+++ /dev/null
-#include <math.h>
-#include <string.h>
-#include <stdlib.h>
-
-#include "idct.h"
-
-void* idct_reference_alloc(const uint32_t* quant_table)
-{
- uint32_t* qt_copy = (uint32_t*)malloc(DCTSIZE2 * sizeof(uint32_t));
- // FIXME: check for NULL return
-
- memcpy(qt_copy, quant_table, DCTSIZE2 * sizeof(uint32_t));
-
- return qt_copy;
-}
-
-void idct_reference_free(void* userdata)
-{
- free(userdata);
-}
-
-void idct_reference(const int16_t* input, const void* userdata, uint8_t* output)
-{
- const uint32_t* quant_table = (const uint32_t*)userdata;
- double temp[DCTSIZE2];
-
- for (unsigned y = 0; y < 8; ++y) {
- for (unsigned x = 0; x < 8; ++x) {
- double acc = 0.0;
- for (unsigned u = 0; u < 8; ++u) {
- for (unsigned v = 0; v < 8; ++v) {
- double c_u = (u == 0) ? 1/sqrt(2.0) : 1.0;
- double c_v = (v == 0) ? 1/sqrt(2.0) : 1.0;
- acc += c_u * c_v
- * input[u * DCTSIZE + v] * quant_table[u * DCTSIZE + v]
- * cos((2 * x + 1) * v * M_PI / 16.0)
- * cos((2 * y + 1) * u * M_PI / 16.0);
- }
- }
- temp[y * DCTSIZE + x] = 0.25 * acc;
- }
- }
-
- for (unsigned y = 0; y < 8; ++y) {
- for (unsigned x = 0; x < 8; ++x) {
- double val = temp[y * DCTSIZE + x];
- if (val < 0.0) {
- output[y * DCTSIZE + x] = 0;
- } else if (val >= 255.0) {
- output[y * DCTSIZE + x] = 255;
- } else {
- output[y * DCTSIZE + x] = (uint8_t)(val + 0.5);
- }
- }
- }
-}
-
-// AA&N (Arai, Agui and Nakajima) floating-point IDCT.
-// This IDCT is based on the same DCT that libjpeg uses -- in fact, exactly the
-// same figure from the same book ("JPEG: Still Image Data Compression Standard",
-// page 52, figure 4-8). However, it is coded from scratch, and uses the
-// transposition method for converting DCT -> IDCT suggested in the book.
-// (libjpeg seems to use some other method that yields similar, but not
-// the same, code.)
-
-// As this is generally meant as a reference and not useful code (we expect
-// a SIMD fixed-point algorithm to be used in most cases), it has not been
-// attempted significantly optimized. We assume the compiler will be smart
-// enough to do all the variable propagation for us anyway.
-
-// Scale factors; 1.0 / (sqrt(2.0) * cos(k * M_PI / 16.0)), except for the first which is 1.
-static const double scalefac[] = {
- 1.0, 0.7209598220069479, 0.765366864730180, 0.8504300947672564,
- 1.0, 1.2727585805728336, 1.847759065022573, 3.6245097854115502
-};
-
-// Premultiply the scale factors and the overall 1/8 factor into the quantization
-// table entries (and convert to double).
-void* idct_float_alloc(const uint32_t* quant_table)
-{
- double* qt_copy = (double*)malloc(DCTSIZE2 * sizeof(double));
-
- for (unsigned y = 0; y < DCTSIZE; ++y) {
- for (unsigned x = 0; x < DCTSIZE; ++x) {
- qt_copy[y * DCTSIZE + x] = (1.0/DCTSIZE) * quant_table[y * DCTSIZE + x] *
- scalefac[x] * scalefac[y];
- }
- }
-
- return qt_copy;
-}
-
-void idct_float_free(void* userdata)
-{
- free(userdata);
-}
-
-// 1D 8-point DCT.
