blob: 7ad39ec1b9fbad84e62ed00ffc3db9e2774ec7a4 [file] [log] [blame]
/*
* Copyright (C) 2014 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <string.h>
#include <strings.h>
#include <errno.h>
#include <assert.h>
#include <ctype.h>
#include <ipxe/uaccess.h>
#include <ipxe/deflate.h>
/** @file
*
* DEFLATE decompression algorithm
*
* This file implements the decompression half of the DEFLATE
* algorithm specified in RFC 1951.
*
* Portions of this code are derived from wimboot's xca.c.
*
*/
/**
* Byte reversal table
*
* For some insane reason, the DEFLATE format stores some values in
* bit-reversed order.
*/
static uint8_t deflate_reverse[256];
/** Literal/length base values
*
* We include entries only for literal/length codes 257-284. Code 285
* does not fit the pattern (it represents a length of 258; following
* the pattern from the earlier codes would give a length of 259), and
* has no extra bits. Codes 286-287 are invalid, but can occur. We
* treat any code greater than 284 as meaning "length 258, no extra
* bits".
*/
static uint8_t deflate_litlen_base[28];
/** Distance base values
*
* We include entries for all possible codes 0-31, avoiding the need
* to check for undefined codes 30 and 31 before performing the
* lookup. Codes 30 and 31 are never initialised, and will therefore
* be treated as meaning "14 extra bits, base distance 0".
*/
static uint16_t deflate_distance_base[32];
/** Code length map */
static uint8_t deflate_codelen_map[19] = {
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15
};
/** Static Huffman alphabet length patterns */
static struct deflate_static_length_pattern deflate_static_length_patterns[] = {
/* Literal/length code lengths */
{ 0x88, ( ( ( 143 - 0 ) + 1 ) / 2 ) },
{ 0x99, ( ( ( 255 - 144 ) + 1 ) / 2 ) },
{ 0x77, ( ( ( 279 - 256 ) + 1 ) / 2 ) },
{ 0x88, ( ( ( 287 - 280 ) + 1 ) / 2 ) },
/* Distance code lengths */
{ 0x55, ( ( ( 31 - 0 ) + 1 ) / 2 ) },
/* End marker */
{ 0, 0 }
};
/**
* Transcribe binary value (for debugging)
*
* @v value Value
* @v bits Length of value (in bits)
* @ret string Transcribed value
*/
static const char * deflate_bin ( unsigned long value, unsigned int bits ) {
static char buf[ ( 8 * sizeof ( value ) ) + 1 /* NUL */ ];
char *out = buf;
/* Sanity check */
assert ( bits < sizeof ( buf ) );
/* Transcribe value */
while ( bits-- )
*(out++) = ( ( value & ( 1 << bits ) ) ? '1' : '0' );
*out = '\0';
return buf;
}
/**
* Set Huffman symbol length
*
* @v deflate Decompressor
* @v index Index within lengths
* @v bits Symbol length (in bits)
*/
static void deflate_set_length ( struct deflate *deflate, unsigned int index,
unsigned int bits ) {
deflate->lengths[ index / 2 ] |= ( bits << ( 4 * ( index % 2 ) ) );
}
/**
* Get Huffman symbol length
*
* @v deflate Decompressor
* @v index Index within lengths
* @ret bits Symbol length (in bits)
*/
static unsigned int deflate_length ( struct deflate *deflate,
unsigned int index ) {
return ( ( deflate->lengths[ index / 2 ] >> ( 4 * ( index % 2 ) ) )
& 0x0f );
}
/**
* Determine Huffman alphabet name (for debugging)
*
* @v deflate Decompressor
* @v alphabet Huffman alphabet
* @ret name Alphabet name
*/
static const char * deflate_alphabet_name ( struct deflate *deflate,
