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FreeRDP/libfreerdp/codec/mppc_enc.c

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/**
* FreeRDP: A Remote Desktop Protocol Implementation
* Implements Microsoft Point to Point Compression (MPPC) protocol
*
* Copyright 2012 Laxmikant Rashinkar <LK.Rashinkar@gmail.com>
* Copyright 2012 Jay Sorg <jay.sorg@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winpr/crt.h>
#include <freerdp/codec/mppc_dec.h>
#include <freerdp/codec/mppc_enc.h>
#define MPPC_ENC_DEBUG 0
/* local defines */
#define RDP_40_HIST_BUF_LEN (1024 * 8) /* RDP 4.0 uses 8K history buf */
#define RDP_50_HIST_BUF_LEN (1024 * 64) /* RDP 5.0 uses 64K history buf */
#define CRC_INIT 0xFFFF
#define CRC(crcval, newchar) crcval = (crcval >> 8) ^ crc_table[(crcval ^ newchar) & 0x00ff]
/* CRC16 defs */
static const UINT16 crc_table[256] =
{
0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
};
/*****************************************************************************
insert 2 bits into outputBuffer
******************************************************************************/
#define insert_2_bits(_data) \
do \
{ \
if ((bits_left >= 3) && (bits_left <= 8)) \
{ \
i = bits_left - 2; \
outputBuffer[opb_index] |= _data << i; \
bits_left = i; \
} \
else \
{ \
i = 2 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 3 bits into outputBuffer
******************************************************************************/
#define insert_3_bits(_data) \
do \
{ \
if ((bits_left >= 4) && (bits_left <= 8)) \
{ \
i = bits_left - 3; \
outputBuffer[opb_index] |= _data << i; \
bits_left = i; \
} \
else \
{ \
i = 3 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 4 bits into outputBuffer
******************************************************************************/
#define insert_4_bits(_data) \
do \
{ \
if ((bits_left >= 5) && (bits_left <= 8)) \
{ \
i = bits_left - 4; \
outputBuffer[opb_index] |= _data << i; \
bits_left = i; \
} \
else \
{ \
i = 4 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 5 bits into outputBuffer
******************************************************************************/
#define insert_5_bits(_data) \
do \
{ \
if ((bits_left >= 6) && (bits_left <= 8)) \
{ \
i = bits_left - 5; \
outputBuffer[opb_index] |= _data << i; \
bits_left = i; \
} \
else \
{ \
i = 5 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 6 bits into outputBuffer
******************************************************************************/
#define insert_6_bits(_data) \
do \
{ \
if ((bits_left >= 7) && (bits_left <= 8)) \
{ \
i = bits_left - 6; \
outputBuffer[opb_index] |= (_data << i); \
bits_left = i; \
} \
else \
{ \
i = 6 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= (_data >> i); \
outputBuffer[opb_index] |= (_data << j); \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 7 bits into outputBuffer
******************************************************************************/
#define insert_7_bits(_data) \
do \
{ \
if (bits_left == 8) \
{ \
outputBuffer[opb_index] |= _data << 1; \
bits_left = 1; \
} \
else \
{ \
i = 7 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 8 bits into outputBuffer
******************************************************************************/
#define insert_8_bits(_data) \
do \
{ \
if (bits_left == 8) \
{ \
outputBuffer[opb_index++] |= _data; \
bits_left = 8; \
} \
else \
{ \
i = 8 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= _data >> i; \
outputBuffer[opb_index] |= _data << j; \
bits_left = j; \
} \
} while (0)
/*****************************************************************************
insert 9 bits into outputBuffer
