windows-nt/Source/XPSP1/NT/base/ntos/rtl/xdecode.c
2020-09-26 16:20:57 +08:00

401 lines
9.7 KiB
C

#include "xprs.h"
#define ALLOCATE_ON_STACK 1
#define MAGIC_DECODE 0x35DEC0DE
typedef struct
{
struct
{
uchar *end, *beg, *careful, *stop, *last;
} dst;
struct
{
const uchar *end, *beg, *careful, *end_1, *end_tag, *end_bitmask2, *last;
}
src;
int result;
int eof;
int magic;
#if CODING & (CODING_HUFF_LEN | CODING_HUFF_PTR | CODING_HUFF_ALL)
uint16 table[(1 << DECODE_BITS) + (HUFF_SIZE << 1)];
#endif
} decode_info;
#if CODING == CODING_BY_BIT
static int bit_to_len_initialized = 0;
static uchar bit_to_len1[1 << (9 - MIN_MATCH)];
static uchar bit_to_len2[1 << (9 - MIN_MATCH)];
static void bit_to_len_init (void)
{
int i, k;
if (bit_to_len_initialized) return;
bit_to_len1[0] = 0;
bit_to_len2[0] = 9 - MIN_MATCH;
for (k = 1, i = 1 << (8 - MIN_MATCH); i != 0; i >>= 1, ++k)
{
memset (bit_to_len1 + i, k, i);
memset (bit_to_len2 + i, k - 1, i);
}
bit_to_len_initialized = 1;
}
#endif
#if CODING & (CODING_HUFF_LEN | CODING_HUFF_PTR | CODING_HUFF_ALL)
static int huffman_decode_create (uint16 *table, const uchar *length)
{
xint i, j, k, last, freq[16], sum[16];
/* calculate number of codewords */
memset (freq, 0, sizeof (freq));
i = HUFF_SIZE >> 1;
do
{
k = length[--i];
++freq[k & 0xf];
++freq[k >> 4];
}
while (i != 0);
/* handle special case(s) -- 0 and 1 symbols in alphabet */
if (freq[0] == HUFF_SIZE)
goto ok;
if (freq[0] == HUFF_SIZE - 1)
goto bad;
#if 0
{
if (freq[1] != 1)
goto bad;
i = -1; do ++i; while (length[i] == 0);
k = i << 1;
if (length[i] != 1) ++k;
i = 1 << DECODE_BITS;
do
*table++ = (uint16) k;
while (--i > 0);
goto ok;
}
#endif
/* save frequences */
memcpy (sum, freq, sizeof (sum));
/* check code correctness */
k = 0;
i = 15;
do
{
if ((k += freq[i]) & 1)
goto bad;
k >>= 1;
}
while (--i != 0);
if (k != 1)
goto bad;
/* sort symbols */
k = 0;
for (i = 1; i < 16; ++i)
freq[i] = (k += freq[i]);
last = freq[15]; /* preserve number of symbols in alphabet */
i = HUFF_SIZE << 4;
do
{
i -= 1 << 4;
k = length[i >> 5] >> 4;
if (k != 0)
table[--freq[k]] = (uint16) (k | i);
i -= 1 << 4;
k = length[i >> 5] & 0xf;
if (k != 0)
table[--freq[k]] = (uint16) (k | i);
}
while (i != 0);
/* now create decoding table */
k = i = (1 << DECODE_BITS) + (HUFF_SIZE << 1);
{
xint n;
for (n = 15; n > DECODE_BITS; --n)
{
j = i;
while (k > j)
table[--i] = (uint16) ((k -= 2) | 0x8000);
for (k = sum[n]; --k >= 0;)
table[--i] = table[--last];
k = j;
}
}
j = i;
i = 1 << DECODE_BITS;
while (k > j)
table[--i] = (uint16) ((k -= 2) | 0x8000);
while (last > 0)
{
k = table[--last];
j = i - ((1 << DECODE_BITS) >> (k & 15));
do
table[--i] = (uint16) k;
while (i != j);
}
assert ((i | last) == 0);
ok:
return (1);
bad:
return (0);
}
#endif /* CODING */
#if DEBUG
#define RET_OK do {printf ("OK @ %d\n", __LINE__); goto ret_ok;} while (0)
#define RET_ERR do {printf ("ERR @ %d\n", __LINE__); goto ret_err;} while (0)
#else
#define RET_OK goto ret_ok
#define RET_ERR goto ret_err
#endif
#define GET_UINT16(x,p) x = *(__unaligned uint16 *)(p); p += 2
#define COPY_8_BYTES(dst,src) \
dst[0] = src[0]; dst[1] = src[1]; dst[2] = src[2]; dst[3] = src[3]; \
dst[4] = src[4]; dst[5] = src[5]; dst[6] = src[6]; dst[7] = src[7]
/* do not use "memcpy" -- it makes it hard if "dst" and "src" are close */
#define COPY_BLOCK_SLOW(dst,src,len) \
if (len > 8) do \
{ \
COPY_8_BYTES (dst, src); \
len -= 8; dst += 8; src += 8; \
} \
while (len > 8); \
do \
*dst++ = *src++, --len; \
while (len)
#ifdef __alpha
#define COPY_BLOCK_FAST_8(dst,src) \
COPY_8_BYTES (dst, src)
#else
#if 0
#define COPY_BLOCK_FAST_8(dst,src) \
((__unaligned uint32 *) dst)[0] = ((__unaligned uint32 *) src)[0]; \
((__unaligned uint32 *) dst)[1] = ((__unaligned uint32 *) src)[1]
#else
#define COPY_BLOCK_FAST_8(dst,src) \
((__unaligned __int64 *) dst)[0] = ((__unaligned __int64 *) src)[0]
#endif
#endif
#define BIORD(bits) \
(Mask >> (sizeof (Mask) * 8 - (bits)))
#define CONCAT2(x,y) x##y
#define CONCAT(x,y) CONCAT2(x,y)
#define bits_t signed char
#define BIORD_MORE0(bits) \
if ((Bits = (bits_t) (Bits - (bits))) < 0) \
