diff options
author | John Beppu <beppu@lbox.org> | 2000-06-21 23:06:16 +0400 |
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committer | John Beppu <beppu@lbox.org> | 2000-06-21 23:06:16 +0400 |
commit | 0021679b0dc5767e0c023b28b36eeb1476dc2364 (patch) | |
tree | 04ff8031a2151a0f95040bbc4bdf2f616d68a540 /dc.c | |
parent | b405dfa54df117201d93dcb7d24e9e9873737da6 (diff) |
+ added dc (aka the function formerly known as math)
+ did all the housekeeping that this change requires.
Diffstat (limited to 'dc.c')
-rw-r--r-- | dc.c | 194 |
1 files changed, 194 insertions, 0 deletions
@@ -0,0 +1,194 @@ +/* vi: set sw=4 ts=4: */ +#include "internal.h" +#include <ctype.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <math.h> + +/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */ + +static const char dc_usage[] = "math expression ...\n" +#ifndef BB_FEATURE_TRIVIAL_HELP + "\nThis is a Tiny RPN calculator that understands the\n" + "following operations: +, -, /, *, and, or, not, eor.\n" + "i.e. 'math 2 2 add' -> 4, and 'math 8 8 \\* 2 2 + /' -> 16\n" +#endif + ; + +static double stack[100]; +static unsigned int pointer; + +static void push(double a) +{ + if (pointer >= (sizeof(stack) / sizeof(*stack))) { + fprintf(stderr, "math: stack overflow\n"); + exit(-1); + } else + stack[pointer++] = a; +} + +static double pop() +{ + if (pointer == 0) { + fprintf(stderr, "math: stack underflow\n"); + exit(-1); + } + return stack[--pointer]; +} + +static void add() +{ + push(pop() + pop()); +} + +static void sub() +{ + double subtrahend = pop(); + + push(pop() - subtrahend); +} + +static void mul() +{ + push(pop() * pop()); +} + +static void divide() +{ + double divisor = pop(); + + push(pop() / divisor); +} + +static void and() +{ + push((unsigned int) pop() & (unsigned int) pop()); +} + +static void or() +{ + push((unsigned int) pop() | (unsigned int) pop()); +} + +static void eor() +{ + push((unsigned int) pop() ^ (unsigned int) pop()); +} + +static void not() +{ + push(~(unsigned int) pop()); +} + +static void print() +{ + printf("%g\n", pop()); +} + +struct op { + const char *name; + void (*function) (); +}; + +static const struct op operators[] = { + {"+", add}, + {"add", add}, + {"-", sub}, + {"sub", sub}, + {"*", mul}, + {"mul", mul}, + {"/", divide}, + {"div", divide}, + {"and", and}, + {"or", or}, + {"not", not}, + {"eor", eor}, + {0, 0} +}; + +static void stack_machine(const char *argument) +{ + char *endPointer = 0; + double d; + const struct op *o = operators; + + if (argument == 0) { + print(); + return; + } + + d = strtod(argument, &endPointer); + + if (endPointer != argument) { + push(d); + return; + } + + while (o->name != 0) { + if (strcmp(o->name, argument) == 0) { + (*(o->function)) (); + return; + } + o++; + } + fprintf(stderr, "math: %s: syntax error.\n", argument); + exit(-1); +} + +/* return pointer to next token in buffer and set *buffer to one char + * past the end of the above mentioned token + */ +static char *get_token(char **buffer) +{ + char *start = NULL; + char *current = *buffer; + + while (isspace(*current)) { current++; } + if (*current != 0) { + start = current; + while (!isspace(*current) && current != 0) { current++; } + *buffer = current; + } + return start; +} + +/* In Perl one might say, scalar m|\s*(\S+)\s*|g */ +static int number_of_tokens(char *buffer) +{ + int i = 0; + char *b = buffer; + while (get_token(&b)) { i++; } + return i; +} + +int dc_main(int argc, char **argv) +{ + /* take stuff from stdin if no args are given */ + if (argc <= 1) { + int i, len; + char *line = NULL; + char *cursor = NULL; + char *token = NULL; + while ((line = cstring_lineFromFile(stdin))) { + cursor = line; + len = number_of_tokens(line); + for (i = 0; i < len; i++) { + token = get_token(&cursor); + *cursor++ = 0; + stack_machine(token); + } + free(line); + } + } else { + if (*argv[1]=='-') + usage(dc_usage); + while (argc >= 2) { + stack_machine(argv[1]); + argv++; + argc--; + } + } + stack_machine(0); + return( TRUE); +} |