Jonathon Fletcher / Mbed 2 deprecated MBEDZlib

Basic gzip/gunzip in memory buffer examples using zlib code.

Dependencies:   mbed-rtos mbed

There are small changes needed to the zconf.h file in the zlib distribution (I used 1.2.7). The zlib license applies to the zlib code - I have only imported a subset of the source.

The MBED has limited memory, so we need the following (near the top of zconf.h) to restrict memory allocation sizes:

#define    MAX_MEM_LEVEL    3
#define    MAX_WBITS        10

Because MAX_MEM_LEVEL and MAX_WBITS are so much lower than the default, there is a danger that the mbed cannot gunzip data compressed by a 'normal' zlib build. My use-case is to gzip on the mbed more than gunzip on the mbed so I have not given much time to this issue.

I also included this (also near the top of zconf.h) to prefix defines with Z_

#define    Z_PREFIX

In zconf.h, in the zlib distribution, the includes for <fcntl.h> and <sys/types.h> need commenting out when using the online compiler. No need when using GCC4MBED.

I also looked at miniz. I chose zlib because I needed the gzip headers and miniz does not implement them.

The sample main.cpp reads source data, compresses it, decompresses it, and finally compares the input data with the output data to confirm they are the same.

    unsigned char input_data[2048];
    unsigned long input_data_length = 0;
    FILE *ifp = fopen("/local/src.txt", "r");
    if (ifp) {
        int br = fread(input_data, 1, sizeof(input_data), ifp);
        fclose(ifp);
        input_data_length = br;
    }
    printf("%s:%d: input_data_length:%lu%s", __FILE__, __LINE__, input_data_length, newline);
 
 
    unsigned char gzip_data[2048];
    unsigned long gzip_data_length = 0;
    if (input_data_length > 0) {
        gzip_data_length = sizeof(gzip_data);
        int rv = gzip(gzip_data, &gzip_data_length, input_data, input_data_length);
        if (Z_OK == rv) {
            FILE *ofp = fopen("/local/dst.gz", "w");
            if (ofp) {
                int bw = fwrite(gzip_data, 1, gzip_data_length, ofp);
                fclose(ofp);
            }
        } else {
            printf("%s:%d: %d%s", __FILE__, __LINE__, rv, newline);
        }
    }
    printf("%s:%d: gzip_data_length:%lu%s", __FILE__, __LINE__, gzip_data_length, newline);
 
 
    unsigned char output_data[2048];
    unsigned long output_data_length = 0;
    if (gzip_data_length > 0) {
        output_data_length = sizeof(output_data);
        int rv = gunzip(output_data, &output_data_length, gzip_data, gzip_data_length);
        if (Z_OK != rv) {
            printf("%s:%d: %d%s", __FILE__, __LINE__, rv, newline);
        }
    }
    printf("%s:%d: output_data_length:%lu%s", __FILE__, __LINE__, output_data_length, newline);
 
 
    if (input_data_length > 0 and input_data_length > 0) {
        bool input_matches_output = false;
        if (input_data_length == output_data_length) {
            input_matches_output = true;
            for ( size_t i = 0 ; input_matches_output && i < input_data_length ; i++ ) {
                if (input_data[i] != output_data[i]) {
                    input_matches_output = false;
                }
            }
        }
        printf("%s:%d: input (%lu bytes) %s output (%lu bytes)%s", __FILE__, __LINE__, input_data_length, input_matches_output?"matches":"does not match", output_data_length, newline);
    } else {
        printf("%s:%d: input and/or output length is 0%s", __FILE__, __LINE__, newline);
    }

zlib/zutil.h

Committer:
jonathonfletcher
Date:
2012-10-21
Revision:
0:54f5be781526

File content as of revision 0:54f5be781526:

/* zutil.h -- internal interface and configuration of the compression library
 * Copyright (C) 1995-2012 Jean-loup Gailly.
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

/* WARNING: this file should *not* be used by applications. It is
   part of the implementation of the compression library and is
   subject to change. Applications should only use zlib.h.
 */

/* @(#) $Id$ */

#ifndef ZUTIL_H
#define ZUTIL_H

#ifdef HAVE_HIDDEN
#  define ZLIB_INTERNAL __attribute__((visibility ("hidden")))
#else
#  define ZLIB_INTERNAL
#endif

