// Filename: code_generate.cpp

// Update on 2021 Nov. 8

// Fix some bugs and change the code for the test in Computer Organization course in Fall, 2021

#include<fstream>

#include<vector>

#include<algorithm>

#include<cstdlib>

#include<ctime>

using namespace std;

ofstream cout("mips_code.txt");

struct op{      // type=0:nop, type=1:addu, type=2:subu, type=3:lui, type=4:ori, type=5:lw, type=6:sw, type=7:beq

	int type,r1,r2,r3;

	op(){}

	op(int a1,int a2,int a3,int a4){

		type=a1,r1=a2,r2=a3,r3=a4;

	}

};

int size_im,size_dm,size_op,small_reg;

op a[10010];

vector<int> branch[10010];

int is_small[40],small[40],val[40],cnt;

int r(int a,int b,int except1){  // Randomly generate a register except the $1($at), because $1 may cause some unexpected errors

                                 // Function: Generate a random number in range (a, b), except number 1 when except1=1

	int t0=rand()*2+rand()%2;

	int res=t0%(b-a+1)+a;

	return ((res==1)&&except1==1)?0:res;

}

int t[10010];

void get_small(){               // Randomly select some registers for process 'lw' and 'sw' in the test

	int i;

	for(i=1;i<=26;i++) t[i]=i;

	for(i=1;i<=26;i++) swap(t[i],t[rand()%30+1]);

	for(i=1;i<=small_reg;i++) small[i]=t[i]+1,is_small[t[i]+1]=1;

}

int nosmall(){                  // Randomly generate a register which is not in the array small[]

	int u=r(0,27,1);

	while(is_small[u]==1){u=r(0,27,1);}

	return u;

}

void print(int x){

	if(a[x].type==0) cout<<"nop"<<endl;

	if(a[x].type==1) cout<<"addu $"<<a[x].r1<<",$"<<a[x].r2<<",$"<<a[x].r3<<endl;

	if(a[x].type==2) cout<<"subu $"<<a[x].r1<<",$"<<a[x].r2<<",$"<<a[x].r3<<endl;

	if(a[x].type==3) cout<<"lui $"<<a[x].r1<<","<<a[x].r3<<endl;

	if(a[x].type==4) cout<<"ori $"<<a[x].r1<<",$"<<a[x].r2<<","<<a[x].r3<<endl;

	if(a[x].type==5) cout<<"lw $"<<a[x].r1<<","<<a[x].r3<<"($"<<a[x].r2<<")"<<endl;

	if(a[x].type==6) cout<<"sw $"<<a[x].r1<<","<<a[x].r3<<"($"<<a[x].r2<<")"<<endl;

	if(a[x].type==7) cout<<"beq $"<<a[x].r1<<",$"<<a[x].r2<<",branch"<<a[x].r3<<endl;

}

int main(){

	int i,j;

	srand(time(NULL));

	size_im=32,size_dm=32,size_op=8,small_reg=8;		// The size of IM and DM is 32 in the test

	get_small();

	for(i=1;i<=small_reg;i++)                       	// Firstly, use 'ori' to assign primary data for the registers

		a[i]=(op(4,small[i],0,val[small[i]]=r(0,size_dm-1,0)));

	for(i=small_reg+1;i<=size_im;i++){

		int op0=r(0,size_op-1,0),r1,r2,r3;

		if(op0==0) a[i]=(op(0,0,0,0));

		if(op0==1||op0==2){                             // 'addu' and 'subu'

			a[i]=op(op0,nosmall(),r(0,27,1),r(0,27,1));

		}

		if(op0==3||op0==4){                             // 'lui' and 'ori'

			a[i]=(op(op0,nosmall(),r(0,27,1),r(0,65535,0)));

		}

		if(op0==5){                                     // 'lw'

			r1=r(0,size_dm-1,0);

			r2=r(1,small_reg,0);

			a[i]=(op(op0,nosmall(),small[r2],(r1-val[small[r2]])*4));

		}

		if(op0==6){                                     // 'sw'

			r1=r(0,size_dm-1,0);

			r2=r(1,small_reg,0);

			a[i]=(op(op0,r(0,27,1),small[r2],(r1-val[small[r2]])*4));

		}

		if(op0==7){                                     // 'beq' branch above may cause bugs, just generate branch below

			r3=r(i,size_im,0);

			a[i]=(op(op0,r(0,27,1),r(0,27,1),++cnt));

			branch[r3].push_back(cnt);                  // Randomly put the branch tags

		}

	}

	for(i=1;i<=size_im;i++) {

		print(i);

		for(j=0;j<branch[i].size();j++)

			cout << "branch" << branch[i][j] << ":" << endl;

	}

	return 0;

}