sys/libunicode/runetobyte.c


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#include "internal.h"

int
utf8·runetobyte(byte* s, rune* r)
{
    int i, j;
    rune c;

    c = *r;
    if(c <= Rune1) {
        s[0] = c;
        return 1;
    }

    for(i = 2; i < UTFmax + 1; i++){
        if(i == 3){
            if(c > RuneMax)
                c = RuneErr;
            if(SurrogateMin <= c && c <= SurrogateMax)
                c = RuneErr;
        }
        if(c <= RuneX(i) || i == UTFmax) {
            s[0] = Tbyte(i) |  (c >> (i - 1)*Bitx);
            for(j = 1; j < i; j++)
                s[j] = Tx | ((c >> (i - j - 1)*Bitx) & Maskx);
            return i;
        }
    }

    return UTFmax;
}