Diff: extlib/BaseJpegDecode/inverseDCT.cpp

Revision:

0:d69efd0ee139

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/extlib/BaseJpegDecode/inverseDCT.cpp	Thu Sep 18 15:21:47 2014 +0000
@@ -0,0 +1,68 @@
+#include "mbed.h"
+#include "inverseDCT.h"
+
+#ifdef USE_IDCT_AAN
+const int zigzag[64] =
+          {0,
+           1, 8,
+          16, 9, 2,
+           3,10,17,24,
+          32,25,18,11, 4,
+          5,12,19,26,33,40,
+          48,41,34,27,20,13,6,
+           7,14,21,28,35,42,49,56,
+          57,50,43,36,29,22,15,
+          23,30,37,44,51,58,
+          59,52,45,38,31,
+          39,46,53,60,
+          61,54,47,
+          55,62,
+          63};
+
+void inverseDCT::inputBLOCK(int mcu, int block, int scan, int value) {
+    if (scan == 0) {
+        for(int i = 0; i < 64; i++) {
+            m_s[i] = 0;
+        }
+    }
+    m_s[zigzag[scan]] = value;
+    if (scan == 63) { // last
+        idct.conv(reinterpret_cast<int8_t*>(m_s), m_s);
+        outputBLOCK(mcu, block, reinterpret_cast<int8_t*>(m_s));
+    }
+};
+#endif //USE_IDCT_AAN
+
+#ifdef USE_IDCT_TABLE
+#include "inverseDCT_table.h"
+void inverseDCT::inputBLOCK(int mcu, int block, int scan, int value)
+{
+    if (scan == 0) {
+        int t = value * 32 / 8;
+        for(int i = 0; i < 64; i++) {
+            m_sum[i] = t;
+        }
+        return;
+    }
+
+    if (value != 0) {
+        for(int xy = 0; xy < 64; xy++) {
+            m_sum[xy] += idct_table[scan*64+xy] * value / 16;
+        }
+    }
+    
+    if (scan == 63) {
+        int8_t* result = reinterpret_cast<int8_t*>(m_sum);
+        for(int i = 0; i < 64; i++) {
+            int t = m_sum[i] / 32;
+            if (t > 127) {
+                t = 127;
+            } else if (t < -128) {
+                t = -128;
+            }
+            result[i] = t;
+        }
+        outputBLOCK(mcu, block, result);
+    }
+}
+#endif //USE_IDCT_TABLE