struct deflate_alphabet *alphabet ){
if ( alphabet == &deflate->litlen ) {
return "litlen";
} else if ( alphabet == &deflate->distance_codelen ) {
return "distance/codelen";
} else {
return "<UNKNOWN>";
}
}
/**
* Dump Huffman alphabet (for debugging)
*
* @v deflate Decompressor
* @v alphabet Huffman alphabet
*/
static void deflate_dump_alphabet ( struct deflate *deflate,
struct deflate_alphabet *alphabet ) {
struct deflate_huf_symbols *huf_sym;
unsigned int bits;
unsigned int huf;
unsigned int i;
/* Do nothing unless debugging is enabled */
if ( ! DBG_EXTRA )
return;
/* Dump symbol table for each utilised length */
for ( bits = 1 ; bits <= ( sizeof ( alphabet->huf ) /
sizeof ( alphabet->huf[0] ) ) ; bits++ ) {
huf_sym = &alphabet->huf[ bits - 1 ];
if ( huf_sym->freq == 0 )
continue;
huf = ( huf_sym->start >> huf_sym->shift );
DBGC2 ( alphabet, "DEFLATE %p \"%s\" length %d start \"%s\" "
"freq %d:", deflate,
deflate_alphabet_name ( deflate, alphabet ), bits,
deflate_bin ( huf, huf_sym->bits ), huf_sym->freq );
for ( i = 0 ; i < huf_sym->freq ; i++ ) {
DBGC2 ( alphabet, " %03x",
huf_sym->raw[ huf + i ] );
}
DBGC2 ( alphabet, "\n" );
}
/* Dump quick lookup table */
DBGC2 ( alphabet, "DEFLATE %p \"%s\" quick lookup:", deflate,
deflate_alphabet_name ( deflate, alphabet ) );
for ( i = 0 ; i < ( sizeof ( alphabet->lookup ) /
sizeof ( alphabet->lookup[0] ) ) ; i++ ) {
DBGC2 ( alphabet, " %d", ( alphabet->lookup[i] + 1 ) );
}
DBGC2 ( alphabet, "\n" );
}
/**
* Construct Huffman alphabet
*
* @v deflate Decompressor
* @v alphabet Huffman alphabet
* @v count Number of symbols
* @v offset Starting offset within length table
* @ret rc Return status code
*/
static int deflate_alphabet ( struct deflate *deflate,
struct deflate_alphabet *alphabet,
unsigned int count, unsigned int offset ) {
struct deflate_huf_symbols *huf_sym;
unsigned int huf;
unsigned int cum_freq;
unsigned int bits;
unsigned int raw;
unsigned int adjustment;
unsigned int prefix;
int complete;
/* Clear symbol table */
memset ( alphabet->huf, 0, sizeof ( alphabet->huf ) );
/* Count number of symbols with each Huffman-coded length */
for ( raw = 0 ; raw < count ; raw++ ) {
bits = deflate_length ( deflate, ( raw + offset ) );
if ( bits )
alphabet->huf[ bits - 1 ].freq++;
}
/* Populate Huffman-coded symbol table */
huf = 0;
cum_freq = 0;
for ( bits = 1 ; bits <= ( sizeof ( alphabet->huf ) /
sizeof ( alphabet->huf[0] ) ) ; bits++ ) {
huf_sym = &alphabet->huf[ bits - 1 ];
huf_sym->bits = bits;
huf_sym->shift = ( 16 - bits );
huf_sym->start = ( huf << huf_sym->shift );
huf_sym->raw = &alphabet->raw[cum_freq];
huf += huf_sym->freq;
if ( huf > ( 1U << bits ) ) {
DBGC ( alphabet, "DEFLATE %p \"%s\" has too many "
"symbols with lengths <=%d\n", deflate,
deflate_alphabet_name ( deflate, alphabet ),
bits );
return -EINVAL;
}
huf <<= 1;
cum_freq += huf_sym->freq;
}
complete = ( huf == ( 1U << bits ) );
/* Populate raw symbol table */
for ( raw = 0 ; raw < count ; raw++ ) {
bits = deflate_length ( deflate, ( raw + offset ) );
if ( bits ) {
huf_sym = &alphabet->huf[ bits - 1 ];
*(huf_sym->raw++) = raw;
}
}
/* Adjust Huffman-coded symbol table raw pointers and populate
* quick lookup table.
