input.c

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#include "c.h"


static void pragma(void);
static void resynch(void);

static int bsize;
static unsigned char buffer[MAXLINE+1 + BUFSIZE+1];
unsigned char *cp;  /* current input character */
char *file;     /* current input file name */
char *firstfile;    /* first input file */
unsigned char *limit;   /* points to last character + 1 */
char *line;     /* current line */
int lineno;     /* line number of current line */

void nextline(void) {
    do {
        if (cp >= limit) {
            fillbuf();
            if (cp >= limit)
                cp = limit;
            if (cp == limit)
                return;
        } else {
            lineno++;
            for (line = (char *)cp; *cp==' ' || *cp=='\t'; cp++)
                ;
            if (*cp == '#') {
                resynch();
                nextline();
            }
        }
    } while (*cp == '\n' && cp == limit);
}
void fillbuf(void) {
    if (bsize == 0)
        return;
    if (cp >= limit)
        cp = &buffer[MAXLINE+1];
    else
        {
            int n = limit - cp;
            unsigned char *s = &buffer[MAXLINE+1] - n;
            assert(s >= buffer);
            line = (char *)s - ((char *)cp - line);
            while (cp < limit)
                *s++ = *cp++;
            cp = &buffer[MAXLINE+1] - n;
        }
    if (feof(stdin))
        bsize = 0;
    else
        bsize = fread(&buffer[MAXLINE+1], 1, BUFSIZE, stdin);
    if (bsize < 0) {
        error("read error\n");
        exit(EXIT_FAILURE);
    }
    limit = &buffer[MAXLINE+1+bsize];
    *limit = '\n';
}
void input_init(int argc, char *argv[]) {
    static int inited;

    if (inited)
        return;
    inited = 1;
    main_init(argc, argv);
    limit = cp = &buffer[MAXLINE+1];
    bsize = -1;
    lineno = 0;
    file = NULL;
    fillbuf();
    if (cp >= limit)
        cp = limit;
    nextline();
}

/* pragma - handle #pragma ref id... */
static void pragma(void) {
    if ((t = gettok()) == ID && strcmp(token, "ref") == 0)
        for (;;) {
            while (*cp == ' ' || *cp == '\t')
                cp++;
            if (*cp == '\n' || *cp == 0)
                break;
            if ((t = gettok()) == ID && tsym) {
                tsym->ref++;
                use(tsym, src);
            }   
        }
}

/* resynch - set line number/file name in # n [ "file" ] and #pragma ... */
static void resynch(void) {
    for (cp++; *cp == ' ' || *cp == '\t'; )
        cp++;
    if (limit - cp < MAXLINE)
        fillbuf();
    if (strncmp((char *)cp, "pragma", 6) == 0) {
        cp += 6;
        pragma();
    } else if (*cp >= '0' && *cp <= '9') {
    line:   for (lineno = 0; *cp >= '0' && *cp <= '9'; )
            lineno = 10*lineno + *cp++ - '0';
        lineno--;
        while (*cp == ' ' || *cp == '\t')
            cp++;
        if (*cp == '"') {
            file = (char *)++cp;
            while (*cp && *cp != '"' && *cp != '\n')
                cp++;
            file = stringn(file, (char *)cp - file);
            if (*cp == '\n')
                warning("missing \" in preprocessor line\n");
            if (firstfile == 0)
                firstfile = file;
        }
    } else if (strncmp((char *)cp, "line", 4) == 0) {
        for (cp += 4; *cp == ' ' || *cp == '\t'; )
            cp++;
        if (*cp >= '0' && *cp <= '9')
            goto line;
        if (Aflag >= 2)
            warning("unrecognized control line\n");
    } else if (Aflag >= 2 && *cp != '\n')
        warning("unrecognized control line\n");
    while (*cp)
        if (*cp++ == '\n')
            if (cp == limit + 1)
                nextline();
            else
                break;
}

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