url_mem.c

MIDI解码程序(用VC编写)

/*
    TiMidity++ -- MIDI to WAVE converter and player
    Copyright (C) 1999-2002 Masanao Izumo <[e-mail]>
    Copyright (C) 1995 Tuukka Toivonen <[e-mail]>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#include <stdio.h>
#include <stdlib.h>
#ifndef NO_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */
#include "timidity.h"
#include "url.h"

typedef struct _URL_mem
{
    char common[sizeof(struct _URL)];
    char *memory;
    long  memsiz;
    long  mempos;
    int   autofree;
} URL_mem;

static long url_mem_read(URL url, void *buff, long n);
static char *url_mem_gets(URL url, char *buff, int n);
static int url_mem_fgetc(URL url);
static long url_mem_seek(URL url, long offset, int whence);
static long url_mem_tell(URL url);
static void url_mem_close(URL url);

URL url_mem_open(char *memory, long memsiz, int autofree)
{
    URL_mem *url;

    url = (URL_mem *)alloc_url(sizeof(URL_mem));
    if(url == NULL)
    {
	url_errno = errno;
	if(autofree)
	{
	    free(memory);
	    errno = url_errno;
	}
	return NULL;
    }

    /* common members */
    URLm(url, type)      = URL_mem_t;
    URLm(url, url_read)  = url_mem_read;
    URLm(url, url_gets)  = url_mem_gets;
    URLm(url, url_fgetc) = url_mem_fgetc;
    URLm(url, url_seek)  = url_mem_seek;
    URLm(url, url_tell)  = url_mem_tell;
    URLm(url, url_close) = url_mem_close;

    /* private members */
    url->memory = memory;
    url->memsiz = memsiz;
    url->mempos = 0;
    url->autofree = autofree;

    return (URL)url;
}

static long url_mem_read(URL url, void *buff, long n)
{
    URL_mem *urlp = (URL_mem *)url;
    long s;
    char *p = (char *)buff;

    s = urlp->memsiz - urlp->mempos;
    if(s > n)
	s = n;
    if(s <= 0)
	return 0;
    memcpy(p, urlp->memory + urlp->mempos, s);
    urlp->mempos += s;
    return s;
}

static char *url_mem_gets(URL url, char *buff, int n)
{
    URL_mem *urlp = (URL_mem *)url;
    long s;
    char *nlp, *p;

    if(urlp->memsiz == urlp->mempos)
	return NULL;
    if(n <= 0)
	return buff;
    if(n == 1)
    {
	*buff = '\0';
	return buff;
    }
    n--; /* for '\0' */
    s = urlp->memsiz - urlp->mempos;
    if(s > n)
	s = n;
    p = urlp->memory + urlp->mempos;
    nlp = (char *)memchr(p, url_newline_code, s);
    if(nlp != NULL)
	s = nlp - p + 1;
    memcpy(buff, p, s);
    buff[s] = '\0';
    urlp->mempos += s;
    return buff;
}

static int url_mem_fgetc(URL url)
{
    URL_mem *urlp = (URL_mem *)url;

    if(urlp->memsiz == urlp->mempos)
	return EOF;
    return (int)(unsigned char)urlp->memory[urlp->mempos++];
}

static long url_mem_seek(URL url, long offset, int whence)
{
    URL_mem *urlp = (URL_mem *)url;
    long ret;

    ret = urlp->mempos;
    switch(whence)
    {
      case SEEK_SET:
	urlp->mempos = offset;
	break;
      case SEEK_CUR:
	urlp->mempos += offset;
	break;
      case SEEK_END:
	urlp->mempos = urlp->memsiz + offset;
	break;
    }
    if(urlp->mempos > urlp->memsiz)
	urlp->mempos = urlp->memsiz;
    else if(urlp->mempos < 0)
	urlp->mempos = 0;

    return ret;
}

static long url_mem_tell(URL url)
{
    return ((URL_mem *)url)->mempos;
}

static void url_mem_close(URL url)
{
    int save_errno = errno;
    URL_mem *urlp = (URL_mem *)url;
    if(urlp->autofree)
	free(urlp->memory);
    free(url);
    errno = save_errno;
}