/* inffast.c -- fast decoding * Copyright (C) 1995-2004 Mark Adler * For conditions of distribution and use, see copyright notice in zlib.h */ #include "zutil.h" #include "inftrees.h" #include "inflate.h" #include "inffast.h" #ifdef __i386__ void inflate_fast(strm, start) z_streamp strm; unsigned start; /* inflate()'s starting value for strm->avail_out */ { struct inflate_state FAR *state; struct inffast_ar { void *esp; /* esp save */ unsigned char FAR *in; /* local strm->next_in */ unsigned char FAR *last; /* while in < last, enough input available */ unsigned char FAR *out; /* local strm->next_out */ unsigned char FAR *beg; /* inflate()'s initial strm->next_out */ unsigned char FAR *end; /* while out < end, enough space available */ unsigned wsize; /* window size or zero if not using window */ unsigned write; /* window write index */ unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */ unsigned long hold; /* local strm->hold */ unsigned bits; /* local strm->bits */ code const FAR *lcode; /* local strm->lencode */ code const FAR *dcode; /* local strm->distcode */ unsigned lmask; /* mask for first level of length codes */ unsigned dmask; /* mask for first level of distance codes */ unsigned len; /* match length, unused bytes */ unsigned dist; /* match distance */ unsigned status; /* this is set when state changes */ } ar; /* copy state to local variables */ state = (struct inflate_state FAR *)strm->state; ar.in = strm->next_in; ar.last = ar.in + (strm->avail_in - 5); ar.out = strm->next_out; ar.beg = ar.out - (start - strm->avail_out); ar.end = ar.out + (strm->avail_out - 257); ar.wsize = state->wsize; ar.write = state->write; ar.window = state->window; ar.hold = state->hold; ar.bits = state->bits; ar.lcode = state->lencode; ar.dcode = state->distcode; ar.lmask = (1U << state->lenbits) - 1; ar.dmask = (1U << state->distbits) - 1; /* decode literals and length/distances until end-of-block or not enough input data or output space */ /* align in on 2 byte boundary */ if (((unsigned long)(void *)ar.in & 0x1) != 0) { ar.hold += (unsigned long)*ar.in++ << ar.bits; ar.bits += 8; } __asm__ __volatile__ ( " leal %0, %%eax\n" " pushf\n" " pushl %%ebp\n" " movl %%esp, (%%eax)\n" " movl %%eax, %%esp\n" " movl 4(%%esp), %%esi\n" /* esi = in */ " movl 12(%%esp), %%edi\n" /* edi = out */ " movl 36(%%esp), %%edx\n" /* edx = hold */ " movl 40(%%esp), %%ebx\n" /* ebx = bits */ " movl 44(%%esp), %%ebp\n" /* ebp = lcode */ " cld\n" " jmp .L_do_loop\n" ".L_while_test:\n" " cmpl %%edi, 20(%%esp)\n" " jbe .L_break_loop\n" " cmpl %%esi, 8(%%esp)\n" " jbe .L_break_loop\n" ".L_do_loop:\n" " cmpb $15, %%bl\n" " ja .L_get_length_code\n" /* if (15 < bits) */ " xorl %%eax, %%eax\n" " lodsw\n" /* al = *(ushort *)in++ */ " movb %%bl, %%cl\n" /* cl = bits, needs it for shifting */ " addb $16, %%bl\n" /* bits += 16 */ " shll %%cl, %%eax\n" " orl %%eax, %%edx\n" /* hold |= *((ushort *)in)++ << bits */ ".L_get_length_code:\n" " movl 52(%%esp), %%eax\n" /* eax = lmask */ " andl %%edx, %%eax\n" /* eax &= hold */ " movl (%%ebp,%%eax,4), %%eax\n" /* eax = lcode[hold & lmask] */ ".L_dolen:\n" " movb %%ah, %%cl\n" /* cl = this.bits */ " subb %%ah, %%bl\n" /* bits -= this.bits */ " shrl %%cl, %%edx\n" /* hold >>= this.bits */ " testb %%al, %%al\n" " jnz .L_test_for_length_base\n" /* if (op != 0) 45.7% */ " shrl $16, %%eax\n" /* output this.val char */ " stosb\n" " jmp .L_while_test\n" ".L_test_for_length_base:\n" " movl %%eax, %%ecx\n" /* len = this */ " shrl $16, %%ecx\n" /* len = this.val */ " movl %%ecx, 60(%%esp)\n" /* len = this */ " movb %%al, %%cl\n" " testb $16, %%al\n" " jz .L_test_for_second_level_length\n" /* if ((op & 16) == 0) 8% */ " andb $15, %%cl\n" /* op &= 15 */ " jz .L_decode_distance\n" /* if (!op) */ " cmpb %%cl, %%bl\n" " jae .L_add_bits_to_len\n" /* if (op <= bits) */ " movb %%cl, %%ch\n" /* stash op in ch, freeing cl */ " xorl %%eax, %%eax\n" " lodsw\n" /* al = *(ushort *)in++ */ " movb %%bl, %%cl\n" /* cl = bits, needs it for shifting */ " addb $16, %%bl\n" /* bits += 16 */ " shll %%cl, %%eax\n" " orl %%eax, %%edx\n" /* hold |= *((ushort *)in)++ << bits */ " movb %%ch, %%cl\n" /* move op back to ecx */ ".L_add_bits_to_len:\n" " movl $1, %%eax\n" " shll %%cl, %%eax\n" " decl %%eax\n" " subb %%cl, %%bl\n" " andl %%edx, %%eax\n" /* eax &= hold */ " shrl %%cl, %%edx\n" " addl %%eax, 60(%%esp)\n" /* len += hold & mask[op] */ ".L_decode_distance:\n" " cmpb $15, %%bl\n" " ja .L_get_distance_code\n" /* if (15 < bits) */ " xorl %%eax, %%eax\n" " lodsw\n" /* al = *(ushort *)in++ */ " movb %%bl, %%cl\n" /* cl = bits, needs it for shifting */ " addb $16, %%bl\n" /* bits += 16 */ " shll %%cl, %%eax\n" " orl %%eax, %%edx\n" /* hold |= *((ushort *)in)++ << bits */ ".L_get_distance_code:\n" " movl 56(%%esp), %%eax\n" /* eax = dmask */ " movl 48(%%esp), %%ecx\n" /* ecx = dcode */ " andl %%edx, %%eax\n" /* eax &= hold */ " movl (%%ecx,%%eax,4), %%eax\n"/* eax = dcode[hold & dmask] */ ".L_dodist:\n" " movl %%eax, %%ebp\n" /* dist = this */ " shrl $16, %%ebp\n" /* dist = this.val */ " movb %%ah, %%cl\n" " subb %%ah, %%bl\n" /* bits -= this.bits */ " shrl %%cl, %%edx\n" /* hold >>= this.bits */ " movb %%al, %%cl\n" /* cl = this.op */ " testb $16, %%al\n" /* if ((op & 16) == 0) */ " jz .L_test_for_second_level_dist\n" " andb $15, %%cl\n" /* op &= 15 */ " jz .L_check_dist_one\n" " cmpb %%cl, %%bl\n" " jae .L_add_bits_to_dist\n" /* if (op <= bits) 97.6% */ " movb %%cl, %%ch\n" /* stash op in ch, freeing cl */ " xorl %%eax, %%eax\n" " lodsw\n" /* al = *(ushort *)in++ */ " movb %%bl, %%cl\n" /* cl = bits, needs it for shifting */ " addb $16, %%bl\n" /* bits += 16 */ " shll %%cl, %%eax\n" " orl %%eax, %%edx\n" /* hold |= *((ushort *)in)++ << bits */ " movb %%ch, %%cl\n" /* move op back to ecx */ ".L_add_bits_to_dist:\n" " movl $1, %%eax\n" " shll %%cl, %%eax\n" " decl %%eax\n" /* (1 << op) - 1 */ " subb %%cl, %%bl\n" " andl %%edx, %%eax\n" /* eax &= hold */ " shrl %%cl, %%edx\n" " addl %%eax, %%ebp\n" /* dist += hold & ((1 << op) - 1) */ ".L_check_window:\n" " movl %%esi, 4(%%esp)\n" /* save in so from can use it's reg */ " movl %%edi, %%eax\n" " subl 16(%%esp), %%eax\n" /* nbytes = out - beg */ " cmpl %%ebp, %%eax\n" " jb .L_clip_window\n" /* if (dist > nbytes) 4.2% */ " movl 60(%%esp), %%ecx\n" " movl %%edi, %%esi\n" " subl %%ebp, %%esi\n" /* from = out - dist */ " subl $3, %%ecx\n" /* copy from to out */ " movb (%%esi), %%al\n" " movb %%al, (%%edi)\n" " movb 1(%%esi), %%al\n" " movb 2(%%esi), %%ah\n" " addl $3, %%esi\n" " movb %%al, 1(%%edi)\n" " movb %%ah, 2(%%edi)\n" " addl $3, %%edi\n" " rep movsb\n" " movl 4(%%esp), %%esi\n" /* move in back to %esi, toss from */ " movl 