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Diffstat (limited to 'media/libjpeg/jidctred.c')
-rw-r--r-- | media/libjpeg/jidctred.c | 409 |
1 files changed, 409 insertions, 0 deletions
diff --git a/media/libjpeg/jidctred.c b/media/libjpeg/jidctred.c new file mode 100644 index 0000000000..1dd65a94d9 --- /dev/null +++ b/media/libjpeg/jidctred.c @@ -0,0 +1,409 @@ +/* + * jidctred.c + * + * This file was part of the Independent JPEG Group's software: + * Copyright (C) 1994-1998, Thomas G. Lane. + * libjpeg-turbo Modifications: + * Copyright (C) 2015, D. R. Commander. + * For conditions of distribution and use, see the accompanying README.ijg + * file. + * + * This file contains inverse-DCT routines that produce reduced-size output: + * either 4x4, 2x2, or 1x1 pixels from an 8x8 DCT block. + * + * The implementation is based on the Loeffler, Ligtenberg and Moschytz (LL&M) + * algorithm used in jidctint.c. We simply replace each 8-to-8 1-D IDCT step + * with an 8-to-4 step that produces the four averages of two adjacent outputs + * (or an 8-to-2 step producing two averages of four outputs, for 2x2 output). + * These steps were derived by computing the corresponding values at the end + * of the normal LL&M code, then simplifying as much as possible. + * + * 1x1 is trivial: just take the DC coefficient divided by 8. + * + * See jidctint.c for additional comments. + */ + +#define JPEG_INTERNALS +#include "jinclude.h" +#include "jpeglib.h" +#include "jdct.h" /* Private declarations for DCT subsystem */ + +#ifdef IDCT_SCALING_SUPPORTED + + +/* + * This module is specialized to the case DCTSIZE = 8. + */ + +#if DCTSIZE != 8 + Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ +#endif + + +/* Scaling is the same as in jidctint.c. */ + +#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_211164243 ((JLONG)1730) /* FIX(0.211164243) */ +#define FIX_0_509795579 ((JLONG)4176) /* FIX(0.509795579) */ +#define FIX_0_601344887 ((JLONG)4926) /* FIX(0.601344887) */ +#define FIX_0_720959822 ((JLONG)5906) /* FIX(0.720959822) */ +#define FIX_0_765366865 ((JLONG)6270) /* FIX(0.765366865) */ +#define FIX_0_850430095 ((JLONG)6967) /* FIX(0.850430095) */ +#define FIX_0_899976223 ((JLONG)7373) /* FIX(0.899976223) */ +#define FIX_1_061594337 ((JLONG)8697) /* FIX(1.061594337) */ +#define FIX_1_272758580 ((JLONG)10426) /* FIX(1.272758580) */ +#define FIX_1_451774981 ((JLONG)11893) /* FIX(1.451774981) */ +#define FIX_1_847759065 ((JLONG)15137) /* FIX(1.847759065) */ +#define FIX_2_172734803 ((JLONG)17799) /* FIX(2.172734803) */ +#define FIX_2_562915447 ((JLONG)20995) /* FIX(2.562915447) */ +#define FIX_3_624509785 ((JLONG)29692) /* FIX(3.624509785) */ +#else +#define FIX_0_211164243 FIX(0.211164243) +#define FIX_0_509795579 FIX(0.509795579) +#define FIX_0_601344887 FIX(0.601344887) +#define FIX_0_720959822 FIX(0.720959822) +#define FIX_0_765366865 FIX(0.765366865) +#define FIX_0_850430095 FIX(0.850430095) +#define FIX_0_899976223 FIX(0.899976223) +#define FIX_1_061594337 FIX(1.061594337) +#define FIX_1_272758580 FIX(1.272758580) +#define FIX_1_451774981 FIX(1.451774981) +#define