hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jidctred.c |
| 3 | * |
Jonathan Wright | db870df | 2020-08-05 11:42:22 +0100 | [diff] [blame] | 4 | * This file was part of the Independent JPEG Group's software: |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 5 | * Copyright (C) 1994-1998, Thomas G. Lane. |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 6 | * libjpeg-turbo Modifications: |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 7 | * Copyright (C) 2015, D. R. Commander. |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 8 | * For conditions of distribution and use, see the accompanying README.ijg |
| 9 | * file. |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 10 | * |
| 11 | * This file contains inverse-DCT routines that produce reduced-size output: |
| 12 | * either 4x4, 2x2, or 1x1 pixels from an 8x8 DCT block. |
| 13 | * |
| 14 | * The implementation is based on the Loeffler, Ligtenberg and Moschytz (LL&M) |
| 15 | * algorithm used in jidctint.c. We simply replace each 8-to-8 1-D IDCT step |
| 16 | * with an 8-to-4 step that produces the four averages of two adjacent outputs |
| 17 | * (or an 8-to-2 step producing two averages of four outputs, for 2x2 output). |
| 18 | * These steps were derived by computing the corresponding values at the end |
| 19 | * of the normal LL&M code, then simplifying as much as possible. |
| 20 | * |
| 21 | * 1x1 is trivial: just take the DC coefficient divided by 8. |
| 22 | * |
| 23 | * See jidctint.c for additional comments. |
| 24 | */ |
| 25 | |
| 26 | #define JPEG_INTERNALS |
| 27 | #include "jinclude.h" |
| 28 | #include "jpeglib.h" |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 29 | #include "jdct.h" /* Private declarations for DCT subsystem */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 30 | |
| 31 | #ifdef IDCT_SCALING_SUPPORTED |
| 32 | |
| 33 | |
| 34 | /* |
| 35 | * This module is specialized to the case DCTSIZE = 8. |
| 36 | */ |
| 37 | |
| 38 | #if DCTSIZE != 8 |
| 39 | Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ |
| 40 | #endif |
| 41 | |
| 42 | |
| 43 | /* Scaling is the same as in jidctint.c. */ |
| 44 | |
| 45 | #if BITS_IN_JSAMPLE == 8 |
| 46 | #define CONST_BITS 13 |
| 47 | #define PASS1_BITS 2 |
| 48 | #else |
| 49 | #define CONST_BITS 13 |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 50 | #define PASS1_BITS 1 /* lose a little precision to avoid overflow */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 51 | #endif |
| 52 | |
| 53 | /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus |
| 54 | * causing a lot of useless floating-point operations at run time. |
| 55 | * To get around this we use the following pre-calculated constants. |
| 56 | * If you change CONST_BITS you may want to add appropriate values. |
| 57 | * (With a reasonable C compiler, you can just rely on the FIX() macro...) |
| 58 | */ |
| 59 | |
| 60 | #if CONST_BITS == 13 |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 61 | #define FIX_0_211164243 ((JLONG)1730) /* FIX(0.211164243) */ |
| 62 | #define FIX_0_509795579 ((JLONG)4176) /* FIX(0.509795579) */ |
| 63 | #define FIX_0_601344887 ((JLONG)4926) /* FIX(0.601344887) */ |
| 64 | #define FIX_0_720959822 ((JLONG)5906) /* FIX(0.720959822) */ |
| 65 | #define FIX_0_765366865 ((JLONG)6270) /* FIX(0.765366865) */ |
| 66 | #define FIX_0_850430095 ((JLONG)6967) /* FIX(0.850430095) */ |
| 67 | #define FIX_0_899976223 ((JLONG)7373) /* FIX(0.899976223) */ |
| 68 | #define FIX_1_061594337 ((JLONG)8697) /* FIX(1.061594337) */ |
| 69 | #define FIX_1_272758580 ((JLONG)10426) /* FIX(1.272758580) */ |
| 70 | #define FIX_1_451774981 ((JLONG)11893) /* FIX(1.451774981) */ |
| 71 | #define FIX_1_847759065 ((JLONG)15137) /* FIX(1.847759065) */ |
| 72 | #define FIX_2_172734803 ((JLONG)17799) /* FIX(2.172734803) */ |
| 73 | #define FIX_2_562915447 ((JLONG)20995) /* FIX(2.562915447) */ |
| 74 | #define FIX_3_624509785 ((JLONG)29692) /* FIX(3.624509785) */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 75 | #else |
