_BITS<=13 && PASS1_BITS<=2 | |

#define MULTIPLY(var,const) MULTIPLY16C16(var,const) | |

#else | |

#define MULTIPLY(var,const) ((var) * (const)) | |

#endif | |

static av_always_inline void FUNC(row_fdct)(int16_t *data) | |

{ | |

int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |

int tmp10, tmp11, tmp12, tmp13; | |

int z1, z2, z3, z4, z5; | |

int16_t *dataptr; | |

int ctr; | |

/* Pass 1: process rows. */ | |

/* Note results are scaled up by sqrt(8) compared to a true DCT; */ | |

/* furthermore, we scale the results by 2**PASS1_BITS. */ | |

dataptr = data; | |

for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |

tmp0 = dataptr[0] + dataptr[7]; | |

tmp7 = dataptr[0] - dataptr[7]; | |

tmp1 = dataptr[1] + dataptr[6]; | |

tmp6 = dataptr[1] - dataptr[6]; | |

tmp2 = dataptr[2] + dataptr[5]; | |

tmp5 = dataptr[2] - dataptr[5]; | |

tmp3 = dataptr[3] + dataptr[4]; | |

tmp4 = dataptr[3] - dataptr[4]; | |

/* Even part per LL&M figure 1 --- note that published figure is faulty; | |

* rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | |

*/ | |

tmp10 = tmp0 + tmp3; | |

tmp13 = tmp0 - tmp3; | |

tmp11 = tmp1 + tmp2; | |

tmp12 = tmp1 - tmp2; | |

dataptr[0] = (int16_t) ((tmp10 + tmp11) * (1 << PASS1_BITS)); | |

dataptr[4] = (int16_t) ((tmp10 - tmp11) * (1 << PASS1_BITS)); | |

z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |

dataptr[2] = (int16_t) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |

CONST_BITS-PASS1_BITS); | |

dataptr[6] = (int16_t) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |

CONST_BITS-PASS1_BITS); | |

/* Odd part per figure 8 --- note paper omits factor of sqrt(2). | |

* cK represents cos(K*pi/16). | |

* i0..i3 in the paper are tmp4..tmp7 here. | |

*/ | |

z1 = tmp4 + tmp7; | |

z2 = tmp5 + tmp6; | |

z3 = tmp4 + tmp6; | |

z4 = tmp5 + tmp7; | |

z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |

tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |

tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |

tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |

tmp7 = MULTIPLY(tmp7, 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; | |

dataptr[7] = (int16_t) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS); | |

dataptr[5] = (int16_t) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS); | |

dataptr[3] = (int16_t) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS); | |

dataptr[1] = (int16_t) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS); | |

dataptr += DCTSIZE; /* advance pointer to next row */ | |

} | |

} | |

/* | |

* Perform the forward DCT on one block of samples. | |

*/ | |

GLOBAL(void) | |

FUNC(ff_jpeg_fdct_islow)(int16_t *data) | |

{ | |

int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |

int tmp10, tmp11, tmp12, tmp13; | |

int z1, z2, z3, z4, z5; | |

int16_t *dataptr; | |

int ctr; | |

FUNC(row_fdct)(data); | |

/* Pass 2: process columns. | |

* We remove the PASS1_BITS scaling, but leave the results scaled up | |

* by an overall factor of 8. | |

*/ | |

dataptr = data; | |

for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |

tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7]; | |

tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7]; | |

tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6]; | |

tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6]; | |

tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5]; | |

tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5]; | |

tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4]; | |

tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4]; | |

/* Even part per LL&M figure 1 --- note that published figure is faulty; | |

* rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | |

*/ | |

tmp10 = tmp0 + tmp3; | |

tmp13 = tmp0 - tmp3; | |

tmp11 = tmp1 + tmp2; | |

tmp12 = tmp1 - tmp2; | |

dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |

dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |

z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |

dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |

CONST_BITS + OUT_SHIFT); | |

dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |

CONST_BITS + OUT_SHIFT); | |

/* Odd part per figure 8 --- note paper omits factor of sqrt(2). | |

* cK represents cos(K*pi/16). | |

* i0..i3 in the paper are tmp4..tmp7 here. | |

*/ | |

z1 = tmp4 + tmp7; | |

z2 = tmp5 + tmp6; | |

z3 = tmp4 + tmp6; | |

z4 = tmp5 + tmp7; | |

z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |

tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |

tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |

tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |

tmp7 = MULTIPLY(tmp7, 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; | |

dataptr[DCTSIZE*7] = DESCALE(tmp4 + z1 + z3, CONST_BITS + OUT_SHIFT); | |

dataptr[DCTSIZE*5] = DESCALE(tmp5 + z2 + z4, CONST_BITS + OUT_SHIFT); | |

dataptr[DCTSIZE*3] = DESCALE(tmp6 + z2 + z3, CONST_BITS + OUT_SHIFT); | |

dataptr[DCTSIZE*1] = DESCALE(tmp7 + z1 + z4, CONST_BITS + OUT_SHIFT); | |

dataptr++; /* advance pointer to next column */ | |

} | |

} | |

/* | |

* The secret of DCT2-4-8 is really simple -- you do the usual 1-DCT | |

* on the rows and then, instead of doing even and odd, part on the columns | |

* you do even part two times. | |

*/ | |

GLOBAL(void) | |

FUNC(ff_fdct248_islow)(int16_t *data) | |

{ | |

int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | |

int tmp10, tmp11, tmp12, tmp13; | |

int z1; | |

int16_t *dataptr; | |

int ctr; | |

FUNC(row_fdct)(data); | |

/* Pass 2: process columns. | |

* We remove the PASS1_BITS scaling, but leave the results scaled up | |

* by an overall factor of 8. | |

*/ | |

dataptr = data; | |

for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |

tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1]; | |

tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3]; | |

tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5]; | |

tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7]; | |

tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1]; | |

tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3]; | |

tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5]; | |

tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7]; | |

tmp10 = tmp0 + tmp3; | |

tmp11 = tmp1 + tmp2; | |

tmp12 = tmp1 - tmp2; | |

tmp13 = tmp0 - tmp3; | |

dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |

dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |

z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |

dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |

CONST_BITS+OUT_SHIFT); | |

dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |

CONST_BITS+OUT_SHIFT); | |

tmp10 = tmp4 + tmp7; | |

tmp11 = tmp5 + tmp6; | |

tmp12 = tmp5 - tmp6; | |

tmp13 = tmp4 - tmp7; | |

dataptr[DCTSIZE*1] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |

dataptr[DCTSIZE*5] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |

z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |

dataptr[DCTSIZE*3] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |

CONST_BITS + OUT_SHIFT); | |

dataptr[DCTSIZE*7] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |

CONST_BITS + OUT_SHIFT); | |

dataptr++; /* advance pointer to next column */ | |

} | |

} |