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/* -*- c-basic-offset: 8 -*- |
/* -*- c-basic-offset: 8 -*- |
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rdesktop: A Remote Desktop Protocol client. |
rdesktop: A Remote Desktop Protocol client. |
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Protocol services - RDP decompression |
Protocol services - RDP decompression |
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Copyright (C) Matthew Chapman 1999-2004 |
Copyright (C) Matthew Chapman 1999-2008 |
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This program is free software; you can redistribute it and/or modify |
This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
it under the terms of the GNU General Public License as published by |
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mppc_expand(uint8 * data, uint32 clen, uint8 ctype, uint32 * roff, uint32 * rlen) |
mppc_expand(uint8 * data, uint32 clen, uint8 ctype, uint32 * roff, uint32 * rlen) |
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{ |
{ |
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int k, walker_len = 0, walker; |
int k, walker_len = 0, walker; |
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int i = 0; |
uint32 i = 0; |
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int next_offset, match_off; |
int next_offset, match_off; |
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int match_len; |
int match_len; |
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int old_offset, match_bits; |
int old_offset, match_bits; |
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|
RD_BOOL big = ctype & RDP_MPPC_BIG ? True : False; |
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|
|
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uint8 *dict = g_mppc_dict.hist; |
uint8 *dict = g_mppc_dict.hist; |
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|
|
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/* decode offset */ |
/* decode offset */ |
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/* length pair */ |
/* length pair */ |
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walker <<= 1; |
walker <<= 1; |
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if (--walker_len < 2) |
if (--walker_len < (big ? 3 : 2)) |
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{ |
{ |
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if (i >= clen) |
if (i >= clen) |
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return -1; |
return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
walker |= (data[i++] & 0xff) << (24 - walker_len); |
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walker_len += 8; |
walker_len += 8; |
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} |
} |
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/* offset decoding where offset len is: |
|
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-63: 1111 followed by the lower 6 bits of the value |
if (big) |
|
64-319: 1110 followed by the lower 8 bits of the value ( value - 64 ) |
|
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320-8191: 110 followed by the lower 13 bits of the value ( value - 320 ) |
|
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*/ |
|
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switch (((uint32) walker) >> ((uint32) 30)) |
|
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{ |
{ |
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case 3: /* - 63 */ |
/* offset decoding where offset len is: |
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if (walker_len < 8) |
-63: 11111 followed by the lower 6 bits of the value |
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{ |
64-319: 11110 followed by the lower 8 bits of the value ( value - 64 ) |
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if (i >= clen) |
320-2367: 1110 followed by lower 11 bits of the value ( value - 320 ) |
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return -1; |
2368-65535: 110 followed by lower 16 bits of the value ( value - 2368 ) |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
*/ |
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walker_len += 8; |
switch (((uint32) walker) >> ((uint32) 29)) |
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} |
{ |
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walker <<= 2; |
case 7: /* - 63 */ |
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match_off = ((uint32) walker) >> ((uint32) 26); |
for (; walker_len < 9; walker_len += 8) |
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walker <<= 6; |
{ |
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walker_len -= 8; |
if (i >= clen) |
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break; |
return -1; |
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|
walker |= (data[i++] & 0xff) << (24 - walker_len); |
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} |
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walker <<= 3; |
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match_off = ((uint32) walker) >> ((uint32) 26); |
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walker <<= 6; |
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walker_len -= 9; |
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break; |
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|
|
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case 2: /* 64 - 319 */ |
case 6: /* 64 - 319 */ |
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for (; walker_len < 10; walker_len += 8) |
for (; walker_len < 11; walker_len += 8) |
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{ |
{ |
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if (i >= clen) |
if (i >= clen) |
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return -1; |
return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
walker |= (data[i++] & 0xff) << (24 - walker_len); |
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} |
} |
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|
|
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walker <<= 2; |
walker <<= 3; |
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match_off = (((uint32) walker) >> ((uint32) 24)) + 64; |
match_off = (((uint32) walker) >> ((uint32) 24)) + 64; |
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walker <<= 8; |
walker <<= 8; |
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walker_len -= 10; |
walker_len -= 11; |
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break; |
break; |
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|
|
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default: /* 320 - 8191 */ |
case 5: |
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for (; walker_len < 14; walker_len += 8) |
case 4: /* 320 - 2367 */ |
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{ |
for (; walker_len < 13; walker_len += 8) |
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if (i >= clen) |
{ |
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return -1; |
if (i >= clen) |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
return -1; |
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} |
walker |= (data[i++] & 0xff) << (24 - walker_len); |
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|
} |
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|
|
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match_off = (walker >> 18) + 320; |
walker <<= 2; |
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walker <<= 14; |
match_off = (((uint32) walker) >> ((uint32) 21)) + 320; |
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walker_len -= 14; |
walker <<= 11; |
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break; |
walker_len -= 13; |