| 76 | #define FIX_0_211164243 FIX(0.211164243) |
| 77 | #define FIX_0_509795579 FIX(0.509795579) |
| 78 | #define FIX_0_601344887 FIX(0.601344887) |
| 79 | #define FIX_0_720959822 FIX(0.720959822) |
| 80 | #define FIX_0_765366865 FIX(0.765366865) |
| 81 | #define FIX_0_850430095 FIX(0.850430095) |
| 82 | #define FIX_0_899976223 FIX(0.899976223) |
| 83 | #define FIX_1_061594337 FIX(1.061594337) |
| 84 | #define FIX_1_272758580 FIX(1.272758580) |
| 85 | #define FIX_1_451774981 FIX(1.451774981) |
| 86 | #define FIX_1_847759065 FIX(1.847759065) |
| 87 | #define FIX_2_172734803 FIX(2.172734803) |
| 88 | #define FIX_2_562915447 FIX(2.562915447) |
| 89 | #define FIX_3_624509785 FIX(3.624509785) |
| 90 | #endif |
| 91 | |
| 92 | |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 93 | /* Multiply a JLONG variable by a JLONG constant to yield a JLONG result. |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 94 | * For 8-bit samples with the recommended scaling, all the variable |
| 95 | * and constant values involved are no more than 16 bits wide, so a |
| 96 | * 16x16->32 bit multiply can be used instead of a full 32x32 multiply. |
| 97 | * For 12-bit samples, a full 32-bit multiplication will be needed. |
| 98 | */ |
| 99 | |
| 100 | #if BITS_IN_JSAMPLE == 8 |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 101 | #define MULTIPLY(var, const) MULTIPLY16C16(var, const) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 102 | #else |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 103 | #define MULTIPLY(var, const) ((var) * (const)) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 104 | #endif |
| 105 | |
| 106 | |
| 107 | /* Dequantize a coefficient by multiplying it by the multiplier-table |
| 108 | * entry; produce an int result. In this module, both inputs and result |
| 109 | * are 16 bits or less, so either int or short multiply will work. |
| 110 | */ |
| 111 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 112 | #define DEQUANTIZE(coef, quantval) (((ISLOW_MULT_TYPE)(coef)) * (quantval)) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 113 | |
| 114 | |
| 115 | /* |
| 116 | * Perform dequantization and inverse DCT on one block of coefficients, |
| 117 | * producing a reduced-size 4x4 output block. |
| 118 | */ |
| 119 | |
| 120 | GLOBAL(void) |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 121 | jpeg_idct_4x4(j_decompress_ptr cinfo, jpeg_component_info *compptr, |
| 122 | JCOEFPTR coef_block, JSAMPARRAY output_buf, |
| 123 | JDIMENSION output_col) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 124 | { |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 125 | JLONG tmp0, tmp2, tmp10, tmp12; |
| 126 | JLONG z1, z2, z3, z4; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 127 | JCOEFPTR inptr; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 128 | ISLOW_MULT_TYPE *quantptr; |
| 129 | int *wsptr; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 130 | JSAMPROW outptr; |
| 131 | JSAMPLE *range_limit = IDCT_range_limit(cinfo); |
| 132 | int ctr; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 133 | int workspace[DCTSIZE * 4]; /* buffers data between passes */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 134 | SHIFT_TEMPS |
| 135 | |
| 136 | /* Pass 1: process columns from input, store into work array. */ |
| 137 | |
| 138 | inptr = coef_block; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 139 | quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 140 | wsptr = workspace; |
| 141 | for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { |
| 142 | /* Don't bother to process column 4, because second pass won't use it */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 143 | if (ctr == DCTSIZE - 4) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 144 | continue; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 145 | if (inptr[DCTSIZE * 1] == 0 && inptr[DCTSIZE * 2] == 0 && |