*/
for ( bits = 1 ; bits <= ( sizeof ( alphabet->huf ) /
sizeof ( alphabet->huf[0] ) ) ; bits++ ) {
huf_sym = &alphabet->huf[ bits - 1 ];
/* Adjust raw pointer */
huf_sym->raw -= huf_sym->freq; /* Reset to first symbol */
adjustment = ( huf_sym->start >> huf_sym->shift );
huf_sym->raw -= adjustment; /* Adjust for quick indexing */
/* Populate quick lookup table */
for ( prefix = ( huf_sym->start >> DEFLATE_HUFFMAN_QL_SHIFT ) ;
prefix < ( 1 << DEFLATE_HUFFMAN_QL_BITS ) ; prefix++ ) {
alphabet->lookup[prefix] = ( bits - 1 );
}
}
/* Dump alphabet (for debugging) */
deflate_dump_alphabet ( deflate, alphabet );
/* Check that there are no invalid codes */
if ( ! complete ) {
DBGC ( alphabet, "DEFLATE %p \"%s\" is incomplete\n", deflate,
deflate_alphabet_name ( deflate, alphabet ) );
return -EINVAL;
}
return 0;
}
/**
* Attempt to accumulate bits from input stream
*
* @v deflate Decompressor
* @v in Compressed input data
* @v target Number of bits to accumulate
* @ret excess Number of excess bits accumulated (may be negative)
*/
static int deflate_accumulate ( struct deflate *deflate,
struct deflate_chunk *in,
unsigned int target ) {
uint8_t byte;
while ( deflate->bits < target ) {
/* Check for end of input */
if ( in->offset >= in->len )
break;
/* Acquire byte from input */
copy_from_user ( &byte, in->data, in->offset++,
sizeof ( byte ) );
deflate->accumulator = ( deflate->accumulator |
( byte << deflate->bits ) );
deflate->rotalumucca = ( deflate->rotalumucca |
( deflate_reverse[byte] <<
( 24 - deflate->bits ) ) );
deflate->bits += 8;
/* Sanity check */
assert ( deflate->bits <=
( 8 * sizeof ( deflate->accumulator ) ) );
}
return ( deflate->bits - target );
}
/**
* Consume accumulated bits from the input stream
*
* @v deflate Decompressor
* @v count Number of accumulated bits to consume
* @ret data Consumed bits
*/
static int deflate_consume ( struct deflate *deflate, unsigned int count ) {
int data;
/* Sanity check */
assert ( count <= deflate->bits );
/* Extract data and consume bits */
data = ( deflate->accumulator & ( ( 1 << count ) - 1 ) );
deflate->accumulator >>= count;
deflate->rotalumucca <<= count;
deflate->bits -= count;
return data;
}
/**
* Attempt to extract a fixed number of bits from input stream
*
* @v deflate Decompressor
* @v in Compressed input data
* @v target Number of bits to extract
* @ret data Extracted bits (or negative if not yet accumulated)
*/
static int deflate_extract ( struct deflate *deflate, struct deflate_chunk *in,
unsigned int target ) {
int excess;
int data;
/* Return immediately if we are attempting to extract zero bits */
if ( target == 0 )
return 0;
/* Attempt to accumulate bits */
excess = deflate_accumulate ( deflate, in, target );
if ( excess < 0 )
return excess;
/* Extract data and consume bits */
data = deflate_consume ( deflate, target );
DBGCP ( deflate, "DEFLATE %p extracted %s = %#x = %d\n", deflate,
deflate_bin ( data, target ), data, data );
return data;
}
/**
* Attempt to decode a Huffman-coded symbol from input stream
*
* @v deflate Decompressor
* @v in Compressed input data
* @v alphabet Huffman alphabet
* @ret code Raw code (or negative if not yet accumulated)
*/
static int deflate_decode ( struct deflate *deflate,
struct deflate_chunk *in,
struct deflate_alphabet *alphabet ) {
struct deflate_huf_symbols *huf_sym;
uint16_t huf;
unsigned int lookup_index;
int excess;
unsigned int raw;
/* Attempt to accumulate maximum required number of bits.
* There may be fewer bits than this remaining in the stream,
* even if the stream still contains some complete
* Huffman-coded symbols.
