thirdparty/scummvm
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A little Delphine unpacker documentation addition and variable renaming.

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svn-id: r32660
This commit is contained in:
Kari Salminen 2008-06-10 22:37:55 +00:00
parent 235504e600
commit efc4fd7ae0
2 changed files with 22 additions and 16 deletions
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28
engines/cine/unpack.cpp
View file

@ -36,23 +36,23 @@ uint32 CineUnpacker::readSource() {
return value; return value;
} }
int CineUnpacker::rcr(int CF) { int CineUnpacker::rcr(int inputCarry) {
int rCF = (_chk & 1); int outputCarry = (_chunk32b & 1);
_chk >>= 1; _chunk32b >>= 1;
if (CF) { if (inputCarry) {
_chk |= 0x80000000; _chunk32b |= 0x80000000;
} }
return rCF; return outputCarry;
} }
int CineUnpacker::nextBit() { int CineUnpacker::nextBit() {
int CF = rcr(0); int carry = rcr(0);
if (_chk == 0) { if (_chunk32b == 0) {
_chk = readSource(); _chunk32b = readSource();
_crc ^= _chk; _crc ^= _chunk32b;
CF = rcr(1); carry = rcr(1);
} }
return CF; return carry;
} }
uint16 CineUnpacker::getBits(byte numBits) { uint16 CineUnpacker::getBits(byte numBits) {
@ -85,8 +85,8 @@ bool CineUnpacker::unpack(byte *dst, const byte *src, int srcLen) {
_datasize = readSource(); _datasize = readSource();
_dst = dst + _datasize - 1; _dst = dst + _datasize - 1;
_crc = readSource(); _crc = readSource();
_chk = readSource(); _chunk32b = readSource();
_crc ^= _chk; _crc ^= _chunk32b;
do { do {
if (!nextBit()) { if (!nextBit()) {
if (!nextBit()) { if (!nextBit()) {

10
engines/cine/unpack.h
View file

@ -38,7 +38,13 @@ public:
private: private:
/** Reads a single big endian 32-bit integer from the source and goes backwards 4 bytes. */ /** Reads a single big endian 32-bit integer from the source and goes backwards 4 bytes. */
uint32 readSource(); uint32 readSource();
int rcr(int CF);
/**
* Shifts the current internal 32-bit chunk to the right by one.
* Puts input carry into internal chunk's topmost (i.e. leftmost) bit.
* Returns the least significant bit that was shifted out.
*/
int rcr(int inputCarry);
int nextBit(); int nextBit();
uint16 getBits(byte numBits); uint16 getBits(byte numBits);
void unpackBytes(uint16 numBytes); void unpackBytes(uint16 numBytes);
@ -46,7 +52,7 @@ private:
private: private:
int _datasize; int _datasize;
uint32 _crc; uint32 _crc;
uint32 _chk; uint32 _chunk32b; //!< The current internal 32-bit chunk
byte *_dst; byte *_dst;
const byte *_src; const byte *_src;
}; };