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windows-nt/Source/XPSP1/NT/ds/xpress/xdecode.i

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2020-09-26 03:20:57 -05:00
/* ------------------------------------------------------------------------ */
/* */
/* Copyright (c) Microsoft Corporation, 2000-2001. All rights reserved. */
/* Copyright (c) Andrew Kadatch, 1991-2001. All rights reserved. */
/* */
/* Microsoft Confidential -- do not redistribute. */
/* */
/* ------------------------------------------------------------------------ */
/*
Decoding is splitted into two phases:
1. Fast decoding. Check bounds rarely (when loading new tag and after copying
of a long string) and switch into Careful only when we are too close to the
end of input or output buffer.
2. Careful decoding. Before performing any memory access all bounds are checked
to make sure no buffer overrun or underrun will happen. Careful decoding is
usually 1.5 times slower than Fast one, but only last several hundred bytes
are decoded this way; all the rest is decoded Fast.
As long as decoding code is essentially the same except for bounds checks that
differ in Fast and Careful mode, in order to avoid code duplication this file
is included twice with different setting of CAREFUL macro (first it is 0, then
1).
Run "cl -EP xdecode.c >xdecode.pp" to see actual code.
*/
#if CAREFUL
#define LABEL(label) careful_##label
#define CAREFUL_OK_IF(cond) if (cond) RET_OK
#define CAREFUL_ERR_IF(cond) if (cond) RET_ERR
#define CAREFUL_EOF_IF(cond) if (cond) goto ret_ok_eof;
#define CAREFUL_IF(cond, label) label:
#if CODING & (CODING_HUFF_LEN | CODING_HUFF_PTR | CODING_HUFF_ALL)
#define START careful_start:
#else
#define START
#endif
#else /* !CAREFUL */
#define LABEL(label) label
#define CAREFUL_OK_IF(cond)
#define CAREFUL_ERR_IF(cond)
#define CAREFUL_EOF_IF(cond)
#define CAREFUL_IF(cond, label) if (cond) goto label
#define START start:
static void do_decode (decode_info *info)
{
#endif
/* ----------------------- CODING_HUFF_ALL ------------------------ */
/* --------------- */
// C code: 26.3 MB/s, asm code: 32.3 MB/s at P3-500
#if CODING == CODING_HUFF_ALL
#ifndef i386
#if !CAREFUL
ubitmask4 Mask;
bits_t Bits, bits;
xint len;
uxint ofs;
uchar *dst = info->dst.beg;
const uchar *src = info->src.beg;
Mask = * (__unaligned ubitmask2 *) src; src += sizeof (ubitmask2);
Mask <<= sizeof (ubitmask2) * 8;
Mask += * (__unaligned ubitmask2 *) src; src += sizeof (ubitmask2);
Bits = 8 * sizeof (ubitmask2);
if (src >= info->src.careful || dst >= info->dst.careful)
goto careful_next;
goto LABEL(next);
#endif /* CAREFUL */
LABEL(decode_more):
// too close to end of buffer? -- switch to careful mode...
CAREFUL_IF (src >= info->src.careful, decode_more1);
CAREFUL_IF (dst >= info->dst.careful, decode_more2);
// input buffer ovverrun? -- corrupted compressed data
CAREFUL_ERR_IF (src >= info->src.end_bitmask2);
// read 16 bits more and update Mask&Bits respectively
bits = Bits;
ofs = * (__unaligned ubitmask2 *) src;
bits = (bits_t) (-bits);
src += sizeof (ubitmask2);
ofs <<= bits;
Bits += 8 * sizeof (ubitmask2);
Mask += (ubitmask4) ofs;
if ((len -= 256) >= 0)
goto LABEL (pointer);
for (;;)
{
CAREFUL_OK_IF (dst >= info->dst.stop);
*dst = (uchar) len; // copy literal byte to output
ofs = (uxint) (Mask >> (8 * sizeof (Mask) - DECODE_BITS));
++dst;
len = ((int16 *) info->table)[ofs];
bits = 15;
if (len < 0)
goto LABEL(long_codeword);
// short codeword -- already decoded
bits &= len; // bits = # of bit used in Mask
len >>= 4; // len = token
Mask <<= bits; // update Mask&Bits
