icalc3.tc

[ Ed Davis - 27 Jul 2022

    ed_davis2@yahoo.com

    Tiny integer calculator

    Pritory Operator

    11      ()
    10      exponentiation: **
    9       unary +, -, !
    8       *, /, %
    7       +, -
    6       <<, >>
    5       <, <=, >, >=
    4       ==, !=
    3       && ("and" is a synonym)
    2       || ("or" is a synonym)
    1       assignment: =

    Follows standard C precedence where applicable

    Expressions can also contain:

    numbers
    spaces
    Also has 26 variables, named a,b, ..z
    Also two functions: abs(expr) and rnd(expr)
    Rnd returns a number >= 0 <= expr

    For some reason, tiny-c doesn't like input from the clipboard,
    so input has to be typed in.

    examples:

    2 + 3 * 4
    = 14

    (-1 * ((-1 * (5 * 15)) / 10))
    = 7

    (155 + 2 + 3 - 155 - 2 - 3 + 4) * 2
    = 8

    Spaces are not needed between operators and operands
    (155+2+3-155-2-3+4)*2
    = 8

    a = 3 ** 4 / 5
    = 16

]

// icalc.tc - 7/27/21 - minor edits - lrb
// fixed parsing error in expr function - ed - 7/28/21
// added exponentiation and introductory messages - lrb - 7/29/21
// tweaked support for ^ per author's suggestions - lrb - 7/29/21

// library: gs
// Read a line from the terminal into buffer as a string
// Also handle backspace
gs char q(0) [
    int x
    x=0
    while ((q(x) = MC(2)) != 10) [
        if (q(x) == 13) break
        if (q(x) == 24) [x = 0; pl("")]
        else if (q(x) == 127) [if (x > 0) x = x - 1]
        else if (q(x) == 8) [
            if(x > 0) [
                x = x - 1;
                putchar(' ');
                putchar(8);
            ]
        ]
        else x = x + 1
    ]
    q(x) = 0
    pl ""
    return x
]

int buf_p, buf_len  // pos in input buffer, and len
char buf(80)        // input buffer
int the_num, sym    // last number read, symbol read
int data(26)        // data store for var a,..z
int data_index      // index of current var
int error           // error encountered?

// these are used as constants
int eof_t, number_t, ident_t, unknown_t, NE, EQL, OR, AND, GE, LE, SHL, SHR, POW, RND, ABS
char lparen, rparen, minus, bang, plus

// get the next char from input string
my_getc [
    int ch

    if (buf_p >= buf_len) return 26
    ch = buf(buf_p)
    buf_p = buf_p + 1
    return ch
]

// need to rescan the last character
my_putb [
    buf_p = buf_p - 1
]

// boolean: is c numeric?
digit char c [
    return ((c >= '0') * (c <= '9'))
]

// end of transmission: ^z windows, ^d linux
eot int c [
    return ((c == 26) + (c == 4))
]

// get the next symbol from the input
getsym [
    int ch, p
    char tmp(32)

    // skip spaces
    while (1) [
        ch = my_getc()
        if (ch != ' ') break
    ]