44(%%esp), %%ebp\n" /* ebp = lcode */ " jmp .L_while_test\n" ".L_check_dist_one:\n" " cmpl $1, %%ebp\n" /* if dist 1, is a memset */ " jne .L_check_window\n" " cmpl %%edi, 16(%%esp)\n" " je .L_check_window\n" " decl %%edi\n" " movl 60(%%esp), %%ecx\n" " movb (%%edi), %%al\n" " subl $3, %%ecx\n" " movb %%al, 1(%%edi)\n" /* memset out with from[-1] */ " movb %%al, 2(%%edi)\n" " movb %%al, 3(%%edi)\n" " addl $4, %%edi\n" " rep stosb\n" " movl 44(%%esp), %%ebp\n" /* ebp = lcode */ " jmp .L_while_test\n" ".L_test_for_second_level_length:\n" " testb $64, %%al\n" " jnz .L_test_for_end_of_block\n" /* if ((op & 64) != 0) */ " movl $1, %%eax\n" " shll %%cl, %%eax\n" " decl %%eax\n" " andl %%edx, %%eax\n" /* eax &= hold */ " addl 60(%%esp), %%eax\n" /* eax += this.val */ " movl (%%ebp,%%eax,4), %%eax\n" /* eax = lcode[val+(hold&mask[op])]*/ " jmp .L_dolen\n" ".L_test_for_second_level_dist:\n" " testb $64, %%al\n" " jnz .L_invalid_distance_code\n" /* if ((op & 64) != 0) */ " movl $1, %%eax\n" " shll %%cl, %%eax\n" " decl %%eax\n" " andl %%edx, %%eax\n" /* eax &= hold */ " addl %%ebp, %%eax\n" /* eax += this.val */ " movl 48(%%esp), %%ecx\n" /* ecx = dcode */ " movl (%%ecx,%%eax,4), %%eax\n" /* eax = dcode[val+(hold&mask[op])]*/ " jmp .L_dodist\n" ".L_clip_window:\n" " movl %%eax, %%ecx\n" " movl 24(%%esp), %%eax\n" /* prepare for dist compare */ " negl %%ecx\n" /* nbytes = -nbytes */ " movl 32(%%esp), %%esi\n" /* from = window */ " cmpl %%ebp, %%eax\n" " jb .L_invalid_distance_too_far\n" /* if (dist > wsize) */ " addl %%ebp, %%ecx\n" /* nbytes = dist - nbytes */ " cmpl $0, 28(%%esp)\n" " jne .L_wrap_around_window\n" /* if (write != 0) */ " subl %%ecx, %%eax\n" " addl %%eax, %%esi\n" /* from += wsize - nbytes */ " movl 60(%%esp), %%eax\n" " cmpl %%ecx, %%eax\n" " jbe .L_do_copy1\n" /* if (nbytes >= len) */ " subl %%ecx, %%eax\n" /* len -= nbytes */ " rep movsb\n" " movl %%edi, %%esi\n" " subl %%ebp, %%esi\n" /* from = out - dist */ " jmp .L_do_copy1\n" " cmpl %%ecx, %%eax\n" " jbe .L_do_copy1\n" /* if (nbytes >= len) */ " subl %%ecx, %%eax\n" /* len -= nbytes */ " rep movsb\n" " movl %%edi, %%esi\n" " subl %%ebp, %%esi\n" /* from = out - dist */ " jmp .L_do_copy1\n" ".L_wrap_around_window:\n" " movl 28(%%esp), %%eax\n" " cmpl %%eax, %%ecx\n" " jbe .L_contiguous_in_window\n" /* if (write >= nbytes) */ " addl 24(%%esp), %%esi\n" " addl %%eax, %%esi\n" " subl %%ecx, %%esi\n" /* from += wsize + write - nbytes */ " subl %%eax, %%ecx\n" /* nbytes -= write */ " movl 60(%%esp), %%eax\n" " cmpl %%ecx, %%eax\n" " jbe .L_do_copy1\n" /* if (nbytes >= len) */ " subl %%ecx, %%eax\n" /* len -= nbytes */ " rep movsb\n" " movl 32(%%esp), %%esi\n" /* from = window */ " movl 28(%%esp), %%ecx\n" /* nbytes = write */ " cmpl %%ecx, %%eax\n" " jbe .L_do_copy1\n" /* if (nbytes >= len) */ " subl %%ecx, %%eax\n" /* len -= nbytes */ " rep movsb\n" " movl %%edi, %%esi\n" " subl %%ebp, %%esi\n" /* from = out - dist */ " jmp .L_do_copy1\n" ".L_contiguous_in_window:\n" " addl %%eax, %%esi\n" " subl %%ecx, %%esi\n" /* from += write - nbytes */ " movl 60(%%esp), %%eax\n" " cmpl %%ecx, %%eax\n" " jbe .L_do_copy1\n" /* if (nbytes >= len) */ " subl %%ecx, %%eax\n" /* len -= nbytes */ " rep movsb\n" " movl %%edi, %%esi\n" " subl %%ebp, %%esi\n" /* from = out - dist */ ".L_do_copy1:\n" " movl %%eax, %%ecx\n" " rep