Bits = (bits_t) (Bits - bits); // read more bits if necessary
if (Bits < 0)
goto LABEL (decode_more);
if ((len -= 256) < 0) // (len -= 256) < 0 ? literal : pointer
continue;
goto LABEL (pointer);
LABEL(next): // decode next token via lookup table
ofs = (uxint) (Mask >> (8 * sizeof (Mask) - DECODE_BITS));
len = ((int16 *) info->table)[ofs];
bits = 15;
if (len >= 0)
{
// short codeword -- already decoded
bits &= len; // bits = # of bit used in Mask
len >>= 4; // len = token
Mask <<= bits; // update Mask&Bits
Bits = (bits_t) (Bits - bits); // read more bits if necessary
if (Bits < 0)
goto LABEL (decode_more);
if ((len -= 256) < 0) // (len -= 256) < 0 ? literal : pointer
continue;
}
else
{
LABEL (long_codeword):
// long codeword -- decode bit by bit
Mask <<= DECODE_BITS; // DECODE_BITS alreay parsed
do
{
len += ((bitmask4) Mask) < 0; // len += MSB (Mask)
Mask <<= 1; // 1 more bit was used
len = ((int16 *) info->table)[len + 0x8000];
}
while (len < 0);
bits &= len; // bits = # of bit used in Mask
len >>= 4; // len = token
Bits = (bits_t) (Bits - bits); // read more bits if necessary
if (Bits < 0)
goto LABEL (decode_more);
if ((len -= 256) < 0) // (len -= 256) < 0 ? literal : pointer
continue;
}
LABEL(pointer):
CAREFUL_EOF_IF (dst >= info->dst.stop);
bits = (bits_t) (len >> MAX_LENGTH_LOG); // # of bits in offset
ofs = (uxint) ((Mask >> 1) | (((ubitmask4) 1) << (8 * sizeof (Mask) - 1)));
Mask <<= bits; // update Mask and Bits
Bits = (bits_t) (Bits - bits);
bits ^= 8 * sizeof (ofs) - 1; // bits = 31 - bits
len &= MAX_LENGTH - 1; // run length - MIN_MATCH
ofs >>= bits; // ofs = (1<<bits) | (Mask<<(32-bits))
info->src.last = src; // save src
ofs = (uxint) (- (xint) ofs); // ofs = real negative offset
#if !CAREFUL && 8-MIN_MATCH < MAX_LENGTH-1
if (len <= 8-MIN_MATCH)
{
src = dst + (xint) ofs; // src = beginning of string
#ifdef _M_IX86 // unligned access is faster only on x86
if (ofs < ~2)
{
if (src < info->dst.beg) // buffer underrun? -- corrupted data
RET_ERR;
ofs = ((__unaligned uint32 *) src)[0]; // copy 8 bytes
((__unaligned uint32 *) dst)[0] = ofs;
ofs = ((__unaligned uint32 *) src)[1];
((__unaligned uint32 *) dst)[1] = ofs;
src = info->src.last; // restore src
dst = dst + len + MIN_MATCH; // dst = next output position
if (Bits >= 0) // have enough Bits in Mask? -- proceed further
goto LABEL (next);
goto LABEL (mask_more); // otherwise, read more bits
}
#endif
if (src < info->dst.beg) // buffer underrun? -- corrupted data
RET_ERR;
COPY_8_BYTES (dst, src); // copy 8 bytes one by one
// NB: dst & src may overlap
src = info->src.last; // restore src
dst = dst + len + MIN_MATCH; // dst = next output position
if (Bits >= 0) // have enough Bits in Mask? -- proceed further
goto LABEL (next);
goto LABEL (mask_more); // otherwise, read more bits
}
#endif /* CAREFUL */
if (len == MAX_LENGTH - 1) // long length? -- decode it
{
// if input data overrun then compressed data corrupted
CAREFUL_ERR_IF (src >= info->src.end);
len = *src++ + (MAX_LENGTH-1);
if (len == 255 + MAX_LENGTH-1)
{
CAREFUL_ERR_IF (src >= info->src.end_1);
len = * (__unaligned uint16 *) src;
src += 2;
if (len < 255 + MAX_LENGTH-1) // length should be large enough
RET_ERR;
}
info->src.last = src; // save input buffer pointer
}
len += MIN_MATCH; // len = actual length
src = dst + (xint) ofs; // src = pointer to the beginning of string
dst += len; // dst = last output position
if (src < info->dst.beg) // buffer underrun? -- corrupted data
RET_ERR;
#if !CAREFUL
if (dst >= info->dst.careful)
goto careful_check_overrun;
#else
careful_check_overrun:
if (dst > info->dst.stop) // more to copy than necessary?
