170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * jidctred.c 370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Copyright (C) 1994-1998, Thomas G. Lane. 570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file is part of the Independent JPEG Group's software. 670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * For conditions of distribution and use, see the accompanying README file. 770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file contains inverse-DCT routines that produce reduced-size output: 970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * either 4x4, 2x2, or 1x1 pixels from an 8x8 DCT block. 1070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The implementation is based on the Loeffler, Ligtenberg and Moschytz (LL&M) 1270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * algorithm used in jidctint.c. We simply replace each 8-to-8 1-D IDCT step 1370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * with an 8-to-4 step that produces the four averages of two adjacent outputs 1470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (or an 8-to-2 step producing two averages of four outputs, for 2x2 output). 1570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * These steps were derived by computing the corresponding values at the end 1670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * of the normal LL&M code, then simplifying as much as possible. 1770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1x1 is trivial: just take the DC coefficient divided by 8. 1970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 2070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * See jidctint.c for additional comments. 2170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 2270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define JPEG_INTERNALS 2470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#include "jinclude.h" 2570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#include "jpeglib.h" 2670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#include "jdct.h" /* Private declarations for DCT subsystem */ 2770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#ifdef IDCT_SCALING_SUPPORTED 2970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 3270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This module is specialized to the case DCTSIZE = 8. 3370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 3470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if DCTSIZE != 8 3670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ 3770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 3870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 4070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Scaling is the same as in jidctint.c. */ 4170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 4270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if BITS_IN_JSAMPLE == 8 4370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define CONST_BITS 13 4470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define PASS1_BITS 2 4570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#else 4670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define CONST_BITS 13 4770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define PASS1_BITS 1 /* lose a little precision to avoid overflow */ 4870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 4970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 5070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Some C compilers fail to reduce "FIX(constant)" at compile time, thus 5170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * causing a lot of useless floating-point operations at run time. 5270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * To get around this we use the following pre-calculated constants. 5370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * If you change CONST_BITS you may want to add appropriate values. 5470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * (With a reasonable C compiler, you can just rely on the FIX() macro...) 5570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 5670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 5770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if CONST_BITS == 13 5870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_211164243 ((INT32) 1730) /* FIX(0.211164243) */ 5970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_509795579 ((INT32) 4176) /* FIX(0.509795579) */ 6070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_601344887 ((INT32) 4926) /* FIX(0.601344887) */ 6170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_720959822 ((INT32) 5906) /* FIX(0.720959822) */ 6270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_765366865 ((INT32) 6270) /* FIX(0.765366865) */ 6370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_850430095 ((INT32) 6967) /* FIX(0.850430095) */ 6470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_899976223 ((INT32) 7373) /* FIX(0.899976223) */ 6570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_061594337 ((INT32) 8697) /* FIX(1.061594337) */ 6670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_272758580 ((INT32) 10426) /* FIX(1.272758580) */ 6770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_451774981 ((INT32) 11893) /* FIX(1.451774981) */ 6870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_847759065 ((INT32) 15137) /* FIX(1.847759065) */ 6970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_2_172734803 ((INT32) 17799) /* FIX(2.172734803) */ 7070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_2_562915447 ((INT32) 20995) /* FIX(2.562915447) */ 7170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_3_624509785 ((INT32) 29692) /* FIX(3.624509785) */ 7270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#else 7370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_211164243 FIX(0.211164243) 7470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_509795579 FIX(0.509795579) 7570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_601344887 FIX(0.601344887) 7670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_720959822 FIX(0.720959822) 7770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_765366865 FIX(0.765366865) 7870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_850430095 FIX(0.850430095) 7970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_0_899976223 FIX(0.899976223) 8070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_061594337 FIX(1.061594337) 8170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_272758580 FIX(1.272758580) 8270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_451774981 FIX(1.451774981) 8370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_1_847759065 FIX(1.847759065) 8470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_2_172734803 FIX(2.172734803) 8570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_2_562915447 FIX(2.562915447) 8670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define FIX_3_624509785 FIX(3.624509785) 8770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 8870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 8970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 9070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Multiply an INT32 variable by an INT32 constant to yield an INT32 result. 9170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * For 8-bit samples with the recommended scaling, all the variable 9270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * and constant values involved are no more than 16 bits wide, so a 9370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 16x16->32 bit multiply can be used instead of a full 32x32 multiply. 9470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * For 12-bit samples, a full 32-bit multiplication will be needed. 