c hex snippet

hex.c

/*************************************************************************
    > File Name: hex.c
    > Author: jige003
    > Created Time: Thu 25 Apr 2019 02:08:49 PM CST
 ************************************************************************/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>

#define P printf

size_t hexchr2bin(const char hex, char *out){
	if (out == NULL)
		return 0;

	if (hex >= '0' && hex <= '9') {
		*out = hex - '0';
	} else if (hex >= 'A' && hex <= 'F') {
		*out = hex - 'A' + 10;
	} else if (hex >= 'a' && hex <= 'f') {
		*out = hex - 'a' + 10;
	} else {
		return 0;
	}
	return 1;
}

size_t hexs2bin(const char *hex, unsigned char **out){
	size_t len;
	char   b1;
	char   b2;
	size_t i;

	if (hex == NULL || *hex == '\0' || out == NULL)
		return 0;

	len = strlen(hex);
	if (len % 2 != 0)
		return 0;
	len /= 2;

	*out = (unsigned char *)malloc(len);
	memset(*out, 'A', len);
	for (i=0; i<len; i++) {
		if (!hexchr2bin(hex[i*2], &b1) || !hexchr2bin(hex[i*2+1], &b2)) {
			return 0;
		}
		(*out)[i] = (b1 << 4) | b2;
	}
	return len;
}

size_t bin2hex(const unsigned char *bin, size_t blen, unsigned char **hexout){
	if (bin == NULL || blen == 0) return -1;
    *hexout = (unsigned char *)malloc(blen * 2);
    unsigned char *hex = *hexout;

    size_t i;
	for (i=0; i < blen; ++i) {
		hex[i*2] = "0123456789ABCDEF"[bin[i] >> 4];
		hex[i*2+1] = "0123456789ABCDEF"[bin[i] & 0x0F];
	}
	hex[blen*2] = '\0';
    return blen*2;
}

size_t hex2bin(const unsigned char *old, unsigned char **str){
    size_t target_length = strlen(old) >> 1;
    *str = (unsigned char *) malloc(target_length);
    unsigned char *ret = *str;
    size_t i, j;

    for (i = j = 0; i < target_length; i++) {
        unsigned char c = old[j++];
        unsigned char d;

        if (c >= '0' && c <= '9') {
            d = (c - '0') << 4;
        } else if (c >= 'a' && c <= 'f') {
            d = (c - 'a' + 10) << 4;
        } else if (c >= 'A' && c <= 'F') {
            d = (c - 'A' + 10) << 4;
        } else {
            free(str);
            return -1;
        }
        c = old[j++];
        if (c >= '0' && c <= '9') {
            d |= c - '0';
        } else if (c >= 'a' && c <= 'f') {
            d |= c - 'a' + 10;
        } else if (c >= 'A' && c <= 'F') {
            d |= c - 'A' + 10;
        } else {
            free(str);
            return -1;
        }
        ret[i] = d;
    }
    ret[i] = '\0';

    return i;
}



int main(){
    /* test bin 2 hex */
    unsigned char bindata[] = "this is a test str by jige003";
    unsigned char *hexdata;
    int hlen;
    hlen = bin2hex(bindata, strlen(bindata), &hexdata);
    P("hexdata: %s\n", hexdata);

    /* test hex to bin */
    unsigned char *origdata;
    int blen;
    blen = hex2bin(hexdata, &origdata);
    P("orig data:%s\n", origdata);

    assert( strcmp(bindata, origdata) == 0 );

    return 0;
}

hex.md

api

size_t bin2hex(const unsigned char *bin, size_t blen, unsigned char **hexout)

size_t hex2bin(const unsigned char *old, unsigned char **str)