inffas86.c

本代码为LZW算法的C语言实现程序

/* inffas86.c is a hand tuned assembler version of
 *
 * inffast.c -- fast decoding
 * Copyright (C) 1995-2003 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 *
 * Copyright (C) 2003 Chris Anderson <[e-mail]>
 * Please use the copyright conditions above.
 *
 * Mar-13-2003 -- Most of this is derived from inffast.S which is derived from
 * the gcc -S output of zlib-1.2.0/inffast.c.  Zlib-1.2.0 is in beta release at
 * the moment.  I have successfully compiled and tested this code with gcc2.96,
 * gcc3.2, icc5.0, msvc6.0.  It is very close to the speed of inffast.S
 * compiled with gcc -DNO_MMX, but inffast.S is still faster on the P3 with MMX
 * enabled.  I will attempt to merge the MMX code into this version.  Newer
 * versions of this and inffast.S can be found at
 * http://www.eetbeetee.com/zlib/ and http://www.charm.net/~christop/zlib/
 */

#include "zutil.h"
#include "inftrees.h"
#include "inflate.h"
#include "inffast.h"

/* Mark Adler's comments from inffast.c: */

/*
   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;
    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;
    }

#if defined( __GNUC__ ) || defined( __ICC )
    __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"