{
dst -= len; // dst = first output position
len = (xint) (info->dst.stop - dst); // len = max length to copy
COPY_BLOCK_SLOW (dst, src, len); // copy last run
src = info->src.last; // restore input buffer pointer
RET_OK; // OK but no EOF mark was found
}
#endif
dst -= len; // dst = first output position
COPY_BLOCK_SLOW (dst, src, len); // input & output may overlap -- copy byte by byte
src = info->src.last; // restore input buffer pointer
CAREFUL_IF (dst >= info->dst.careful, copy1);
if (Bits >= 0) // enough Bits in Mask?
goto LABEL (next); // decode next token
#if !CAREFUL && 8-MIN_MATCH < MAX_LENGTH-1
LABEL(mask_more):
#endif
// have 2 more bytes in input buffer?
CAREFUL_ERR_IF (src >= info->src.end_bitmask2);
// read 16 bits more and update Mask&Bits respectively
bits = Bits;
ofs = * (__unaligned ubitmask2 *) src;
bits = (bits_t) (-bits);
src += sizeof (ubitmask2);
ofs <<= bits;
Bits += 8 * sizeof (ubitmask2);
Mask += (ubitmask4) ofs;
goto LABEL (next); // decode next token
} /* of for(;;) */
#if CAREFUL
ret_ok_eof:
if (dst == info->dst.end && len == 0)
info->eof = 1;
ret_ok:
info->src.last = src;
info->dst.last = dst;
info->result = 1;
return;
ret_err:
info->result = 0;
return;
#endif /* CAREFUL */
#else /* ---------------------- defined i386 --------------------- */
#if !CAREFUL
__asm
{
mov eax,info ; save info
push esi ; save registers
push edi
push edx
push ecx
push ebx
push ebp
mov ebp,eax ; (ebp) = info
mov ebx,[ebp].src.beg ; (ebx) = src
mov edi,[ebp].dst.beg ; (edx) = dst
xor esi,esi ; initialize Mask
mov si,[ebx]
shl esi,16
mov si,[ebx+2]
add ebx,4
mov ch,16 ; (ch) = Bits = 16
cmp ebx,[ebp].src.careful ; too close to the end of src buffer?
jae careful_next ; yes, be careful...
cmp edi,[ebp].dst.careful ; too close to the end of dst buffer?
jae careful_next ; yes, be careful...
jmp LABEL (next)
#endif /* CAREFUL */
LABEL(literal):
#if CAREFUL
cmp edi,[ebp].dst.stop ; decoded as much as asked?
jae ret_ok ; done, but no EOF mark
#endif
mov edx,esi ; (edx) = Mask
mov [edi],al ; store literal byte
shr edx,32-DECODE_BITS
inc edi ; (edi) = next output position
movsx eax,word ptr [ebp+edx*2].table ; (eax) = respective decode table entry
mov cl,15 ; (cl) = 15
test eax,eax ; need further decoding? (= codelen > DECODE_BITS?)
jl LABEL(long_code) ; yes, do it
and cl,al ; (cl) = # of bits used in mask
shr eax,4 ; (eax) = token
shl esi,cl ; (esi) = resulting mask
sub ch,cl ; (ch) = # of available bits left in dx
jl LABEL(decode_more) ; if ch < 0 need to read more bits
sub eax,256 ; (eax) = token - 256
jl LABEL(literal) ; if < 0 then al = code of literal
jmp LABEL(pointer) ; otherwise it's pointer
LABEL(next):
mov edx,esi ; (edx) = Mask
mov cl,15 ; (cl) = 15
shr edx,32-DECODE_BITS ; (edx) = DECODE_BITS most significant bits of Mask
movsx eax,word ptr [ebp+edx*2].table ; (eax) = respective decode table entry
test eax,eax ; need further decoding?
jl LABEL(long_code) ; yes, continue
and cl,al ; (cl) = # of bits used in mask
shr eax,4 ; (eax) = current token
shl esi,cl ; (esi) = resulting mask
sub ch,cl ; (ch) = # of available bits left in dx
jl LABEL(decode_more) ; if ch < 0 need to read more bits
sub eax,256 ; (eax) = token - 256
jl LABEL(literal) ; if < 0 then al = code of literal
jmp LABEL(pointer) ; otherwise it's pointer
LABEL(long_code):
shl esi, DECODE_BITS ; DECODE_BITS were used; remove them
LABEL(next_bit):
add esi,esi ; Mask <<= 1 (and get carry)
adc eax,0 ; eax += (old Mask < 0)
movsx eax,word ptr [ebp+eax*2+0x10000].table ; (eax) = token
test eax,eax ; need further decoding?
