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authorMax Horn2009-10-20 12:21:43 +0000
committerMax Horn2009-10-20 12:21:43 +0000
commit5ce23633e26a66f8a3ba4bfe88b4bb7f23622d6e (patch)
tree7b3275221658fcc707fcd32e34966506a1eb162f /engines
parent53e08b32e8a082e6451dc8768bf6859b1531f167 (diff)
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AGI: Oopify LZW decoder
svn-id: r45265
Diffstat (limited to 'engines')
-rw-r--r--engines/agi/lzw.cpp111
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