movsb\n" " movl 4(%%esp), %%esi\n" /* move in back to %esi, toss from */ " movl 44(%%esp), %%ebp\n" /* ebp = lcode */ " jmp .L_while_test\n" ".L_test_for_end_of_block:\n" " testb $32, %%al\n" " jz .L_invalid_literal_length_code\n" " movl $1, 68(%%esp)\n" " jmp .L_break_loop_with_status\n" ".L_invalid_literal_length_code:\n" " movl $2, 68(%%esp)\n" " jmp .L_break_loop_with_status\n" ".L_invalid_distance_code:\n" " movl $3, 68(%%esp)\n" " jmp .L_break_loop_with_status\n" ".L_invalid_distance_too_far:\n" " movl 4(%%esp), %%esi\n" " movl $4, 68(%%esp)\n" " jmp .L_break_loop_with_status\n" ".L_break_loop:\n" " movl $0, 68(%%esp)\n" ".L_break_loop_with_status:\n" /* put in, out, bits, and hold back into ar and pop esp */ " movl %%esi, 4(%%esp)\n" " movl %%edi, 12(%%esp)\n" " movl %%ebx, 40(%%esp)\n" " movl %%edx, 36(%%esp)\n" " movl (%%esp), %%esp\n" " popl %%ebp\n" " popf\n" : : "m" (ar) : "memory", "%eax", "%ebx", "%ecx", "%edx", "%esi", "%edi" ); if (ar.status > 1) { if (ar.status == 2) strm->msg = "invalid literal/length code"; else if (ar.status == 3) strm->msg = "invalid distance code"; else strm->msg = "invalid distance too far back"; state->mode = BAD; } else if ( ar.status == 1 ) { state->mode = TYPE; } /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ ar.len = ar.bits >> 3; ar.in -= ar.len; ar.bits -= ar.len << 3; ar.hold &= (1U << ar.bits) - 1; /* update state and return */ strm->next_in = ar.in; strm->next_out = ar.out; strm->avail_in = (unsigned)(ar.in < ar.last ? 5 + (ar.last - ar.in) : 5 - (ar.in - ar.last)); strm->avail_out = (unsigned)(ar.out < ar.end ? 257 + (ar.end - ar.out) : 257 - (ar.out - ar.end)); state->hold = ar.hold; state->bits = ar.bits; return; } #else /* Allow machine dependent optimization for post-increment or pre-increment. Based on testing to date, Pre-increment preferred for: - PowerPC G3 (Adler) - MIPS R5000 (Randers-Pehrson) Post-increment preferred for: - none No measurable difference: - Pentium III (Anderson) - M68060 (Nikl) */ #ifdef POSTINC # define OFF 0 # define PUP(a) *(a)++ #else # define OFF 1 # define PUP(a) *++(a) #endif /* Decode literal, length, and distance codes and write out the resulting literal and match bytes until either not enough input or output is available, an end-of-block is encountered, or a data error is encountered. When large enough input and output buffers are supplied to inflate(), for example, a 16K input buffer and a 64K output buffer, more than 95% of the inflate execution time is spent in this routine. Entry assumptions: state->mode == LEN strm->avail_in >= 6 strm->avail_out >= 258 start >= strm->avail_out state->bits < 8 On return, state->mode is one of: LEN -- ran out of enough output space or enough available input TYPE -- reached end of block code, inflate() to interpret next block BAD -- error in block data Notes: - The maximum input bits used by a length/distance pair is 15 bits for the length code, 5 bits for the length extra, 15 bits for the distance code, and 13 bits for the distance extra. This totals 48 bits, or six bytes. Therefore if strm->avail_in >= 6, then there is enough input to avoid checking for available input while decoding. - The maximum bytes that a single length/distance pair can output is 258 bytes, which is the maximum length that can be coded. inflate_fast() requires strm->avail_out >= 258 for each loop to avoid checking for output space. */ void inflate_fast(strm, start) z_streamp strm; unsigned start; /* inflate()'s starting value for strm->avail_out */ { struct inflate_state FAR *state; unsigned char FAR *in; /* local strm->next_in */ unsigned char FAR *last; /* while in < last, enough input available */ unsigned char FAR *out; /* local strm->next_out */ unsigned char FAR *beg; /* inflate()'s initial strm->next_out */ unsigned char FAR *end; /* while out < end, enough space available */ #ifdef INFLATE_STRICT unsigned dmax; /* maximum distance from zlib header */ #endif unsigned wsize; /* window size or zero if not using window */ unsigned whave; /* valid bytes in the window */ unsigned write; /* window write index */ unsigned char FAR *window; /* allocated sliding window, if wsize != 0 */ unsigned long hold; /* local strm->hold */ unsigned bits; /* local strm->bits */ code const FAR *lcode; /* local strm->lencode */ code const FAR *dcode; /* local strm->distcode */ unsigned lmask; /* mask for first level of length codes */ unsigned dmask; /* mask for first level of distance codes */ code this; /* retrieved table entry */ unsigned op; /* code bits, operation, extra bits, or */ /* window position, window bytes to copy */ unsigned len; /* match length, unused bytes */ unsigned dist; /* match distance */ unsigned char FAR *from; /* where to copy match from */ /* copy state to local variables */ state = (struct inflate_state FAR *)strm->state; in = strm->next_in - OFF; last = in + (strm->avail_in - 5); out = strm->next_out - OFF; beg = out - (start - strm->avail_out); end = out + (strm->avail_out - 257); #ifdef INFLATE_STRICT dmax = state->dmax; #endif wsize = state->wsize; whave = state->whave; write = state->write; window = state->window; hold = state->hold; bits = state->bits; lcode = state->lencode; dcode = state->distcode; lmask = (1U << state->lenbits) - 1; dmask = (1U << state->distbits) - 1; /* decode literals and length/distances until end-of-block or not enough input data or output space */ do { if (bits < 15) { hold += (unsigned long)(PUP(in)) << bits; bits += 8; hold += (unsigned long)(PUP(in)) << bits; bits += 8; } this = lcode[hold & lmask]; dolen: op = (unsigned)(this.bits); hold >>= op; bits -= op; op = (unsigned)(this.op); if (op == 0) { /* literal */ Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ? "inflate: literal '%c'\n" : "inflate: literal 0x%02x\n", this.val)); PUP(out) = (unsigned char)(this.val); } else if (op & 16) { /* length base */ len = (unsigned)(this.val); op &= 15; /* number of extra bits */ if (op) { if (bits < op) { hold += (unsigned long)(PUP(in)) << bits; bits += 8; } len += (unsigned)hold & ((1U << op) - 1); hold >>= op; bits -= op; } Tracevv((stderr, "inflate: length %u\n", len)); if (bits < 15) { hold += (unsigned long)(PUP(in)) << bits; bits += 8; hold += (unsigned long)(PUP(in)) << bits; bits += 8; } this = dcode[hold & dmask]; dodist: op = (unsigned)(this.bits); hold >>= op; bits -= op; op = (unsigned)(this.op); if (op & 16) { /* distance base */ dist = (unsigned)(this.val); op &= 15; /* number of extra bits */ if (bits < op) { hold += (unsigned long)(PUP(in)) << bits; bits += 8; if (bits < op) { hold += (unsigned long)(PUP(in)) << bits; bits += 8; } } dist += (unsigned)hold & ((1U << op) - 