*/
deflate_accumulate ( deflate, in, DEFLATE_HUFFMAN_BITS );
/* Normalise the bit-reversed accumulated value to 16 bits */
huf = ( deflate->rotalumucca >> 16 );
/* Find symbol set for this length */
lookup_index = ( huf >> DEFLATE_HUFFMAN_QL_SHIFT );
huf_sym = &alphabet->huf[ alphabet->lookup[ lookup_index ] ];
while ( huf < huf_sym->start )
huf_sym--;
/* Calculate number of excess bits, and return if not yet complete */
excess = ( deflate->bits - huf_sym->bits );
if ( excess < 0 )
return excess;
/* Consume bits */
deflate_consume ( deflate, huf_sym->bits );
/* Look up raw symbol */
raw = huf_sym->raw[ huf >> huf_sym->shift ];
DBGCP ( deflate, "DEFLATE %p decoded %s = %#x = %d\n", deflate,
deflate_bin ( ( huf >> huf_sym->shift ), huf_sym->bits ),
raw, raw );
return raw;
}
/**
* Discard bits up to the next byte boundary
*
* @v deflate Decompressor
*/
static void deflate_discard_to_byte ( struct deflate *deflate ) {
deflate_consume ( deflate, ( deflate->bits & 7 ) );
}
/**
* Copy data to output buffer (if available)
*
* @v out Output data buffer
* @v start Source data
* @v offset Starting offset within source data
* @v len Length to copy
*/
static void deflate_copy ( struct deflate_chunk *out,
userptr_t start, size_t offset, size_t len ) {
size_t out_offset = out->offset;
size_t copy_len;
/* Copy data one byte at a time, to allow for overlap */
if ( out_offset < out->len ) {
copy_len = ( out->len - out_offset );
if ( copy_len > len )
copy_len = len;
while ( copy_len-- ) {
memcpy_user ( out->data, out_offset++,
start, offset++, 1 );
}
}
out->offset += len;
}
/**
* Inflate compressed data
*
* @v deflate Decompressor
* @v in Compressed input data
* @v out Output data buffer
* @ret rc Return status code
*
* The caller can use deflate_finished() to determine whether a
* successful return indicates that the decompressor is merely waiting
* for more input.
*
* Data will not be written beyond the specified end of the output
* data buffer, but the offset within the output data buffer will be
* updated to reflect the amount that should have been written. The
* caller can use this to find the length of the decompressed data
* before allocating the output data buffer.
*/
int deflate_inflate ( struct deflate *deflate,
struct deflate_chunk *in,
struct deflate_chunk *out ) {
/* This could be implemented more neatly if gcc offered a
* means for enforcing tail recursion.
*/
if ( deflate->resume ) {
goto *(deflate->resume);
} else switch ( deflate->format ) {
case DEFLATE_RAW: goto block_header;
case DEFLATE_ZLIB: goto zlib_header;
default: assert ( 0 );
}
zlib_header: {
int header;
int cm;
/* Extract header */
header = deflate_extract ( deflate, in, ZLIB_HEADER_BITS );
if ( header < 0 ) {
deflate->resume = &&zlib_header;
return 0;
}
/* Parse header */
cm = ( ( header >> ZLIB_HEADER_CM_LSB ) & ZLIB_HEADER_CM_MASK );
if ( cm != ZLIB_HEADER_CM_DEFLATE ) {
DBGC ( deflate, "DEFLATE %p unsupported ZLIB "
"compression method %d\n", deflate, cm );
return -ENOTSUP;
}
if ( header & ( 1 << ZLIB_HEADER_FDICT_BIT ) ) {
DBGC ( deflate, "DEFLATE %p unsupported ZLIB preset "
"dictionary\n", deflate );
return -ENOTSUP;
}
/* Process first block header */
goto block_header;
}
block_header: {
int header;
int bfinal;
int btype;
/* Extract block header */
header = deflate_extract ( deflate, in, DEFLATE_HEADER_BITS );
if ( header < 0 ) {
deflate->resume = &&block_header;
return 0;
}
/* Parse header */
deflate->header = header;
bfinal = ( header & ( 1 << DEFLATE_HEADER_BFINAL_BIT ) );
btype = ( header >> DEFLATE_HEADER_BTYPE_LSB );
DBGC ( deflate, "DEFLATE %p found %sblock type %#x\n",
deflate, ( bfinal ? "final " : "" ), btype );
switch ( btype ) {
case DEFLATE_HEADER_BTYPE_LITERAL:
