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/* A program for converting characters to UTF-8 and vice versa */
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
/* The valid ranges for UTF-8 characters are:
0000 0000 to 0000 007f 1 byte (ascii)
0000 0080 to 0000 07ff 2 bytes
0000 0800 to 0000 ffff 3 bytes
0001 0000 to 001f ffff 4 bytes
0020 0000 to 03ff ffff 5 bytes
0400 0000 to 7fff ffff 6 bytes
*/
static const int utf8_table1[] = {
0x0000007f, 0x000007ff, 0x0000ffff, 0x001fffff, 0x03ffffff, 0x7fffffff};
static const int utf8_table2[] = {
0, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc};
static const int utf8_table3[] = {
0xff, 0x1f, 0x0f, 0x07, 0x03, 0x01};
static const unsigned char utf8_table4[] = {
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,
3,3,3,3,3,3,3,3,4,4,4,4,5,5,6,6 };
/*************************************************
* Convert character value to UTF-8 *
*************************************************/
/* This function takes an integer value in the range 0 - 0x7fffffff
and encodes it as a UTF-8 character in 1 to 6 bytes.
Arguments:
cvalue the character value
buffer pointer to buffer for result - at least 6 bytes long
Returns: number of characters placed in the buffer
-1 if input character is negative
0 if input character is positive but too big (only when
int is longer than 32 bits)
*/
int
ord2utf8(int cvalue, unsigned char *buffer)
{
register int i, j;
for (i = 0; i < sizeof(utf8_table1)/sizeof(int); i++)
if (cvalue <= utf8_table1[i]) break;
if (i >= sizeof(utf8_table1)/sizeof(int)) return 0;
if (cvalue < 0) return -1;
buffer += i;
for (j = i; j > 0; j--)
{
*buffer-- = 0x80 | (cvalue & 0x3f);
cvalue >>= 6;
}
*buffer = utf8_table2[i] | cvalue;
return i + 1;
}
/*************************************************
* Convert UTF-8 string to value *
*************************************************/
/* This function takes one or more bytes that represents a UTF-8 character,
and returns the value of the character.
Argument:
buffer a pointer to the byte vector
vptr a pointer to an int to receive the value
Returns: > 0 => the number of bytes consumed
-6 to 0 => malformed UTF-8 character at offset = (-return)
*/
int
utf82ord(unsigned char *buffer, int *vptr)
{
int c = *buffer++;
int d = c;
int i, j, s;
for (i = -1; i < 6; i++) /* i is number of additional bytes */
{
if ((d & 0x80) == 0) break;
d <<= 1;
}
if (i == -1) { *vptr = c; return 1; } /* ascii character */
if (i == 0 || i == 6) return 0; /* invalid UTF-8 */
/* i now has a value in the range 1-5 */
s = 6*i;
d = (c & utf8_table3[i]) << s;
for (j = 0; j < i; j++)
{
c = *buffer++;
if ((c & 0xc0) != 0x80) return -(j+1);
s -= 6;
d |= (c & 0x3f) << s;
}
/* Check that encoding was the correct unique one */
for (j = 0; j < sizeof(utf8_table1)/sizeof(int); j++)
if (d <= utf8_table1[j]) break;
if (j != i) return -(i+1);
/* Valid value */
*vptr = d;
return i+1;
}
/*************************************************
* Main Program *
*************************************************/
int
main(int argc, char **argv)
{
int i;
unsigned char buffer[8];
for (i = 1; i < argc; i++)
{
unsigned char *x = argv[i];
if (strncmp(x, "0x", 2) == 0)
{
int j;
int d = strtol(x+2, NULL, 16);
int rc = ord2utf8(d, buffer);
printf("0x%08x => ", d);
if (rc <= 0) printf("*** Error %d ***", rc);
else for (j = 0; j < rc; j++) printf("%02x ", buffer[j]);
printf("\n");
}
else
{
int d, rc;
int j = 0;
int y = 0;
int z = 0;
for (;;)
{
while (*x == ' ') x++;
if (*x == 0 && !z) break;
if (!isxdigit(*x))
{
printf("Malformed hex string: %s\n", argv[i]);
j = -1;
break;
}
y = y * 16 + tolower(*x) - ((isdigit(*x))? '0' : 'W');
x++;
if (z)
{
buffer[j++] = y;
y = 0;
}
z ^= 1;
}
if (j < 0) continue;
buffer[j] = 0;
rc = utf82ord(buffer, &d);
if (rc > 0) printf("0x%08x <= %s\n", d, argv[i]);
else printf("Error %d <= %s\n", rc, argv[i]);
}
}
return 0;
}
/* End */
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