9570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 9670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 9770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#if BITS_IN_JSAMPLE == 8 9870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define MULTIPLY(var,const) MULTIPLY16C16(var,const) 9970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#else 10070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define MULTIPLY(var,const) ((var) * (const)) 10170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 10270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Dequantize a coefficient by multiplying it by the multiplier-table 10570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * entry; produce an int result. In this module, both inputs and result 10670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * are 16 bits or less, so either int or short multiply will work. 10770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 10870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define DEQUANTIZE(coef,quantval) (((ISLOW_MULT_TYPE) (coef)) * (quantval)) 11070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 11170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 11270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 11370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Perform dequantization and inverse DCT on one block of coefficients, 11470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * producing a reduced-size 4x4 output block. 11570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 11670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 11770a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineGLOBAL(void) 11870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinejpeg_idct_4x4 (j_decompress_ptr cinfo, jpeg_component_info * compptr, 11970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JCOEFPTR coef_block, 12070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY output_buf, JDIMENSION output_col) 12170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 12270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 tmp0, tmp2, tmp10, tmp12; 12370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 z1, z2, z3, z4; 12470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JCOEFPTR inptr; 12570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ISLOW_MULT_TYPE * quantptr; 12670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int * wsptr; 12770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW outptr; 12870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE *range_limit = IDCT_range_limit(cinfo); 12970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int ctr; 13070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int workspace[DCTSIZE*4]; /* buffers data between passes */ 13170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine SHIFT_TEMPS 13270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 13370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Pass 1: process columns from input, store into work array. */ 13470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 13570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr = coef_block; 13670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table; 13770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr = workspace; 13870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { 13970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Don't bother to process column 4, because second pass won't use it */ 14070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (ctr == DCTSIZE-4) 14170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 14270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 && 14370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*5] == 0 && 14470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr[DCTSIZE*6] == 0 && inptr[DCTSIZE*7] == 0) { 14570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* AC terms all zero; we need not examine term 4 for 4x4 output */ 14670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS; 14770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*0] = dcval; 14970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*1] = dcval; 15070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*2] = dcval; 15170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*3] = dcval; 15270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 15470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 15570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Even part */ 15770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); 15970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 <<= (CONST_BITS+1); 16070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 16170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z2 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]); 16270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]); 16370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 16470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp2 = MULTIPLY(z2, FIX_1_847759065) + MULTIPLY(z3, - FIX_0_765366865); 16570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 16670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp10 = tmp0 + tmp2; 16770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp12 = tmp0 - tmp2; 16870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 16970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Odd part */ 17070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 17170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]); 17270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z2 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]); 17370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z3 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]); 17470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]); 17570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 17670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = MULTIPLY(z1, - FIX_0_211164243) /* sqrt(2) * (c3-c1) */ 17770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z2, FIX_1_451774981) /* sqrt(2) * (c3+c7) */ 17870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z3, - FIX_2_172734803) /* sqrt(2) * (-c1-c5) */ 17970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * (c5+c7) */ 18070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 18170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp2 = MULTIPLY(z1, - FIX_0_509795579) /* sqrt(2) * (c7-c5) */ 18270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z2, - FIX_0_601344887) /* sqrt(2) * (c5-c1) */ 18370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z3, FIX_0_899976223) /* sqrt(2) * (c3-c7) */ 18470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ 18570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 18670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Final output stage */ 18770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 18870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*0] = (int) DESCALE(tmp10 + tmp2, CONST_BITS-PASS1_BITS+1); 18970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*3] = (int) DESCALE(tmp10 - tmp2, CONST_BITS-PASS1_BITS+1); 19070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*1] = (int) DESCALE(tmp12 + tmp0, CONST_BITS-PASS1_BITS+1); 19170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*2] = (int) DESCALE(tmp12 - tmp0, CONST_BITS-PASS1_BITS+1); 19270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 19370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Pass 2: process 4 rows from work array, store into output array. */ 19570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr = workspace; 19770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ctr = 0; ctr < 4; ctr++) { 19870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr = output_buf[ctr] + output_col; 19970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* It's not clear whether a zero row test is worthwhile here ... */ 20070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 20170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#ifndef NO_ZERO_ROW_TEST 20270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && 20370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) { 20470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* AC terms all zero */ 20570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE dcval = range_limit[(int) DESCALE((INT32) wsptr[0], PASS1_BITS+3) 20670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 20770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 20870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[0] = dcval; 20970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[1] = dcval; 21070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[2] = dcval; 21170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[3] = dcval; 21270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 21370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr += DCTSIZE; /* advance pointer to next row */ 21470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 21570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 21670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 21770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 21870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Even part */ 21970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 22070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = ((INT32) wsptr[0]) << (CONST_BITS+1); 22170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 22270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp2 = MULTIPLY((INT32) wsptr[2], FIX_1_847759065) 22370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY((INT32) wsptr[6], - FIX_0_765366865); 22470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 22570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp10 = tmp0 + tmp2; 22670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp12 = tmp0 - tmp2; 22770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 22870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Odd part */ 22970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 23070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = (INT32) wsptr[7]; 23170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z2 = (INT32) wsptr[5]; 23270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z3 = (INT32) wsptr[3]; 23370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z4 = (INT32) wsptr[1]; 23470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 23570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = MULTIPLY(z1, - FIX_0_211164243) /* sqrt(2) * (c3-c1) */ 23670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z2, FIX_1_451774981) /* sqrt(2) * (c3+c7) */ 23770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z3, - FIX_2_172734803) /* sqrt(2) * (-c1-c5) */ 23870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z4, FIX_1_061594337); /* sqrt(2) * (c5+c7) */ 23970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 24070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp2 = MULTIPLY(z1, - FIX_0_509795579) /* sqrt(2) * (c7-c5) */ 24170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z2, - FIX_0_601344887) /* sqrt(2) * (c5-c1) */ 24270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z3, FIX_0_899976223) /* sqrt(2) * (c3-c7) */ 24370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY(z4, FIX_2_562915447); /* sqrt(2) * (c1+c3) */ 24470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 24570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Final output stage */ 24670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 24770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp2, 24870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+1) 24970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 25070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[3] = range_limit[(int) DESCALE(tmp10 - tmp2, 25170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+1) 25270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 25370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[1] = range_limit[(int) DESCALE(tmp12 + tmp0, 25470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+1) 25570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 25670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[2] = range_limit[(int) DESCALE(tmp12 - tmp0, 25770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+1) 25870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 25970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 26070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr += DCTSIZE; /* advance pointer to next row */ 26170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 26270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 26370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 26470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 26570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 26670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Perform dequantization and inverse DCT on one block of coefficients, 26770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * producing a reduced-size 2x2 output block. 26870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 26970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 27070a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineGLOBAL(void) 27170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinejpeg_idct_2x2 (j_decompress_ptr cinfo, jpeg_component_info * compptr, 27270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JCOEFPTR coef_block, 27370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY output_buf, JDIMENSION output_col) 27470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 27570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 tmp0, tmp10, z1; 27670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JCOEFPTR inptr; 27770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ISLOW_MULT_TYPE * quantptr; 27870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int * wsptr; 27970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPROW outptr; 28070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE *range_limit = IDCT_range_limit(cinfo); 28170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int ctr; 28270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int workspace[DCTSIZE*2]; /* buffers data between passes */ 28370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine SHIFT_TEMPS 28470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 28570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Pass 1: process columns from input, store into work array. */ 28670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 28770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr = coef_block; 28870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table; 28970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr = workspace; 29070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ctr = DCTSIZE; ctr > 0; inptr++, quantptr++, wsptr++, ctr--) { 29170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Don't bother to process columns 2,4,6 */ 29270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (ctr == DCTSIZE-2 || ctr == DCTSIZE-4 || ctr == DCTSIZE-6) 29370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 29470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*3] == 0 && 29570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*7] == 0) { 29670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* AC terms all zero; we need not examine terms 2,4,6 for 2x2 output */ 29770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]) << PASS1_BITS; 29870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 29970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*0] = dcval; 30070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*1] = dcval; 