goto literal_block;
case DEFLATE_HEADER_BTYPE_STATIC:
goto static_block;
case DEFLATE_HEADER_BTYPE_DYNAMIC:
goto dynamic_block;
default:
DBGC ( deflate, "DEFLATE %p unsupported block type "
"%#x\n", deflate, btype );
return -ENOTSUP;
}
}
literal_block: {
/* Discard any bits up to the next byte boundary */
deflate_discard_to_byte ( deflate );
}
literal_len: {
int len;
/* Extract LEN field */
len = deflate_extract ( deflate, in, DEFLATE_LITERAL_LEN_BITS );
if ( len < 0 ) {
deflate->resume = &&literal_len;
return 0;
}
/* Record length of literal data */
deflate->remaining = len;
DBGC2 ( deflate, "DEFLATE %p literal block length %#04zx\n",
deflate, deflate->remaining );
}
literal_nlen: {
int nlen;
/* Extract NLEN field */
nlen = deflate_extract ( deflate, in, DEFLATE_LITERAL_LEN_BITS);
if ( nlen < 0 ) {
deflate->resume = &&literal_nlen;
return 0;
}
/* Verify NLEN */
if ( ( ( deflate->remaining ^ ~nlen ) &
( ( 1 << DEFLATE_LITERAL_LEN_BITS ) - 1 ) ) != 0 ) {
DBGC ( deflate, "DEFLATE %p invalid len/nlen "
"%#04zx/%#04x\n", deflate,
deflate->remaining, nlen );
return -EINVAL;
}
}
literal_data: {
size_t in_remaining;
size_t len;
/* Calculate available amount of literal data */
in_remaining = ( in->len - in->offset );
len = deflate->remaining;
if ( len > in_remaining )
len = in_remaining;
/* Copy data to output buffer */
deflate_copy ( out, in->data, in->offset, len );
/* Consume data from input buffer */
in->offset += len;
deflate->remaining -= len;
/* Finish processing if we are blocked */
if ( deflate->remaining ) {
deflate->resume = &&literal_data;
return 0;
}
/* Otherwise, finish block */
goto block_done;
}
static_block: {
struct deflate_static_length_pattern *pattern;
uint8_t *lengths = deflate->lengths;
/* Construct static Huffman lengths as per RFC 1950 */
for ( pattern = deflate_static_length_patterns ;
pattern->count ; pattern++ ) {
memset ( lengths, pattern->fill, pattern->count );
lengths += pattern->count;
}
deflate->litlen_count = 288;
deflate->distance_count = 32;
goto construct_alphabets;
}
dynamic_block:
dynamic_header: {
int header;
unsigned int hlit;
unsigned int hdist;
unsigned int hclen;
/* Extract block header */
header = deflate_extract ( deflate, in, DEFLATE_DYNAMIC_BITS );
if ( header < 0 ) {
deflate->resume = &&dynamic_header;
return 0;
}
/* Parse header */
hlit = ( ( header >> DEFLATE_DYNAMIC_HLIT_LSB ) &
DEFLATE_DYNAMIC_HLIT_MASK );
hdist = ( ( header >> DEFLATE_DYNAMIC_HDIST_LSB ) &
DEFLATE_DYNAMIC_HDIST_MASK );
hclen = ( ( header >> DEFLATE_DYNAMIC_HCLEN_LSB ) &
DEFLATE_DYNAMIC_HCLEN_MASK );
deflate->litlen_count = ( hlit + 257 );
deflate->distance_count = ( hdist + 1 );
deflate->length_index = 0;
deflate->length_target = ( hclen + 4 );
DBGC2 ( deflate, "DEFLATE %p dynamic block %d codelen, %d "
"litlen, %d distance\n", deflate,
deflate->length_target, deflate->litlen_count,
deflate->distance_count );
/* Prepare for decoding code length code lengths */
memset ( &deflate->lengths, 0, sizeof ( deflate->lengths ) );
}
dynamic_codelen: {
int len;
unsigned int index;
int rc;
/* Extract all code lengths */
while ( deflate->length_index < deflate->length_target ) {
/* Extract code length length */
len = deflate_extract ( deflate, in,
DEFLATE_CODELEN_BITS );
if ( len < 0 ) {
deflate->resume = &&dynamic_codelen;
return 0;
}
/* Store code length */
index = deflate_codelen_map[deflate->length_index++];
deflate_set_length ( deflate, index, len );
DBGCP ( deflate, "DEFLATE %p codelen for %d is %d\n",
deflate, index, len );
}
/* Generate code length alphabet */
if ( ( rc = deflate_alphabet ( deflate,
&deflate->distance_codelen,
( DEFLATE_CODELEN_MAX_CODE + 1 ),
0 ) ) != 0 )
return rc;
