1793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler/* 2793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * jidctflt.c 3793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * 4793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * Copyright (C) 1994-1998, Thomas G. Lane. 5793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * Modified 2010 by Guido Vollbeding. 6793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * This file is part of the Independent JPEG Group's software. 7793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * For conditions of distribution and use, see the accompanying README file. 8793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * 9793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * This file contains a floating-point implementation of the 10793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * inverse DCT (Discrete Cosine Transform). In the IJG code, this routine 11793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * must also perform dequantization of the input coefficients. 12793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * 13793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * This implementation should be more accurate than either of the integer 14793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * IDCT implementations. However, it may not give the same results on all 15793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * machines because of differences in roundoff behavior. Speed will depend 16793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * on the hardware's floating point capacity. 17793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * 18793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * A 2-D IDCT can be done by 1-D IDCT on each column followed by 1-D IDCT 19793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * on each row (or vice versa, but it's more convenient to emit a row at 20793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * a time). Direct algorithms are also available, but they are much more 21793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * complex and seem not to be any faster when reduced to code. 22793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * 23793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * This implementation is based on Arai, Agui, and Nakajima's algorithm for 24793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * scaled DCT. Their original paper (Trans. IEICE E-71(11):1095) is in 25793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * Japanese, but the algorithm is described in the Pennebaker & Mitchell 26793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * JPEG textbook (see REFERENCES section in file README). The following code 27793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * is based directly on figure 4-8 in P&M. 28793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * While an 8-point DCT cannot be done in less than 11 multiplies, it is 29793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * possible to arrange the computation so that many of the multiplies are 30793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * simple scalings of the final outputs. These multiplies can then be 31793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * folded into the multiplications or divisions by the JPEG quantization 32793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * table entries. The AA&N method leaves only 5 multiplies and 29 adds 33793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * to be done in the DCT itself. 34793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * The primary disadvantage of this method is that with a fixed-point 35793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * implementation, accuracy is lost due to imprecise representation of the 36793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * scaled quantization values. However, that problem does not arise if 37793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * we use floating point arithmetic. 38793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 39793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 40793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#define JPEG_INTERNALS 41793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#include "jinclude.h" 42793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#include "jpeglib.h" 43793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#include "jdct.h" /* Private declarations for DCT subsystem */ 44793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 45793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#ifdef DCT_FLOAT_SUPPORTED 46793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 47793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 48793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler/* 49793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * This module is specialized to the case DCTSIZE = 8. 50793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 51793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 52793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#if DCTSIZE != 8 53793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ 54793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#endif 55793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 56793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 57793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler/* Dequantize a coefficient by multiplying it by the multiplier-table 58793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * entry; produce a float result. 59793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 60793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 61793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#define DEQUANTIZE(coef,quantval) (((FAST_FLOAT) (coef)) * (quantval)) 62793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 63793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 64793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler/* 65793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * Perform dequantization and inverse DCT on one block of coefficients. 66793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 67793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 68793ee12c6df9cad3806238d32528c49a3ff9331dNoah PreslerGLOBAL(void) 69793ee12c6df9cad3806238d32528c49a3ff9331dNoah Preslerjpeg_idct_float (j_decompress_ptr cinfo, jpeg_component_info * compptr, 70793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler JCOEFPTR coef_block, 71793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler JSAMPARRAY output_buf, JDIMENSION output_col) 72793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler{ 73793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; 74793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT tmp10, tmp11, tmp12, tmp13; 75793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT z5, z10, z11, z12, z13; 76793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler JCOEFPTR inptr; 77793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FLOAT_MULT_TYPE * quantptr; 78793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT * wsptr; 79793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler JSAMPROW outptr; 80793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler JSAMPLE *range_limit = cinfo->sample_range_limit; 81793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler int ctr; 82793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT workspace[DCTSIZE2]; /* buffers data between passes */ 83793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 84793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Pass 1: process columns from input, store into work array. */ 85793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 86793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr = coef_block; 87793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler quantptr = (FLOAT_MULT_TYPE *) compptr->dct_table; 88793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr = workspace; 89793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler for (ctr = DCTSIZE; ctr > 0; ctr--) { 90793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Due to quantization, we will usually find that many of the input 91793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * coefficients are zero, especially the AC terms. We can exploit this 92793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * by short-circuiting the IDCT calculation for any column in which all 93793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * the AC terms are zero. In that case each output is equal to the 94793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * DC coefficient (with scale factor as needed). 