Leaked source code of windows server 2003
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/*
* encapi.c
*
* Encoder API entrypoints.
*/
#define ALLOC_VARS
#include "encoder.h"
bool
__fastcall
LZX_EncodeInit(
t_encoder_context ** enc_context,
long compression_window_size,
long second_partition_size,
PFNALLOC pfnma,
HANDLE hAllocator,
int (__stdcall * pfnlzx_output_callback)(
void * pfol,
unsigned char * compressed_data,
long compressed_size,
long uncompressed_size
),
void * fci_data
)
{
t_encoder_context *context = pfnma( hAllocator, sizeof( t_encoder_context ));
if ( context == NULL ) {
return false;
}
*enc_context = context;
/* to pass back in lzx_output_callback() */
context->enc_fci_data = fci_data;
context->enc_window_size = compression_window_size;
/*
* The second partition size must be a multiple of 32K
*/
if (second_partition_size & (CHUNK_SIZE-1))
second_partition_size &= (~(CHUNK_SIZE-1));
/*
* The minimum allowed is 32K because of the way that
* our translation works.
*/
if (second_partition_size < CHUNK_SIZE)
second_partition_size = CHUNK_SIZE;
/*
* Our window size must be at least 32K
*/
if (compression_window_size < CHUNK_SIZE)
return false;
context->enc_encoder_second_partition_size = second_partition_size;
context->enc_output_callback_function = pfnlzx_output_callback;
context->enc_malloc = pfnma;
context->enc_mallochandle = hAllocator;
/* Error allocating memory? */
if (comp_alloc_compress_memory(context) == false)
return false;
LZX_EncodeNewGroup(context);
return true;
}
/*
* Sets up the encoder for a new group of files.
*
* All this does is reset the lookup table, re-initialise to the
* default match estimation tables for the optimal parser, and
* reset a few variables.
*/
void __fastcall LZX_EncodeNewGroup(t_encoder_context *context)
{
init_compression_memory(context);
}
long __fastcall LZX_Encode(
t_encoder_context *context,
byte * input_data,
long input_size,
long * estimated_bytes_compressed,
long file_size_for_translation
)
{
context->enc_input_ptr = input_data;
context->enc_input_left = input_size;
context->enc_file_size_for_translation = file_size_for_translation;
/* perform the encoding */
encoder_start(context);
if (context->enc_output_overflow)
{
*estimated_bytes_compressed = 0;
return ENCODER_WRITE_FAILURE;
}
*estimated_bytes_compressed = estimate_buffer_contents(context);
return ENCODER_SUCCESS;
}
bool __fastcall LZX_EncodeFlush(t_encoder_context *context)
{
flush_all_pending_blocks(context);
if (context->enc_output_overflow)
return false;
return true;
}
//
// But doesn't remove history data
//
bool __fastcall LZX_EncodeResetState(t_encoder_context *context)
{
/*
* Most of this copied from init.c
*/
/*
* Clear item array and reset literal and distance
* counters
*/
memset(context->enc_ItemType, 0, (MAX_LITERAL_ITEMS/8));
context->enc_literals = 0;
context->enc_distances = 0;
/*
* Reset encoder state
*/
context->enc_last_matchpos_offset[0] = 1;
context->enc_last_matchpos_offset[1] = 1;
context->enc_last_matchpos_offset[2] = 1;
context->enc_repeated_offset_at_literal_zero[0] = 1;
context->enc_repeated_offset_at_literal_zero[1] = 1;
context->enc_repeated_offset_at_literal_zero[2] = 1;
context->enc_input_running_total = 0;
/*
* The last lengths are zeroed in both the encoder and decoder,
* since our tree representation is delta format.
