cscg22-gearboy

CSCG 2022 Challenge 'Gearboy'
git clone https://git.sinitax.com/sinitax/cscg22-gearboy
Log | Files | Refs | sfeed.txt

rpn.c (1391B)

      1#include <stdint.h>
      2#include <stdio.h>
      3#include <ctype.h>
      4
      5#define MAXOP     40
      6#define NUMBER    '0'
      7#define STACKSIZE 40
      8
      9uint8_t sp;
     10int16_t stack[STACKSIZE];
     11
     12char s[MAXOP];
     13uint8_t pos;
     14int16_t n;
     15
     16void push(int16_t l)
     17{
     18  if(sp < STACKSIZE)
     19    stack[sp++] = l;
     20  else
     21    puts("Stack full");
     22}
     23
     24int16_t pop(void)
     25{
     26  if(sp > 0)
     27    return stack[--sp];
     28  else
     29    puts("Stack empty");
     30  return 0;
     31}
     32
     33int16_t top(void)
     34{
     35  if(sp > 0)
     36    return stack[sp-1];
     37  else
     38    puts("Stack empty");
     39  return 0;
     40}
     41
     42int8_t read_op(void)
     43{
     44    if(pos == 0) {
     45	gets(s);
     46    }
     47
     48    while(s[pos] == ' ' || s[pos] == '\t')
     49	pos++;
     50
     51    if(s[pos] == '\0') {
     52	pos = 0;
     53	return('\n');
     54    }
     55
     56    if(!isdigit(s[pos]))
     57	return(s[pos++]);
     58
     59    n = s[pos] - '0';
     60    while(isdigit(s[++pos]))
     61	n = 10 * n + s[pos] - '0';
     62
     63    return NUMBER;
     64}
     65
     66void main(void)
     67{
     68  int8_t type;
     69  int16_t op2;
     70
     71  puts("RPN Calculator");
     72  sp = 0;
     73  pos = 0;
     74
     75  while((type = read_op()) != 0) {
     76    switch(type) {
     77    case NUMBER:
     78      push(n);
     79      break;
     80    case '+':
     81      push(pop() + pop());
     82      break;
     83    case '*':
     84      push(pop() * pop());
     85      break;
     86    case '-':
     87      op2 = pop();
     88      push(pop() - op2);
     89      break;
     90    case '/':
     91      op2 = pop();
     92      if(op2 != 0)
     93	push(pop() / op2);
     94      else
     95	puts("Divide by 0");
     96      break;
     97    case '\n':
     98      printf("==> %d\n", top());
     99      break;
    100    }
    101  }
    102}