// ushort* lens -> ushort[] lens + int lens_ind
// code** table -> code[] table + ref int table_ind
private static int inflate_table(codetype type, ushort[] lens, int lens_ind, uint codes, code[] table, ref int table_ind, ref uint bits, ushort[] work)
{
uint len; // a code's length in bits
uint sym; // index of code symbols
uint min, max; // minimum and maximum code lengths
uint root; // number of index bits for root table
uint curr; // number of index bits for current table
uint drop; // code bits to drop for sub-table
int left; // number of prefix codes available
uint used; // code entries in table used
uint huff; // Huffman code
uint incr; // for incrementing code, index
uint fill; // index for replicating entries
uint low; // low bits for current root entry
uint mask; // mask for low root bits
code here; // table entry for duplication
int next; // next available space in table
ushort[] _base; // base value table to use
int base_ind; // index in _base
ushort[] extra; // extra bits table to use
int extra_ind; // index in extra
int end; // use base and extra for symbol > end
ushort[] count = new ushort[MAXBITS + 1]; // number of codes of each length
ushort[] offs = new ushort[MAXBITS + 1]; // offsets in table for each length
// Process a set of code lengths to create a canonical Huffman code. The
// code lengths are lens[0..codes-1]. Each length corresponds to the
// symbols 0..codes-1. The Huffman code is generated by first sorting the
// symbols by length from short to long, and retaining the symbol order
// for codes with equal lengths. Then the code starts with all zero bits
// for the first code of the shortest length, and the codes are integer
// increments for the same length, and zeros are appended as the length
// increases. For the deflate format, these bits are stored backwards
// from their more natural integer increment ordering, and so when the
// decoding tables are built in the large loop below, the integer codes
// are incremented backwards.
// This routine assumes, but does not check, that all of the entries in
// lens[] are in the range 0..MAXBITS. The caller must assure this.
// 1..MAXBITS is interpreted as that code length. zero means that that
// symbol does not occur in this code.
// The codes are sorted by computing a count of codes for each length,
// creating from that a table of starting indices for each length in the
// sorted table, and then entering the symbols in order in the sorted
// table. The sorted table is work[], with that space being provided by
// the caller.
// The length counts are used for other purposes as well, i.e. finding
// the minimum and maximum length codes, determining if there are any
// codes at all, checking for a valid set of lengths, and looking ahead
// at length counts to determine sub-table sizes when building the
// decoding tables.
// accumulate lengths for codes (assumes lens[] all in 0..MAXBITS)
for (len = 0; len <= MAXBITS; len++)
{
count[len] = 0;
}
for (sym = 0; sym < codes; sym++)
{
count[lens[lens_ind + sym]]++;
}
// bound code lengths, force root to be within code lengths
root = bits;
for (max = MAXBITS; max >= 1; max--)
{
if (count[max] != 0)
{
break;
}
}
if (root > max)
{
root = max;
}
if (max == 0)
{ // no symbols to code at all
here = new code(64, 1, 0); // invalid code marker
table[table_ind++] = here.Clone(); // make a table to force an error
table[table_ind++] = here.Clone();
bits = 1;
return(0); // no symbols, but wait for decoding to report error
}
for (min = 1; min < max; min++)
{
if (count[min] != 0)
{
break;
}
}
if (root < min)
{
root = min;
}
// check for an over-subscribed or incomplete set of lengths
left = 1;
for (len = 1; len <= MAXBITS; len++)
{
left <<= 1;
left -= count[len];
if (left < 0)
{
return(-1); // over-subscribed
}
}
if (left > 0 && (type == codetype.CODES || max != 1))
{
return(-1); // incomplete set
}
// generate offsets into symbol table for each length for sorting
offs[1] = 0;
for (len = 1; len < MAXBITS; len++)
{
offs[len + 1] = (ushort)(offs[len] + count[len]);
}
// sort symbols by length, by symbol order within each length
for (sym = 0; sym < codes; sym++)
{
if (lens[lens_ind + sym] != 0)
{
work[offs[lens[lens_ind + sym]]++] = (ushort)sym;
}
}
// Create and fill in decoding tables. In this loop, the table being
// filled is at next and has curr index bits. The code being used is huff
// with length len. That code is converted to an index by dropping drop
// bits off of the bottom. For codes where len is less than drop + curr,
// those top drop + curr - len bits are incremented through all values to
// fill the table with replicated entries.
