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Combine two internal functions which are always used together.

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This commit is contained in:
Tsuda Kageyu 2017-01-21 01:34:50 +09:00
parent 6bb92c34fa
commit c4a3c3ab97
3 changed files with 17 additions and 17 deletions
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16
taglib/mpeg/mpegfile.cpp
View File

@ -346,7 +346,7 @@ void MPEG::File::setID3v2FrameFactory(const ID3v2::FrameFactory *factory)
long MPEG::File::nextFrameOffset(long position)
{
char frameSyncBytes[2] = {};
ByteVector frameSyncBytes(2, '\0');
while(true) {
seek(position);
@ -357,7 +357,7 @@ long MPEG::File::nextFrameOffset(long position)
for(unsigned int i = 0; i < buffer.size(); ++i) {
frameSyncBytes[0] = frameSyncBytes[1];
frameSyncBytes[1] = buffer[i];
if(firstSyncByte(frameSyncBytes[0]) && secondSynchByte(frameSyncBytes[1])) {
if(isFrameSync(frameSyncBytes)) {
Header header(this, position + i - 1, true);
if(header.isValid())
return position + i - 1;
@ -370,7 +370,7 @@ long MPEG::File::nextFrameOffset(long position)
long MPEG::File::previousFrameOffset(long position)
{
char frameSyncBytes[2] = {};
ByteVector frameSyncBytes(2, '\0');
while(position > 0) {
const long size = std::min<long>(position, bufferSize());
@ -384,7 +384,7 @@ long MPEG::File::previousFrameOffset(long position)
for(int i = buffer.size() - 1; i >= 0; i--) {
frameSyncBytes[1] = frameSyncBytes[0];
frameSyncBytes[0] = buffer[i];
if(firstSyncByte(frameSyncBytes[0]) && secondSynchByte(frameSyncBytes[1])) {
if(isFrameSync(frameSyncBytes)) {
Header header(this, position + i, true);
if(header.isValid())
return position + i + header.frameLength();
@ -494,8 +494,8 @@ long MPEG::File::findID3v2()
// Look for an ID3v2 tag until reaching the first valid MPEG frame.
char frameSyncBytes[2] = {};
char tagHeaderBytes[4] = {};
ByteVector frameSyncBytes(2, '\0');
ByteVector tagHeaderBytes(3, '\0');
long position = 0;
while(true) {
@ -507,7 +507,7 @@ long MPEG::File::findID3v2()
for(unsigned int i = 0; i < buffer.size(); ++i) {
frameSyncBytes[0] = frameSyncBytes[1];
frameSyncBytes[1] = buffer[i];
if(firstSyncByte(frameSyncBytes[0]) && secondSynchByte(frameSyncBytes[1])) {
if(isFrameSync(frameSyncBytes)) {
Header header(this, position + i - 1, true);
if(header.isValid())
return -1;
@ -516,7 +516,7 @@ long MPEG::File::findID3v2()
tagHeaderBytes[0] = tagHeaderBytes[1];
tagHeaderBytes[1] = tagHeaderBytes[2];
tagHeaderBytes[2] = buffer[i];
if(headerID == tagHeaderBytes)
if(tagHeaderBytes == headerID)
return position + i - 2;
}

2
taglib/mpeg/mpegheader.cpp
View File

@ -182,7 +182,7 @@ void MPEG::Header::parse(File *file, long offset, bool checkLength)
// Check for the MPEG synch bytes.
if(!firstSyncByte(data[0]) || !secondSynchByte(data[1])) {
if(!isFrameSync(data)) {
debug("MPEG::Header::parse() -- MPEG header did not match MPEG synch.");
return;
}

16
taglib/mpeg/mpegutils.h
View File

@ -41,17 +41,17 @@ namespace TagLib
* MPEG frames can be recognized by the bit pattern 11111111 111, so the
* first byte is easy to check for, however checking to see if the second byte
* starts with \e 111 is a bit more tricky, hence these functions.
*
* \note This does not check the length of the vector, since this is an
* internal utility function.
*/
inline bool firstSyncByte(unsigned char byte)
inline bool isFrameSync(const ByteVector &bytes)
{
return (byte == 0xFF);
}
// 0xFF in the second byte is possible in theory, but it's very unlikely.
inline bool secondSynchByte(unsigned char byte)
{
// 0xFF is possible in theory, but it's very unlikely be a header.
return (byte != 0xFF && ((byte & 0xE0) == 0xE0));
const unsigned char b1 = bytes[0];
const unsigned char b2 = bytes[1];
return (b1 == 0xFF && b2 != 0xFF && (b2 & 0xE0) == 0xE0);
}
}