#include "zlib.h"

#if defined(STDC) && !defined(Z_SOLO)
#  if !(defined(_WIN32_WCE) && defined(_MSC_VER))
#    include <stddef.h>
#  endif
#  include <string.h>
#  include <stdlib.h>
#endif

#ifdef Z_SOLO
   typedef long ptrdiff_t;  /* guess -- will be caught if guess is wrong */
#endif

#ifndef local
#  define local static
#endif
/* compile with -Dlocal if your debugger can't find static symbols */

typedef unsigned char  uch;
typedef uch FAR uchf;
typedef unsigned short ush;
typedef ush FAR ushf;
typedef unsigned long  ulg;

extern const char * const z_errmsg[10]; /* indexed by 2-zlib_error */
/* (size given to avoid silly warnings with Visual C++) */

#define ERR_MSG(err) z_errmsg[Z_NEED_DICT-(err)]

#define ERR_RETURN(strm,err) \
  return (strm->msg = (char*)ERR_MSG(err), (err))
/* To be used only when the state is known to be valid */

        /* common constants */

#ifndef DEF_WBITS
#  define DEF_WBITS MAX_WBITS
#endif
/* default windowBits for decompression. MAX_WBITS is for compression only */

#if MAX_MEM_LEVEL >= 8
#  define DEF_MEM_LEVEL 8
#else
#  define DEF_MEM_LEVEL  MAX_MEM_LEVEL
#endif
/* default memLevel */

#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES    2
/* The three kinds of block type */

#define MIN_MATCH  3
#define MAX_MATCH  258
/* The minimum and maximum match lengths */

#define PRESET_DICT 0x20 /* preset dictionary flag in zlib header */

        /* target dependencies */

#if defined(MSDOS) || (defined(WINDOWS) && !defined(WIN32))
#  define OS_CODE  0x00
#  ifndef Z_SOLO
#    if defined(__TURBOC__) || defined(__BORLANDC__)
#      if (__STDC__ == 1) && (defined(__LARGE__) || defined(__COMPACT__))
         /* Allow compilation with ANSI keywords only enabled */
         void _Cdecl farfree( void *block );
         void *_Cdecl farmalloc( unsigned long nbytes );
#      else
#        include <alloc.h>
#      endif
#    else /* MSC or DJGPP */
#      include <malloc.h>
#    endif
#  endif
#endif

#ifdef AMIGA
#  define OS_CODE  0x01
#endif

#if defined(VAXC) || defined(VMS)
#  define OS_CODE  0x02
#  define F_OPEN(name, mode) \
     fopen((name), (mode), "mbc=60", "ctx=stm", "rfm=fix", "mrs=512")
#endif

#if defined(ATARI) || defined(atarist)
#  define OS_CODE  0x05
#endif

#ifdef OS2
#  define OS_CODE  0x06
#  if defined(M_I86) && !defined(Z_SOLO)
#    include <malloc.h>
#  endif
#endif

#if defined(MACOS) || defined(TARGET_OS_MAC)
#  define OS_CODE  0x07
#  ifndef Z_SOLO
#    if defined(__MWERKS__) && __dest_os != __be_os && __dest_os != __win32_os
#      include <unix.h> /* for fdopen */
#    else
#      ifndef fdopen
#        define fdopen(fd,mode) NULL /* No fdopen() */
#      endif
#    endif
#  endif
#endif

#ifdef TOPS20
#  define OS_CODE  0x0a
#endif

#ifdef WIN32
#  ifndef __CYGWIN__  /* Cygwin is Unix, not Win32 */
#    define OS_CODE  0x0b
#  endif
#endif

#ifdef __50SERIES /* Prime/PRIMOS */
#  define OS_CODE  0x0f
#endif

#if defined(_BEOS_) || defined(RISCOS)
#  define fdopen(fd,mode) NULL /* No fdopen() */
#endif