// root is the number of index bits for the root table. When len exceeds
// root, sub-tables are created pointed to by the root entry with an index
// of the low root bits of huff. This is saved in low to check for when a
// new sub-table should be started. drop is zero when the root table is
// being filled, and drop is root when sub-tables are being filled.
// When a new sub-table is needed, it is necessary to look ahead in the
// code lengths to determine what size sub-table is needed. The length
// counts are used for this, and so count[] is decremented as codes are
// entered in the tables.
// used keeps track of how many table entries have been allocated from the
// provided *table space. It is checked for LENS and DIST tables against
// the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
// the initial root table size constants. See the comments in inftrees.h
// for more information.
// sym increments through all symbols, and the loop terminates when
// all codes of length max, i.e. all codes, have been processed. This
// routine permits incomplete codes, so another loop after this one fills
// in the rest of the decoding tables with invalid code markers.
// set up for code type
switch (type)
{
case codetype.CODES:
base_ind = extra_ind = 0;
_base = extra = work; // dummy value--not used
end = 19;
break;
case codetype.LENS:
_base = lbase;
base_ind = -257;
extra = lext;
extra_ind = -257;
end = 256;
break;
default: // DISTS
base_ind = extra_ind = 0;
_base = dbase;
extra = dext;
end = -1;
break;
}
// initialize state for loop
huff = 0; // starting code
sym = 0; // starting code symbol
len = min; // starting code length
next = table_ind; // current table to fill in
curr = root; // current table index bits
drop = 0; // current bits to drop from code for index
low = uint.MaxValue; // trigger new sub-table when len > root
used = 1U << (int)root; // use root table entries
mask = used - 1; // mask for comparing low
// check available table space
if ((type == codetype.LENS && used >= ENOUGH_LENS) || (type == codetype.DISTS && used >= ENOUGH_DISTS))
{
return(1);
}
// process all codes and make table entries
for (; ;)
{
// create table entry
here = new code(0, (byte)(len - drop), 0);
if ((int)(work[sym]) < end)
{
here.op = 0;
here.val = work[sym];
}
else if ((int)(work[sym]) > end)
{
here.op = (byte)(extra[extra_ind + work[sym]]);
here.val = _base[base_ind + work[sym]];
}
else
{
here.op = 32 + 64; // end of block
here.val = 0;
}
// replicate for those indices with low len bits equal to huff
incr = 1U << (int)(len - drop);
fill = 1U << (int)curr;
min = fill; // save offset to next table
do
{
fill -= incr;
table[next + (huff >> (int)drop) + fill] = here.Clone();
} while(fill != 0);
// backwards increment the len-bit code huff
incr = 1U << (int)(len - 1);
while ((huff & incr) != 0)
{
incr >>= 1;
}
if (incr != 0)
{
huff &= incr - 1;
huff += incr;
}
else
{
huff = 0;
}
// go to next symbol, update count, len
sym++;
if (--(count[len]) == 0)
{
if (len == max)
{
break;
}
len = lens[lens_ind + work[sym]];
}
// create new sub-table if needed
if (len > root && (huff & mask) != low)
{
// if first time, transition to sub-tables
if (drop == 0)
{
drop = root;
}
// increment past last table
next += (int)min; // here min is 1 << curr
// determine length of next table
curr = len - drop;
left = 1 << (int)curr;
while (curr + drop < max)
{
left -= count[curr + drop];
if (left <= 0)
{
break;
}
curr++;
left <<= 1;
}
// check for enough space
used += 1U << (int)curr;
if ((type == codetype.LENS && used >= ENOUGH_LENS) || (type == codetype.DISTS && used >= ENOUGH_DISTS))
{
return(1);
}
// point entry in root table to sub-table
low = huff & mask;
table[table_ind + low] = new code((byte)curr, (byte)root, (ushort)(next - table_ind));
}
}
// Fill in rest of table for incomplete codes. This loop is similar to the
// loop above in incrementing huff for table indices. It is assumed that
// len is equal to curr + drop, so there is no loop needed to increment
// through high index bits. When the current sub-table is filled, the loop
// drops back to the root table to fill in any remaining entries there.