jl LABEL(next_bit) ; yes, continue
and cl,al ; (cl) = # of bits used in mask
shr eax,4 ; (eax) = token
sub ch,cl ; (ch) = # of available bits left in Mask
jl LABEL(decode_more) ; if ch < 0 need to read more bits
sub eax,256 ; (eax) = token - 256
jl LABEL(literal) ; if < 0 then al = code of literal
jmp LABEL(pointer) ; otherwise it's pointer
LABEL(decode_more):
#if !CAREFUL
cmp ebx,[ebp].src.careful ; too close to the end of src buffer?
jae careful_decode_more ; yes, be careful...
cmp edi,[ebp].dst.careful ; too close to the end of dst buffer?
jae careful_decode_more ; yes, be careful...
#else
cmp ebx,[ebp].src.end_bitmask2 ; buffer overrun?
jae LABEL(error_1) ; yes, error...
#endif
mov cl,ch ; (cl) = (# of have - # of used)
xor edx,edx
mov dx,[ebx] ; (edx) = next 16 bits
neg cl ; (cl) = # unused bits in Mask
add ebx,2 ; (ebx) = ptr to next token
shl edx,cl ; (edx) = 16 aligned on required boundary
add ch,16 ; (ch) = # of free bits in Mask
add esi,edx ; (esi) = Mask + next 16 bits
sub eax,256 ; (eax) = token - 256
jl LABEL(literal) ; if < 0 then al = code of literal
LABEL(pointer):
#if CAREFUL
cmp edi,[ebp].dst.stop ; reached end of buffer?
jae ret_ok_eof ; yes, done, and probably EOF (check later)
#endif
mov cl,al ; prepare to obtain # of bits in offset
mov edx,esi ; (edx) = mask
shr cl,MAX_LENGTH_LOG ; (cl) = # of bits in offset
or edx,1 ; set less significant bit
shl esi,cl ; (esi) = (Mask << cl)
sub ch,cl ; (ch) = # of bits left in mask
ror edx,1 ; (edx) = (Mask >> 1) | 0x80000000
xor cl,31 ; (cl) = 31 - (# of bits in mask)
and eax,MAX_LENGTH-1 ; (eax) = length - MIN_MATCH
shr edx,cl ; (edx) = (1 << #) + (Mask >> (32-#)) = offset
push esi ; save mask
neg edx ; (edx) = negative offset
#if !CAREFUL && 8-MIN_MATCH < MAX_LENGTH-1
cmp eax,8-MIN_MATCH ; length > 8?
ja LABEL(long_string)
lea esi, [edi+edx] ; esi = beginning of string
cmp edx,-3 ; offset < 4?
jae LABEL(copy_by_one) ; yes, copy byte by byte
cmp esi, [ebp].dst.beg ; output buffer underrun?
jb LABEL(error_pop_1) ; yes, corrupted data
mov edx,[esi] ; get first 4 bytes
mov [edi],edx ; store them
mov edx,[esi+4] ; get next 4 byte
mov [edi+4],edx ; store them
pop esi ; restore mask
lea edi,[edi+eax+MIN_MATCH] ; (edi) = next output location
test ch,ch ; have enough bits in Mask?
jge LABEL(next) ; yes, proceed further
jmp LABEL(mask_more) ; no, need to read in more bits
LABEL(copy_by_one):
cmp esi, [ebp].dst.beg ; output buffer underrun?
jb LABEL(error_pop_2) ; yes, corrupted data
mov dl,[esi] ; copy 8 bytes by one
mov [edi],dl ; NB: no readahead is allowed here
mov dl,[esi+1] ; because source and destination
mov [edi+1],dl ; may overlap
mov dl,[esi+2]
mov [edi+2],dl
mov dl,[esi+3]
mov [edi+3],dl
mov dl,[esi+4]
mov [edi+4],dl
mov dl,[esi+5]
mov [edi+5],dl
mov dl,[esi+6]
mov [edi+6],dl
mov dl,[esi+7]
mov [edi+7],dl
pop esi ; restore mask
lea edi,[edi+eax+MIN_MATCH] ; (edi) = next output location
test ch,ch ; have enough bits in Mask?
