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COMMON: Extend some method comments in Common::BitStream

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Adding examples to getBits() and addBit().
This commit is contained in:
Sven Hesse 2011-10-21 00:16:57 +02:00
parent 657ee2da59
commit 42b39cb7ec
1 changed files with 29 additions and 4 deletions
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33
common/bitstream.h
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@ -64,7 +64,7 @@ public:
/** Read a multi-bit value from the bit stream, without changing the stream's position. */
virtual uint32 peekBits(uint8 n) = 0;
/** Add a bit to the value x, making it an n-bit value. */
/** Add a bit to the value x, making it an n+1-bit value. */
virtual void addBit(uint32 &x, uint32 n) = 0;
protected:
@ -76,7 +76,7 @@ protected:
* A template implementing a bit stream for different data memory layouts.
*
* Such a bit stream reads valueBits-wide values from the data stream and
* gives * access to their bits, one at a time.
* gives access to their bits, one at a time.
*
* For example, a bit stream with the layout parameters 32, true, false
* for valueBits, isLE and isMSB2LSB, reads 32bit little-endian values
@ -174,7 +174,16 @@ public:
return b;
}
/** Read a multi-bit value from the bit stream. */
/**
* Read a multi-bit value from the bit stream.
*
* The value is read as if just taken as a whole from the bitstream.
*
* For example:
* Reading a 4-bit value from an 8-bit bitstream with the contents 01010011:
* If the bitstream is MSB2LSB, the 4-bit value would be 0101.
* If the bitstream is LSB2MSB, the 4-bit value would be 0011.
*/
uint32 getBits(uint8 n) {
if (n == 0)
return 0;
@ -198,6 +207,7 @@ public:
return v;
}
/** Read a bit from the bit stream, without changing the stream's position. */
uint32 peekBit() {
uint32 value = _value;
uint8 inValue = _inValue;
@ -212,6 +222,11 @@ public:
return v;
}
/**
* Read a multi-bit value from the bit stream, without changing the stream's position.
*
* The bit order is the same as in getBits().
*/
uint32 peekBits(uint8 n) {
uint32 value = _value;
uint8 inValue = _inValue;
@ -226,7 +241,17 @@ public:
return v;
}
/** Add a bit to the value x, making it an n-bit value. */
/**
* Add a bit to the value x, making it an n+1-bit value.
*
* The current value is shifted and the bit is added to the
* appropriate place, dependant on the stream's bitorder.
*
* For example:
* A bit y is added to the value 00001100 with size 4.
* If the stream's bitorder is MSB2LSB, the resulting value is 0001100y.
* If the stream's bitorder is LSB2MSB, the resulting value is 000y1100.
*/
void addBit(uint32 &x, uint32 n) {
if (n >= 32)
error("BitStreamImpl::addBit(): Too many bits requested to be read");