inverseDCT.cpp

00001 #include "mbed.h"
00002 #include "inverseDCT.h"
00003 
00004 #ifdef USE_IDCT_AAN
00005 const int zigzag[64] =
00006           {0,
00007            1, 8,
00008           16, 9, 2,
00009            3,10,17,24,
00010           32,25,18,11, 4,
00011           5,12,19,26,33,40,
00012           48,41,34,27,20,13,6,
00013            7,14,21,28,35,42,49,56,
00014           57,50,43,36,29,22,15,
00015           23,30,37,44,51,58,
00016           59,52,45,38,31,
00017           39,46,53,60,
00018           61,54,47,
00019           55,62,
00020           63};
00021 
00022 void inverseDCT::inputBLOCK(int mcu, int block, int scan, int value) {
00023     if (scan == 0) {
00024         for(int i = 0; i < 64; i++) {
00025             m_s[i] = 0;
00026         }
00027     }
00028     m_s[zigzag[scan]] = value;
00029     if (scan == 63) { // last
00030         idct.conv(reinterpret_cast<int8_t*>(m_s), m_s);
00031         outputBLOCK(mcu, block, reinterpret_cast<int8_t*>(m_s));
00032     }
00033 };
00034 #endif //USE_IDCT_AAN
00035 
00036 #ifdef USE_IDCT_TABLE
00037 #include "inverseDCT_table.h"
00038 void inverseDCT::inputBLOCK(int mcu, int block, int scan, int value)
00039 {
00040     if (scan == 0) {
00041         int t = value * 32 / 8;
00042         for(int i = 0; i < 64; i++) {
00043             m_sum[i] = t;
00044         }
00045         return;
00046     }
00047 
00048     if (value != 0) {
00049         for(int xy = 0; xy < 64; xy++) {
00050             m_sum[xy] += idct_table[scan*64+xy] * value / 16;
00051         }
00052     }
00053     
00054     if (scan == 63) {
00055         int8_t* result = reinterpret_cast<int8_t*>(m_sum);
00056         for(int i = 0; i < 64; i++) {
00057             int t = m_sum[i] / 32;
00058             if (t > 127) {
00059                 t = 127;
00060             } else if (t < -128) {
00061                 t = -128;
00062             }
00063             result[i] = t;
00064         }
00065         outputBLOCK(mcu, block, result);
00066     }
00067 }
00068 #endif //USE_IDCT_TABLE