jge LABEL(next) ; yes, proceed further
jmp LABEL(mask_more) ; no, need to read in more bits
LABEL(long_string):
#endif /* CAREFUL */
cmp eax,MAX_LENGTH-1 ; long length?
je LABEL(long_length) ; yes, decode it
LABEL(long_length_done):
lea esi,[edi+edx] ; (esi) = source pointer
add eax,MIN_MATCH ; (edx) = length
lea edx,[esi+eax] ; (eax) = last output position
cmp esi,[ebp].dst.beg ; output buffer underrun?
jb LABEL(error_pop_3) ; yes, corrupted data
xchg eax,ecx ; (ecx) = length, (ah) = bit counter
#if !CAREFUL
cmp edx,[ebp].dst.careful ; too close to the end of buffer?
jae careful_check_overrun ; yes, be careful
#else
careful_check_overrun:
cmp edx,[ebp].dst.stop ; too much to output?
jbe careful_no_overrun ; yes, adjust length
sub edx,[ebp].dst.stop ; (edx) = excess
sub ecx,edx ; (ecx) = exact length
rep movsb ; copy bytes
pop esi ; restore mask
jmp ret_ok ; OK, but not EOF
careful_no_overrun:
#endif
rep movsb ; copy bytes
mov ch,ah ; restore byte counter
pop esi ; restore Mask
#if !CAREFUL
cmp edi,[ebp].dst.careful ; too close to the end of input buffer?
jae careful_copy ; yes, switch into careful mode
#else
careful_copy:
#endif
test ch,ch ; have enough bits in Mask?
jge LABEL(next) ; yes, proceed further
#if CAREFUL
cmp ebx,[ebp].src.end_bitmask2 ; input buffer overrun?
jae LABEL(error_2)
#else
LABEL(mask_more):
#endif
mov cl,ch ; (cl) = (# of have - # of used)
xor edx,edx
mov dx,[ebx] ; (edx) = next 16 bits
neg cl ; (cl) = # unused bits in Mask
add ebx,2 ; (ebx) = ptr to next token
shl edx,cl ; (edx) = 16 aligned on required boundary
add ch,16 ; (ch) = # of free bits in Mask
add esi,edx ; (esi) = Mask + next 16 bits
jmp LABEL(next) ; decode next token
LABEL(long_length):
#if CAREFUL
cmp ebx,[ebp].src.end ; input buffer overrun?
jae LABEL(error_pop_4) ; yes, corrupted data
#endif
xor eax,eax
mov al,[ebx] ; (eax) = next byte
inc ebx ; (ebx) = ptr to next token
cmp al,255 ; (eax) == 255?
lea eax,[eax+MAX_LENGTH-1] ; (eax) = next byte + MAX_LENGTH-1
jne LABEL(long_length_done) ; no, length decoded
#if CAREFUL
cmp ebx,[ebp].src.end_1 ; input buffer overrun?
jae LABEL(error_pop_5) ; yes, corrupted data
#endif
xor eax,eax
mov ax,[ebx] ; (eax) = next word
add ebx,2 ; (ebx) = ptr to next token
cmp ax,255+MAX_LENGTH-1 ; length should be long enough
jae LABEL(long_length_done)
jmp LABEL(error_3)
#if CAREFUL
#ifndef DEBUG_LABEL
#if DEBUG
#define DEBUG_LABEL(label) label: mov eax, eax
#else
#define DEBUG_LABEL(label) label:
#endif /* DEBUG */
#endif /* DEBUG_LABEL */
DEBUG_LABEL(error_pop_1)
DEBUG_LABEL(error_pop_2)
DEBUG_LABEL(error_pop_3)
DEBUG_LABEL(careful_error_pop_3)
DEBUG_LABEL(careful_error_pop_4)
DEBUG_LABEL(careful_error_pop_5)
pop eax ; pop Mask saved on stack
DEBUG_LABEL(careful_error_1)
DEBUG_LABEL(careful_error_2)
DEBUG_LABEL(error_3)
DEBUG_LABEL(careful_error_3)
xor eax,eax ; decode error: return 0
jmp ret_common
ret_ok_eof:
cmp edi,[ebp].dst.end
jne ret_ok
test eax,eax
jne ret_ok ; eof iff eax == 0
mov eax,1
mov [ebp].eof,eax
ret_ok:
mov eax,1 ; no [obvious] error: return 0