******************************************************************************/
#define insert_9_bits(_data16) \
do \
{ \
i = 9 - bits_left; \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
if (bits_left == 0) \
{ \
opb_index++; \
bits_left = 8; \
} \
} while (0)
/*****************************************************************************
insert 10 bits into outputBuffer
******************************************************************************/
#define insert_10_bits(_data16) \
do \
{ \
i = 10 - bits_left; \
if ((bits_left >= 3) && (bits_left <= 8)) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 11 bits into outputBuffer
******************************************************************************/
#define insert_11_bits(_data16) \
do \
{ \
i = 11 - bits_left; \
if ((bits_left >= 4) && (bits_left <= 8)) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 12 bits into outputBuffer
******************************************************************************/
#define insert_12_bits(_data16) \
do \
{ \
i = 12 - bits_left; \
if ((bits_left >= 5) && (bits_left <= 8)) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 13 bits into outputBuffer
******************************************************************************/
#define insert_13_bits(_data16) \
do \
{ \
i = 13 - bits_left; \
if ((bits_left >= 6) && (bits_left <= 8)) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 14 bits into outputBuffer
******************************************************************************/
#define insert_14_bits(_data16) \
do \
{ \
i = 14 - bits_left; \
if ((bits_left >= 7) && (bits_left <= 8)) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 15 bits into outputBuffer
******************************************************************************/
#define insert_15_bits(_data16) \
do \
{ \
i = 15 - bits_left; \
if (bits_left == 8) \
{ \
j = 8 - i; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index] |= (char) (_data16 << j); \
bits_left = j; \
} \
else \
{ \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} \
} while (0)
/*****************************************************************************
insert 16 bits into outputBuffer
******************************************************************************/
#define insert_16_bits(_data16) \
do \
{ \
i = 16 - bits_left; \
j = i - 8; \
k = 8 - j; \
outputBuffer[opb_index++] |= (char) (_data16 >> i); \
outputBuffer[opb_index++] |= (char) (_data16 >> j); \
outputBuffer[opb_index] |= (char) (_data16 << k); \
bits_left = k; \
} while (0)
#if MPPC_ENC_DEBUG
#define DLOG(_args) printf _args
#else
#define DLOG(_args) do { } while (0)
#endif
/**
* Initialize mppc_enc structure
*
* @param protocol_type PROTO_RDP_40 or PROTO_RDP_50
*
* @return struct rdp_mppc_enc* or nil on failure
*/
struct rdp_mppc_enc* mppc_enc_new(int protocol_type)
{
struct rdp_mppc_enc* enc;
enc = (struct rdp_mppc_enc*) malloc(sizeof(struct rdp_mppc_enc));
ZeroMemory(enc, sizeof(struct rdp_mppc_enc));
if (enc == NULL)
return NULL;
switch (protocol_type)
{
case PROTO_RDP_40:
enc->protocol_type = PROTO_RDP_40;
enc->buf_len = RDP_40_HIST_BUF_LEN;
break;
case PROTO_RDP_50:
enc->protocol_type = PROTO_RDP_50;
enc->buf_len = RDP_50_HIST_BUF_LEN;
break;
default:
free(enc);
return NULL;
}
enc->first_pkt = 1;
enc->historyBuffer = (char*) malloc(enc->buf_len);
ZeroMemory(enc->historyBuffer, enc->buf_len);
if (enc->historyBuffer == NULL)
{
free(enc);
return NULL;
}
enc->outputBufferPlus = (char*) malloc(enc->buf_len + 64);
ZeroMemory(enc->outputBufferPlus, enc->buf_len + 64);
if (enc->outputBufferPlus == NULL)
{
free(enc->historyBuffer);
free(enc);
return NULL;
}
enc->outputBuffer = enc->outputBufferPlus + 64;
enc->hash_table = (UINT16*) malloc(enc->buf_len * 2);
