150 lines
2.0 KiB
C
150 lines
2.0 KiB
C
#include "internal.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <math.h>
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/* Tiny RPN calculator, because "expr" didn't give me bitwise operations. */
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const char math_usage[] = "math expression ...";
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static double stack[100];
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static unsigned int pointer;
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static void
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push(double a)
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{
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if ( pointer >= (sizeof(stack) / sizeof(*stack)) ) {
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fprintf(stderr, "math: stack overflow\n");
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exit(-1);
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}
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else
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stack[pointer++] = a;
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}
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static double
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pop()
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{
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if ( pointer == 0 ) {
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fprintf(stderr, "math: stack underflow\n");
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exit(-1);
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}
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return stack[--pointer];
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}
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static void
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add()
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{
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push(pop() + pop());
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}
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static void
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sub()
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{
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double subtrahend = pop();
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push(pop() - subtrahend);
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}
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static void
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mul()
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{
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push(pop() * pop());
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}
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static void
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divide()
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{
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double divisor = pop();
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push(pop() / divisor);
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}
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static void
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and()
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{
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push((unsigned int)pop() & (unsigned int)pop());
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}
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static void
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or()
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{
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push((unsigned int)pop() | (unsigned int)pop());
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}
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static void
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eor()
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{
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push((unsigned int)pop() ^ (unsigned int)pop());
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}
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static void
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not()
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{
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push(~(unsigned int)pop());
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}
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static void
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print()
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{
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printf("%g\n", pop());
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}
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struct op {
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const char * name;
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void (*function)();
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};
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static const struct op operators[] = {
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{ "add", add },
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{ "and", and },
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{ "div", divide },
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{ "eor", eor },
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{ "mul", mul },
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{ "not", not },
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{ "or", or },
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{ "sub", sub },
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{ 0, 0 }
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};
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static void
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stack_machine(const char * argument)
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{
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char * endPointer = 0;
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double d;
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const struct op * o = operators;
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if ( argument == 0 ) {
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print();
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return;
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}
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d = strtod(argument, &endPointer);
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if ( endPointer != argument ) {
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push(d);
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return;
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}
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while ( o->name != 0 ) {
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if ( strcmp(o->name, argument) == 0 ) {
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(*(o->function))();
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return;
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}
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o++;
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}
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fprintf(stderr, "math: %s: syntax error.\n", argument);
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exit(-1);
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}
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int
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math_main(struct FileInfo * i, int argc, char * * argv)
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{
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while ( argc >= 2 ) {
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stack_machine(argv[1]);
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argv++;
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argc--;
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}
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stack_machine(0);
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return 0;
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}
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