19f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project/* 29f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * jfdctflt.c 39f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * 49f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * Copyright (C) 1994-1996, Thomas G. Lane. 59f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * This file is part of the Independent JPEG Group's software. 69f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * For conditions of distribution and use, see the accompanying README file. 79f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * 89f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * This file contains a floating-point implementation of the 99f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * forward DCT (Discrete Cosine Transform). 109f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * 119f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * This implementation should be more accurate than either of the integer 129f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * DCT implementations. However, it may not give the same results on all 139f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * machines because of differences in roundoff behavior. Speed will depend 149f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * on the hardware's floating point capacity. 159f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * 169f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT 179f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * on each column. Direct algorithms are also available, but they are 189f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * much more complex and seem not to be any faster when reduced to code. 199f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * 209f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * This implementation is based on Arai, Agui, and Nakajima's algorithm for 219f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * scaled DCT. Their original paper (Trans. IEICE E-71(11):1095) is in 229f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * Japanese, but the algorithm is described in the Pennebaker & Mitchell 239f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * JPEG textbook (see REFERENCES section in file README). The following code 249f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * is based directly on figure 4-8 in P&M. 259f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * While an 8-point DCT cannot be done in less than 11 multiplies, it is 269f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * possible to arrange the computation so that many of the multiplies are 279f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * simple scalings of the final outputs. These multiplies can then be 289f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * folded into the multiplications or divisions by the JPEG quantization 299f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * table entries. The AA&N method leaves only 5 multiplies and 29 adds 309f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * to be done in the DCT itself. 319f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * The primary disadvantage of this method is that with a fixed-point 329f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * implementation, accuracy is lost due to imprecise representation of the 339f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * scaled quantization values. However, that problem does not arise if 349f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * we use floating point arithmetic. 359f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project */ 369f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 379f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#define JPEG_INTERNALS 389f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#include "jinclude.h" 399f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#include "jpeglib.h" 409f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#include "jdct.h" /* Private declarations for DCT subsystem */ 419f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 429f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#ifdef DCT_FLOAT_SUPPORTED 439f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 449f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 459f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project/* 469f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * This module is specialized to the case DCTSIZE = 8. 479f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project */ 489f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 499f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#if DCTSIZE != 8 509f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ 519f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#endif 529f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 539f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 549f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project/* 559f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project * Perform the forward DCT on one block of samples. 569f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project */ 579f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 589f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source ProjectGLOBAL(void) 599f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Projectjpeg_fdct_float (FAST_FLOAT * data) 609f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project{ 619f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project FAST_FLOAT tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; 629f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project FAST_FLOAT tmp10, tmp11, tmp12, tmp13; 639f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project FAST_FLOAT z1, z2, z3, z4, z5, z11, z13; 649f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project FAST_FLOAT *dataptr; 659f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project int ctr; 669f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 679f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Pass 1: process rows. */ 689f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 699f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr = data; 709f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { 719f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp0 = dataptr[0] + dataptr[7]; 729f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp7 = dataptr[0] - dataptr[7]; 739f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp1 = dataptr[1] + dataptr[6]; 749f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp6 = dataptr[1] - dataptr[6]; 759f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp2 = dataptr[2] + dataptr[5]; 769f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp5 = dataptr[2] - dataptr[5]; 779f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp3 = dataptr[3] + dataptr[4]; 789f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp4 = dataptr[3] - dataptr[4]; 799f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 809f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Even part */ 819f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 829f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp10 = tmp0 + tmp3; /* phase 2 */ 839f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp13 = tmp0 - tmp3; 849f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp11 = tmp1 + tmp2; 859f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp12 = tmp1 - tmp2; 869f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 879f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[0] = tmp10 + tmp11; /* phase 3 */ 889f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[4] = tmp10 - tmp11; 899f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 909f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */ 919f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[2] = tmp13 + z1; /* phase 5 */ 929f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[6] = tmp13 - z1; 939f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 949f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Odd part */ 959f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 969f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp10 = tmp4 + tmp5; /* phase 2 */ 979f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp11 = tmp5 + tmp6; 989f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp12 = tmp6 + tmp7; 999f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1009f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* The rotator is modified from fig 4-8 to avoid extra negations. */ 1019f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */ 1029f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */ 1039f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */ 1049f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */ 1059f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1069f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z11 = tmp7 + z3; /* phase 5 */ 1079f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z13 = tmp7 - z3; 1089f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1099f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[5] = z13 + z2; /* phase 6 */ 1109f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[3] = z13 - z2; 1119f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[1] = z11 + z4; 1129f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[7] = z11 - z4; 1139f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1149f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr += DCTSIZE; /* advance pointer to next row */ 1159f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project } 1169f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1179f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Pass 2: process columns. */ 1189f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1199f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr = data; 1209f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { 1219f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7]; 1229f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7]; 1239f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6]; 1249f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6]; 1259f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5]; 1269f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5]; 1279f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4]; 1289f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4]; 1299f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1309f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Even part */ 1319f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1329f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp10 = tmp0 + tmp3; /* phase 2 */ 1339f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp13 = tmp0 - tmp3; 1349f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp11 = tmp1 + tmp2; 1359f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp12 = tmp1 - tmp2; 1369f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1379f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*0] = tmp10 + tmp11; /* phase 3 */ 1389f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*4] = tmp10 - tmp11; 1399f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1409f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z1 = (tmp12 + tmp13) * ((FAST_FLOAT) 0.707106781); /* c4 */ 1419f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*2] = tmp13 + z1; /* phase 5 */ 1429f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*6] = tmp13 - z1; 1439f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1449f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* Odd part */ 1459f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1469f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp10 = tmp4 + tmp5; /* phase 2 */ 1479f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp11 = tmp5 + tmp6; 1489f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project tmp12 = tmp6 + tmp7; 1499f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1509f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project /* The rotator is modified from fig 4-8 to avoid extra negations. */ 1519f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z5 = (tmp10 - tmp12) * ((FAST_FLOAT) 0.382683433); /* c6 */ 1529f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z2 = ((FAST_FLOAT) 0.541196100) * tmp10 + z5; /* c2-c6 */ 1539f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z4 = ((FAST_FLOAT) 1.306562965) * tmp12 + z5; /* c2+c6 */ 1549f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z3 = tmp11 * ((FAST_FLOAT) 0.707106781); /* c4 */ 1559f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1569f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z11 = tmp7 + z3; /* phase 5 */ 1579f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project z13 = tmp7 - z3; 1589f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1599f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*5] = z13 + z2; /* phase 6 */ 1609f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*3] = z13 - z2; 1619f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*1] = z11 + z4; 1629f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr[DCTSIZE*7] = z11 - z4; 1639f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1649f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project dataptr++; /* advance pointer to next column */ 1659f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project } 1669f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project} 1679f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project 1689f5d49a1588e438ae7ceabd0c94172117e3303aaThe Android Open Source Project#endif /* DCT_FLOAT_SUPPORTED */ 169