/* Prepare for decoding literal/length/distance code lengths */
memset ( &deflate->lengths, 0, sizeof ( deflate->lengths ) );
deflate->length_index = 0;
deflate->length_target = ( deflate->litlen_count +
deflate->distance_count );
deflate->length = 0;
}
dynamic_litlen_distance: {
int len;
int index;
/* Decode literal/length/distance code length */
len = deflate_decode ( deflate, in, &deflate->distance_codelen);
if ( len < 0 ) {
deflate->resume = &&dynamic_litlen_distance;
return 0;
}
/* Prepare for extra bits */
if ( len < 16 ) {
deflate->length = len;
deflate->extra_bits = 0;
deflate->dup_len = 1;
} else {
static const uint8_t dup_len[3] = { 3, 3, 11 };
static const uint8_t extra_bits[3] = { 2, 3, 7 };
index = ( len - 16 );
deflate->dup_len = dup_len[index];
deflate->extra_bits = extra_bits[index];
if ( index )
deflate->length = 0;
}
}
dynamic_litlen_distance_extra: {
int extra;
unsigned int dup_len;
/* Extract extra bits */
extra = deflate_extract ( deflate, in, deflate->extra_bits );
if ( extra < 0 ) {
deflate->resume = &&dynamic_litlen_distance_extra;
return 0;
}
/* Store code lengths */
dup_len = ( deflate->dup_len + extra );
while ( ( deflate->length_index < deflate->length_target ) &&
dup_len-- ) {
deflate_set_length ( deflate, deflate->length_index++,
deflate->length );
}
/* Process next literal/length or distance code
* length, if more are required.
*/
if ( deflate->length_index < deflate->length_target )
goto dynamic_litlen_distance;
/* Construct alphabets */
goto construct_alphabets;
}
construct_alphabets: {
unsigned int distance_offset = deflate->litlen_count;
unsigned int distance_count = deflate->distance_count;
int rc;
/* Generate literal/length alphabet */
if ( ( rc = deflate_alphabet ( deflate, &deflate->litlen,
deflate->litlen_count, 0 ) ) !=0)
return rc;
/* Handle degenerate case of a single distance code
* (for which it is impossible to construct a valid,
* complete Huffman alphabet). RFC 1951 states:
*
* If only one distance code is used, it is encoded
* using one bit, not zero bits; in this case there
* is a single code length of one, with one unused
* code. One distance code of zero bits means that
* there are no distance codes used at all (the data
* is all literals).
*
* If we have only a single distance code, then we
* instead use two distance codes both with length 1.
* This results in a valid Huffman alphabet. The code
* "0" will mean distance code 0 (which is either
* correct or irrelevant), and the code "1" will mean
* distance code 1 (which is always irrelevant).
*/
if ( deflate->distance_count == 1 ) {
deflate->lengths[0] = 0x11;
distance_offset = 0;
distance_count = 2;
}
/* Generate distance alphabet */
if ( ( rc = deflate_alphabet ( deflate,
&deflate->distance_codelen,
distance_count,
distance_offset ) ) != 0 )
return rc;
}
lzhuf_litlen: {
int code;
uint8_t byte;
unsigned int extra;
unsigned int bits;
/* Decode Huffman codes */
while ( 1 ) {
/* Decode Huffman code */
code = deflate_decode ( deflate, in, &deflate->litlen );
if ( code < 0 ) {
deflate->resume = &&lzhuf_litlen;
return 0;
}
/* Handle according to code type */
if ( code < DEFLATE_LITLEN_END ) {
/* Literal value: copy to output buffer */
byte = code;
DBGCP ( deflate, "DEFLATE %p literal %#02x "
"('%c')\n", deflate, byte,
( isprint ( byte ) ? byte : '.' ) );
deflate_copy ( out, virt_to_user ( &byte ), 0,
sizeof ( byte ) );
} else if ( code == DEFLATE_LITLEN_END ) {
/* End of block */
goto block_done;
} else {
/* Length code: process extra bits */
extra = ( code - DEFLATE_LITLEN_END - 1 );
if ( extra < 28 ) {
bits = ( extra / 4 );
if ( bits )
bits--;
deflate->extra_bits = bits;
deflate->dup_len =
deflate_litlen_base[extra];
} else {
deflate->extra_bits = 0;
