diff options
Diffstat (limited to 'engines')
-rw-r--r-- | engines/agi/lzw.cpp | 111 |
1 files changed, 62 insertions, 49 deletions
diff --git a/engines/agi/lzw.cpp b/engines/agi/lzw.cpp index bc2f169322..bca4f749d1 100644 --- a/engines/agi/lzw.cpp +++ b/engines/agi/lzw.cpp @@ -40,18 +40,36 @@ namespace Agi { -#define MAXBITS 12 -#define TABLE_SIZE 18041 // strange number -#define START_BITS 9 - -static int32 BITS, MAX_VALUE, MAX_CODE; -static uint32 *prefixCode; -static uint8 *appendCharacter; -static uint8 *decodeStack; -static int32 inputBitCount = 0; // Number of bits in input bit buffer -static uint32 inputBitBuffer = 0L; - -static void initLZW() { + +class LZWDecoder { +private: + + enum { + MAXBITS = 12, + TABLE_SIZE = 18041, // strange number + START_BITS = 9 + }; + + int32 BITS, MAX_VALUE, MAX_CODE; + uint32 *prefixCode; + uint8 *appendCharacter; + uint8 *decodeStack; + int32 inputBitCount; // Number of bits in input bit buffer + uint32 inputBitBuffer; + +public: + LZWDecoder(); + ~LZWDecoder(); + + void lzwExpand(uint8 *in, uint8 *out, int32 len); + +private: + int setBits(int32 value); + uint8 *decodeString(uint8 *buffer, uint32 code); + uint32 inputCode(uint8 **input); +}; + +LZWDecoder::LZWDecoder() { decodeStack = (uint8 *)calloc(1, 8192); prefixCode = (uint32 *)malloc(TABLE_SIZE * sizeof(uint32)); appendCharacter = (uint8 *)malloc(TABLE_SIZE * sizeof(uint8)); @@ -59,19 +77,16 @@ static void initLZW() { inputBitBuffer = 0L; } -static void closeLZW() { +LZWDecoder::~LZWDecoder() { free(decodeStack); free(prefixCode); free(appendCharacter); } -/*************************************************************************** -** setBits -** -** Purpose: To adjust the number of bits used to store codes to the value -** passed in. -***************************************************************************/ -int setBits(int32 value) { +/** + * Adjust the number of bits used to store codes to the value passed in. + */ +int LZWDecoder::setBits(int32 value) { if (value == MAXBITS) return true; @@ -82,14 +97,12 @@ int setBits(int32 value) { return false; } -/*************************************************************************** -** decode_string -** -** Purpose: To return the string that the code taken from the input buffer -** represents. The string is returned as a stack, i.e. the characters are -** in reverse order. -***************************************************************************/ -static uint8 *decodeString(uint8 *buffer, uint32 code) { +/** + * Return the string that the code taken from the input buffer + * represents. The string is returned as a stack, i.e. the characters are + * in reverse order. + */ +uint8 *LZWDecoder::decodeString(uint8 *buffer, uint32 code) { uint32 i; for (i = 0; code > 255;) { @@ -104,12 +117,10 @@ static uint8 *decodeString(uint8 *buffer, uint32 code) { return buffer; } -/*************************************************************************** -** input_code -** -** Purpose: To return the next code from the input buffer. -***************************************************************************/ -static uint32 inputCode(uint8 **input) { +/** + * Return the next code from the input buffer. + */ +uint32 LZWDecoder::inputCode(uint8 **input) { uint32 r; while (inputBitCount <= 24) { @@ -123,23 +134,21 @@ static uint32 inputCode(uint8 **input) { return r; } -/*************************************************************************** -** expand -** -** Purpose: To uncompress the data contained in the input buffer and store -** the result in the output buffer. The fileLength parameter says how -** many bytes to uncompress. The compression itself is a form of LZW that -** adjusts the number of bits that it represents its codes in as it fills -** up the available codes. Two codes have special meaning: -** -** code 256 = start over -** code 257 = end of data -***************************************************************************/ -void lzwExpand(uint8 *in, uint8 *out, int32 len) { +/** + * Uncompress the data contained in the input buffer and store + * the result in the output buffer. The fileLength parameter says how + * many bytes to uncompress. The compression itself is a form of LZW that + * adjusts the number of bits that it represents its codes in as it fills + * up the available codes. Two codes have special meaning: + * + * code 256 = start over + * code 257 = end of data + */ +void LZWDecoder::lzwExpand(uint8 *in, uint8 *out, int32 len) { int32 c, lzwnext, lzwnew, lzwold; uint8 *s, *end; - initLZW(); + LZWDecoder d; setBits(START_BITS); // Starts at 9-bits lzwnext = 257; // Next available code to define @@ -184,7 +193,11 @@ void lzwExpand(uint8 *in, uint8 *out, int32 len) { lzwnew = inputCode(&in); } } - closeLZW(); +} + +void lzwExpand(uint8 *in, uint8 *out, int32 len) { + LZWDecoder d; + d.lzwExpand(in, out, len); } } // End of namespace Agi |