flate.s

zip压缩

;===========================================================================
; Copyright (c) 1990-2001 Info-ZIP.  All rights reserved.
;
; See the accompanying file LICENSE, version 2000-Apr-09 or later
; (the contents of which are also included in unzip.h) for terms of use.
; If, for some reason, all these files are missing, the Info-ZIP license
; also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html
;===========================================================================
; flate.a created by Paul Kienitz, 20 June 94.  Last modified 03 Mar 2001.
;
; 68000 assembly language version of inflate_codes(), for Amiga.  Prototype:
;
;   int inflate_codes(__GPRO__ struct huft *tl, struct huft *td,
;                     int bl, int bd);
;
; Where __GPRO__ expands to "Uz_Globs *G," if REENTRANT is defined,
; otherwise to nothing.  In the latter case G is a global variable.
;
; Define the symbol FUNZIP if this is for fUnZip.  It overrides REENTRANT.
;
; Define AZTEC to use the Aztec C macro version of getc() instead of the
; library getc() with FUNZIP.  AZTEC is ignored if FUNZIP is not defined.
;
; Define NO_CHECK_EOF to not use the fancy paranoid version of NEEDBITS --
; this is equivalent to removing the #define CHECK_EOF from inflate.c.
;
; Define INT16 if ints are short, otherwise it assumes ints are long.
;
; Define USE_DEFLATE64 if we're supporting Deflate64 decompression.
;
; Do NOT define WSIZE; it is always 32K or 64K depending on USE_DEFLATE64.
;
; 1999/09/23: for Human68k: Modified by Shimazaki Ryo.

X:              EQU     $7ffe

                IFDEF   INT16
MOVINT           MACRO  _1,_2
        move.w          _1,_2
                 ENDM
INTSIZE equ     2
                ELSE    ; !INT16
MOVINT           MACRO  _1,_2
        move.l          _1,_2
                 ENDM
INTSIZE equ     4
                ENDC

                IFDEF   REENTRANT
                 IFNDEF FUNZIP
REENT_G equ     1
                 ENDC
                ENDC

; The following include file is generated from globals.h, and gives us equates
; that give the offsets in Uz_Globs of the fields we use, which are:
;       ulg bb
;       unsigned int bk, wp
;       (either array of unsigned char, or pointer to unsigned char) redirslide
; For fUnZip:
;       FILE *in
; For regular UnZip but not fUnZip:
;       int incnt, mem_mode
;       long csize
;       uch *inptr
; It also defines a value SIZEOF_slide, which tells us whether the appropriate
; slide field in G (either area.Slide or redirect_pointer) is a pointer or an
; array instance.  It is 4 in the former case and a large value in the latter.
; Lastly, this include will define CRYPT as 1 if appropriate.

                IFDEF   FUNZIP
        INCLUDE  human68k/G_offs_.mac
                ELSE
                 IFDEF  SFX
        INCLUDE  human68k/G_offsf.mac"
                 ELSE
        INCLUDE  human68k/G_offs.mac
                 ENDC
                ENDC

; struct huft is defined as follows:
;
;   struct huft {
;     uch e;                /* number of extra bits or operation */
;     uch b;                /* number of bits in this code or subcode */
;     union {
;       ush n;              /* literal, length base, or distance base */
;       struct huft *t;     /* pointer to next level of table */
;     } v;
;   };                      /* sizeof(struct huft) == 6 */
;
; The G_offs include defines offsets h_e, h_b, h_v_n, and h_v_t in this
; struct, plus SIZEOF_huft.

; G.bb is the global buffer that holds bits from the huffman code stream, which
; we cache in the register variable b.  G.bk is the number of valid bits in it,
; which we cache in k.  The macros NEEDBITS(n) and DUMPBITS(n) have side effects
; on b and k.

                IFDEF   REENT_G
G_SIZE  equ     4
G_PUSH           MACRO          ; this macro passes "__G__" to functions
        move.l          G,-(sp)
                 ENDM
                ELSE
        xref    _G              ; Uz_Globs
G_SIZE  equ     0
G_PUSH           MACRO
        ds.b            0       ; does nothing; the assembler dislikes MACRO ENDM
                 ENDM
                ENDC    ; REENT_G

;;      xref    _mask_bits      ; const ush mask_bits[17];
                IFDEF   FUNZIP
                 IF     CRYPT
        xref    _encrypted      ; int -- boolean flag
        xref    _update_keys    ; int update_keys(__GPRO__ int)
        xref    _decrypt_byte   ; int decrypt_byte(__GPRO)
                 ENDC   ; CRYPT
                ELSE    ; !FUNZIP
        xref    _memflush       ; int memflush(__GPRO__ uch *, ulg)
        xref    _readbyte       ; int readbyte(__GPRO)
                ENDC    ; FUNZIP

        xref    _flush          ; if FUNZIP:  int flush(__GPRO__ ulg)
                                ; else:  int flush(__GPRO__ uch *, ulg, int)