deflate->dup_len = 258;
}
goto lzhuf_litlen_extra;
}
}
}
lzhuf_litlen_extra: {
int extra;
/* Extract extra bits */
extra = deflate_extract ( deflate, in, deflate->extra_bits );
if ( extra < 0 ) {
deflate->resume = &&lzhuf_litlen_extra;
return 0;
}
/* Update duplicate length */
deflate->dup_len += extra;
}
lzhuf_distance: {
int code;
unsigned int extra;
unsigned int bits;
/* Decode Huffman code */
code = deflate_decode ( deflate, in,
&deflate->distance_codelen );
if ( code < 0 ) {
deflate->resume = &&lzhuf_distance;
return 0;
}
/* Process extra bits */
extra = code;
bits = ( extra / 2 );
if ( bits )
bits--;
deflate->extra_bits = bits;
deflate->dup_distance = deflate_distance_base[extra];
}
lzhuf_distance_extra: {
int extra;
size_t dup_len;
size_t dup_distance;
/* Extract extra bits */
extra = deflate_extract ( deflate, in, deflate->extra_bits );
if ( extra < 0 ) {
deflate->resume = &&lzhuf_distance_extra;
return 0;
}
/* Update duplicate distance */
dup_distance = ( deflate->dup_distance + extra );
dup_len = deflate->dup_len;
DBGCP ( deflate, "DEFLATE %p duplicate length %zd distance "
"%zd\n", deflate, dup_len, dup_distance );
/* Sanity check */
if ( dup_distance > out->offset ) {
DBGC ( deflate, "DEFLATE %p bad distance %zd (max "
"%zd)\n", deflate, dup_distance, out->offset );
return -EINVAL;
}
/* Copy data, allowing for overlap */
deflate_copy ( out, out->data, ( out->offset - dup_distance ),
dup_len );
/* Process next literal/length symbol */
goto lzhuf_litlen;
}
block_done: {
DBGCP ( deflate, "DEFLATE %p end of block\n", deflate );
/* If this was not the final block, process next block header */
if ( ! ( deflate->header & ( 1 << DEFLATE_HEADER_BFINAL_BIT ) ))
goto block_header;
/* Otherwise, process footer (if any) */
switch ( deflate->format ) {
case DEFLATE_RAW: goto finished;
case DEFLATE_ZLIB: goto zlib_footer;
default: assert ( 0 );
}
}
zlib_footer: {
/* Discard any bits up to the next byte boundary */
deflate_discard_to_byte ( deflate );
}
zlib_adler32: {
int excess;
/* Accumulate the 32 bits of checksum. We don't check
* the value, stop processing immediately afterwards,
* and so don't have to worry about the nasty corner
* cases involved in calling deflate_extract() to
* obtain a full 32 bits.
*/
excess = deflate_accumulate ( deflate, in, ZLIB_ADLER32_BITS );
if ( excess < 0 ) {
deflate->resume = &&zlib_adler32;
return 0;
}
/* Finish processing */
goto finished;
}
finished: {
/* Mark as finished and terminate */
DBGCP ( deflate, "DEFLATE %p finished\n", deflate );
deflate->resume = NULL;
return 0;
}
}
/**
* Initialise decompressor
*
* @v deflate Decompressor
* @v format Compression format code
*/
void deflate_init ( struct deflate *deflate, enum deflate_format format ) {
static int global_init_done;
uint8_t i;
uint8_t bit;
uint8_t byte;
unsigned int base;
unsigned int bits;
/* Perform global initialisation if required */
if ( ! global_init_done ) {
/* Initialise byte reversal table */
for ( i = 255 ; i ; i-- ) {
for ( bit = 1, byte = 0 ; bit ; bit <<= 1 ) {
byte <<= 1;
if ( i & bit )
byte |= 1;
}
deflate_reverse[i] = byte;
}
/* Initialise literal/length extra bits table */
base = 3;
for ( i = 0 ; i < 28 ; i++ ) {
bits = ( i / 4 );
if ( bits )
bits--;
deflate_litlen_base[i] = base;
base += ( 1 << bits );
}
assert ( base == 259 ); /* sic */
/* Initialise distance extra bits table */
base = 1;
for ( i = 0 ; i < 30 ; i++ ) {
bits = ( i / 2 );
if ( bits )
bits--;
deflate_distance_base[i] = base;
base += ( 1 << bits );
}
assert ( base == 32769 );
/* Record global initialisation as complete */
global_init_done = 1;
}
/* Initialise structure */
memset ( deflate, 0, sizeof ( *deflate ) );
deflate->format = format;
}