here = new code(64, (byte)(len - drop), 0); // invalid code marker
while (huff != 0)
{
// when done with sub-table, drop back to root table
if (drop != 0 && (huff & mask) != low)
{
drop = 0;
len = root;
next = table_ind;
here.bits = (byte)len;
}
// put invalid code marker in table
table[next + huff >> (int)drop] = here.Clone();
// backwards increment the len-bit code huff
incr = 1U << (int)(len - 1);
while ((huff & incr) != 0)
{
incr >>= 1;
}
if (incr != 0)
{
huff &= incr - 1;
huff += incr;
}
else
{
huff = 0;
}
}
// set return parameters
table_ind += (int)used;
bits = root;
return(0);
}
// ushort* lens -> ushort[] lens + int lens_ind
// code** table -> code[] table + ref int table_ind
private static int inflate_table(codetype type, ushort[] lens, int lens_ind, uint codes, code[] table, ref int table_ind, ref uint bits, ushort[] work)
{
uint len; // a code's length in bits
uint sym; // index of code symbols
uint min, max; // minimum and maximum code lengths
uint root; // number of index bits for root table
uint curr; // number of index bits for current table
uint drop; // code bits to drop for sub-table
int left; // number of prefix codes available
uint used; // code entries in table used
uint huff; // Huffman code
uint incr; // for incrementing code, index
uint fill; // index for replicating entries
uint low; // low bits for current root entry
uint mask; // mask for low root bits
code here; // table entry for duplication
int next; // next available space in table
ushort[] _base; // base value table to use
int base_ind; // index in _base
ushort[] extra; // extra bits table to use
int extra_ind; // index in extra
int end; // use base and extra for symbol > end
ushort[] count=new ushort[MAXBITS+1]; // number of codes of each length
ushort[] offs=new ushort[MAXBITS+1]; // offsets in table for each length
// Process a set of code lengths to create a canonical Huffman code. The
// code lengths are lens[0..codes-1]. Each length corresponds to the
// symbols 0..codes-1. The Huffman code is generated by first sorting the
// symbols by length from short to long, and retaining the symbol order
// for codes with equal lengths. Then the code starts with all zero bits
// for the first code of the shortest length, and the codes are integer
// increments for the same length, and zeros are appended as the length
// increases. For the deflate format, these bits are stored backwards
// from their more natural integer increment ordering, and so when the
// decoding tables are built in the large loop below, the integer codes
// are incremented backwards.
// This routine assumes, but does not check, that all of the entries in
// lens[] are in the range 0..MAXBITS. The caller must assure this.
// 1..MAXBITS is interpreted as that code length. zero means that that
// symbol does not occur in this code.
// The codes are sorted by computing a count of codes for each length,
// creating from that a table of starting indices for each length in the
// sorted table, and then entering the symbols in order in the sorted
// table. The sorted table is work[], with that space being provided by
// the caller.
// The length counts are used for other purposes as well, i.e. finding
// the minimum and maximum length codes, determining if there are any
// codes at all, checking for a valid set of lengths, and looking ahead
// at length counts to determine sub-table sizes when building the
// decoding tables.