ret_common:
mov [ebp].result, eax ; store result
mov [ebp].src.last,ebx ; save last value of source ptr
mov [ebp].dst.last,edi ; save last value of destination ptr
pop ebp ; restore registers we used
pop ebx
pop ecx
pop edx
pop edi
pop esi ; and return
} /* end of __asm */
#endif /* CAREFUL */
#endif /* i386 */
#endif /* -------------------- CODING_HUFF_ALL ------------------ */
/* ----------------------- CODING_DIRECT2 ------------------------ */
/* -------------- */
#if CODING == CODING_DIRECT2
#ifndef i386
// C code: 73 MB/s at P3-500; asm code 80.5 MB/s
/*
Pseudocode:
----------
length = NextWord ();
offset = length >> DIRECT2_LEN_LOG;
length &= DIRECT2_MAX_LEN;
if (length == DIRECT2_MAX_LEN)
{
length = NextQuad ();
if (length == 15)
{
length = NextByte ();
if (length == 255)
length = NextWord () - 15 - DIRECT2_MAX_LEN;
length += 15;
}
length += DIRECT2_MAX_LEN;
}
length += MIN_MATCH;
++offset;
memcpy (dst, dst - offset, length);
dst += length;
*/
#if !CAREFUL
tag_t bmask = 0;
xint ofs, len;
const uchar *ptr = 0;
uchar *dst = info->dst.beg;
const uchar *src = info->src.beg;
goto start;
#endif /* !CAREFUL */
LABEL (next):
if (bmask >= 0) do // while MSB(bmask) == 0
{
bmask <<= 1;
LABEL (copy_byte):
CAREFUL_OK_IF (dst >= info->dst.stop);
CAREFUL_ERR_IF (src >= info->src.end);
*dst++ = *src++; // copy next byte
} while (bmask >= 0);
if ((bmask <<= 1) == 0) // if bmask == 0 reload it
{
START;
CAREFUL_IF (src >= info->src.careful || dst >= info->dst.careful, restart);
CAREFUL_ERR_IF (src >= info->src.end_tag);
bmask = * (__unaligned tag_t *) src;
src += sizeof (tag_t);
if (bmask >= 0)
{
bmask = (bmask << 1) + 1;
goto LABEL (copy_byte);
}
bmask = (bmask << 1) + 1;
}
#if !CAREFUL
assert (dst < info->dst.end - 8);
#endif
CAREFUL_EOF_IF (dst >= info->dst.stop);
CAREFUL_ERR_IF (src >= info->src.end_1);
ofs = * (__unaligned uint16 *) src;
src += 2;
len = ofs;
ofs >>= DIRECT2_LEN_LOG;
len &= DIRECT2_MAX_LEN;
ofs = ~ofs;
#if !CAREFUL && (8 - MIN_MATCH < DIRECT2_MAX_LEN)
if (len <= 8 - MIN_MATCH)
{
const uchar *src1 = dst + ofs;
#ifdef _M_IX86 // unaligned access is faster only on x86
if (ofs < ~2)
{
if (src1 < info->dst.beg) RET_ERR; // check for buffer underrun
ofs = ((__unaligned uint32 *) src1)[0]; // quickly copy 8 bytes
((__unaligned uint32 *) dst)[0] = ofs;
ofs = ((__unaligned uint32 *) src1)[1];
((__unaligned uint32 *) dst)[1] = ofs;
dst += len + MIN_MATCH; // dst = next output position
goto LABEL (next); // decode next token
}
#endif
if (src1 < info->dst.beg) RET_ERR; // check for buffer overrun
COPY_8_BYTES (dst, src1);
dst += len + MIN_MATCH;
goto LABEL (next);
}
#endif
if (len == DIRECT2_MAX_LEN) // decode long length
{
if (ptr == 0)
{
CAREFUL_ERR_IF (src >= info->src.end);
ptr = src;
len = *src++ & 15;
}
else
{
len = *ptr >> 4;
ptr = 0;
}
if (len == 15)
{
CAREFUL_ERR_IF (src >= info->src.end);
len = *src++;
if (len == 255)
{
CAREFUL_ERR_IF (src >= info->src.end_1);
len = * (__unaligned uint16 *) src;
src += 2;
if (len < 255 + 15 + DIRECT2_MAX_LEN) RET_ERR;
len += MIN_MATCH;
goto LABEL (done_len);