ZeroMemory(enc->hash_table, enc->buf_len * 2);
if (enc->hash_table == NULL)
{
free(enc->historyBuffer);
free(enc->outputBufferPlus);
free(enc);
return NULL;
}
return enc;
}
/**
* deinit mppc_enc structure
*
* @param enc struct to be deinited
*/
void mppc_enc_free(struct rdp_mppc_enc* enc)
{
if (enc == NULL)
return;
free(enc->historyBuffer);
free(enc->outputBufferPlus);
free(enc->hash_table);
free(enc);
}
/**
* encode (compress) data
*
* @param enc encoder state info
* @param srcData uncompressed data
* @param len length of srcData
*
* @return TRUE on success, FALSE on failure
*/
BOOL compress_rdp(struct rdp_mppc_enc* enc, BYTE* srcData, int len)
{
if ((enc == NULL) || (srcData == NULL) || (len <= 0) || (len > enc->buf_len))
return FALSE;
switch (enc->protocol_type)
{
case PROTO_RDP_40:
return compress_rdp_4(enc, srcData, len);
break;
case PROTO_RDP_50:
return compress_rdp_5(enc, srcData, len);
break;
}
return FALSE;
}
/**
* encode (compress) data using RDP 4.0 protocol
*
* @param enc encoder state info
* @param srcData uncompressed data
* @param len length of srcData
*
* @return TRUE on success, FALSE on failure
*/
BOOL compress_rdp_4(struct rdp_mppc_enc* enc, BYTE* srcData, int len)
{
/* RDP 4.0 encoding not yet implemented */
return FALSE;
}
/**
* encode (compress) data using RDP 5.0 protocol using hash table
*
* @param enc encoder state info
* @param srcData uncompressed data
* @param len length of srcData
*
* @return TRUE on success, FALSE on failure
*/
BOOL compress_rdp_5(struct rdp_mppc_enc* enc, BYTE* srcData, int len)
{
char* outputBuffer; /* points to enc->outputBuffer */
char* hptr_end; /* points to end of history data */
char* historyPointer; /* points to first byte of srcData in historyBuffer */
char* hbuf_start; /* points to start of history buffer */
char* cptr1;
char* cptr2;
int opb_index; /* index into outputBuffer */
int bits_left; /* unused bits in current byte in outputBuffer */
UINT32 copy_offset; /* pattern match starts here... */
UINT32 lom; /* ...and matches this many bytes */
int last_crc_index; /* don't compute CRC beyond this index */
UINT16 *hash_table; /* hash table for pattern matching */
UINT32 i;
UINT32 j;
UINT32 k;
UINT32 x;
BYTE data;
UINT16 data16;
UINT32 historyOffset;
UINT16 crc;
UINT32 ctr;
UINT32 saved_ctr;
UINT32 data_end;
BYTE byte_val;
crc = 0;
opb_index = 0;
bits_left = 8;
copy_offset = 0;
hash_table = enc->hash_table;
hbuf_start = enc->historyBuffer;
outputBuffer = enc->outputBuffer;
memset(outputBuffer, 0, len);
enc->flags = PACKET_COMPR_TYPE_64K;
if (enc->first_pkt)
{
enc->first_pkt = 0;
enc->flagsHold |= PACKET_AT_FRONT;
}
if ((enc->historyOffset + len) > enc->buf_len)
{
/* historyBuffer cannot hold srcData - rewind it */
enc->historyOffset = 0;
enc->flagsHold |= PACKET_AT_FRONT;
memset(hash_table, 0, enc->buf_len * 2);
}
/* point to next free byte in historyBuffer */
historyOffset = enc->historyOffset;
/* add / append new data to historyBuffer */
memcpy(&(enc->historyBuffer[historyOffset]), srcData, len);
/* point to start of data to be compressed */
historyPointer = &(enc->historyBuffer[historyOffset]);
ctr = copy_offset = lom = 0;
/* if we are at start of history buffer, do not attempt to compress */
/* first 2 bytes,because minimum LoM is 3 */
if (historyOffset == 0)
{
/* encode first two bytes are literals */
for (x = 0; x < 2; x++)
{
data = *(historyPointer + x);
DLOG(("%.2x ", (unsigned char) data));
if (data & 0x80)
{
/* insert encoded literal */
insert_2_bits(0x02);
data &= 0x7f;
insert_7_bits(data);
}
else
{
/* insert literal */
insert_8_bits(data);
}
}
/* store hash for first two entries in historyBuffer */
crc = CRC_INIT;
byte_val = enc->historyBuffer[0];
CRC(crc, byte_val);
