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