encode JIS 7bit kanji strings to MIME strings

encode.c

/*
 *      encode JIS 7bit kanji strings to MIME strings (ISO-2022JP)
 */

#include <stdio.h>

static struct codeTable {
    char    code;
    char    key;
}       codetbl[] =     {
    { 'A',     0 }, { 'B',     1 }, { 'C',     2 }, { 'D',     3 },
    { 'E',     4 }, { 'F',     5 }, { 'G',     6 }, { 'H',     7 },
    { 'I',     8 }, { 'J',     9 }, { 'K',    10 }, { 'L',    11 },
    { 'M',    12 }, { 'N',    13 }, { 'O',    14 }, { 'P',    15 },
    { 'Q',    16 }, { 'R',    17 }, { 'S',    18 }, { 'T',    19 },
    { 'U',    20 }, { 'V',    21 }, { 'W',    22 }, { 'X',    23 },
    { 'Y',    24 }, { 'Z',    25 }, { 'a',    26 }, { 'b',    27 },
    { 'c',    28 }, { 'd',    29 }, { 'e',    30 }, { 'f',    31 },
    { 'g',    32 }, { 'h',    33 }, { 'i',    34 }, { 'j',    35 },
    { 'k',    36 }, { 'l',    37 }, { 'm',    38 }, { 'n',    39 },
    { 'o',    40 }, { 'p',    41 }, { 'q',    42 }, { 'r',    43 },
    { 's',    44 }, { 't',    45 }, { 'u',    46 }, { 'v',    47 },
    { 'w',    48 }, { 'x',    49 }, { 'y',    50 }, { 'z',    51 },
    { '0',    52 }, { '1',    53 }, { '2',    54 }, { '3',    55 },
    { '4',    56 }, { '5',    57 }, { '6',    58 }, { '7',    59 },
    { '8',    60 }, { '9',    61 }, { '+',    62 }, { '/',    63 }
};


static int
code( c )
int     c;
{
    int     ret = -1, i;

    for ( i = 0; i < 64; i++ ) {
        if ( c == codetbl[i].key ) {
            ret = codetbl[i].code;
            break;
        }
    }

    return ( ret );
}


static void
pushCode( c, p )
int     c;
char    *p;
{
    static int  cnt = 0, i = 0;
    static int  c1, c2;
    static char buf[BUFSIZ];

    switch ( cnt++ % 3 ) {
    case 0:
        c1 = c;
        break;
    case 1:
        c2 = c;
        if ( p ) {
            buf[i++] = code( (c1 >> 2) & 0x3f );
            buf[i++] = code( (c1 << 4) & 0x3f );
            buf[i++] = '=';
            buf[i++] = '=';
        }
        break;
    case 2:
        buf[i++] = code( (c1 >> 2) & 0x3f );
        buf[i++] = code( ((c1 << 4) | (c2 >> 4)) & 0x3f );
        buf[i++] = code( ((c2 << 2) | (c  >> 6)) & 0x3f );
        buf[i++] = !p ? code( c & 0x3f ) : '=';
        break;
    }

    if ( p ) {
        buf[i] = NULL;
        strcpy( p, buf );
        cnt = i = 0;
    }
}


char    *
encodeMIME( p )
char    *p;
{
    static char buf[BUFSIZ];
    int         flag = 0, i = 0;

    while ( *p ) {
        if ( !flag ) {
            if ( *p == '\033' ) {
                if ( *(p+1) == '$' ) {
                    if ( ( *(p+2) == 'B' ) || ( *(p+2) == '@' ) ) {
                        strcpy( &buf[i], "=?ISO-2022-JP?B?" );
                        i += 16;
                        flag = 1;
                        pushCode( *p++, NULL );
                        pushCode( *p++, NULL );
                        pushCode( *p++, NULL );
                        continue;
                    }
                }
            }
            buf[i++] = *p++;
            continue;
        }

        if ( *p == '\033' ) {
            if ( *(p+1) == '(' ) {
                if ( ( *(p+2) == 'J' ) ||
                     ( *(p+2) == 'B' ) ||
                     ( *(p+2) == 'H' )    ) {
                    if ( ( *(p+3) != ' ' ) || ( *(p+4) != '\033' ) ) {
                        pushCode( *p++, NULL );
                        pushCode( *p++, NULL );
                        pushCode( *p++, NULL );
                        pushCode( 0, &buf[i] );
                        i = strlen( buf );
                        buf[i++] = '?';
                        buf[i++] = '=';
                        flag = 0;
                        continue;
                    }
                }
            }
        }

        pushCode( *p++, NULL );
    }
    buf[i] = NULL;

    return ( buf );
}


#ifdef  TEST
void
main( argc, argv )
int     argc;
char    *argv[];
{
    char    *p, buf[BUFSIZ];
    FILE    *fp;
    int     i;

    if ( argc <= 1 ) {
        while ( ( p = fgets( buf, BUFSIZ - 1, stdin ) ) != NULL )
            fputs( encodeMIME( p ), stdout );
    }
    else {
        for ( i = 1; i < argc; i++ ) {
            if ( ( fp = fopen( argv[i], "r" ) ) != NULL ) {
                while ( ( p = fgets( buf, BUFSIZ - 1, fp ) ) != NULL )
                    fputs( encodeMIME( p ), stdout );
                fclose( fp );
            }
        }
    }
}
#endif