harvey/sys/src/ape/lib/utf/utfecpy.c

/*
 * The authors of this software are Rob Pike and Ken Thompson.
 *              Copyright (c) 2002 by Lucent Technologies.
 * Permission to use, copy, modify, and distribute this software for any
 * purpose without fee is hereby granted, provided that this entire notice
 * is included in all copies of any software which is or includes a copy
 * or modification of this software and in all copies of the supporting
 * documentation for such software.
 * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTY.  IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
 * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
 * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
 */
#include <stdarg.h>
#include <string.h>
#include "utf.h"
#include "utfdef.h"

static void*
memccpy(void *a1, void *a2, int c, ulong n)
{
	uchar *s1, *s2;

	s1 = a1;
	s2 = a2;
	c &= 0xFF;
	while(n > 0) {
		if((*s1++ = *s2++) == c)
			return s1;
		n--;
	}
	return 0;
}
char*
utfecpy(char *to, char *e, char *from)
{
	char *end;

	if(to >= e)
		return to;
	end = memccpy(to, from, '\0', e - to);
	if(end == nil){
		end = e-1;
		while(end>to && (*--end&0xC0)==0x80)
			;
		*end = '\0';
	}else{
		end--;
	}
	return end;
}