95793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * With typical images and quantization tables, half or more of the 96793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * column DCT calculations can be simplified this way. 97793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 98793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 99793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 && 100793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 && 101793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 && 102793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr[DCTSIZE*7] == 0) { 103793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* AC terms all zero */ 104793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler FAST_FLOAT dcval = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); 105793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 106793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*0] = dcval; 107793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*1] = dcval; 108793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*2] = dcval; 109793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*3] = dcval; 110793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*4] = dcval; 111793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*5] = dcval; 112793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*6] = dcval; 113793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*7] = dcval; 114793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 115793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr++; /* advance pointers to next column */ 116793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler quantptr++; 117793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr++; 118793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler continue; 119793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler } 120793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 121793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Even part */ 122793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 123793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); 124793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]); 125793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]); 126793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]); 127793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 128793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp10 = tmp0 + tmp2; /* phase 3 */ 129793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp11 = tmp0 - tmp2; 130793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 131793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp13 = tmp1 + tmp3; /* phases 5-3 */ 132793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp12 = (tmp1 - tmp3) * ((FAST_FLOAT) 1.414213562) - tmp13; /* 2*c4 */ 133793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 134793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp0 = tmp10 + tmp13; /* phase 2 */ 135793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp3 = tmp10 - tmp13; 136793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp1 = tmp11 + tmp12; 137793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp2 = tmp11 - tmp12; 138793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 139793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Odd part */ 140793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 141793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]); 142793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp5 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]); 143793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp6 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]); 144793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp7 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]); 145793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 146793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z13 = tmp6 + tmp5; /* phase 6 */ 147793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z10 = tmp6 - tmp5; 148793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z11 = tmp4 + tmp7; 149793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z12 = tmp4 - tmp7; 150793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 151793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp7 = z11 + z13; /* phase 5 */ 152793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562); /* 2*c4 */ 153793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 154793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */ 155793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */ 156793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */ 157793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 158793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp6 = tmp12 - tmp7; /* phase 2 */ 159793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp5 = tmp11 - tmp6; 160793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp4 = tmp10 - tmp5; 161793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 162793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*0] = tmp0 + tmp7; 163793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*7] = tmp0 - tmp7; 164793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*1] = tmp1 + tmp6; 165793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*6] = tmp1 - tmp6; 166793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*2] = tmp2 + tmp5; 167793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*5] = tmp2 - tmp5; 168793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*3] = tmp3 + tmp4; 169793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr[DCTSIZE*4] = tmp3 - tmp4; 170793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 171793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler inptr++; /* advance pointers to next column */ 172793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler quantptr++; 173793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr++; 174793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler } 175793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 176793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Pass 2: process rows from work array, store into output array. */ 177793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 178793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr = workspace; 179793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler for (ctr = 0; ctr < DCTSIZE; ctr++) { 180793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr = output_buf[ctr] + output_col; 181793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Rows of zeroes can be exploited in the same way as we did with columns. 182793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * However, the column calculation has created many nonzero AC terms, so 183793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * the simplification applies less often (typically 5% to 10% of the time). 184793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler * And testing floats for zero is relatively expensive, so we don't bother. 185793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler */ 186793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 187793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Even part */ 188793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 189793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Apply signed->unsigned and prepare float->int conversion */ 190793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z5 = wsptr[0] + ((FAST_FLOAT) CENTERJSAMPLE + (FAST_FLOAT) 0.5); 191793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp10 = z5 + wsptr[4]; 192793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp11 = z5 - wsptr[4]; 193793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 194793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp13 = wsptr[2] + wsptr[6]; 195793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp12 = (wsptr[2] - wsptr[6]) * ((FAST_FLOAT) 1.414213562) - tmp13; 196793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 197793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp0 = tmp10 + tmp13; 198793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp3 = tmp10 - tmp13; 199793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp1 = tmp11 + tmp12; 200793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp2 = tmp11 - tmp12; 201793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 202793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Odd part */ 203793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 204793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z13 = wsptr[5] + wsptr[3]; 205793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z10 = wsptr[5] - wsptr[3]; 206793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z11 = wsptr[1] + wsptr[7]; 207793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z12 = wsptr[1] - wsptr[7]; 208793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 209793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp7 = z11 + z13; 210793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp11 = (z11 - z13) * ((FAST_FLOAT) 1.414213562); 211793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 212793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler z5 = (z10 + z12) * ((FAST_FLOAT) 1.847759065); /* 2*c2 */ 213793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp10 = z5 - z12 * ((FAST_FLOAT) 1.082392200); /* 2*(c2-c6) */ 214793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp12 = z5 - z10 * ((FAST_FLOAT) 2.613125930); /* 2*(c2+c6) */ 215793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 216793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp6 = tmp12 - tmp7; 217793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp5 = tmp11 - tmp6; 218793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler tmp4 = tmp10 - tmp5; 219793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 220793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler /* Final output stage: float->int conversion and range-limit */ 221793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 222793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[0] = range_limit[((int) (tmp0 + tmp7)) & RANGE_MASK]; 223793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[7] = range_limit[((int) (tmp0 - tmp7)) & RANGE_MASK]; 224793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[1] = range_limit[((int) (tmp1 + tmp6)) & RANGE_MASK]; 225793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[6] = range_limit[((int) (tmp1 - tmp6)) & RANGE_MASK]; 226793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[2] = range_limit[((int) (tmp2 + tmp5)) & RANGE_MASK]; 227793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[5] = range_limit[((int) (tmp2 - tmp5)) & RANGE_MASK]; 228793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[3] = range_limit[((int) (tmp3 + tmp4)) & RANGE_MASK]; 229793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler outptr[4] = range_limit[((int) (tmp3 - tmp4)) & RANGE_MASK]; 230793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 231793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler wsptr += DCTSIZE; /* advance pointer to next row */ 232793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler } 233793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler} 234793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler 235793ee12c6df9cad3806238d32528c49a3ff9331dNoah Presler#endif /* DCT_FLOAT_SUPPORTED */ 236