*/
memset(context->enc_main_tree_prev_len, 0, MAIN_TREE_ELEMENTS);
memset(context->enc_secondary_tree_prev_len, 0, NUM_SECONDARY_LENGTHS);
/* reset bit buffer */
context->enc_bitcount = 32;
context->enc_bitbuf = 0;
context->enc_output_overflow = false;
/* need to recalculate stats soon */
context->enc_need_to_recalc_stats = true;
context->enc_next_tree_create = TREE_CREATE_INTERVAL;
/* pretend we just output everything up to now as a block */
context->enc_bufpos_last_output_block = context->enc_BufPos;
/* don't allow re-doing */
context->enc_first_block = false;
/* reset instruction pointer (for translation) to zero */
reset_translation(context);
/* so we output the file xlat header */
context->enc_first_time_this_group = true;
/* reset frame counter */
context->enc_num_cfdata_frames = 0;
/* haven't split the block */
context->enc_num_block_splits = 0;
return true;
}
unsigned char * __fastcall LZX_GetInputData(
t_encoder_context *context,
unsigned long *input_position,
unsigned long *bytes_available
)
{
unsigned long filepos;
// note that BufPos-window_size is the real position in the file
filepos = context->enc_BufPos - context->enc_window_size;
if (filepos < context->enc_window_size)
{
*input_position = 0;
*bytes_available = filepos;
return &context->enc_MemWindow[context->enc_window_size];
}
else
{
*input_position = filepos - context->enc_window_size;
*bytes_available = context->enc_window_size;
return &context->enc_MemWindow[context->enc_BufPos - context->enc_window_size];
}
}
//
// This is used to quickly insert the old file into the history.
//
bool __fastcall LZX_EncodeInsertDictionary(
t_encoder_context *context,
byte * input_data,
ulong input_size
)
{
ulong BufPos;
ulong RealBufPos;
ulong BufPosEnd;
ulong BytesRead;
ulong i;
ulong end_pos;
context->enc_input_ptr = input_data;
context->enc_input_left = input_size;
context->enc_file_size_for_translation = 0;
context->enc_first_time_this_group = false;
RealBufPos = context->enc_BufPos - (ulong)(context->enc_RealMemWindow - context->enc_MemWindow);
BytesRead = comp_read_input(context, RealBufPos, input_size);
BufPos = context->enc_BufPos;
BufPosEnd = context->enc_BufPos + BytesRead;
while (BufPos < BufPosEnd)
{
quick_insert_bsearch_findmatch(
context,
BufPos,
BufPos - context->enc_window_size+4
);
BufPos++;
}
context->enc_earliest_window_data_remaining = BufPos - context->enc_window_size;
end_pos = BufPos - (context->enc_window_size-4-BREAK_LENGTH);
for (i = 1; (i <= BREAK_LENGTH); i++)
binary_search_remove_node(context, BufPos-i, end_pos);
context->enc_BufPos = BufPos;
context->enc_bufpos_at_last_block = BufPos;
return true;
}
#ifdef TRACING
ULONG TracingRunningTotal;
ULONG TracingPrevPos;
void
__stdcall
EncTracingMatch(
ulong BufPos,
ulong MatchLength,
ulong MatchPos,
ulong MatchOff
)
{
if ( BufPos < TracingPrevPos ) {
printf( "REWIND to %08X\n", BufPos );
TracingRunningTotal -= ( TracingPrevPos - BufPos );
}
TracingPrevPos = BufPos;
TracingRunningTotal += MatchLength;
#ifdef TRACING2
printf(
"MATCH: At %08X, %c%c Off %08X (%08X), Length %5d, Total %08X\n",
BufPos,
MatchPos < 3 ? 'R' : ' ',
MatchPos < 3 ? MatchPos + '0' : ' ',
MatchOff,
BufPos - MatchOff,
MatchLength,
TracingRunningTotal
);
#else
printf(
"MATCH: At %08X, From %08X, Length %5d\n",
BufPos,
BufPos - MatchOff,
MatchLength
);
#endif
}
void
__stdcall
EncTracingLiteral(
ulong BufPos,
ulong ch
)
{
if ( BufPos < TracingPrevPos ) {
printf( "REWIND to %08X\n", BufPos );
TracingRunningTotal -= ( TracingPrevPos - BufPos );
}
TracingPrevPos = BufPos;
++TracingRunningTotal;
#ifdef TRACING2
printf(
"LITER: At %08X, 0x%02X Total %08X\n",
BufPos,
ch,
TracingRunningTotal
);
#else
printf(
"LITER: At %08X, 0x%02X\n",
BufPos,
ch
);
#endif
}
void
__stdcall
EncTracingDefineOffsets(
unsigned long WindowSize,
unsigned long InterFileBytes,
unsigned long OldFileSize
)
{
}
#endif /* TRACING */