my_format.c

/*
 * Copyright (c) 2023 DomainTools LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <arpa/inet.h>

#include "libmy/my_format.h"


static inline const char *
_my_byte_to_hex_str(uint8_t byte, bool is_upper, char *dst)
{
	static const char *__hexchars = "0123456789abcdef";
	static const char *__HEXCHARS = "0123456789ABCDEF";
	const char *table = (is_upper ? __HEXCHARS : __hexchars);

	dst[0] = table[(byte >> 4) & 0xf];
	dst[1] = table[byte & 0xf];

	return dst;
}

size_t
my_bytes_to_hex_str(const uint8_t *src, size_t len, bool is_upper, char *dst, size_t dst_size)
{
	size_t n;

	if ((len * 2) > (dst_size - 1))
		len = (dst_size - 1) / 2;

	for (n = 0; n < len; n++)
		_my_byte_to_hex_str(src[n], is_upper, &dst[n * 2]);

	dst[n * 2] = '\x00';

	return len * 2;
}

size_t
my_uint16_to_hex_str(uint16_t num, bool is_upper, char *dst, size_t dst_size)
{
	uint16_t nval = htons(num);

	return my_bytes_to_hex_str((const uint8_t *) &nval, sizeof(nval), is_upper, dst, dst_size);
}

size_t
my_uint64_to_str(uint64_t num, char *dst, size_t dst_size, const char **start)
{
	size_t ndigits = 0;
	char *ptr = &dst[dst_size - 1];

	*ptr-- = '\0';

	while (ptr >= dst) {
		*ptr = '0' + num % 10;
		ndigits++;
		num /= 10;

		if (num == 0 || ptr == dst)
			break;

		ptr--;
	}

	if (start != NULL)
		*start = ptr;

	return ndigits;
}