FIX_1_847759065 FIX(1.847759065) +#define FIX_2_172734803 FIX(2.172734803) +#define FIX_2_562915447 FIX(2.562915447) +#define FIX_3_624509785 FIX(3.624509785) +#endif + + +/* Multiply a JLONG variable by a JLONG constant to yield a JLONG 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, + * producing a reduced-size 4x4 output block. + */ + +GLOBAL(void) +jpeg_idct_4x4(j_decompress_ptr cinfo, jpeg_component_info *compptr, + JCOEFPTR coef_block, JSAMPARRAY output_buf, + JDIMENSION output_col) +{ + JLONG tmp0, tmp2, tmp10, tmp12; + JLONG z1, z2, z3, z4; + JCOEFPTR inptr; + ISLOW_MULT_TYPE *quantptr; + int *wsptr; + JSAMPROW outptr; + JSAMPLE *range_limit = IDCT_range_limit(cinfo); + int ctr; + int workspace[DCTSIZE * 4]; /* buffers data between passes */ + SHIFT_TEMPS + + /* Pass 1: process columns from input, store into work array. */ + + inptr = coef_block; + quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; + wsptr = workspace; + for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { + /* Don't bother to process column 4, because second pass won't use it */ + if (ctr == DCTSIZE - 4) + continue; + if (inptr[DCTSIZE * 1] == 0 && inptr[DCTSIZE * 2] == 0 && + inptr[DCTSIZE * 3] == 0 && inptr[DCTSIZE * 5] == 0 && + inptr[DCTSIZE * 6] == 0 && inptr[DCTSIZE * 7] == 0) { + /* AC terms all zero; we need not examine term 4 for 4x4 output */ + int dcval = LEFT_SHIFT(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; + + continue; + } + + /* Even part */ + + tmp0 = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]); + tmp0 = LEFT_SHIFT(tmp0, CONST_BITS + 1); + + z2 = DEQUANTIZE(inptr[DCTSIZE * 2], quantptr[DCTSIZE * 2]); + z3 = DEQUANTIZE(inptr[DCTSIZE * 6], quantptr[DCTSIZE * 6]); + + tmp2 = MULTIPLY(z2, FIX_1_847759065) + MULTIPLY(z3, -FIX_0_765366865); + + tmp10 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + + /* Odd part */ + + z1 = DEQUANTIZE(inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7]); + z2 = DEQUANTIZE(inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5]); + z3 = DEQUANTIZE(inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3]); + z4 = DEQUANTIZE(inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1]); + + tmp0 = MULTIPLY(z1, -FIX_0_211164243) + /* sqrt(2) * ( c3-c1) */ + MULTIPLY(z2, FIX_1_451774981) + /* sqrt(2) * ( c3+c7) */ + MULTIPLY(z3, -FIX_2_172734803) + /* sqrt(2) * (-c1-c5) */ + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * ( c5+c7) */ + + tmp2 = MULTIPLY(z1, -FIX_0_509795579) + /* sqrt(2) * (c7-c5) */ + MULTIPLY(z2, -FIX_0_601344887) + /* sqrt(2) * (c5-c1) */ + MULTIPLY(z3, FIX_0_899976223) + /* sqrt(2) * (c3-c7) */ + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ + + /* Final output stage */ + + wsptr[DCTSIZE * 0] = + (int)DESCALE(tmp10 + tmp2, CONST_BITS - PASS1_BITS + 1); + wsptr[DCTSIZE * 3] = + (int)DESCALE(tmp10 - tmp2, CONST_BITS - PASS1_BITS + 1); + wsptr[DCTSIZE * 1] = + (int)DESCALE(tmp12 + tmp0, CONST_BITS - PASS1_BITS + 1); + wsptr[DCTSIZE * 2] = + (int)DESCALE(tmp12 - tmp0, CONST_BITS - PASS1_BITS + 1); + } + + /* Pass 2: process 4 rows from work array, store