// accumulate lengths for codes (assumes lens[] all in 0..MAXBITS)
for(len=0; len<=MAXBITS; len++) count[len]=0;
for(sym=0; sym<codes; sym++) count[lens[lens_ind+sym]]++;
// bound code lengths, force root to be within code lengths
root=bits;
for(max=MAXBITS; max>=1; max--) if(count[max]!=0) break;
if(root>max) root=max;
if(max==0)
{ // no symbols to code at all
here=new code(64, 1, 0); // invalid code marker
table[table_ind++]=here.Clone(); // make a table to force an error
table[table_ind++]=here.Clone();
bits=1;
return 0; // no symbols, but wait for decoding to report error
}
for(min=1; min<max; min++) if(count[min]!=0) break;
if(root<min) root=min;
// check for an over-subscribed or incomplete set of lengths
left=1;
for(len=1; len<=MAXBITS; len++)
{
left<<=1;
left-=count[len];
if(left<0) return -1; // over-subscribed
}
if(left>0&&(type==codetype.CODES||max!=1)) return -1; // incomplete set
// generate offsets into symbol table for each length for sorting
offs[1]=0;
for(len=1; len<MAXBITS; len++) offs[len+1]=(ushort)(offs[len]+count[len]);
// sort symbols by length, by symbol order within each length
for(sym=0; sym<codes; sym++)
if(lens[lens_ind+sym]!=0) work[offs[lens[lens_ind+sym]]++]=(ushort)sym;
// Create and fill in decoding tables. In this loop, the table being
// filled is at next and has curr index bits. The code being used is huff
// with length len. That code is converted to an index by dropping drop
// bits off of the bottom. For codes where len is less than drop + curr,
// those top drop + curr - len bits are incremented through all values to
// fill the table with replicated entries.
// root is the number of index bits for the root table. When len exceeds
// root, sub-tables are created pointed to by the root entry with an index
// of the low root bits of huff. This is saved in low to check for when a
// new sub-table should be started. drop is zero when the root table is
// being filled, and drop is root when sub-tables are being filled.
// When a new sub-table is needed, it is necessary to look ahead in the
// code lengths to determine what size sub-table is needed. The length
// counts are used for this, and so count[] is decremented as codes are
// entered in the tables.
// used keeps track of how many table entries have been allocated from the
// provided *table space. It is checked for LENS and DIST tables against
// the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
// the initial root table size constants. See the comments in inftrees.h
// for more information.
// sym increments through all symbols, and the loop terminates when
// all codes of length max, i.e. all codes, have been processed. This
// routine permits incomplete codes, so another loop after this one fills
// in the rest of the decoding tables with invalid code markers.
// set up for code type
switch(type)
{
case codetype.CODES:
base_ind=extra_ind=0;
_base=extra=work; // dummy value--not used
end=19;
break;
case codetype.LENS:
_base=lbase;
base_ind=-257;
extra=lext;
extra_ind=-257;
end=256;
break;
default: // DISTS
base_ind=extra_ind=0;
_base=dbase;
extra=dext;
end=-1;
break;
}
// initialize state for loop
huff=0; // starting code
sym=0; // starting code symbol
len=min; // starting code length
next=table_ind; // current table to fill in
curr=root; // current table index bits
drop=0; // current bits to drop from code for index
low=uint.MaxValue; // trigger new sub-table when len > root
used=1U<<(int)root; // use root table entries
mask=used-1; // mask for comparing low
// check available table space
if((type==codetype.LENS&&used>=ENOUGH_LENS)||(type==codetype.DISTS&&used>=ENOUGH_DISTS)) return 1;
// process all codes and make table entries
for(; ; )
{
// create table entry
here=new code(0, (byte)(len-drop), 0);
if((int)(work[sym])<end)
{
here.op=0;
here.val=work[sym];
}
else if((int)(work[sym])>end)
{
here.op=(byte)(extra[extra_ind+work[sym]]);
here.val=_base[base_ind+work[sym]];
}
else
{
here.op=32+64; // end of block
here.val=0;
}
// replicate for those indices with low len bits equal to huff
incr=1U<<(int)(len-drop);
fill=1U<<(int)curr;
min=fill; // save offset to next table
do
{
fill-=incr;
table[next+(huff>>(int)drop)+fill]=here.Clone();
} while(fill!=0);
// backwards increment the len-bit code huff
incr=1U<<(int)(len-1);
while((huff&incr)!=0) incr>>=1;
if(incr!=0)
{
huff&=incr-1;
huff+=incr;
}
else huff=0;
// go to next symbol, update count, len
sym++;
if(--(count[len])==0)
{
if(len==max) break;
len=lens[lens_ind+work[sym]];
}
// create new sub-table if needed
if(len>root&&(huff&mask)!=low)
{
// if first time, transition to sub-tables
if(drop==0) drop=root;
// increment past last table
next+=(int)min; // here min is 1 << curr