{ \
CAREFUL_ERR_IF (src >= info->src.end_1); \
Mask += ((ubitmask4) *(__unaligned ubitmask2 *)src) << (-Bits); \
src += sizeof (ubitmask2); \
Bits += (bits_t) (sizeof (ubitmask2) * 8); \
}
#define BIORD_MORE(bits) \
Mask <<= (bits_t)(bits); \
BIORD_MORE0 (bits)
#define BIORD_WORD(result,bits) \
result = 1 << (bits); \
if (bits) \
{ \
result += BIORD (bits); \
BIORD_MORE (bits); \
}
#define BIORD_DECODE(result,table) { \
bits_t __bits; \
result = ((int16 *)(table))[BIORD (DECODE_BITS)]; \
if (result < 0) \
{ \
Mask <<= DECODE_BITS; \
do \
{ \
result &= 0x7fff; \
if ((bitmask4) Mask < 0) ++result; \
result = ((int16 *)(table))[result]; \
Mask <<= 1; \
} \
while (result < 0); \
__bits = (bits_t)(result & 15); \
} \
else \
{ \
__bits = (bits_t)(result & 15); \
Mask <<= __bits; \
} \
result >>= 4; \
Bits = (bits_t) (Bits - __bits); \
} \
if (Bits < 0) \
{ \
CAREFUL_ERR_IF (src >= info->src.end_1); \
if (CODING == CODING_HUFF_ALL) \
{CAREFUL_IF (src >= info->src.careful, rdmore);} \
Mask += ((ubitmask4) *(__unaligned ubitmask2 *)src) << (-Bits); \
src += sizeof (ubitmask2); \
Bits += (bits_t) (sizeof (ubitmask2) * 8); \
}
#ifdef _MSC_VER
#pragma optimize ("aw", off)
#endif
#define CAREFUL 0
#include "xdecode.i"
#define CAREFUL 1
#include "xdecode.i"
#ifdef _MSC_VER
#pragma optimize ("aw", on)
#endif
int XPRESS_CALL XpressDecode
(
XpressDecodeStream stream,
void *orig, int orig_size, int decode_size,
const void *comp, int comp_size
)
{
decode_info *info;
const uchar *src;
#if ALLOCATE_ON_STACK
decode_info stack_info;
info = &stack_info;
info->src.beg = (void *) stream;
#else
if (stream == 0 || (info = (decode_info *) stream)->magic != MAGIC_DECODE)
return (-1);
#endif
if (comp_size == orig_size)
return (decode_size);
if (orig_size < comp_size
|| comp_size < 0
|| orig_size <= MIN_SIZE
|| comp_size < MIN_SIZE
)
return (-1);
if (orig_size > BUFF_SIZE || decode_size <= 0)
return (decode_size);
src = comp;
info->dst.beg = orig;
info->dst.end = (uchar *) orig + orig_size;
info->dst.stop = (uchar *) orig + decode_size;
info->src.end = src + comp_size;
info->src.end_1 = info->src.end - 1;
info->src.end_tag = info->src.end - (sizeof (tag_t) - 1);
info->src.end_bitmask2 = info->src.end - (sizeof (bitmask2) - 1);
// check bounds when we read new mask (at most 8 * sizeof (tag_t)) pointers
// we may write at most 8 bytes without checks
#define RESERVE_DST ((8 * 8 + 2) * sizeof (tag_t))
info->dst.careful = info->dst.beg;
if (info->dst.stop - info->dst.beg > RESERVE_DST)
info->dst.careful = info->dst.stop - RESERVE_DST;
// we may read at most 7 bytes
#define RESERVE_SRC ((7 * 8 + 2) * sizeof (tag_t))
info->src.careful = info->src.beg;
if (info->src.end - info->src.beg > RESERVE_SRC)
info->src.careful = info->src.end - RESERVE_SRC;
#if CODING & (CODING_HUFF_LEN | CODING_HUFF_PTR | CODING_HUFF_ALL)
if (!huffman_decode_create (info->table, src))
return (-1);
src += HUFF_SIZE >> 1;
#endif
#if CODING == CODING_BY_BIT
bit_to_len_init ();
#endif
info->src.beg = src;
info->result = 0;
info->eof = 0;
do_decode (info);
if (!info->result || info->dst.last > info->dst.stop || info->src.last > info->src.end
|| (info->dst.stop == info->dst.end && !info->eof)
)
return (-1);
return (decode_size);
}
XpressDecodeStream
XPRESS_CALL
XpressDecodeCreate
(
void *context, // user-defined context info (will be passed to AllocFn)
XpressAllocFn *AllocFn // memory allocation callback
)
{
#if ALLOCATE_ON_STACK
return ((XpressDecodeStream) 1);
#else
decode_info *info;
if (AllocFn == 0 || (info = AllocFn (context, sizeof (*info))) == 0)
return (0);
info->magic = MAGIC_DECODE;
return ((XpressDecodeStream) info);
#endif
}
void
XPRESS_CALL
XpressDecodeClose
(
XpressDecodeStream stream, // encoder's workspace
void *context, // user-defined context info (will be passed to FreeFn)
XpressFreeFn *FreeFn // callback that releases the memory
)
{
#if ALLOCATE_ON_STACK
/* do nothing */
#else
if (FreeFn != 0 && stream != 0 && ((decode_info *) stream)->magic == MAGIC_DECODE)
{
((decode_info *) stream)->magic = 0;
FreeFn (context, stream);
}
#endif
}