#if (defined(_MSC_VER) && (_MSC_VER > 600)) && !defined __INTERIX
#  if defined(_WIN32_WCE)
#    define fdopen(fd,mode) NULL /* No fdopen() */
#    ifndef _PTRDIFF_T_DEFINED
       typedef int ptrdiff_t;
#      define _PTRDIFF_T_DEFINED
#    endif
#  else
#    define fdopen(fd,type)  _fdopen(fd,type)
#  endif
#endif

#if defined(__BORLANDC__) && !defined(MSDOS)
  #pragma warn -8004
  #pragma warn -8008
  #pragma warn -8066
#endif

/* provide prototypes for these when building zlib without LFS */
#if !defined(_WIN32) && (!defined(_LARGEFILE64_SOURCE) || _LFS64_LARGEFILE-0 == 0)
    ZEXTERN uLong ZEXPORT adler32_combine64 OF((uLong, uLong, z_off_t));
    ZEXTERN uLong ZEXPORT crc32_combine64 OF((uLong, uLong, z_off_t));
#endif

        /* common defaults */

#ifndef OS_CODE
#  define OS_CODE  0x03  /* assume Unix */
#endif

#ifndef F_OPEN
#  define F_OPEN(name, mode) fopen((name), (mode))
#endif

         /* functions */

#if defined(pyr) || defined(Z_SOLO)
#  define NO_MEMCPY
#endif
#if defined(SMALL_MEDIUM) && !defined(_MSC_VER) && !defined(__SC__)
 /* Use our own functions for small and medium model with MSC <= 5.0.
  * You may have to use the same strategy for Borland C (untested).
  * The __SC__ check is for Symantec.
  */
#  define NO_MEMCPY
#endif
#if defined(STDC) && !defined(HAVE_MEMCPY) && !defined(NO_MEMCPY)
#  define HAVE_MEMCPY
#endif
#ifdef HAVE_MEMCPY
#  ifdef SMALL_MEDIUM /* MSDOS small or medium model */
#    define zmemcpy _fmemcpy
#    define zmemcmp _fmemcmp
#    define zmemzero(dest, len) _fmemset(dest, 0, len)
#  else
#    define zmemcpy memcpy
#    define zmemcmp memcmp
#    define zmemzero(dest, len) memset(dest, 0, len)
#  endif
#else
   void ZLIB_INTERNAL zmemcpy OF((Bytef* dest, const Bytef* source, uInt len));
   int ZLIB_INTERNAL zmemcmp OF((const Bytef* s1, const Bytef* s2, uInt len));
   void ZLIB_INTERNAL zmemzero OF((Bytef* dest, uInt len));
#endif

/* Diagnostic functions */
#ifdef DEBUG
#  include <stdio.h>
   extern int ZLIB_INTERNAL z_verbose;
   extern void ZLIB_INTERNAL z_error OF((char *m));
#  define Assert(cond,msg) {if(!(cond)) z_error(msg);}
#  define Trace(x) {if (z_verbose>=0) fprintf x ;}
#  define Tracev(x) {if (z_verbose>0) fprintf x ;}
#  define Tracevv(x) {if (z_verbose>1) fprintf x ;}
#  define Tracec(c,x) {if (z_verbose>0 && (c)) fprintf x ;}
#  define Tracecv(c,x) {if (z_verbose>1 && (c)) fprintf x ;}
#else
#  define Assert(cond,msg)
#  define Trace(x)
#  define Tracev(x)
#  define Tracevv(x)
#  define Tracec(c,x)
#  define Tracecv(c,x)
#endif

#ifndef Z_SOLO
   voidpf ZLIB_INTERNAL zcalloc OF((voidpf opaque, unsigned items,
                                    unsigned size));
   void ZLIB_INTERNAL zcfree  OF((voidpf opaque, voidpf ptr));
#endif

#define ZALLOC(strm, items, size) \
           (*((strm)->zalloc))((strm)->opaque, (items), (size))
#define ZFREE(strm, addr)  (*((strm)->zfree))((strm)->opaque, (voidpf)(addr))
#define TRY_FREE(s, p) {if (p) ZFREE(s, p);}

/* Reverse the bytes in a 32-bit value */
#define ZSWAP32(q) ((((q) >> 24) & 0xff) + (((q) >> 8) & 0xff00) + \
                    (((q) & 0xff00) << 8) + (((q) & 0xff) << 24))

#endif /* ZUTIL_H */