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* *

* Get the header information. *

* *

*****************************************************************************/

hsize = sizeof(int);

memcpy(&size, compressed, sizeof(int));

/*****************************************************************************

* *

* Initialize the sliding window and the look-ahead buffer. *

* *

*****************************************************************************/

memset(window, 0, LZ77_WINDOW_SIZE);

memset(buffer, 0, LZ77_BUFFER_SIZE);

/*****************************************************************************

* *

* Uncompress the data. *

* *

*****************************************************************************/

ipos = hsize * 8;

opos = 0;

remaining = size;

while (remaining > 0) {

/**************************************************************************

* *

* Get the next bit in the compressed data. *

* *

**************************************************************************/

state = bit_get(compressed, ipos);

ipos++;

if (state == 1) {

/***********************************************************************

* *

* Handle processing a phrase token. *

* *

***********************************************************************/

memset(&offset, 0, sizeof(int));

for (i = 0; i < LZ77_WINOFF_BITS; i++) {

tpos = (sizeof(int) * 8) - LZ77_WINOFF_BITS + i;

bit_set((unsigned char *)&offset, tpos, bit_get(compressed, ipos));

ipos++;

}

memset(&length, 0, sizeof(int));

for (i = 0; i < LZ77_BUFLEN_BITS; i++) {

tpos = (sizeof(int) * 8) - LZ77_BUFLEN_BITS + i;

bit_set((unsigned char *)&length, tpos, bit_get(compressed, ipos));

ipos++;

}

next = 0x00;

for (i = 0; i < LZ77_NEXT_BITS; i++) {

tpos = (sizeof(unsigned char) * 8) - LZ77_NEXT_BITS + i;

bit_set((unsigned char *)&next, tpos, bit_get(compressed, ipos));

ipos++;

}

/***********************************************************************

* *

* Ensure that the offset and length have the correct byte ordering *

* for the system. *

* *

***********************************************************************/

offset = ntohl(offset);

length = ntohl(length);

/***********************************************************************

* *

* Write the phrase from the window to the buffer of original data. *

* *

***********************************************************************/

i = 0;

if (opos > 0) {

if ((temp = (unsigned char *)realloc(orig, opos+length+1)) == NULL) {

free(orig);

return -1;

}

orig = temp;

}

else {

if ((orig = (unsigned char *)malloc(length + 1)) == NULL)

return -1;

}

while (i < length && remaining > 0) {

orig[opos] = window[offset + i];

opos++;

/********************************************************************

* *

* Record each symbol in the look-ahead buffer until ready to *

* update the sliding window. *

* *

********************************************************************/

buffer[i] = window[offset + i];

i++;

/********************************************************************

* *

* Adjust the total symbols remaining to account for each symbol *

* consumed. *

* *

********************************************************************/

remaining--;

}

/***********************************************************************

* *

* Write the unmatched symbol to the buffer of original data. *

* *

***********************************************************************/

if (remaining > 0) {

orig[opos] = next;

opos++;

/********************************************************************

* *

* Also record this symbol in the look-ahead buffer. *

* *

********************************************************************/

buffer[i] = next;

/********************************************************************

* *

* Adjust the total symbols remaining to account for the unmatched *

* symbol. *

* *

********************************************************************/

remaining--;

}

/***********************************************************************