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break; |
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|
|
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default: /* 2368 - 65535 */ |
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for (; walker_len < 17; walker_len += 8) |
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{ |
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if (i >= clen) |
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return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
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} |
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|
|
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walker <<= 1; |
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match_off = (((uint32) walker) >> ((uint32) 16)) + 2368; |
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walker <<= 16; |
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walker_len -= 17; |
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break; |
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|
} |
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|
} |
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|
else |
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|
{ |
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|
/* offset decoding where offset len is: |
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|
-63: 1111 followed by the lower 6 bits of the value |
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|
64-319: 1110 followed by the lower 8 bits of the value ( value - 64 ) |
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|
320-8191: 110 followed by the lower 13 bits of the value ( value - 320 ) |
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*/ |
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switch (((uint32) walker) >> ((uint32) 30)) |
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|
{ |
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case 3: /* - 63 */ |
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if (walker_len < 8) |
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{ |
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if (i >= clen) |
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return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
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walker_len += 8; |
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} |
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walker <<= 2; |
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match_off = ((uint32) walker) >> ((uint32) 26); |
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walker <<= 6; |
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walker_len -= 8; |
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break; |
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|
|
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case 2: /* 64 - 319 */ |
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for (; walker_len < 10; walker_len += 8) |
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{ |
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if (i >= clen) |
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return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
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} |
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|
|
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walker <<= 2; |
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match_off = (((uint32) walker) >> ((uint32) 24)) + 64; |
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walker <<= 8; |
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walker_len -= 10; |
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break; |
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|
|
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default: /* 320 - 8191 */ |
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for (; walker_len < 14; walker_len += 8) |
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{ |
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if (i >= clen) |
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return -1; |
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walker |= (data[i++] & 0xff) << (24 - walker_len); |
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} |
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|
|
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match_off = (walker >> 18) + 320; |
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walker <<= 14; |
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walker_len -= 14; |
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break; |
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|
} |
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} |
} |
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if (walker_len == 0) |
if (walker_len == 0) |
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{ |
{ |
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i.e. 4097 is encoded as: 111111111110 000000000001 |
i.e. 4097 is encoded as: 111111111110 000000000001 |
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meaning 4096 + 1... |
meaning 4096 + 1... |
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*/ |
*/ |
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match_bits = 11; /* 11 bits of value at most */ |
match_bits = big ? 14 : 11; /* 11 or 14 bits of value at most */ |
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do |
do |
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{ |
{ |
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walker <<= 1; |
walker <<= 1; |
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} |
} |
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} |
} |
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while (1); |
while (1); |
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match_len = 13 - match_bits; |
match_len = (big ? 16 : 13) - match_bits; |
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walker <<= 1; |
walker <<= 1; |
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if (--walker_len < match_len) |
if (--walker_len < match_len) |
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{ |
{ |
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|
|
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match_bits = match_len; |
match_bits = match_len; |
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match_len = |
match_len = |
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((walker >> (32 - match_bits)) & (~(-1 << match_bits))) | (1 << match_bits); |
((walker >> (32 - match_bits)) & (~(-1 << match_bits))) | (1 << |
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|
match_bits); |
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walker <<= match_bits; |
walker <<= match_bits; |
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walker_len -= match_bits; |
walker_len -= match_bits; |
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} |
} |
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return -1; |
return -1; |
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} |
} |
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/* memory areas can overlap - meaning we can't use memXXX functions */ |
/* memory areas can overlap - meaning we can't use memXXX functions */ |
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k = (next_offset - match_off) & (RDP_MPPC_DICT_SIZE - 1); |
k = (next_offset - match_off) & (big ? 65535 : 8191); |
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do |
do |
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{ |
{ |
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dict[next_offset++] = dict[k++]; |
dict[next_offset++] = dict[k++]; |