First

README.md

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+# RPCALC
+
+This program compiles reverse-polish-notation expressions to x86 16-bit
+GNU-Assembly instructions. This is to be an educational supplement to teach
+compiler theory.
+
+## LICENSE
+
+Public Domain.

c.sh

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+#!/bin/sh
+rm rpcalc
+cl
+cc -O3 -std=c89 -Wall -Wextra -Wmain -Wpedantic -Werror main.c -o rpcalc && ./rpcalc

example.txt

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+100
+100
++
+200
+200
++
+*

example2.txt

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+1000
+3
+*
+100
+-

main.c

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+/*********************************************
+ * Description - RPCalc compiler
+ * Author - Vilyaem
+ * Date - Jun 05 2024
+ * *******************************************/
+
+#include <stdio.h>
+#include <string.h>
+
+char* regnames[] = { "%ax","%bx","%cx","%dx" };
+
+
+int main(void){
+
+  int stackptr = 0;
+  char strbuf[8];
+  char regnamebuf[16];
+  char regnamebuf2[16];
+
+  puts("/*Compiled with Vilyaem's simple rpcalc compiler*/");
+
+  while(fgets(strbuf,8,stdin) != NULL){
+    if(strbuf[0] == '\n'){
+      break;
+    }
+    strbuf[strlen(strbuf)-1] = '\0';
+    switch(strbuf[0]){
+      case '+':
+        strcpy(regnamebuf,regnames[stackptr-1]);
+        strcpy(regnamebuf2,regnames[stackptr-2]);
+        printf("add %%%s,%%%s\n",regnamebuf,regnamebuf2);
+        --stackptr;
+        break;
+      case '-':
+        strcpy(regnamebuf,regnames[stackptr-1]);
+        strcpy(regnamebuf2,regnames[stackptr-2]);
+        printf("sub %%%s,%%%s\n",regnamebuf,regnamebuf2);
+        --stackptr;
+        break;
+      case '*':
+        strcpy(regnamebuf,regnames[stackptr-1]);
+        strcpy(regnamebuf2,regnames[stackptr-2]);
+        printf("imul %%%s,%%%s\n",regnamebuf,regnamebuf2);
+        --stackptr;
+        break;
+      default:  /*assume it is a numeric to be pushed*/
+        printf("mv $%s,%%%s\n",strbuf,regnames[stackptr]);
+        ++stackptr;
+        break;
+    }
+    /*printf("# stackptr: %d", stackptr); for debugging*/
+  }
+
+  return 0;
+}