into output array. */ + + wsptr = workspace; + for (ctr = 0; ctr < 4; ctr++) { + outptr = output_buf[ctr] + output_col; + /* It's not clear whether a zero row test is worthwhile here ... */ + +#ifndef NO_ZERO_ROW_TEST + if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && + wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) { + /* AC terms all zero */ + JSAMPLE dcval = range_limit[(int)DESCALE((JLONG)wsptr[0], + PASS1_BITS + 3) & RANGE_MASK]; + + outptr[0] = dcval; + outptr[1] = dcval; + outptr[2] = dcval; + outptr[3] = dcval; + + wsptr += DCTSIZE; /* advance pointer to next row */ + continue; + } +#endif + + /* Even part */ + + tmp0 = LEFT_SHIFT((JLONG)wsptr[0], CONST_BITS + 1); + + tmp2 = MULTIPLY((JLONG)wsptr[2], FIX_1_847759065) + + MULTIPLY((JLONG)wsptr[6], -FIX_0_765366865); + + tmp10 = tmp0 + tmp2; + tmp12 = tmp0 - tmp2; + + /* Odd part */ + + z1 = (JLONG)wsptr[7]; + z2 = (JLONG)wsptr[5]; + z3 = (JLONG)wsptr[3]; + z4 = (JLONG)wsptr[1]; + + tmp0 = MULTIPLY(z1, -FIX_0_211164243) + /* sqrt(2) * ( c3-c1) */ + MULTIPLY(z2, FIX_1_451774981) + /* sqrt(2) * ( c3+c7) */ + MULTIPLY(z3, -FIX_2_172734803) + /* sqrt(2) * (-c1-c5) */ + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * ( c5+c7) */ + + tmp2 = MULTIPLY(z1, -FIX_0_509795579) + /* sqrt(2) * (c7-c5) */ + MULTIPLY(z2, -FIX_0_601344887) + /* sqrt(2) * (c5-c1) */ + MULTIPLY(z3, FIX_0_899976223) + /* sqrt(2) * (c3-c7) */ + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ + + /* Final output stage */ + + outptr[0] = range_limit[(int)DESCALE(tmp10 + tmp2, + CONST_BITS + PASS1_BITS + 3 + 1) & + RANGE_MASK]; + outptr[3] = range_limit[(int)DESCALE(tmp10 - tmp2, + CONST_BITS + PASS1_BITS + 3 + 1) & + RANGE_MASK]; + outptr[1] = range_limit[(int)DESCALE(tmp12 + tmp0, + CONST_BITS + PASS1_BITS + 3 + 1) & + RANGE_MASK]; + outptr[2] = range_limit[(int)DESCALE(tmp12 - tmp0, + CONST_BITS + PASS1_BITS + 3 + 1) & + RANGE_MASK]; + + wsptr += DCTSIZE; /* advance pointer to next row */ + } +} + + +/* + * Perform dequantization and inverse DCT on one block of coefficients, + * producing a reduced-size 2x2 output block. + */ + +GLOBAL(void) +jpeg_idct_2x2(j_decompress_ptr cinfo, jpeg_component_info *compptr, + JCOEFPTR coef_block, JSAMPARRAY output_buf, + JDIMENSION output_col) +{ + JLONG tmp0, tmp10, z1; + JCOEFPTR inptr; + ISLOW_MULT_TYPE *quantptr; + int *wsptr; + JSAMPROW outptr; + JSAMPLE *range_limit = IDCT_range_limit(cinfo); + int ctr; + int workspace[DCTSIZE * 2]; /* buffers data between passes */ + SHIFT_TEMPS + + /* Pass 1: process columns from input, store into work array. */ + + inptr = coef_block; + quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; + wsptr = workspace; + for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { + /* Don't bother to process columns 2,4,6 */ + if (ctr == DCTSIZE - 2 || ctr == DCTSIZE - 4 || ctr == DCTSIZE - 6) + continue; + if (inptr[DCTSIZE * 1] == 0 && inptr[DCTSIZE * 3] == 0 && + inptr[DCTSIZE * 5] == 0 && inptr[DCTSIZE * 7] == 0) { + /* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */ + int dcval = LEFT_SHIFT(DEQUANTIZE(inptr[DCTSIZE * 