/* ------------------------------------------------------------------------ */ /* */ /* 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<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