// determine length of next table
curr=len-drop;
left=1<<(int)curr;
while(curr+drop<max)
{
left-=count[curr+drop];
if(left<=0) break;
curr++;
left<<=1;
}
// check for enough space
used+=1U<<(int)curr;
if((type==codetype.LENS&&used>=ENOUGH_LENS)||(type==codetype.DISTS&&used>=ENOUGH_DISTS)) return 1;
// point entry in root table to sub-table
low=huff&mask;
table[table_ind+low]=new code((byte)curr, (byte)root, (ushort)(next-table_ind));
}
}
// Fill in rest of table for incomplete codes. This loop is similar to the
// loop above in incrementing huff for table indices. It is assumed that
// len is equal to curr + drop, so there is no loop needed to increment
// through high index bits. When the current sub-table is filled, the loop
// drops back to the root table to fill in any remaining entries there.
here=new code(64, (byte)(len-drop), 0); // invalid code marker
while(huff!=0)
{
// when done with sub-table, drop back to root table
if(drop!=0&&(huff&mask)!=low)
{
drop=0;
len=root;
next=table_ind;
here.bits=(byte)len;
}
// put invalid code marker in table
table[next+huff>>(int)drop]=here.Clone();
// backwards increment the len-bit code huff
incr=1U<<(int)(len-1);
while((huff&incr)!=0) incr>>=1;
if(incr!=0)
{
huff&=incr-1;
huff+=incr;
}
else huff=0;
}
// set return parameters
table_ind+=(int)used;
bits=root;
return 0;
}
/*
* Build a set of tables to decode the provided canonical Huffman code.
* The code lengths are lens[0..codes-1]. The result starts at *table,
* whose indices are 0..2^bits-1. work is a writable array of at least
* lens shorts, which is used as a work area. type is the type of code
* to be generated, CODES, LENS, or DISTS. On return, zero is success,
* -1 is an invalid code, and +1 means that ENOUGH isn't enough. table
* on return points to the next available entry's address. bits is the
* requested root table index bits, and on return it is the actual root
* table index bits. It will differ if the request is greater than the
* longest code or if it is less than the shortest code.
*/
internal static int inflate_table(
codetype type,
ushort[] lens_array,
long lens_index,
uint codes,
code[] table_array,
ref long table_index,
ref uint bits,
ushort[] work
)
{
uint len; /* a code's length in bits */
uint sym; /* index of code symbols */
uint min, max; /* minimum and maximum code lengths */
uint root; /* number of index bits for root table */
uint curr; /* number of index bits for current table */
uint drop; /* code bits to drop for sub-table */
int left; /* number of prefix codes available */
uint used; /* code entries in table used */
uint huff; /* Huffman code */
uint incr; /* for incrementing code, index */
uint fill; /* index for replicating entries */
uint low; /* low bits for current root entry */
uint mask; /* mask for low root bits */
code here = new code(); /* table entry for duplication */
long next; /* next available space in table */
ushort[] @base; /* base value table to use */
ushort[] extra; /* extra bits table to use */
uint match; /* use base and extra for symbol >= match */
int MAXBITS = inftrees.MAXBITS;
ushort[] count = new ushort[MAXBITS + 1]; /* number of codes of each length */
ushort[] offs = new ushort[MAXBITS + 1]; /* offsets in table for each length */
/*static const*/
ushort[] lbase = new ushort[31] { /* Length codes 257..285 base */
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
};
/*static const*/
ushort[] lext = new ushort[31] { /* Length codes 257..285 extra */
16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18,
19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 77, 202
};
/*static const*/
ushort[] dbase = new ushort[32] { /* Distance codes 0..29 base */
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
8193, 12289, 16385, 24577, 0, 0
};
/*static const*/
ushort[] dext = new ushort[32] { /* Distance codes 0..29 extra */
16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22,
23, 23, 24, 24, 25, 25, 26, 26, 27, 27,
28, 28, 29, 29, 64, 64
};
/*
* Process a set of code lengths to create a canonical Huffman code. The
* code lengths are lens[0..codes-1]. Each length corresponds to the
* symbols 0..codes-1. The Huffman code is generated by first sorting the
* symbols by length from short to long, and retaining the symbol order
* for codes with equal lengths. Then the code starts with all zero bits
* for the first code of the shortest length, and the codes are integer
* increments for the same length, and zeros are appended as the length
* increases. For the deflate format, these bits are stored backwards
* from their more natural integer increment ordering, and so when the
* decoding tables are built in the large loop below, the integer codes
* are incremented backwards.
