maybev2.c

/* Match flags. */
#define M_NI  0 /* Unconditionally not increment.     */
#define M_I   1 /* Unconditionally increment.         */
#define M_IC  2 /* Increment conditionally (if true.) */
#define M_NS  1 /* Not suppress error msgs.           */
#define M_S   0 /* Suppress error messages.           */

/**
 *
 */
static inline void skip_whitespace(char **s)
{
    char *p = *s;
    while (isblank(*p))
        p++;
    *s = p;
}

/**
 *
 */
static inline int match(char **s, char c, int inc, int supr)
{
    int ret = 0;
    char *p = *s;

    if (tolower(*p) == c)
        ret = 1;
    else
    {
        if (supr)
            fprintf(stderr, "file.c:%d: Error: expected '%c', found '%c'\n",
                current_line, c, *p);
    }
    /* Increment. */
    if (inc == M_I)
        *s = p + 1;
    else if (inc == M_IC && ret)
        *s = p + 1;
    return (ret);
}

/**
 *
 */
static inline int match_lt(char **s, char c, int inc, int supr)
{
    int ret = 0;
    char *p = *s;

    if (*p < c)
        ret = 1;
    else
    {
        if (supr)
            fprintf(stderr, "file.c:%d: Error: expected '%c' < '%c'\n",
                current_line, c, *p);
    }
    if (inc == M_I)
        *s = p + 1;
    else if (inc == M_IC && ret)
        *s = p + 1;
    return (ret);
}

/**
 *
 */
static inline int match_gt(char **s, char c, int inc, int supr)
{
    int ret = 0;
    char *p = *s;

    if (*p > c)
        ret = 1;
    else
    {
        if (supr)
            fprintf(stderr, "file.c:%d: Error: expected '%c' > '%c'\n",
                current_line, c, *p);
    }
    if (inc == M_I)
        *s = p + 1;
    else if (inc == M_IC && ret)
        *s = p + 1;
    return (ret);
}

/**
 *
 */
static inline long read_number(char **s)
{
    long number;
    char *nptr = NULL;
    char *p = *s;

    number = strtol(p, &nptr, 0);
    if (p != nptr && errno == 0)
    {
        *s = nptr;
        return (number);
    }
    fprintf(stderr, "file.c:%d: Error: invalid number\n",
        current_line);

    return (LONG_MAX);
}

/**
 *
 */
static int read_first_operand(char **insn, struct insn_tbl *tbl)
{
    if (!match(insn, 'r', M_I, M_NS))
        goto err;

    if (match_lt(insn, '0', M_NI, M_S) ||
        match_gt(insn, '7', M_I,  M_S))
    {
        goto err;
    }
    return (1);
err:
    fprintf(stderr, "file.c:%d: Error: first operand of instruction"
        " '%s' is invalid!\n", current_line, tbl->name);
    return (0);
}

/**
 *
 */
static int read_second_operand(char **insn, struct insn_tbl *tbl)
{
    long imm;

    if (!match(insn, ',', M_I, M_NS))
        goto err;

    skip_whitespace(insn);

    /* If Reg/Reg. */
    if (match(insn, 'r', M_IC, M_S))
    {
        if (match_lt(insn, '0', M_NI, M_S) || match_gt(insn, '7', M_I, M_S))
            goto err;

        skip_whitespace(insn);

        if (!match(insn, '#',  M_NI, M_S) && !match(insn, ';',  M_IC,  M_S) &&
            !match(insn, '\n', M_NI, M_S) && !match(insn, '\0', M_NI, M_S))
        {
            goto err;
        }
    }

    /* Reg/Imm. */
    else
    {
        imm = read_number(insn);
        if (imm == LONG_MAX)
            goto err;

        skip_whitespace(insn);

        if (!match(insn, '#',  M_NI, M_S) && !match(insn, ';',  M_IC,  M_S) &&
            !match(insn, '\n', M_NI, M_S) && !match(insn, '\0', M_NI, M_S))
        {
            goto err;
        }

        printf("num: %ld\n", imm);
    }

    return (1);
err:
    fprintf(stderr, "file.c:%d: Error: second operand of instruction"
        " '%s' is invalid!\n", current_line, tbl->name);
    return (0);
}

/**
 *
 */
static int insn_two_params(char **insn, struct insn_tbl *tbl)
{
    long number;
    char *nptr = NULL;
    char *p = *insn;

    if (!read_first_operand(&p, tbl))
        return (-1);

    skip_whitespace(&p);

    if (!read_second_operand(&p, tbl))
        return (-1);

    /* Update the pointer. */
    *insn = p;
    return (0);
}