; Here are our register variables.

b       reg     d2              ; unsigned long
k       reg     d3              ; unsigned short <= 32
e       reg     d4              ; unsigned int, mostly used as unsigned char
w       reg     d5              ; unsigned long (was short before deflate64)
n       reg     d6              ; unsigned long (was short before deflate64)
d       reg     d7              ; unsigned int, used as unsigned short

t       reg     a2              ; struct huft *
lmask   reg     a3              ; ulg *
G       reg     a6              ; Uz_Globs *

; Couple other items we need:

savregs reg     d2-d7/a2/a3/a6
                IFDEF   USE_DEFLATE64
WSIZE   equ     $10000          ; 64K... be careful not to treat as short!
                ELSE
WSIZE   equ     $08000          ; 32K... be careful not to treat as negative!
                ENDC
EOF     equ     -1
INVALID equ     99

; inflate_codes() returns one of the following status codes:
;          0  OK
;          1  internal inflate error or EOF on input stream
;         the following return codes are passed through from FLUSH() errors
;          50 (PK_DISK)   "overflow of output space"
;          80 (IZ_CTRLC)  "canceled by user's request"

RET_OK  equ     0
RET_ERR equ     1

                IFDEF   FUNZIP
; This does getc(in).  LIBC version is based on #define getc(fp) in stdio.h

GETC              MACRO
        xref    _fgetc          ; int fgetc(FILE *)
        move.l          in-X(G),-(sp)
        jsr             _fgetc
        addq.l          #4,sp
                  ENDM
                ENDC    ; FUNZIP

; Input depends on the NEXTBYTE macro.  This exists in three different forms.
; The first two are for fUnZip, with and without decryption.  The last is for
; regular UnZip with or without decryption.  The resulting byte is returned
; in d0 as a longword, and d1, a0, and a1 are clobbered.

; FLUSH also has different forms for UnZip and fUnZip.  Arg must be a longword.
; The same scratch registers are trashed.

                IFDEF   FUNZIP

NEXTBYTE         MACRO
        move.l   d2,-(sp)
        GETC
                  IF    CRYPT
        tst.w           _encrypted+INTSIZE-2    ; test low word if long
        beq.s           @nbe
        MOVINT          d0,-(sp)                ; save thru next call
        G_PUSH
        jsr             _decrypt_byte
        eor.w           d0,G_SIZE+INTSIZE-2(sp) ; becomes arg to update_keys
        jsr             _update_keys
        addq            #INTSIZE+G_SIZE,sp
@nbe:
                  ENDC  ; !CRYPT
                  IFEQ INTSIZE-2
        ext.l           d0              ; assert -1 <= d0 <= 255
                  ENDC
        move.l   (sp)+,d2
                 ENDM

FLUSH            MACRO  _1
        move.l          d2,-(sp)
        move.l          _1,-(sp)
        G_PUSH
        jsr             _flush
        addq            #4+G_SIZE,sp
        move.l          (sp)+,d2
                 ENDM

                ELSE    ; !FUNZIP

NEXTBYTE         MACRO
        subq.w          #1,incnt+INTSIZE-2-X(G)   ; treat as short
        bge.s           @nbs
                IFNE INTSIZE-2
        subq.w          #1,incnt-X(G)
        bge.s           @nbs
                ENDIF
        move.l          d2,-(sp)
        G_PUSH
        jsr             _readbyte
                  IFNE G_SIZE
        addq            #G_SIZE,sp
                  ENDC
        move.l          (sp)+,d2
                  IFEQ 2-INTSIZE
        ext.l           d0            ; assert -1 <= d0 <= 255
                  ENDC
        bra.s           @nbe
@nbs:   moveq           #0,d0
        move.l          inptr-X(G),a0
        move.b          (a0)+,d0
        move.l          a0,inptr-X(G)
@nbe:
                 ENDM

FLUSH            MACRO  _1
        move.l          d2,-(sp)
        clr.l           -(sp)                   ; unshrink flag: always false
        move.l          _1,-(sp)                ; length
                  IF    SIZEOF_slide>4
        pea             redirslide-X(G)           ; buffer to flush
                  ELSE
        move.l          redirslide-X(G),-(sp)
                  ENDC
        G_PUSH