C程序设计语言--使用GCC（4）

耳朵在《Forth系统入门手册》中，给出了用C语言实现forth系统模型的代码，我完善了这个模型，使它看起来更像一个真正的Forth系统。代码为三个文件 cforth.c code_words.h colon_words.h,使用GCC编译器。对Forth有兴趣的朋友可以编译下试试。

cforth.c文件

#include <stdio.h>
#include <string.h>
int ds[256],rs[256];
int *dsp=ds,*rsp=rs;
int flag;
#include "code_words.h"
#include "colon_words.h"
char inputBuff[1024];
char strBuff[30];
int  main(){
 printf("Cforth 0.1.0, Copyright (C) 2008-2012 Free Software Foundation, Inc.\n");
 printf("Cforth comes with ABSOLUTELY NO WARRANTY; for details type `license'\n");
 printf("Type `bye' to exit\n");
    while (1){
  int i=0;
  int j=0;
  gets(inputBuff);
  while(inputBuff[j] != '\0'){
   if(inputBuff[j]!= ' '){
    strBuff[i] = inputBuff[j];
    i++;
    j++;
   }
   else {
    strBuff[i]='\0';
    if ( !strcmp(".s",strBuff) )  showDS();
          else if( !strcmp("dup",strBuff) ) dup();
          else if( !strcmp(".",strBuff) )  showtopDS();
          else if( !strcmp(">r",strBuff) ) tor();
          else if( !strcmp("r>",strBuff) ) rto();
          else if( !strcmp("drop",strBuff) ) drop();
          else if( !strcmp("+",strBuff) )  add();
          else if( !strcmp("-",strBuff) )  sub();
          else if( !strcmp("*",strBuff) )  mul();
           else if( !strcmp("/d",strBuff) ) ddiv();
          else if( !strcmp("/",strBuff) )  div();
          else if( !strcmp("%",strBuff) )  mod();
       else if( isNum() )      chgNum();
       else if( !strcmp("say",strBuff) ) say();
       else if( !strcmp("bye",strBuff) ) return 0;
          else printf("\n[%s]?\n",strBuff);

          for(i=0;i<30;i++) strBuff[i]='\0';
          i=0;
          j++;
   }
  }
  showOK();
 }
 return 0;
}
int isNum()
{
        char *str=strBuff;
        while(*str)
        {
                if(*str<'0' || *str>'9')         return 0;
                str++;
        }return 1;
}
int   chgNum()
{
        char *str=strBuff;
        int sum=0;
        while(*str)
        {
                sum=10*sum+(int)(*str-'0');
                str++;
        }
        push(sum);
        return 0;
}
int  showOK()
{
 printf("OK\n");
 return 0;
}
int say()
{
 gets(strBuff);
 printf("cforth: [%s]\n",strBuff);
 return 0;
}

code_words.h

//push 输入数字到DS
void push(int a){ dsp++; *dsp=a; }
//>r
void tor(){ rsp++; *rsp=*dsp; dsp--; }
//r>
void rto(){ dsp++; *dsp=*rsp; rsp--; }
//丢弃DS栈顶
void drop(){ dsp--; }
//复制DS栈顶
void dup(){ dsp++; *dsp=*(dsp-1); }
//交换DS栈顶前两个数
void swap(){ int tmp; tmp=*dsp,*dsp=*(dsp-1),*(dsp-1)=tmp; }
//+
void add(){ *(dsp-1)=*(dsp-1) + *dsp;  dsp--; }
//-
void sub(){ *(dsp-1)=*(dsp-1) - *dsp;  dsp--;}
//*
void mul(){ *(dsp-1)=*(dsp-1) * *dsp;  dsp--;}
// /d
void ddiv(){ *(dsp-1)=*(dsp-1) / *dsp;  dsp--;}
// %
void mod(){ *(dsp-1)=*(dsp-1) % *dsp;  dsp--;}
//显示DS
void showDS()
{
        int *tmp=&ds[1];
        while(tmp<=dsp)
        {
                printf("%d ",*tmp);
                tmp++;
        }
        printf(");
}
//显示RS
void showRS()
{
        int *tmp=&rs[1];
        while(tmp<=rsp)
        {
                printf("%d ",*tmp);
                tmp++;
        }
        printf(");
}
//显示DS栈顶，堆栈无影响
void showTOP()
{
 printf("%d\n",*dsp);
}
//若DS栈顶为0，则丢弃栈顶
void ifFlag0()
{
 flag = *dsp;
 if(flag == 0) drop();
}

colon_words.h

//2drop
void drop2(){ drop(); drop();  }
//over
void over(){ tor(); dup(); rto();  swap(); }
//2dup
void dup2(){ over(); over();  }
//show top of DS
void showtopDS(){ showTOP(); drop(); }
//带余数的除法
void div() { dup2(); mod(); tor(); ddiv();rto(); ifFlag0(); }