1); #ifdef INFLATE_STRICT if (dist > dmax) { strm->msg = (char *)"invalid distance too far back"; state->mode = BAD; break; } #endif hold >>= op; bits -= op; Tracevv((stderr, "inflate: distance %u\n", dist)); op = (unsigned)(out - beg); /* max distance in output */ if (dist > op) { /* see if copy from window */ op = dist - op; /* distance back in window */ if (op > whave) { strm->msg = (char *)"invalid distance too far back"; state->mode = BAD; break; } from = window - OFF; if (write == 0) { /* very common case */ from += wsize - op; if (op < len) { /* some from window */ len -= op; do { PUP(out) = PUP(from); } while (--op); from = out - dist; /* rest from output */ } } else if (write < op) { /* wrap around window */ from += wsize + write - op; op -= write; if (op < len) { /* some from end of window */ len -= op; do { PUP(out) = PUP(from); } while (--op); from = window - OFF; if (write < len) { /* some from start of window */ op = write; len -= op; do { PUP(out) = PUP(from); } while (--op); from = out - dist; /* rest from output */ } } } else { /* contiguous in window */ from += write - op; if (op < len) { /* some from window */ len -= op; do { PUP(out) = PUP(from); } while (--op); from = out - dist; /* rest from output */ } } while (len > 2) { PUP(out) = PUP(from); PUP(out) = PUP(from); PUP(out) = PUP(from); len -= 3; } if (len) { PUP(out) = PUP(from); if (len > 1) PUP(out) = PUP(from); } } else { from = out - dist; /* copy direct from output */ do { /* minimum length is three */ PUP(out) = PUP(from); PUP(out) = PUP(from); PUP(out) = PUP(from); len -= 3; } while (len > 2); if (len) { PUP(out) = PUP(from); if (len > 1) PUP(out) = PUP(from); } } } else if ((op & 64) == 0) { /* 2nd level distance code */ this = dcode[this.val + (hold & ((1U << op) - 1))]; goto dodist; } else { strm->msg = (char *)"invalid distance code"; state->mode = BAD; break; } } else if ((op & 64) == 0) { /* 2nd level length code */ this = lcode[this.val + (hold & ((1U << op) - 1))]; goto dolen; } else if (op & 32) { /* end-of-block */ Tracevv((stderr, "inflate: end of block\n")); state->mode = TYPE; break; } else { strm->msg = (char *)"invalid literal/length code"; state->mode = BAD; break; } } while (in < last && out < end); /* return unused bytes (on entry, bits < 8, so in won't go too far back) */ len = bits >> 3; in -= len; bits -= len << 3; hold &= (1U << bits) - 1; /* update state and return */ strm->next_in = in + OFF; strm->next_out = out + OFF; strm->avail_in = (unsigned)(in < last ? 5 + (last - in) : 5 - (in - last)); strm->avail_out = (unsigned)(out < end ? 257 + (end - out) : 257 - (out - end)); state->hold = hold; state->bits = bits; return; } /* inflate_fast() speedups that turned out slower (on a PowerPC G3 750CXe): - Using bit fields for code structure - Different op definition to avoid & for extra bits (do & for table bits) - Three separate decoding do-loops for direct, window, and write == 0 - Special case for distance > 1 copies to do overlapped load and store copy - Explicit branch predictions (based on measured branch probabilities) - Deferring match copy and interspersed it with decoding subsequent codes - Swapping literal/length else - Swapping window/direct else - Larger unrolled copy loops (three is about right) - Moving len -= 3 statement into middle of loop */ #endif /* !i386 */