pass1.c.withallins

51模拟器 51模拟器 51模拟器

			{
				strcpy(AssemblyInstruction,trim(buff));
				
				if((strcasecmp(AssemblyInstruction," " ))==0)
					continue;
						
				info = assemble(AssemblyInstruction) ; //getting the number of bytes in the instruction
				fprintf(fpdest,"%.4X %.2X\n",LocCounter,info->hex_code);  //writing into temp hexfile...
				LocCounter += info->nobytes ;			// incrementing the LC by sizeof present instruction...
				
				
				//printf("%s\n",AssemblyInstruction);
			}
		//sscanf(buff,"%s:%s",Label,Mnemonic);
		
		//printf("%s %s\n",Label,Mnemonic);
		



	}
	
	
		else   // code to handle gas51 special escape sequence...
		{
			if(pat_index(buff,":start"))
				{
					strcpy(temp_info->file,gas51_file_being_assembled);
					temp_info->file_line_no = gas51_line_no ;
					
					push(temp_info);     // pushing the current file info into stack...
					//push(gas51_line_no);
					sscanf(buff,"%c%s%s",&ch,gas51_file_being_assembled,str); //reinit'ing file and line no...	
					gas51_line_no = 0 ;
				}
			else
				if(pat_index(buff,":end"))
					{
						temp_info=pop();
					        strcpy(gas51_file_being_assembled,temp_info->file);
						gas51_line_no = temp_info->file_line_no;	
						gas51_line_no--; // to compensate for the '++' op at start...				
						//current_line_no=pop();
					
					}
					
			
		}
	
	
	
	
	
    }  


	
	
	
	
for(i=0;i<=20;i++)
	
	if(strlen(gas51_symbol_table[i].Symbol)!=0)	
		printf("%s  ->   %d\n",gas51_symbol_table[i].Symbol,gas51_symbol_table[i].Address );
dump_file(fpdest);




}




struct instruct *  assemble(char *Instruction)
{

	
	unsigned int i;
	char tokens[5][10];  //a 2D  array of chars to hold instruction tokens...
	char found_flag=0;  //flag to denote match status -> 0 means match not found while 1 means match found...
	int num ;	
/*	tokens[0]=malloc(10*sizeof(char));
	tokens[1]=malloc(10*sizeof(char));
	tokens[2]=malloc(10*sizeof(char));
	tokens[3]=malloc(10*sizeof(char));
	tokens[4]=malloc(10*sizeof(char));   */
	
	
	for (i=0;i<=0xFF;i++)
	{
		if(!strcasecmp(instructions[i].mnemonic,Instruction ))
		{
			found_flag = 1;			// this is the code to test for 1 byte  ins...
			break ;
		}
		
	
	}
	
	
	if(found_flag==1)  //means instruction matched with opcode...
	{
		info = &instructions[i] ;
		return info ;
	
	
	}
	
	
	else
	{
		//do some stuff here to match a 2 byte instruction...
		// and break the loop immediately if a match occurs..
	
		 num = get_tokens(tokens,Instruction);  //all tokens copied into token array...returns total number of tokens...
		 
		if ((strcasecmp(tokens[0],"cjne")==0) && (num > 4)  )  // when a cjne ins contains more than 4 tokens...
       			{
				gas51_errno = 5 ;
				gas51_perror() ;

			}			

		else if ( (strcasecmp(tokens[0],"cjne")==0) && (num < 4)  )  // when a cjne ins contains less  than 4 tokens...
		{
			gas51_errno = 6 ;
			gas51_perror();


		}

		else if( strcasecmp(tokens[0],"cjne")  &&   num < 3 )
		{
			gas51_errno = 6 ;
			gas51_perror();
			


		}
		
		else if ( strcasecmp(tokens[0],"cjne") &&   num > 3 )
		{

			gas51_errno = 5 ;
			gas51_perror();

		}

		else 
		{	//everything ok...number of tokens are correct...proceeding with matching process...
			
			if (!isstandard(tokens[0]) )   //isstandard() returns 1 if standard , 0 if non-standard token...
			{
				if(substr(tokens[0],"#"))
					strcpy(newtokens[0],#8DATA);
				else 
					strcpy(newtokens[0],ADDR


			}
								



		}


		


	}



		
	
	
	

	if(found_flag==1 )
	{
		info = &instructions[i] ;
		return info ;

	}
	
	
	else
	{

		// do some stuff here to match a 3 byte instruction...
		// and break the loop immediately if a match occurs...




	}
	
	
	if(found_flag==1)
	{
		info = &instructions[i];
		return info ;


	}


			      // we have reached here means that all possible ins have been searched..so there must be an error...	
	else                          // this should come after all instructions are checked...
	{
		gas51_errno = 4 ;   // 4 is the error code for illegal instruction...
		gas51_perror();
		//exit(1);			
	}
	
	
	
	
	//return 0;

}



void push (struct gas51_file_info *temp_info )  
{
	gas51_file_info_stack[gas51_stack_index] = *(temp_info) ;  // hope this copies the whole structure...
	gas51_stack_index++ ;
	
}




struct gas51_file_info * pop(void)

{

	struct  gas51_file_info *temp_info ;
	gas51_stack_index--;

	temp_info = &(gas51_file_info_stack[gas51_stack_index]);

	return temp_info ;
	

}


int get_tokens(char t_addr[][10],char *instruction)
{

	unsigned int i,j,k;
	char buff[10];
	i=0;
	j=0;
	k=1;
	puts(instruction);
	while(instruction[i]!=' '   )   //at this point we may be sure that only a sinle space will be between 1st and 2nd token...
	{
		buff[j]=instruction[i] ;
		i++;
		j++;	


	}		

	buff[j] = '\0' ; // terminating buff with a trailing NULL...
	strcpy(t_addr[0],buff);   //first token gone...two more to go...

	i++;  //to get over the single space...
	j=0 ;  //reiniting j for a new buff...   
	
while(1)
{
	if(instruction[i]=='\n' || instruction[i]=='\0')
	{
		
		buff[j] = '\0' ;
		strcpy(t_addr[k],buff);
		if(strlen(buff))   //increment only if buff is non empty...
		  k++;
		break ;

	}

	
	if(instruction[i]==',' || instruction[i]==' ' || instruction[i]=='\t')
	{ 
		buff[j] = '\0' ;
		strcpy(t_addr[k],buff);
		if(strlen(buff))   // increment only if buff is non empty...
			k++;
		i++;
		j=0;
	}

	else
	{
		buff[j]=instruction[i];
		i++;
		j++;


	}



}

	
	
	
	
	
	/*	while(1)
	{
		





	}   */



	
	
/*	while(instruction[i]!=',' )
	{
		buff[j] = instruction[i];
		i++;
		j++;
	}
	
	buff[j] = '\0' ; //terminating buff with a trailing NULL...	
	strcpy(t_addr[1],buff);  //second token gone...one more to go...
	
	i++;
	j=0;
	while(instruction[i]!='\n')
	{
		buff[j] = instruction[i];
		i++;
		j++;
		



	}    */

	





	
	
return k ;   // returning the total number of tokens found...

	
}