}
len += 15;
}
len += DIRECT2_MAX_LEN + MIN_MATCH;
goto LABEL (done_len);
}
len += MIN_MATCH;
LABEL (done_len):
info->src.last = src;
src = dst + ofs;
#if !CAREFUL
if (dst + len >= info->dst.careful)
goto careful_copy_tail;
#else
careful_copy_tail:
if (dst + len > info->dst.stop)
{
if (src < info->dst.beg) RET_ERR;
len = (xint) (info->dst.stop - dst);
assert (len >= 0);
COPY_BLOCK_SLOW (dst, src, len);
src = info->src.last;
RET_OK;
}
#endif /* !CAREFUL */
if (src < info->dst.beg) RET_ERR;
COPY_BLOCK_SLOW (dst, src, len); // copy block
src = info->src.last; // restore input buffer ptr
goto LABEL (next);
#if CAREFUL
ret_ok_eof:
if (dst == info->dst.end)
info->eof = 1;
ret_ok:
info->src.last = src;
info->dst.last = dst;
info->result = 1;
return;
ret_err:
info->result = 0;
return;
#endif /* CAREFUL */
#else /* ------------------------- i386 ---------------------------- */
#if !CAREFUL
__asm
{
mov eax,info // save info
push ebx // save registers
push ecx
push edx
push esi
push edi
push ebp
#define PTR dword ptr [esp]
#define DST_STOP dword ptr [esp+4*1]
#define DST_CAREFUL dword ptr [esp+4*2]
#define SRC_CAREFUL dword ptr [esp+4*3]
#define SRC_END dword ptr [esp+4*4]
#define SRC_END_1 dword ptr [esp+4*5]
#define SRC_END_TAG dword ptr [esp+4*6]
#define INFO dword ptr [esp+4*7]
#define LOCALS 8
sub esp,4*LOCALS // make room for locals
mov edx,[eax].dst.stop
mov DST_STOP,edx
mov edx,[eax].dst.careful
mov DST_CAREFUL,edx
mov edx,[eax].src.careful
mov SRC_CAREFUL,edx
mov edx,[eax].src.end
mov SRC_END,edx
mov edx,[eax].src.end_1
mov SRC_END_1,edx
mov edx,[eax].src.end_tag
mov SRC_END_TAG,edx
xor edx,edx // ptr = 0
mov PTR,edx
mov INFO,eax
mov edx,[eax].dst.beg
mov ebp,edx
mov edi,[eax].dst.beg
mov ebx,[eax].src.beg
xor eax,eax // bmask = 0
jmp start
#endif /* !CAREFUL */
align 16
LABEL (literal_1):
mov [edi-1],cl
LABEL (literal):
#if CAREFUL
cmp edi,DST_STOP
jae ret_ok // recoded everything?
cmp ebx,SRC_END
jae LABEL(ret_err_1)
#endif
inc edi
mov cl,[ebx] // copy next byte
inc ebx
add eax,eax // check most significant bit
jnc LABEL (literal_1)
mov [edi-1],cl
jz LABEL (start) // need reloading?
LABEL (pointer):
#if CAREFUL
cmp edi,DST_STOP // decoded all the stuff? -- done
jae ret_ok_eof
cmp ebx,SRC_END_1
jae LABEL(ret_err_2)
#endif
xor edx,edx
mov dx,[ebx]
mov ecx,edx
shr edx,DIRECT2_LEN_LOG
add ebx,2
not edx // edx = -offset
and ecx,DIRECT2_MAX_LEN // ecx = length - MIN_LENGTH
lea esi,[edi+edx]
#if !CAREFUL && (8 - MIN_MATCH < DIRECT2_MAX_LEN)
cmp cl,8 - MIN_MATCH // length > 8?
ja LABEL (long_length)
cmp esi,ebp // output buffer underrun?
jb LABEL(ret_err_3)
cmp edx,-3
mov edx,[esi]
jae LABEL (byte_by_byte)
mov [edi],edx
mov edx,[esi+4]
mov [edi+4],edx
lea edi,[edi+ecx+MIN_MATCH]
add eax,eax
jnc LABEL (literal)
jnz LABEL (pointer)
jmp LABEL (start)
LABEL (byte_by_byte):
add ecx,MIN_MATCH
rep movsb
add eax,eax
jnc LABEL (literal)
jnz LABEL (pointer)
jmp LABEL (start)
LABEL (long_length):
#endif /* !CAREFUL && (8 - MIN_MATCH < DIRECT2_MAX_LEN) */
cmp esi,ebp // output buffer underrun?