| 146 | inptr[DCTSIZE * 3] == 0 && inptr[DCTSIZE * 5] == 0 && |
| 147 | inptr[DCTSIZE * 6] == 0 && inptr[DCTSIZE * 7] == 0) { |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 148 | /* AC terms all zero; we need not examine term 4 for 4x4 output */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 149 | int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE * 0], |
| 150 | quantptr[DCTSIZE * 0]), PASS1_BITS); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 151 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 152 | wsptr[DCTSIZE * 0] = dcval; |
| 153 | wsptr[DCTSIZE * 1] = dcval; |
| 154 | wsptr[DCTSIZE * 2] = dcval; |
| 155 | wsptr[DCTSIZE * 3] = dcval; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 156 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 157 | continue; |
| 158 | } |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 159 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 160 | /* Even part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 161 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 162 | tmp0 = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]); |
| 163 | tmp0 = LEFT_SHIFT(tmp0, CONST_BITS + 1); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 164 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 165 | z2 = DEQUANTIZE(inptr[DCTSIZE * 2], quantptr[DCTSIZE * 2]); |
| 166 | z3 = DEQUANTIZE(inptr[DCTSIZE * 6], quantptr[DCTSIZE * 6]); |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 167 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 168 | tmp2 = MULTIPLY(z2, FIX_1_847759065) + MULTIPLY(z3, -FIX_0_765366865); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 169 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 170 | tmp10 = tmp0 + tmp2; |
| 171 | tmp12 = tmp0 - tmp2; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 172 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 173 | /* Odd part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 174 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 175 | z1 = DEQUANTIZE(inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7]); |
| 176 | z2 = DEQUANTIZE(inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5]); |
| 177 | z3 = DEQUANTIZE(inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3]); |
| 178 | z4 = DEQUANTIZE(inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1]); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 179 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 180 | tmp0 = MULTIPLY(z1, -FIX_0_211164243) + /* sqrt(2) * ( c3-c1) */ |
| 181 | MULTIPLY(z2, FIX_1_451774981) + /* sqrt(2) * ( c3+c7) */ |
| 182 | MULTIPLY(z3, -FIX_2_172734803) + /* sqrt(2) * (-c1-c5) */ |
| 183 | MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * ( c5+c7) */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 184 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 185 | tmp2 = MULTIPLY(z1, -FIX_0_509795579) + /* sqrt(2) * (c7-c5) */ |
| 186 | MULTIPLY(z2, -FIX_0_601344887) + /* sqrt(2) * (c5-c1) */ |
| 187 | MULTIPLY(z3, FIX_0_899976223) + /* sqrt(2) * (c3-c7) */ |
| 188 | MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 189 | |
| 190 | /* Final output stage */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 191 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 192 | wsptr[DCTSIZE * 0] = |
| 193 | (int)DESCALE(tmp10 + tmp2, CONST_BITS - PASS1_BITS + 1); |
| 194 | wsptr[DCTSIZE * 3] = |
| 195 | (int)DESCALE(tmp10 - tmp2, CONST_BITS - PASS1_BITS + 1); |
| 196 | wsptr[DCTSIZE * 1] = |
| 197 | (int)DESCALE(tmp12 + tmp0, CONST_BITS - PASS1_BITS + 1); |
| 198 | wsptr[DCTSIZE * 2] = |
| 199 | (int)DESCALE(tmp12 - tmp0, CONST_BITS - PASS1_BITS + 1); |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 200 | } |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 201 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 202 | /* Pass 2: process 4 rows from work array, store into output array. */ |