0], + quantptr[DCTSIZE * 0]), PASS1_BITS); + + wsptr[DCTSIZE * 0] = dcval; + wsptr[DCTSIZE * 1] = dcval; + + continue; + } + + /* Even part */ + + z1 = DEQUANTIZE(inptr[DCTSIZE * 0], quantptr[DCTSIZE * 0]); + tmp10 = LEFT_SHIFT(z1, CONST_BITS + 2); + + /* Odd part */ + + z1 = DEQUANTIZE(inptr[DCTSIZE * 7], quantptr[DCTSIZE * 7]); + tmp0 = MULTIPLY(z1, -FIX_0_720959822); /* sqrt(2) * ( c7-c5+c3-c1) */ + z1 = DEQUANTIZE(inptr[DCTSIZE * 5], quantptr[DCTSIZE * 5]); + tmp0 += MULTIPLY(z1, FIX_0_850430095); /* sqrt(2) * (-c1+c3+c5+c7) */ + z1 = DEQUANTIZE(inptr[DCTSIZE * 3], quantptr[DCTSIZE * 3]); + tmp0 += MULTIPLY(z1, -FIX_1_272758580); /* sqrt(2) * (-c1+c3-c5-c7) */ + z1 = DEQUANTIZE(inptr[DCTSIZE * 1], quantptr[DCTSIZE * 1]); + tmp0 += MULTIPLY(z1, FIX_3_624509785); /* sqrt(2) * ( c1+c3+c5+c7) */ + + /* Final output stage */ + + wsptr[DCTSIZE * 0] = + (int)DESCALE(tmp10 + tmp0, CONST_BITS - PASS1_BITS + 2); + wsptr[DCTSIZE * 1] = + (int)DESCALE(tmp10 - tmp0, CONST_BITS - PASS1_BITS + 2); + } + + /* Pass 2: process 2 rows from work array, store into output array. */ + + wsptr = workspace; + for (ctr = 0; ctr < 2; ctr++) { + outptr = output_buf[ctr] + output_col; + /* It's not clear whether a zero row test is worthwhile here ... */ + +#ifndef NO_ZERO_ROW_TEST + if (wsptr[1] == 0 && wsptr[3] == 0 && wsptr[5] == 0 && wsptr[7] == 0) { + /* AC terms all zero */ + JSAMPLE dcval = range_limit[(int)DESCALE((JLONG)wsptr[0], + PASS1_BITS + 3) & RANGE_MASK]; + + outptr[0] = dcval; + outptr[1] = dcval; + + wsptr += DCTSIZE; /* advance pointer to next row */ + continue; + } +#endif + + /* Even part */ + + tmp10 = LEFT_SHIFT((JLONG)wsptr[0], CONST_BITS + 2); + + /* Odd part */ + + tmp0 = MULTIPLY((JLONG)wsptr[7], -FIX_0_720959822) + /* sqrt(2) * ( c7-c5+c3-c1) */ + MULTIPLY((JLONG)wsptr[5], FIX_0_850430095) + /* sqrt(2) * (-c1+c3+c5+c7) */ + MULTIPLY((JLONG)wsptr[3], -FIX_1_272758580) + /* sqrt(2) * (-c1+c3-c5-c7) */ + MULTIPLY((JLONG)wsptr[1], FIX_3_624509785); /* sqrt(2) * ( c1+c3+c5+c7) */ + + /* Final output stage */ + + outptr[0] = range_limit[(int)DESCALE(tmp10 + tmp0, + CONST_BITS + PASS1_BITS + 3 + 2) & + RANGE_MASK]; + outptr[1] = range_limit[(int)DESCALE(tmp10 - tmp0, + CONST_BITS + PASS1_BITS + 3 + 2) & + RANGE_MASK]; + + wsptr += DCTSIZE; /* advance pointer to next row */ + } +} + + +/* + * Perform dequantization and inverse DCT on one block of coefficients, + * producing a reduced-size 1x1 output block. + */ + +GLOBAL(void) +jpeg_idct_1x1(j_decompress_ptr cinfo, jpeg_component_info *compptr, + JCOEFPTR coef_block, JSAMPARRAY output_buf, + JDIMENSION output_col) +{ + int dcval; + ISLOW_MULT_TYPE *quantptr; + JSAMPLE *range_limit = IDCT_range_limit(cinfo); + SHIFT_TEMPS + + /* We hardly need an inverse DCT routine for this: just take the + * average pixel value, which is one-eighth of the DC coefficient. + */ + quantptr = (ISLOW_MULT_TYPE *)compptr->dct_table; + dcval = DEQUANTIZE(coef_block[0], quantptr[0]); + dcval = (int)DESCALE((JLONG)dcval, 3); + + output_buf[0][output_col] = range_limit[dcval & RANGE_MASK]; +} + +#endif /* IDCT_SCALING_SUPPORTED */ |