30170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 30270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 30370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 30470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 30570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Even part */ 30670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 30770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); 30870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp10 = z1 << (CONST_BITS+2); 30970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 31070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Odd part */ 31170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 31270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]); 31370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = MULTIPLY(z1, - FIX_0_720959822); /* sqrt(2) * (c7-c5+c3-c1) */ 31470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]); 31570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 += MULTIPLY(z1, FIX_0_850430095); /* sqrt(2) * (-c1+c3+c5+c7) */ 31670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]); 31770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 += MULTIPLY(z1, - FIX_1_272758580); /* sqrt(2) * (-c1+c3-c5-c7) */ 31870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine z1 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]); 31970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 += MULTIPLY(z1, FIX_3_624509785); /* sqrt(2) * (c1+c3+c5+c7) */ 32070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Final output stage */ 32270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*0] = (int) DESCALE(tmp10 + tmp0, CONST_BITS-PASS1_BITS+2); 32470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr[DCTSIZE*1] = (int) DESCALE(tmp10 - tmp0, CONST_BITS-PASS1_BITS+2); 32570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 32670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Pass 2: process 2 rows from work array, store into output array. */ 32870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 32970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr = workspace; 33070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine for (ctr = 0; ctr < 2; ctr++) { 33170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr = output_buf[ctr] + output_col; 33270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* It's not clear whether a zero row test is worthwhile here ... */ 33370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 33470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#ifndef NO_ZERO_ROW_TEST 33570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (wsptr[1] == 0 && wsptr[3] == 0 && wsptr[5] == 0 && wsptr[7] == 0) { 33670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* AC terms all zero */ 33770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE dcval = range_limit[(int) DESCALE((INT32) wsptr[0], PASS1_BITS+3) 33870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 33970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 34070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[0] = dcval; 34170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[1] = dcval; 34270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 34370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr += DCTSIZE; /* advance pointer to next row */ 34470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine continue; 34570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 34670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif 34770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 34870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Even part */ 34970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 35070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp10 = ((INT32) wsptr[0]) << (CONST_BITS+2); 35170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 35270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Odd part */ 35370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 35470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine tmp0 = MULTIPLY((INT32) wsptr[7], - FIX_0_720959822) /* sqrt(2) * (c7-c5+c3-c1) */ 35570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY((INT32) wsptr[5], FIX_0_850430095) /* sqrt(2) * (-c1+c3+c5+c7) */ 35670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY((INT32) wsptr[3], - FIX_1_272758580) /* sqrt(2) * (-c1+c3-c5-c7) */ 35770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine + MULTIPLY((INT32) wsptr[1], FIX_3_624509785); /* sqrt(2) * (c1+c3+c5+c7) */ 35870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 35970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Final output stage */ 36070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 36170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[0] = range_limit[(int) DESCALE(tmp10 + tmp0, 36270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+2) 36370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 36470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine outptr[1] = range_limit[(int) DESCALE(tmp10 - tmp0, 36570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine CONST_BITS+PASS1_BITS+3+2) 36670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine & RANGE_MASK]; 36770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 36870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine wsptr += DCTSIZE; /* advance pointer to next row */ 36970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } 37070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 37170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 37270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 37370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 37470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Perform dequantization and inverse DCT on one block of coefficients, 37570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * producing a reduced-size 1x1 output block. 37670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 37770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 37870a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineGLOBAL(void) 37970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinejpeg_idct_1x1 (j_decompress_ptr cinfo, jpeg_component_info * compptr, 38070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JCOEFPTR coef_block, 38170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPARRAY output_buf, JDIMENSION output_col) 38270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ 38370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int dcval; 38470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine ISLOW_MULT_TYPE * quantptr; 38570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JSAMPLE *range_limit = IDCT_range_limit(cinfo); 38670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine SHIFT_TEMPS 38770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 38870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* We hardly need an inverse DCT routine for this: just take the 38970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * average pixel value, which is one-eighth of the DC coefficient. 39070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 39170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine quantptr = (ISLOW_MULT_TYPE *) compptr->dct_table; 39270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dcval = DEQUANTIZE(coef_block[0], quantptr[0]); 39370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine dcval = (int) DESCALE((INT32) dcval, 3); 39470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 39570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine output_buf[0][output_col] = range_limit[dcval & RANGE_MASK]; 39670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 39770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 39870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif /* IDCT_SCALING_SUPPORTED */ 399