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[fbreader] Optimized ZLZipHeader::readShort and readLong

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For little endian CPUs. Unnecessary byte shuffling does show up
on the performance graph. Both Jolla tablet and Jolla phone are
little endian.
This commit is contained in:
Slava Monich 2015-07-29 18:53:48 +03:00
parent 4026ae35d1
commit b3acda416c
1 changed files with 10 additions and 0 deletions
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10
fbreader/fbreader/zlibrary/core/src/filesystem/zip/ZLZipHeader.cpp
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@ -80,12 +80,21 @@ void ZLZipHeader::skipEntry(ZLInputStream &stream, ZLZipHeader &header) {
} }
unsigned short ZLZipHeader::readShort(ZLInputStream &stream) { unsigned short ZLZipHeader::readShort(ZLInputStream &stream) {
#if defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN
u_int16_t result;
return (stream.read((char*)&result, 2) == 2) ? result : 0;
#else
char buffer[2]; char buffer[2];
stream.read(buffer, 2); stream.read(buffer, 2);
return ((((unsigned short)buffer[1]) & 0xFF) << 8) + ((unsigned short)buffer[0] & 0xFF); return ((((unsigned short)buffer[1]) & 0xFF) << 8) + ((unsigned short)buffer[0] & 0xFF);
#endif
} }
unsigned long ZLZipHeader::readLong(ZLInputStream &stream) { unsigned long ZLZipHeader::readLong(ZLInputStream &stream) {
#if defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN
u_int32_t result;
return (stream.read((char*)&result, 4) == 4) ? result : 0;
#else
char buffer[4]; char buffer[4];
stream.read(buffer, 4); stream.read(buffer, 4);
@ -94,4 +103,5 @@ unsigned long ZLZipHeader::readLong(ZLInputStream &stream) {
((((unsigned long)buffer[2]) & 0xFF) << 16) + ((((unsigned long)buffer[2]) & 0xFF) << 16) +
((((unsigned long)buffer[1]) & 0xFF) << 8) + ((((unsigned long)buffer[1]) & 0xFF) << 8) +
((unsigned long)buffer[0] & 0xFF); ((unsigned long)buffer[0] & 0xFF);
#endif
} }