| 203 | |
| 204 | wsptr = workspace; |
| 205 | for (ctr = 0; ctr < 4; ctr++) { |
| 206 | outptr = output_buf[ctr] + output_col; |
| 207 | /* It's not clear whether a zero row test is worthwhile here ... */ |
| 208 | |
| 209 | #ifndef NO_ZERO_ROW_TEST |
| 210 | if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 211 | wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) { |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 212 | /* AC terms all zero */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 213 | JSAMPLE dcval = range_limit[(int)DESCALE((JLONG)wsptr[0], |
| 214 | PASS1_BITS + 3) & RANGE_MASK]; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 215 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 216 | outptr[0] = dcval; |
| 217 | outptr[1] = dcval; |
| 218 | outptr[2] = dcval; |
| 219 | outptr[3] = dcval; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 220 | |
| 221 | wsptr += DCTSIZE; /* advance pointer to next row */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 222 | continue; |
| 223 | } |
| 224 | #endif |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 225 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 226 | /* Even part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 227 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 228 | tmp0 = LEFT_SHIFT((JLONG)wsptr[0], CONST_BITS + 1); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 229 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 230 | tmp2 = MULTIPLY((JLONG)wsptr[2], FIX_1_847759065) + |
| 231 | MULTIPLY((JLONG)wsptr[6], -FIX_0_765366865); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 232 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 233 | tmp10 = tmp0 + tmp2; |
| 234 | tmp12 = tmp0 - tmp2; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 235 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 236 | /* Odd part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 237 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 238 | z1 = (JLONG)wsptr[7]; |
| 239 | z2 = (JLONG)wsptr[5]; |
| 240 | z3 = (JLONG)wsptr[3]; |
| 241 | z4 = (JLONG)wsptr[1]; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 242 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 243 | tmp0 = MULTIPLY(z1, -FIX_0_211164243) + /* sqrt(2) * ( c3-c1) */ |
| 244 | MULTIPLY(z2, FIX_1_451774981) + /* sqrt(2) * ( c3+c7) */ |
| 245 | MULTIPLY(z3, -FIX_2_172734803) + /* sqrt(2) * (-c1-c5) */ |
| 246 | MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * ( c5+c7) */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 247 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 248 | tmp2 = MULTIPLY(z1, -FIX_0_509795579) + /* sqrt(2) * (c7-c5) */ |
| 249 | MULTIPLY(z2, -FIX_0_601344887) + /* sqrt(2) * (c5-c1) */ |
| 250 | MULTIPLY(z3, FIX_0_899976223) + /* sqrt(2) * (c3-c7) */ |
| 251 | MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 252 | |
| 253 | /* Final output stage */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 254 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 255 | outptr[0] = range_limit[(int)DESCALE(tmp10 + tmp2, |
| 256 | CONST_BITS + PASS1_BITS + 3 + 1) & |
| 257 | RANGE_MASK]; |
| 258 | outptr[3] = range_limit[(int)DESCALE(tmp10 - tmp2, |
| 259 | CONST_BITS + PASS1_BITS + 3 + 1) & |
| 260 | RANGE_MASK]; |
| 261 | outptr[1] = range_limit[(int)DESCALE(tmp12 + tmp0, |
| 262 | CONST_BITS + PASS1_BITS + 3 + 1) & |
| 263 | RANGE_MASK]; |
| 264 | outptr[2] = range_limit[(int)DESCALE(tmp12 - tmp0, |
| 265 | CONST_BITS + PASS1_BITS + 3 + 1) & |
| 266 | RANGE_MASK]; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 267 | |
| 268 | wsptr += DCTSIZE; /* advance pointer to next row */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 269 | } |
| 270 | } |
| 271 | |
| 272 | |
| 273 | /* |
| 274 | * Perform dequantization and inverse DCT on one block of coefficients, |
| 275 | * producing a reduced-size 2x2 output block. |
| 276 | */ |
| 277 | |
