diff options
| -rw-r--r-- | common/bitstream.h | 63 |
1 files changed, 49 insertions, 14 deletions
diff --git a/common/bitstream.h b/common/bitstream.h index e867d86ea7..1fbc0065ab 100644 --- a/common/bitstream.h +++ b/common/bitstream.h @@ -29,6 +29,7 @@ #include "common/textconsole.h" #include "common/stream.h" #include "common/types.h" +#include "common/util.h" namespace Common { @@ -115,14 +116,10 @@ public: delete _stream; } - /** Read a bit from the bit stream. */ - uint32 getBit() { - // Check if we need the next value - if (_inValue == 0) - readValue(); - +private: + uint32 getBit_internal() { // Get the current bit - int b = 0; + uint32 b = 0; if (isMSB2LSB) b = ((_value & 0x80000000) == 0) ? 0 : 1; else @@ -134,6 +131,18 @@ public: else _value >>= 1; + return b; + } + +public: + /** Read a bit from the bit stream. */ + uint32 getBit() { + // Check if we need the next value + if (_inValue == 0) + readValue(); + + uint32 b = getBit_internal(); + // Increase the position within the current value _inValue = (_inValue + 1) % valueBits; _pos++; @@ -161,16 +170,42 @@ public: // Read the number of bits uint32 v = 0; - if (isMSB2LSB) { - while (n-- > 0) - v = (v << 1) | getBit(); - } else { - for (uint32 i = 0; i < n; i++) - v = (v >> 1) | (((uint32) getBit()) << 31); + uint8 nOrig = n; + if (_inValue) { + int count = MIN((int)n, valueBits - _inValue); + for (int i = 0; i < count; ++i) { + if (isMSB2LSB) { + v = (v << 1) | getBit_internal(); + } else { + v = (v >> 1) | (getBit_internal() << 31); + } + } + + n -= count; + } + + while (n > 0) { + // NB: readValue doesn't care that _inValue is incorrect here + readValue(); - v >>= (32 - n); + int count = MIN((int)n, valueBits); + for (int i = 0; i < count; ++i) { + if (isMSB2LSB) { + v = (v << 1) | getBit_internal(); + } else { + v = (v >> 1) | (getBit_internal() << 31); + } + } + + n -= count; } + _inValue = (_inValue + nOrig) % valueBits; + _pos += nOrig; + + if (!isMSB2LSB) + v >>= (32 - nOrig); + return v; } |