*
* This routine assumes, but does not check, that all of the entries in
* lens[] are in the range 0..MAXBITS. The caller must assure this.
* 1..MAXBITS is interpreted as that code length. zero means that that
* symbol does not occur in this code.
*
* The codes are sorted by computing a count of codes for each length,
* creating from that a table of starting indices for each length in the
* sorted table, and then entering the symbols in order in the sorted
* table. The sorted table is work[], with that space being provided by
* the caller.
*
* The length counts are used for other purposes as well, i.e. finding
* the minimum and maximum length codes, determining if there are any
* codes at all, checking for a valid set of lengths, and looking ahead
* at length counts to determine sub-table sizes when building the
* decoding tables.
*/
/* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */
for (len = 0; len <= MAXBITS; len++)
{
count[len] = 0;
}
for (sym = 0; sym < codes; sym++)
{
count[lens_array[lens_index + sym]]++;
}
/* bound code lengths, force root to be within code lengths */
root = bits;
for (max = (uint)MAXBITS; max >= 1; max--)
{
if (count[max] != 0)
{
break;
}
}
if (root > max)
{
root = max;
}
if (max == 0) /* no symbols to code at all */
{
here = new code(64, 1, 0); /* invalid code marker */
table_array[table_index++] = here; /* make a table to force an error */
table_array[table_index++] = here;
bits = 1;
return(0); /* no symbols, but wait for decoding to report error */
}
for (min = 1; min < max; min++)
{
if (count[min] != 0)
{
break;
}
}
if (root < min)
{
root = min;
}
/* check for an over-subscribed or incomplete set of lengths */
left = 1;
for (len = 1; len <= MAXBITS; len++)
{
left <<= 1;
left -= count[len];
if (left < 0)
{
return(-1); /* over-subscribed */
}
}
codetype CODES = codetype.CODES;
if (left > 0 && (type == CODES || max != 1))
{
return(-1); /* incomplete set */
}
/* generate offsets into symbol table for each length for sorting */
offs[1] = 0;
for (len = 1; len < MAXBITS; len++)
{
offs[len + 1] = (ushort)(offs[len] + count[len]);
}
/* sort symbols by length, by symbol order within each length */
for (sym = 0; sym < codes; sym++)
{
if (lens_array[lens_index + sym] != 0)
{
work[offs[lens_array[lens_index + sym]]++] = (ushort)sym;
}
}
/*
* Create and fill in decoding tables. In this loop, the table being
* filled is at next and has curr index bits. The code being used is huff
* with length len. That code is converted to an index by dropping drop
* bits off of the bottom. For codes where len is less than drop + curr,
* those top drop + curr - len bits are incremented through all values to
* fill the table with replicated entries.
*
* root is the number of index bits for the root table. When len exceeds
* root, sub-tables are created pointed to by the root entry with an index
* of the low root bits of huff. This is saved in low to check for when a
* new sub-table should be started. drop is zero when the root table is
* being filled, and drop is root when sub-tables are being filled.
*
* When a new sub-table is needed, it is necessary to look ahead in the
* code lengths to determine what size sub-table is needed. The length
* counts are used for this, and so count[] is decremented as codes are
* entered in the tables.
