Subversion Repositories planix.SVN

#include        <plan9.h>

char *argv0;
enum
{
        Bit1    = 7,
        Bitx    = 6,
        Bit2    = 5,
        Bit3    = 4,
        Bit4    = 3,
        Bit5    = 2,

        T1      = ((1<<(Bit1+1))-1) ^ 0xFF,     /* 0000 0000 */
        Tx      = ((1<<(Bitx+1))-1) ^ 0xFF,     /* 1000 0000 */
        T2      = ((1<<(Bit2+1))-1) ^ 0xFF,     /* 1100 0000 */
        T3      = ((1<<(Bit3+1))-1) ^ 0xFF,     /* 1110 0000 */
        T4      = ((1<<(Bit4+1))-1) ^ 0xFF,     /* 1111 0000 */
        T5      = ((1<<(Bit5+1))-1) ^ 0xFF,     /* 1111 1000 */

        Rune1   = (1<<(Bit1+0*Bitx))-1,         /* 0000 0000 0000 0000 0111 1111 */
        Rune2   = (1<<(Bit2+1*Bitx))-1,         /* 0000 0000 0000 0111 1111 1111 */
        Rune3   = (1<<(Bit3+2*Bitx))-1,         /* 0000 0000 1111 1111 1111 1111 */
        Rune4   = (1<<(Bit4+3*Bitx))-1,         /* 0001 1111 1111 1111 1111 1111 */


        Maskx   = (1<<Bitx)-1,                  /* 0011 1111 */
        Testx   = Maskx ^ 0xFF,                 /* 1100 0000 */

        SurrogateMin    = 0xD800,
        SurrogateMax    = 0xDFFF,

        Bad     = Runeerror,
        Runemax         = 0x10FFFF

};

int
chartorune(Rune *rune, char *str)
{
        int c, c1, c2, c3;
        long l;

        /*
         * one character sequence
         *      00000-0007F => T1
         */
        c = *(uchar*)str;
        if(c < Tx) {
                *rune = c;
                return 1;
        }

        /*
         * two character sequence
         *      00080-007FF => T2 Tx
         */
        c1 = *(uchar*)(str+1) ^ Tx;
        if(c1 & Testx)
                goto bad;
        if(c < T3) {
                if(c < T2)
                        goto bad;
                l = ((c << Bitx) | c1) & Rune2;
                if(l <= Rune1)
                        goto bad;
                *rune = l;
                return 2;
        }

        /*
         * three character sequence
         *      00800-0FFFF => T3 Tx Tx
         */
        c2 = *(uchar*)(str+2) ^ Tx;

        if(c2 & Testx)
                goto bad;
        if(c < T4) {
                l = ((((c << Bitx) | c1) << Bitx) | c2) & Rune3;
                if(l <= Rune2)
                        goto bad;
                if (SurrogateMin <= l && l <= SurrogateMax)
                        goto bad;
                *rune = l;
                return 3;
        }

        /*
         * four character sequence
         *      10000-10FFFF => T4 Tx Tx Tx
         */
        if(UTFmax >= 4) {
                c3 = *(uchar*)(str+3) ^ Tx;
                if(c3 & Testx)
                        goto bad;
                if(c < T5) {
                        l = ((((((c << Bitx) | c1) << Bitx) | c2) << Bitx) | c3) & Rune4;
                        if(l <= Rune3)
                                goto bad;
                        if(l > Runemax)
                                goto bad;
                        *rune = l;
                        return 4;
                }
        }

        /*
         * bad decoding
         */
bad:
        *rune = Bad;
        return 1;
}

int
runetochar(char *str, Rune *rune)
{
        long c;

        /*
         * one character sequence
         *      00000-0007F => 00-7F
         */
        c = *rune;
        if(c <= Rune1) {
                str[0] = c;
                return 1;
        }

        /*
         * two character sequence
         *      0080-07FF => T2 Tx
         */
        if(c <= Rune2) {
                str[0] = T2 | (c >> 1*Bitx);
                str[1] = Tx | (c & Maskx);
                return 2;
        }
        /*
         * If the Rune is out of range or a surrogate half, convert it to the error rune.
         * Do this test here because the error rune encodes to three bytes.
         * Doing it earlier would duplicate work, since an out of range
         * Rune wouldn't have fit in one or two bytes.
         */
        if (c > Runemax)
                c = Runeerror;
        if (SurrogateMin <= c && c <= SurrogateMax)
                c = Runeerror;

        /*
         * three character sequence
         *      0800-FFFF => T3 Tx Tx
         */
        if (c <= Rune3) {
                str[0] = T3 |  (c >> 2*Bitx);
                str[1] = Tx | ((c >> 1*Bitx) & Maskx);
                str[2] = Tx |  (c & Maskx);
                return 3;
        }

        /*
         * four character sequence (21-bit value)
         *     10000-1FFFFF => T4 Tx Tx Tx
         */
        str[0] = T4 | (c >> 3*Bitx);
        str[1] = Tx | ((c >> 2*Bitx) & Maskx);
        str[2] = Tx | ((c >> 1*Bitx) & Maskx);
        str[3] = Tx | (c & Maskx);
        return 4;
}

int
runelen(long c)
{
        Rune rune;
        char str[10];

        rune = c;
        return runetochar(str, &rune);
}

int
utflen(char *s)
{
        int c;
        long n;
        Rune rune;

        n = 0;
        for(;;) {
                c = *(uchar*)s;
                if(c < Runeself) {
                        if(c == 0)
                                return n;
                        s++;
                } else
                        s += chartorune(&rune, s);
                n++;
        }
        return 0;
}