encode_ulonglong.c

来自「OTP是开放电信平台的简称」· C语言 代码 · 共 94 行

/* ``The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved via the world wide web at http://www.erlang.org/.
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Original Code is Ericsson Utvecklings AB.
 * Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
 * AB. All Rights Reserved.''
 * 
 *     $Id$
 */
#include "eidef.h"
#include "eiext.h"
#include "putget.h"
#include "ei_x_encode.h"

/*
 * For some 64 bit operations on some operating systems code
 * compiled with GNU cc depends on "libgcc" for some 64 bit
 * operations missing in hardware (or because of gcc bugs).
 * If user code was linked together with the ei lib
 * using other linkers than GNU ld this may cause problems.
 * We moved ei_x_encode_ulonglong() here from "ei_x_encode.c" 
 * to limit this problem to users that actually use the ei 
 * longlong operations, not all ei_x users.
 */
int ei_x_encode_ulonglong(ei_x_buff* x, EI_ULONGLONG n)
{
    int i = x->index;
    ei_encode_ulonglong(NULL, &i, n);
    if (!x_fix_buff(x, i))
	return -1;
    return ei_encode_ulonglong(x->buff, &x->index, n);
}

#ifdef EI_64BIT
int ei_encode_ulong(char *buf, int *index, unsigned long p)
{
    return ei_encode_ulonglong(buf, index, p);
}
#endif

int ei_encode_ulonglong(char *buf, int *index, EI_ULONGLONG p)
{
    char *s = buf + *index;
    char *s0 = s;

    if ((p < 256) && (p >= 0)) {
	if (!buf) s += 2;
	else {
	    put8(s,ERL_SMALL_INTEGER_EXT);
	    put8(s,(p & 0xff));
	}
    } else if (p <= ERL_MAX) {
	if (!buf) s += 5;
	else {
	    put8(s,ERL_INTEGER_EXT);
	    put32be(s,p);
	}
    } else {
	/* We know 28-64 bits needed, i.e four to eight bytes  */
	if (buf) {
	    char *arityp;
	    int arity = 0;
	    put8(s,ERL_SMALL_BIG_EXT);
	    arityp = s++;	/* fill in later */
	    put8(s, 0);		/* save sign separately */
	    while (p) {
		*s++ = p & 0xff; /* take lowest byte */
		p >>= 8;	 /* shift unsigned */
		arity++;
	    }
	    put8(arityp,arity);
	} else {
	    s += 3;		/* Type, arity and sign */
	    while (p) {
		s++;		/* take lowest byte */
		p >>= 8;	/* shift unsigned */
	    }
	}
    }

    *index += s-s0; 

    return 0; 
}