| 278 | GLOBAL(void) |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 279 | jpeg_idct_2x2(j_decompress_ptr cinfo, jpeg_component_info *compptr, |
| 280 | JCOEFPTR coef_block, JSAMPARRAY output_buf, |
| 281 | JDIMENSION output_col) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 282 | { |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 283 | JLONG tmp0, tmp10, z1; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 284 | JCOEFPTR inptr; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 285 | ISLOW_MULT_TYPE *quantptr; |
| 286 | int *wsptr; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 287 | JSAMPROW outptr; |
| 288 | JSAMPLE *range_limit = IDCT_range_limit(cinfo); |
| 289 | int ctr; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 290 | int workspace[DCTSIZE * 2]; /* buffers data between passes */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 291 | SHIFT_TEMPS |
| 292 | |
| 293 | /* Pass 1: process columns from input, store into work array. */ |
| 294 | |
| 295 | inptr = coef_block; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 296 | quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 297 | wsptr = workspace; |
| 298 | for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { |
| 299 | /* Don't bother to process columns 2,4,6 */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 300 | if (ctr == DCTSIZE - 2 || ctr == DCTSIZE - 4 || ctr == DCTSIZE - 6) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 301 | continue; |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 302 | if (inptr[DCTSIZE * 1] == 0 && inptr[DCTSIZE * 3] == 0 && |
| 303 | inptr[DCTSIZE * 5] == 0 && inptr[DCTSIZE * 7] == 0) { |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 304 | /* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 305 | int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE * 0], |
| 306 | quantptr[DCTSIZE * 0]), PASS1_BITS); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 307 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 308 | wsptr[DCTSIZE * 0] = dcval; |
| 309 | wsptr[DCTSIZE * 1] = dcval; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 310 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 311 | continue; |
| 312 | } |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 313 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 314 | /* Even part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 315 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 316 | z1 = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]); |
| 317 | tmp10 = LEFT_SHIFT(z1, CONST_BITS + 2); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 318 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 319 | /* Odd part */ |
| 320 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 321 | z1 = DEQUANTIZE(inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7]); |
| 322 | tmp0 = MULTIPLY(z1, -FIX_0_720959822); /* sqrt(2) * ( c7-c5+c3-c1) */ |
| 323 | z1 = DEQUANTIZE(inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5]); |
| 324 | tmp0 += MULTIPLY(z1, FIX_0_850430095); /* sqrt(2) * (-c1+c3+c5+c7) */ |
| 325 | z1 = DEQUANTIZE(inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3]); |
| 326 | tmp0 += MULTIPLY(z1, -FIX_1_272758580); /* sqrt(2) * (-c1+c3-c5-c7) */ |
| 327 | z1 = DEQUANTIZE(inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1]); |
| 328 | tmp0 += MULTIPLY(z1, FIX_3_624509785); /* sqrt(2) * ( c1+c3+c5+c7) */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 329 | |
| 330 | /* Final output stage */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 331 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 332 | wsptr[DCTSIZE * 0] = |
| 333 | (int)DESCALE(tmp10 + tmp0, CONST_BITS - PASS1_BITS + 2); |
| 334 | wsptr[DCTSIZE * 1] = |
| 335 | (int)DESCALE(tmp10 - tmp0, CONST_BITS - PASS1_BITS + 2); |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 336 | } |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 337 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 338 | /* Pass 2: process 2 rows from work array, store into output array. */ |