byte_val = enc->historyBuffer[1];
CRC(crc, byte_val);
byte_val = enc->historyBuffer[2];
CRC(crc, byte_val);
hash_table[crc] = 0;
crc = CRC_INIT;
byte_val = enc->historyBuffer[1];
CRC(crc, byte_val);
byte_val = enc->historyBuffer[2];
CRC(crc, byte_val);
byte_val = enc->historyBuffer[3];
CRC(crc, byte_val);
hash_table[crc] = 1;
/* first two bytes have already been processed */
ctr = 2;
}
enc->historyOffset += len;
/* point to last byte in new data */
hptr_end = &(enc->historyBuffer[enc->historyOffset - 1]);
/* do not compute CRC beyond this */
last_crc_index = enc->historyOffset - 3;
/* do not search for pattern match beyond this */
data_end = len - 2;
/* start compressing data */
while (ctr < data_end)
{
cptr1 = historyPointer + ctr;
crc = CRC_INIT;
byte_val = *cptr1;
CRC(crc, byte_val);
byte_val = *(cptr1 + 1);
CRC(crc, byte_val);
byte_val = *(cptr1 + 2);
CRC(crc, byte_val);
/* cptr2 points to start of pattern match */
cptr2 = hbuf_start + hash_table[crc];
copy_offset = cptr1 - cptr2;
/* save current entry */
hash_table[crc] = cptr1 - hbuf_start;
/* double check that we have a pattern match */
if ((*cptr1 != *cptr2) ||
(*(cptr1 + 1) != *(cptr2 + 1)) ||
(*(cptr1 + 2) != *(cptr2 + 2)))
{
/* no match found; encode literal byte */
data = *cptr1;
DLOG(("%.2x ", (unsigned char) data));
if (data < 0x80)
{
/* literal byte < 0x80 */
insert_8_bits(data);
}
else
{
/* literal byte >= 0x80 */
insert_2_bits(0x02);
data &= 0x7f;
insert_7_bits(data);
}
ctr++;
continue;
}
/* we have a match - compute Length of Match */
cptr1 += 3;
cptr2 += 3;
lom = 3;
while ((cptr1 <= hptr_end) && (*(cptr1++) == *(cptr2++)))
{
lom++;
}
saved_ctr = ctr + lom;
DLOG(("<%d: %ld,%d> ", (historyPointer + ctr) - hbuf_start, copy_offset, lom));
/* compute CRC for matching segment and store in hash table */
cptr1 = historyPointer + ctr;
if (cptr1 + lom > hbuf_start + last_crc_index)
{
/* we have gone beyond last_crc_index - go back */
j = last_crc_index - (cptr1 - hbuf_start);
}
else
{
j = lom - 1;
}
ctr++;
for (i = 0; i < j; i++)
{
cptr1 = historyPointer + ctr;
/* compute CRC on triplet */
crc = CRC_INIT;
byte_val = *(cptr1++);
CRC(crc, byte_val);
byte_val = *(cptr1++);
CRC(crc, byte_val);
byte_val = *(cptr1++);
CRC(crc, byte_val);
/* save current entry */
hash_table[crc] = (cptr1 - 3) - hbuf_start;
/* point to next triplet */
ctr++;
}
ctr = saved_ctr;
/* encode copy_offset and insert into output buffer */
if (copy_offset <= 63) /* (copy_offset >= 0) is always true */
{
/* insert binary header */
data = 0x1f;
insert_5_bits(data);
/* insert 6 bits of copy_offset */
data = (char) (copy_offset & 0x3f);
insert_6_bits(data);
}
else if ((copy_offset >= 64) && (copy_offset <= 319))
{
/* insert binary header */
data = 0x1e;
insert_5_bits(data);
/* insert 8 bits of copy offset */
data = (char) (copy_offset - 64);
insert_8_bits(data);
}
else if ((copy_offset >= 320) && (copy_offset <= 2367))
{
/* insert binary header */
data = 0x0e;
insert_4_bits(data);
/* insert 11 bits of copy offset */
data16 = copy_offset - 320;;
insert_11_bits(data16);
}
else
{
/* copy_offset is 2368+ */
/* insert binary header */
data = 0x06;
insert_3_bits(data);
/* insert 16 bits of copy offset */
data16 = copy_offset - 2368;;
insert_16_bits(data16);
}
/* encode length of match and insert into output buffer */
if (lom == 3)
{
/* binary header is 'zero'; since outputBuffer is zero */
/* filled, all we have to do is update bits_left */
bits_left--;
if (bits_left == 0)
{
opb_index++;
bits_left = 8;
}
}
else if ((lom >= 4) && (lom <= 7))
{
/* insert binary header */
data = 0x02;
insert_2_bits(data);
/* insert lower 2 bits of LoM */
data = (char) (lom - 4);
insert_2_bits(data);
}
else if ((lom >= 8) && (lom <= 15))
{
/* insert binary header */