    //printf("getsym ch = %c %c", ch, 10)
    // one of our operators? set sym appropriately
    tmp(0) = sym = ch
    if ((p = index("()+-/%", 6, tmp, 1)) > 0) [
        ;
    ] else if (ch == '=') [
        ch = my_getc()
        if (ch == '=')
            sym = EQL
        else if (eot(ch) == 0) my_putb()
    ] else if (ch == '*') [
        ch = my_getc()
        if (ch == '*')
            sym = POW
        else if (eot(ch) == 0) my_putb()
    ] else if (ch == '!') [
        ch = my_getc()
        if (ch == '=')
            sym = NE
        else if (eot(ch) == 0) my_putb()
    ] else if (ch == '<') [
        ch = my_getc()
        if (ch == '=')
            sym = LE
        else if (ch == '<')
            sym = SHL
        else if (eot(ch) == 0) my_putb()
    ] else if (ch == '>') [
        ch = my_getc()
        if (ch == '=')
            sym = GE
        else if (ch == '>')
            sym = SHR
        else if (eot(ch) == 0) my_putb()
    ] else if (ch == '|') [
        ch = my_getc()
        if (ch == '|')
            sym = OR
        else [
            printf("Expecting '||', found |%c%c", ch, 10)
            sym = unknown_t
            error = 1
        ]
    ] else if (ch == '&') [
        ch = my_getc()
        if (ch == '&')
            sym = AND
        else [
            printf("Expecting '&&', found &%c%c", ch, 10)
            sym = unknown_t
            error = 1
        ]
    ] else if (digit(ch)) [
        the_num = 0
        while (digit(ch)) [
            the_num = (10 * the_num) + (ch - '0')
            ch = my_getc()
        ]
        if (eot(ch) == 0) my_putb()
        sym = number_t
    ] else if (alpha(ch)) [
        // fold upper case to lower case
        p = 0
        while (alpha(ch)) [
            if ((ch >= 'A') * (ch <= 'Z')) ch = ch + 32
            if (p < 32) [
                tmp(p) = ch
                p = p + 1
            ]
            ch = my_getc()
        ]
        tmp(p) = 0
        if (ceqn(tmp, "or", 3))
            sym = OR
        else if (ceqn(tmp, "and", 4))
            sym = AND
        else if (ceqn(tmp, "rnd", 4))
            sym = RND
        else if (ceqn(tmp, "abs", 4))
            sym = ABS
        else [
            data_index = tmp(0) - 'a'
            sym = ident_t
        ]
        if (eot(ch) == 0) my_putb()
    ] else if (eot(ch)) [
        sym = eof_t
    ] else [
        printf("unknown char %c%c", ch, 10)
        sym = unknown_t
        error = 1
    ]
    //printf("getsym sym = %d (%c) %c", sym, sym, 10)
]

// boolean: if s matches sym, get next symbol
accept int s [
    if (sym == s) [
        getsym()
        return 1
    ]
    return 0
]

// b ** e (exponentiation)
pow int b, e [
    int i, p

    p = i = 1
    while (i <= e) [
        p = p * b
        i = i + 1
    ]
    return p
]

// a shl b
// 1 = * 2
// 2 = * 4
// 3 = * 8
// 4 = * 16
// 5 = * 32
// 6 = * 64
// 7 = * 128
// 8 = * 256
shl int a, b [
    int mul

    mul = pow(2, b)
    return a * mul
]

shr int a, b [
    int div

    div = pow(2, b)
    return a / div
]

//     ()
// 10  exponentiation: **
// 9   unary +, -, !
// 8   *, /, %
// 7   +, -
// 6   <<, >>
// 5   <, <=, >, >=
// 4   ==, !=
// 3   && ("and" is a synonym)
// 2   || ("or" is a synonym)
// 1   assignment: =
paren_expr [
    int n

    accept(lparen)
    n = expr(0)
    if (accept(rparen) == 0) [
        printf("Expecting right paren %c", 10)
        return error = 1
    ]
    return n
]

// process an expression
expr int minprec [
    int n, offset

    if (accept(minus)) [
        n = -expr(9)
    ] else if (accept(plus)) [
        n = expr(9)
    ] else if (accept(bang)) [
        n = expr(9)
        if (n == 0) n = 1
        else n = 0
    ] else if (sym == lparen) [
        n = paren_expr()
    ] else if (accept(RND)) [
        n = paren_expr()
        n = random(0, n)
    ] else if (accept(ABS)) [
        n = paren_expr()
        if (n < 0) n = -n
    ] else if (sym == number_t) [
        n = the_num; getsym()
    ] else if (sym == ident_t) [
        n = data(data_index)
        offset = data_index
        getsym()
    ] else if (sym == unknown_t) [
        return 0
    ] else [
        printf("found %d, but expecting an operand %c", sym, 10)
        return error = 1
    ]

    while (1) [
        if        ((minprec <= 1) * (sym == '='))  [
            getsym(); n = data(offset) = expr(1)    /* right associative, so no incr */