| 339 | |
| 340 | wsptr = workspace; |
| 341 | for (ctr = 0; ctr < 2; ctr++) { |
| 342 | outptr = output_buf[ctr] + output_col; |
| 343 | /* It's not clear whether a zero row test is worthwhile here ... */ |
| 344 | |
| 345 | #ifndef NO_ZERO_ROW_TEST |
| 346 | if (wsptr[1] == 0 && wsptr[3] == 0 && wsptr[5] == 0 && wsptr[7] == 0) { |
| 347 | /* AC terms all zero */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 348 | JSAMPLE dcval = range_limit[(int)DESCALE((JLONG)wsptr[0], |
| 349 | PASS1_BITS + 3) & RANGE_MASK]; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 350 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 351 | outptr[0] = dcval; |
| 352 | outptr[1] = dcval; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 353 | |
| 354 | wsptr += DCTSIZE; /* advance pointer to next row */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 355 | continue; |
| 356 | } |
| 357 | #endif |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 358 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 359 | /* Even part */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 360 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 361 | tmp10 = LEFT_SHIFT((JLONG)wsptr[0], CONST_BITS + 2); |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 362 | |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 363 | /* Odd part */ |
| 364 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 365 | tmp0 = MULTIPLY((JLONG)wsptr[7], -FIX_0_720959822) + /* sqrt(2) * ( c7-c5+c3-c1) */ |
| 366 | MULTIPLY((JLONG)wsptr[5], FIX_0_850430095) + /* sqrt(2) * (-c1+c3+c5+c7) */ |
| 367 | MULTIPLY((JLONG)wsptr[3], -FIX_1_272758580) + /* sqrt(2) * (-c1+c3-c5-c7) */ |
| 368 | MULTIPLY((JLONG)wsptr[1], FIX_3_624509785); /* sqrt(2) * ( c1+c3+c5+c7) */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 369 | |
| 370 | /* Final output stage */ |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 371 | |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 372 | outptr[0] = range_limit[(int)DESCALE(tmp10 + tmp0, |
| 373 | CONST_BITS + PASS1_BITS + 3 + 2) & |
| 374 | RANGE_MASK]; |
| 375 | outptr[1] = range_limit[(int)DESCALE(tmp10 - tmp0, |
| 376 | CONST_BITS + PASS1_BITS + 3 + 2) & |
| 377 | RANGE_MASK]; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 378 | |
| 379 | wsptr += DCTSIZE; /* advance pointer to next row */ |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 380 | } |
| 381 | } |
| 382 | |
| 383 | |
| 384 | /* |
| 385 | * Perform dequantization and inverse DCT on one block of coefficients, |
| 386 | * producing a reduced-size 1x1 output block. |
| 387 | */ |
| 388 | |
| 389 | GLOBAL(void) |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 390 | jpeg_idct_1x1(j_decompress_ptr cinfo, jpeg_component_info *compptr, |
| 391 | JCOEFPTR coef_block, JSAMPARRAY output_buf, |
| 392 | JDIMENSION output_col) |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 393 | { |
| 394 | int dcval; |
Tom Hudson | 0d47d2d | 2016-05-04 13:22:56 -0400 | [diff] [blame] | 395 | ISLOW_MULT_TYPE *quantptr; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 396 | JSAMPLE *range_limit = IDCT_range_limit(cinfo); |
| 397 | SHIFT_TEMPS |
| 398 | |
| 399 | /* We hardly need an inverse DCT routine for this: just take the |
| 400 | * average pixel value, which is one-eighth of the DC coefficient. |
| 401 | */ |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 402 | quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 403 | dcval = DEQUANTIZE(coef_block[0], quantptr[0]); |
Chris Blume | cca8c4d | 2019-03-01 01:09:50 -0800 | [diff] [blame] | 404 | dcval = (int)DESCALE((JLONG)dcval, 3); |
hbono@chromium.org | f0c4f33 | 2010-11-01 05:14:55 +0000 | [diff] [blame] | 405 | |
| 406 | output_buf[0][output_col] = range_limit[dcval & RANGE_MASK]; |
| 407 | } |
| 408 | |
| 409 | #endif /* IDCT_SCALING_SUPPORTED */ |