jb LABEL(ret_err_4)
mov edx,PTR
cmp cl,DIRECT2_MAX_LEN
jne LABEL (done_len)
test edx,edx
je LABEL (ptr_zero)
xor ecx,ecx
mov cl,[edx]
xor edx,edx
shr ecx,4
jmp LABEL(done_quad)
LABEL (ptr_zero):
#if CAREFUL
cmp ebx,SRC_END
jae LABEL(ret_err_5)
#endif
xor ecx,ecx
mov cl,[ebx]
mov edx,ebx
and ecx,15
inc ebx
LABEL(done_quad):
mov PTR,edx
cmp cl,15
lea ecx,[ecx+DIRECT2_MAX_LEN]
je LABEL(len255)
LABEL(done_len):
lea edx,[edi+ecx+MIN_MATCH] // edx = end of copy
add ecx,MIN_MATCH
#if !CAREFUL
cmp edx,DST_CAREFUL // too close to end of buffer?
jae careful_copy_tail
#else
careful_copy_tail:
cmp edx,DST_STOP // ahead of output buffer?
jbe LABEL (checked_eob)
mov ecx,DST_STOP
sub ecx,edi // ecx = corrected length
rep movsb // copy substring
jmp ret_ok // no errors, no EOF mark
LABEL (checked_eob):
#endif
rep movsb // copy substring
add eax,eax
jnc LABEL (literal)
jnz LABEL (pointer)
align 16
LABEL (start):
#if !CAREFUL
cmp ebx,SRC_CAREFUL // too close to end of buffer(s)?
jae careful_start // be careful if so
cmp edi,DST_CAREFUL
jae careful_start
#else
cmp ebx,SRC_END_TAG // input buffer overrun? -- corrupted data
jae LABEL(ret_err_6)
#endif
mov eax,[ebx]
add ebx,4
test eax,eax
lea eax,[eax+eax+1]
jns LABEL (literal)
jmp LABEL (pointer)
LABEL(len255):
#if CAREFUL
cmp ebx,SRC_END
jae LABEL(ret_err_7)
#endif
xor ecx,ecx
mov cl,[ebx]
inc ebx
cmp cl,255
lea ecx,[ecx+15+DIRECT2_MAX_LEN]
jne LABEL(done_len)
#if CAREFUL
cmp ebx,SRC_END_1
jae LABEL(ret_err_7)
#endif
xor ecx,ecx
mov cx,[ebx]
add ebx,2
cmp ecx,255 + 15 + DIRECT2_MAX_LEN
jae LABEL (done_len)
#if CAREFUL
#ifndef DEBUG_LABEL
#if DEBUG
#define DEBUG_LABEL(label) label: mov eax, eax
#else
#define DEBUG_LABEL(label) label:
#endif /* DEBUG */
#endif /* DEBUG_LABEL */
DEBUG_LABEL(careful_ret_err_1)
DEBUG_LABEL(careful_ret_err_2)
DEBUG_LABEL(ret_err_3)
DEBUG_LABEL(ret_err_4)
DEBUG_LABEL(careful_ret_err_4)
DEBUG_LABEL(careful_ret_err_5)
DEBUG_LABEL(careful_ret_err_6)
DEBUG_LABEL(careful_ret_err_7)
xor eax,eax
jmp ret_common
ret_ok_eof:
mov ecx,INFO
mov eax,1
cmp edi,[ecx].dst.end
jne ret_ok
mov [ecx].eof,eax
ret_ok:
mov eax,1
mov ecx,INFO
mov [ecx].src.last,ebx
mov [ecx].dst.last,edi
ret_common:
MOV ecx,INFO
mov [ecx].result,eax
add esp,4*LOCALS
pop ebp
pop edi
pop esi
pop edx
pop ecx
pop ebx
} /* __asm */
#endif /* CAREFUL */
#endif /* i386 */
#endif /* ----------------- CODING == CODING_DIRECT2 --------------- */
/* --------------------------- End of code ------------------------- */
/* ----------- */
#if CAREFUL
} /* end of "do_decode" */
#endif /* CAREFUL */
#undef CAREFUL
#undef LABEL
#undef CAREFUL_LABEL
#undef CAREFUL_OK_IF
#undef CAREFUL_ERR_IF
#undef CAREFUL_EOF_IF
#undef CAREFUL_IF
#undef START
#undef FAST_COPY_DONE
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