-static inline void idct1d_float(double y0, double y1, double y2, double y3, double y4, double y5, double y6, double y7, double *x)
-{
- // constants
- static const double a1 = 0.7071067811865474; // sqrt(2)
- static const double a2 = 0.5411961001461971; // cos(3/8 pi) * sqrt(2)
- static const double a3 = a1;
- static const double a4 = 1.3065629648763766; // cos(pi/8) * sqrt(2)
- static const double a5 = 0.5 * (a4 - a2);
-
- // phase 1
- const double p1_0 = y0;
- const double p1_1 = y4;
- const double p1_2 = y2;
- const double p1_3 = y6;
- const double p1_4 = y5;
- const double p1_5 = y1;
- const double p1_6 = y7;
- const double p1_7 = y3;
-
- // phase 2
- const double p2_0 = p1_0;
- const double p2_1 = p1_1;
- const double p2_2 = p1_2;
- const double p2_3 = p1_3;
- const double p2_4 = p1_4 - p1_7;
- const double p2_5 = p1_5 + p1_6;
- const double p2_6 = p1_5 - p1_6;
- const double p2_7 = p1_4 + p1_7;
-
- // phase 3
- const double p3_0 = p2_0;
- const double p3_1 = p2_1;
- const double p3_2 = p2_2 - p2_3;
- const double p3_3 = p2_2 + p2_3;
- const double p3_4 = p2_4;
- const double p3_5 = p2_5 - p2_7;
- const double p3_6 = p2_6;
- const double p3_7 = p2_5 + p2_7;
-
- // phase 4
- const double p4_0 = p3_0;
- const double p4_1 = p3_1;
- const double p4_2 = a1 * p3_2;
- const double p4_3 = p3_3;
- const double p4_4 = p3_4 * -a2 + (p3_4 + p3_6) * -a5;
- const double p4_5 = a3 * p3_5;
- const double p4_6 = p3_6 * a4 + (p3_4 + p3_6) * -a5;
- const double p4_7 = p3_7;
-
- // phase 5
- const double p5_0 = p4_0 + p4_1;
- const double p5_1 = p4_0 - p4_1;
- const double p5_2 = p4_2;
- const double p5_3 = p4_2 + p4_3;
- const double p5_4 = p4_4;
- const double p5_5 = p4_5;
- const double p5_6 = p4_6;
- const double p5_7 = p4_7;
-
- // phase 6
- const double p6_0 = p5_0 + p5_3;
- const double p6_1 = p5_1 + p5_2;
- const double p6_2 = p5_1 - p5_2;
- const double p6_3 = p5_0 - p5_3;
- const double p6_4 = -p5_4;
- const double p6_5 = p5_5 - p5_4;
- const double p6_6 = p5_5 + p5_6;
- const double p6_7 = p5_6 + p5_7;
-
- // phase 7
- x[0] = p6_0 + p6_7;
- x[1] = p6_1 + p6_6;
- x[2] = p6_2 + p6_5;
- x[3] = p6_3 + p6_4;
- x[4] = p6_3 - p6_4;
- x[5] = p6_2 - p6_5;
- x[6] = p6_1 - p6_6;
- x[7] = p6_0 - p6_7;
-}
-
-void idct_float(const int16_t* input, const void* userdata, uint8_t* output)
-{
- const double* quant_table = (const double*)userdata;
- double temp[DCTSIZE2];
-
- // IDCT columns.
- for (unsigned x = 0; x < DCTSIZE; ++x) {
- idct1d_float(input[DCTSIZE * 0 + x] * quant_table[DCTSIZE * 0 + x],
- input[DCTSIZE * 1 + x] * quant_table[DCTSIZE * 1 + x],
- input[DCTSIZE * 2 + x] * quant_table[DCTSIZE * 2 + x],
- input[DCTSIZE * 3 + x] * quant_table[DCTSIZE * 3 + x],
- input[DCTSIZE * 4 + x] * quant_table[DCTSIZE * 4 + x],
- input[DCTSIZE * 5 + x] * quant_table[DCTSIZE * 5 + x],
- input[DCTSIZE * 6 + x] * quant_table[DCTSIZE * 6 + x],
- input[DCTSIZE * 7 + x] * quant_table[DCTSIZE * 7 + x],
- temp + x * DCTSIZE);
- }
-
- // IDCT rows.
- for (unsigned y = 0; y < DCTSIZE; ++y) {
- double temp2[DCTSIZE];
- idct1d_float(temp[DCTSIZE * 0 + y],
- temp[DCTSIZE * 1 + y],
- temp[DCTSIZE * 2 + y],
- temp[DCTSIZE * 3 + y],
- temp[DCTSIZE * 4 + y],
- temp[DCTSIZE * 5 + y],
- temp[DCTSIZE * 6 + y],
- temp[DCTSIZE * 7 + y],
- temp2);
- for (unsigned x = 0; x < DCTSIZE; ++x) {
- const double val = temp2[x];
- if (val < 0.0) {
- output[y * DCTSIZE + x] = 0;
- } else if (val >= 255.0) {
- output[y * DCTSIZE + x] = 255;
- } else {
- output[y * DCTSIZE + x] = (uint8_t)(val + 0.5);
- }
- }
- }
-}
projects / fjl / blobdiff