data = 0x06;
insert_3_bits(data);
/* insert lower 3 bits of LoM */
data = (char) (lom - 8);
insert_3_bits(data);
}
else if ((lom >= 16) && (lom <= 31))
{
/* insert binary header */
data = 0x0e;
insert_4_bits(data);
/* insert lower 4 bits of LoM */
data = (char) (lom - 16);
insert_4_bits(data);
}
else if ((lom >= 32) && (lom <= 63))
{
/* insert binary header */
data = 0x1e;
insert_5_bits(data);
/* insert lower 5 bits of LoM */
data = (char) (lom - 32);
insert_5_bits(data);
}
else if ((lom >= 64) && (lom <= 127))
{
/* insert binary header */
data = 0x3e;
insert_6_bits(data);
/* insert lower 6 bits of LoM */
data = (char) (lom - 64);
insert_6_bits(data);
}
else if ((lom >= 128) && (lom <= 255))
{
/* insert binary header */
data = 0x7e;
insert_7_bits(data);
/* insert lower 7 bits of LoM */
data = (char) (lom - 128);
insert_7_bits(data);
}
else if ((lom >= 256) && (lom <= 511))
{
/* insert binary header */
data = 0xfe;
insert_8_bits(data);
/* insert lower 8 bits of LoM */
data = (char) (lom - 256);
insert_8_bits(data);
}
else if ((lom >= 512) && (lom <= 1023))
{
/* insert binary header */
data16 = 0x1fe;
insert_9_bits(data16);
/* insert lower 9 bits of LoM */
data16 = lom - 512;
insert_9_bits(data16);
}
else if ((lom >= 1024) && (lom <= 2047))
{
/* insert binary header */
data16 = 0x3fe;
insert_10_bits(data16);
/* insert 10 lower bits of LoM */
data16 = lom - 1024;
insert_10_bits(data16);
}
else if ((lom >= 2048) && (lom <= 4095))
{
/* insert binary header */
data16 = 0x7fe;
insert_11_bits(data16);
/* insert 11 lower bits of LoM */
data16 = lom - 2048;
insert_11_bits(data16);
}
else if ((lom >= 4096) && (lom <= 8191))
{
/* insert binary header */
data16 = 0xffe;
insert_12_bits(data16);
/* insert 12 lower bits of LoM */
data16 = lom - 4096;
insert_12_bits(data16);
}
else if ((lom >= 8192) && (lom <= 16383))
{
/* insert binary header */
data16 = 0x1ffe;
insert_13_bits(data16);
/* insert 13 lower bits of LoM */
data16 = lom - 8192;
insert_13_bits(data16);
}
else if ((lom >= 16384) && (lom <= 32767))
{
/* insert binary header */
data16 = 0x3ffe;
insert_14_bits(data16);
/* insert 14 lower bits of LoM */
data16 = lom - 16384;
insert_14_bits(data16);
}
else if ((lom >= 32768) && (lom <= 65535))
{
/* insert binary header */
data16 = 0x7ffe;
insert_15_bits(data16);
/* insert 15 lower bits of LoM */
data16 = lom - 32768;
insert_15_bits(data16);
}
} /* end while (ctr < data_end) */
/* add remaining data to the output */
while (len - ctr > 0)
{
data = srcData[ctr];
DLOG(("%.2x ", (unsigned char) data));
if (data < 0x80)
{
/* literal byte < 0x80 */
insert_8_bits(data);
}
else
{
/* literal byte >= 0x80 */
insert_2_bits(0x02);
data &= 0x7f;
insert_7_bits(data);
}
ctr++;
}
/* if bits_left == 8, opb_index has already been incremented */
if ((bits_left == 8) && (opb_index > len))
{
/* compressed data longer than uncompressed data */
/* give up */
enc->historyOffset = 0;
memset(hash_table, 0, enc->buf_len * 2);
enc->flagsHold |= PACKET_FLUSHED;
enc->first_pkt = 1;
return TRUE;
}
else if (opb_index + 1 > len)
{
/* compressed data longer than uncompressed data */
/* give up */
enc->historyOffset = 0;
memset(hash_table, 0, enc->buf_len * 2);
enc->flagsHold |= PACKET_FLUSHED;
enc->first_pkt = 1;
return TRUE;
}
/* if bits_left != 8, increment opb_index, which is zero indexed */
if (bits_left != 8)
{
opb_index++;
}
if (opb_index > len)
{
/* give up */
enc->historyOffset = 0;
memset(hash_table, 0, enc->buf_len * 2);
enc->flagsHold |= PACKET_FLUSHED;
enc->first_pkt = 1;
return TRUE;
}
enc->flags |= PACKET_COMPRESSED;
enc->bytes_in_opb = opb_index;
enc->flags |= enc->flagsHold;
enc->flagsHold = 0;
DLOG(("\n"));
return TRUE;
}
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