*
* used keeps track of how many table entries have been allocated from the
* provided *table space. It is checked for LENS and DIST tables against
* the constants ENOUGH_LENS and ENOUGH_DISTS to guard against changes in
* the initial root table size constants. See the comments in inftrees.h
* for more information.
*
* sym increments through all symbols, and the loop terminates when
* all codes of length max, i.e. all codes, have been processed. This
* routine permits incomplete codes, so another loop after this one fills
* in the rest of the decoding tables with invalid code markers.
*/
/* set up for code type */
switch (type)
{
case codetype.CODES:
@base = extra = work; /* dummy value--not used */
match = 20;
break;
case codetype.LENS:
@base = lbase;
extra = lext;
match = 257;
break;
default: /* DISTS */
@base = dbase;
extra = dext;
match = 0;
break;
}
/* initialize state for loop */
huff = 0; /* starting code */
sym = 0; /* starting code symbol */
len = min; /* starting code length */
next = table_index; /* current table to fill in */
curr = root; /* current table index bits */
drop = 0; /* current bits to drop from code for index */
low = uint.MaxValue; /* trigger new sub-table when len > root */
used = 1U << ((int)root); /* use root table entries */
mask = used - 1; /* mask for comparing low */
/* check available table space */
if ((type == codetype.LENS && used > inftrees.ENOUGH_LENS) ||
(type == codetype.DISTS && used > inftrees.ENOUGH_DISTS))
{
return(1);
}
/* process all codes and make table entries */
for (; ;)
{
/* create table entry */
byte here_bits = (byte)(len - drop);
byte here_op;
ushort here_val;
if (work[sym] + 1U < match)
{
here_op = (byte)0;
here_val = work[sym];
}
else if (work[sym] >= match)
{
here_op = (byte)(extra[work[sym] - match]);
here_val = @base[work[sym] - match];
}
else
{
here_op = (byte)(32 + 64); /* end of block */
here_val = 0;
}
here = new code(here_op, here_bits, here_val);
/* replicate for those indices with low len bits equal to huff */
incr = 1U << (int)(len - drop);
fill = 1U << (int)(curr);
min = fill; /* save offset to next table */
do
{
fill -= incr;
table_array[next + ((huff >> (int)drop) + fill)] = here;
} while (fill != 0);
/* backwards increment the len-bit code huff */
incr = 1U << (int)(len - 1);
while ((huff & incr) != 0)
{
incr >>= 1;
}
if (incr != 0)
{
huff &= incr - 1;
huff += incr;
}
else
{
huff = 0;
}
/* go to next symbol, update count, len */
sym++;
if (--(count[len]) == 0)
{
if (len == max)
{
break;
}
len = lens_array[lens_index + work[sym]];
}
/* create new sub-table if needed */
if (len > root && (huff & mask) != low)
{
/* if first time, transition to sub-tables */
if (drop == 0)
{
drop = root;
}
/* increment past last table */
next += min; /* here min is 1 << curr */
/* determine length of next table */
curr = len - drop;
left = (int)(1 << (int)curr);
while (curr + drop < max)
{
left -= count[curr + drop];
if (left <= 0)
{
break;
}
curr++;
left <<= 1;
}
/* check for enough space */
used += 1U << (int)curr;
if ((type == codetype.LENS && used > ENOUGH_LENS) ||
(type == codetype.DISTS && used > ENOUGH_DISTS))
{
return(1);
}
/* point entry in root table to sub-table */
low = huff & mask;
table_array[table_index + low] = new code((byte)curr, (byte)root, (ushort)(next - table_index));
}
}
/* fill in remaining table entry if code is incomplete (guaranteed to have
* at most one remaining entry, since if the code is incomplete, the
* maximum code length that was allowed to get this far is one bit) */
if (huff != 0)
{
here = new code(64, (byte)(len - drop), 0); /* invalid code marker */
table_array[next + huff] = here;
}
/* set return parameters */
table_index += used;
bits = root;
return(0);
}