now waveforms and thumbnails are cached

io/crc32.cpp

@@ -0,0 +1,73 @@
+#include "crc32.h"
+
+#include <QFile>
+
+Crc32::Crc32()
+{
+    quint32 crc;
+
+    // initialize CRC table
+    for (int i = 0; i < 256; i++)
+    {
+        crc = i;
+        for (int j = 0; j < 8; j++)
+            crc = crc & 1 ? (crc >> 1) ^ 0xEDB88320UL : crc >> 1;
+
+        crc_table[i] = crc;
+    }
+}
+
+quint32 Crc32::calculateFromFile(QString filename)
+{
+    quint32 crc;
+    QFile file;
+
+    char buffer[16000];
+    int len, i;
+
+    crc = 0xFFFFFFFFUL;
+
+    file.setFileName(filename);
+    if (file.open(QIODevice::ReadOnly))
+    {
+        while (!file.atEnd())
+        {
+            len = file.read(buffer, 16000);
+            for (i = 0; i < len; i++)
+                crc = crc_table[(crc ^ buffer[i]) & 0xFF] ^ (crc >> 8);
+        }
+
+        file.close();
+    }
+
+    return crc ^ 0xFFFFFFFFUL;
+}
+
+void Crc32::initInstance(int i)
+{
+    instances[i] = 0xFFFFFFFFUL;
+}
+
+void Crc32::pushData(int i, char *data, int len)
+{
+    quint32 crc = instances[i];
+    if (crc)
+    {
+        for (int j = 0; j < len; j++)
+            crc = crc_table[(crc ^ data[j]) & 0xFF] ^ (crc >> 8);
+
+        instances[i] = crc;
+    }
+}
+
+quint32 Crc32::releaseInstance(int i)
+{
+    quint32 crc32 = instances[i];
+    if (crc32) {
+        instances.remove(i);
+        return crc32 ^ 0xFFFFFFFFUL;
+    }
+    else {
+        return 0;
+    }
+}