        ] else if ((minprec <= 2) * (sym == OR))   [
            getsym(); n = n + expr(3)
            if (n) n = 1
            else n = 0

        ] else if ((minprec <= 3) * (sym == AND))  [
            getsym(); n = n * expr(4)
            if (n) n = 1
            else n = 0

        ] else if ((minprec <= 4) * (sym == EQL))  [
            getsym(); n = n == expr(5)
        ] else if ((minprec <= 4) * (sym == NE))   [
            getsym(); n = n != expr(5)

        ] else if ((minprec <= 5) * (sym == '<'))  [
            getsym(); n = n <  expr(6)
        ] else if ((minprec <= 5) * (sym == LE))   [
            getsym(); n = n <= expr(6)
        ] else if ((minprec <= 5) * (sym == '>'))  [
            getsym(); n = n >  expr(6)
        ] else if ((minprec <= 5) * (sym == GE))   [
            getsym(); n = n >= expr(6)

        ] else if ((minprec <= 6) * (sym == SHL))  [
            getsym(); n = shl(n, expr(7))
        ] else if ((minprec <= 6) * (sym == SHR))  [
            getsym(); n = shr(n, expr(7))

        ] else if ((minprec <= 7) * (sym == '+'))  [
            getsym(); n = n + expr(8)
        ] else if ((minprec <= 7) * (sym == '-'))  [
            getsym(); n = n - expr(8)

        ] else if ((minprec <= 8) * (sym == '*'))  [
            getsym(); n = n * expr(9)
        ] else if ((minprec <= 8) * (sym == '/'))  [
            getsym(); n = n / expr(9)
        ] else if ((minprec <= 8) * (sym == '%'))  [
            getsym(); n = n % expr(9)

        ] else if ((minprec <= 10) * (sym == POW)) [
            getsym(); n = pow(n, expr(10))          /* right associative, so no incr */

        ] else [
            break
        ]
    ]
    return n
]

size char me(0) [
    char foo(13000)
    return readfile me , foo , 13000
]

main [
    eof_t     = 0
    number_t  = 1
    ident_t   = 2
    unknown_t = 3
    NE        = 4
    EQL       = 5
    OR        = 6
    AND       = 7
    GE        = 8
    LE        = 9
    SHL       = 10
    SHR       = 11
    POW       = 12
    RND       = 13
    ABS       = 14
    lparen = '('    // tiny c doesn't always like parens in expressions
    rparen = ')'    // ditto
    minus  = '-'    // or passing '-' instead of a variable
    plus   = '+'    // ditto
    bang   = '!'    // ditto

    char msg(50); strcpy msg, "icalc3.tc - 7/27/22 - source code has"
    printf "%c%s %d bytes%c%c", 10, msg, size("icalc3.tc"), 10, 10

    printf("enter an expression at the > prompt, e.g.%c%c", 10, 10)
    printf("(3 ** 4 / 5) - 7%c", 10)
    printf("or a = (3 ** 4 / 5) - 7%c", 10)
    printf("or b = 3%c", 10)
    printf("or a ** b - 5%c", 10)

    printf("%cpress Enter to quit%c%c", 10, 10, 10)

/*    test the tokenizer
/*    while (1) [
/*        ps(">")
/*        buf_len = gs(buf)
/*        // exit on empty lines
/*        if (buf_len == 0) break
/*
/*        error = buf_p = 0
/*        while (1) [
/*            getsym()
/*            if (sym == eof_t) break
/*            printf("sym %d %c %c", sym, sym, 10)
/*        ]
/*    ]
/*    return

    while (1) [
        int n

        ps(">")
        buf_len = gs(buf)
        // exit on empty lines
        if (buf_len == 0) break

        error = buf_p = 0
        getsym()
        if (sym == eof_t) break
        n = expr(0)
        if (error == 0)
            if (sym == eof_t)
                printf("= %d%c", n, 10)
            else
                printf("cannot parse expression - last sym %d %c", sym, 10)
    ]
]