agxbuf.c

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/* $Id$ $Revision$ */
/* vim:set shiftwidth=4 ts=8: */

/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: See CVS logs. Details at http://www.graphviz.org/
 *************************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <agxbuf.h>

#define N_GNEW(n,t)      (t*)malloc((n)*sizeof(t))

/* agxbinit:
 * Assume if init is non-null, hint = sizeof(init[])
 */
void agxbinit(agxbuf * xb, unsigned int hint, unsigned char *init)
{
    if (init) {
        xb->buf = init;
        xb->dyna = 0;
    } else {
        if (hint == 0)
            hint = BUFSIZ;
        xb->dyna = 1;
        xb->buf = N_GNEW(hint, unsigned char);
    }
    xb->eptr = xb->buf + hint;
    xb->ptr = xb->buf;
    *xb->ptr = '\0';
}

/* agxbmore;
 * Expand buffer to hold at least ssz more bytes.
 */
int agxbmore(agxbuf * xb, size_t ssz)
{
    size_t cnt = 0;         /* current no. of characters in buffer */
    size_t size = 0;        /* current buffer size */
    size_t nsize = 0;       /* new buffer size */
    unsigned char *nbuf;    /* new buffer */

    size = (size_t) (xb->eptr - xb->buf);
    nsize = 2 * size;
    if (size + ssz > nsize)
        nsize = size + ssz;
    cnt = (size_t) (xb->ptr - xb->buf);
    if (xb->dyna) {
        nbuf = realloc(xb->buf, nsize);
    } else {
        nbuf = N_GNEW(nsize, unsigned char);
        memcpy(nbuf, xb->buf, cnt);
        xb->dyna = 1;
    }
    xb->buf = nbuf;
    xb->ptr = xb->buf + cnt;
    xb->eptr = xb->buf + nsize;
    return 0;
}

/* agxbput_n:
 * Append string s of length n onto xb
 */
size_t agxbput_n(agxbuf * xb, const char *s, size_t ssz)
{
    if (xb->ptr + ssz > xb->eptr)
        agxbmore(xb, ssz);
    memcpy(xb->ptr, s, ssz);
    xb->ptr += ssz;
    return ssz;
}

/* agxbput:
 * Append string s into xb
 */
size_t agxbput(agxbuf * xb, const char *s)
{
    size_t ssz = strlen(s);

    return agxbput_n(xb, s, ssz);
}

/* agxbfree:
 * Free any malloced resources.
 */
void agxbfree(agxbuf * xb)
{
    if (xb->dyna)
        free(xb->buf);
}

/* agxbpop:
 * Removes last character added, if any.
 */
int agxbpop(agxbuf * xb)
{
    int c;
    if (xb->ptr > xb->buf) {
        c = *xb->ptr--;
        return c;
    } else
        return -1;

}