sortix--sortix/libc/string/memrchr.c

/*
 * Copyright (c) 2014 Jonas 'Sortie' Termansen.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * string/memrchr.c
 * Scans memory in reverse directory for a character.
 */

#include <stdint.h>
#include <string.h>

void* memrchr(const void* ptr, int c, size_t n)
{
	const unsigned char* buf = (const unsigned char*) ptr;
	for ( size_t i = n; i != 0; i-- )
		if ( buf[i-1] == (unsigned char) c )
			return (void*) (buf + i-1);
	return NULL;
}