src/netascii.c


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#include <stdint.h>
#include <stdlib.h>

#include "netascii.h"

uint8_t is_netascii_char(char c) {
	static const uint64_t LUT[4] = 
		{0xffffffff00003f81,
		 0x7fffffffffffffff,
		 0x00,0x00};
	int i = c / 64;
	int e = i % 64;
	return (LUT[i] >> e) & 1;
}

/// WARNING!  This function is NOT safe.  Use only for strings you have already
/// verified are NULL terminated!
uint8_t is_netascii_str(char *str) {
	for (uint64_t i = 0; str[i] != 0; i++) {
		if (!is_netascii_char(str[i])) {
			return 0;
		} else {
			if (str[i] == '\r') {
				if (str[++i] != '\n') {
					return 0;
				}
			}
		}
	}
	return 1;
}

uint8_t is_netascii_buf(char *buf, size_t len) {
	for (uint64_t i = 0; i < len; i++) {
		if (!is_netascii_char(buf[i])) {
			return 0;
		} else {
			if (buf[i] == '\r') {
				if ((i + 1) < len) {
					switch (buf[++i]) {
						case 0: case '\n':
							break;
						default:
							return 0;
					}
				} else {
					return 0;
				}
			}
		}
	}
	return 1;
}