Simulating MIPS computer with pipelining and forwarding using C programming homework help

The homework deals with implementing a simulator for a simplified MIPS computer using C. The program loads a MIPS assembly program and simulates its execution trace through the pipeline stages. The program can simulate data forwarding and stall due to data or control hazards. Have a look at the following solution where our C programming homework help doers demonstrate MIPS computer simulation.

Simulating Forwarding and Pipelining Processes in MIPS and C Programming

Source Code

#include #include #include #include #define MAX_LABEL_LEN 32 #define MAX_LABELS 100 #define MAX_INSTRUCTIONS 1000 #define MAX_MEMORY 32 #define MAX_OP_LINE 50 #define MAX_LINE 100 #define I_CACHE_BLOCKS 4 #define I_CACHE_BLKSIZE 8 #define D_CACHE_BLOCKS 4 #define D_CACHE_BLKSIZE 4 #define MEM_DELAY 3 #define WRITE_BUFFER_SIZE 100 enum { INVALID=-1, NOP=0, J, BEQ, BNE, LI, AND, ANDI, OR, ORI, LW, SW, ADD, ADDI, SUB, SUBI, MULT, MULTI, HLT }; enum { IF_ID, ID_EX1, EX1_EX2, EX2_EX3, EX3_MEM, MEM_WB, LAST }; char *instructions[] = { "NOP", "J", "BEQ", "BNE", "LI", "AND", "ANDI", "OR", "ORI", "LW", "SW", "ADD", "ADDI", "SUB", "SUBI", "MULT", "MULTI", "HLT" }; int ninstructions = 18; typedef struct { char name[MAX_LABEL_LEN]; int addr; }label_t; typedef struct { int label; int opcode; int rdest; int rsrc; int rsrc2; int imm; int addr; int ex_stages; int wb; int mem_rd; int mem_wr; int mem_data; int mem_addr; int PC; int rsrc_req; int rsrc2_req; int rsrc_val; int rsrc2_val; int rdest_val; int if_cycle; int id_cycle; int ex_cycle; int mem_cycle; int wb_cycle; int stalled; }inst_t; inst_t nop; /* Label table*/ label_t labels[MAX_LABELS]; int nlabels; /* Instruction table */ inst_t inst_table[MAX_INSTRUCTIONS]; int ninst; /* register file */ int registers[32]; /* Data memory */ int memory[MAX_MEMORY]; int mem_size; /* cache definitions */ typedef struct { int valid; int tag; inst_t data[I_CACHE_BLKSIZE]; }i_cache_entry_t; typedef struct { int valid; int tag; int data[D_CACHE_BLKSIZE]; }d_cache_entry_t; /* instruction cache */ i_cache_entry_t i_cache[I_CACHE_BLOCKS]; int i_cache_accesses = 0; int i_cache_hits = 0; int i_cache_reading = 0; int i_cache_index; int i_cache_offset; int i_cache_mem_addr; /* data cache */ d_cache_entry_t d_cache[D_CACHE_BLOCKS]; int d_cache_accesses = 0; int d_cache_hits = 0; int d_cache_reading = 0; int d_cache_index; int d_cache_offset; int d_cache_mem_addr; int d_cache_writing = 0; int d_cache_index_w; int d_cache_offset_w; int d_cache_mem_addr_w; /* Write buffer */ typedef struct { int addr; int data; }buffer_entry_t; buffer_entry_t write_buffer[WRITE_BUFFER_SIZE]; int buffer_pos = 0; int buffer_updating = 0; /* Instruction statistics */ typedef struct { int pos; char line[MAX_LINE]; }stats_entry_t; stats_entry_t stats[MAX_INSTRUCTIONS]; int n_stats = 0; /* Remove whitespace at start and end of string */ char *trim(char *str) { char *ptr = str, *end; while (*ptr && isspace(*ptr)) ptr++; if (!(*ptr)) return ptr; end = &str[strlen(str) - 1]; while(end != ptr && isspace(*end)) end--; end[1] = 0; return ptr; } /* Convert string to uppercase */ void str_to_upper(char *str) { char *ptr = str; while(*ptr) { *ptr = toupper(*ptr); ptr++; } } /* get the pointer to the first space after the current word, inserts a zero at the end of the word to separate it from the next one */ char *get_next_word(char *str) { char *ptr = str; while(*ptr && !isspace(*ptr)) ptr++; if (*ptr) *(ptr++) = 0; return ptr; } /* make a first pass on the input file by loading all labels on a label table */ void first_pass(FILE *input) { char buffer[BUFSIZ], *line; int nline = 0; while (!feof(input)) { if (fgets(buffer, BUFSIZ, input)) { line = trim(buffer); if (line[0]) { get_next_word(line); if (line[strlen(line) - 1] == ':') { line[strlen(line) - 1] = 0; strcpy(labels[nlabels].name, line); labels[nlabels].addr = nline; nlabels++; } nline++; } } } } /* parse the operands for the instruction, which are separated by commas, returns the number of operands or -1 if they are invalid or more than 3 */ int parse_operand(char *oper, char *operands[]) { char *token; int ntokens = 0; token = strtok(oper, ","); while(token) { if (ntokens >= 3) return -1; operands[ntokens] = trim(token); ntokens++; token = strtok(NULL, ","); } return ntokens; } /* Search for an instruction in the instruction table and returns the opcode */ int search_instruction(char *inst) { int i; int opcode = INVALID; for (i = 0; i < ninstructions; i++) if (!strcmp(inst, instructions[i])) { opcode = i; break; } return opcode; } /* Search for a label in the label table and returns the address */ int search_label(char *label) { int i; int addr = INVALID; for (i = 0; i < nlabels; i++) if (!strcmp(label, labels[i].name)) { addr = i; break; } return addr; } /* checks if the string is a valid number, returns 1 if valid, 0 otherwise */ int valid_number(char *str) { char *ptr = str; if (*ptr == '-') { str++; ptr++; } while(*ptr) { if (!isdigit(*ptr)) return 0; ptr++; } if (ptr != str) return 1; else return 0; } /* Validates the string by checking if it corresponds to a valid register name */ int validate_register(char *sreg) { int reg = INVALID; if (sreg[0]!='R') return INVALID; if (!valid_number(&sreg[1])) return INVALID; reg = atoi(&sreg[1]); if (reg < 0 || reg >= 32) return INVALID; return reg; } /* Parses the J instruction with given operands */ inst_t parse_J(char *operands[], int nops, int nline) { int addr; inst_t instruction; if (nops != 1) { fprintf(stderr, "Incorrect number of operands for J instruction in line %d\n", nline); exit(1); } addr = search_label(operands[0]); if (addr == INVALID) { fprintf(stderr, "Unknown label for J instruction in line %d\n", nline); exit(1); } instruction.opcode = J; instruction.addr = addr; return instruction; } /* Parses the branch instruction with given operands */ inst_t parse_B(int opcode, char *operands[], int nops, int nline) { inst_t instruction; if (nops != 3) { fprintf(stderr, "Incorrect number of operands for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.opcode = opcode; instruction.addr = search_label(operands[2]); if (instruction.addr == INVALID) { fprintf(stderr, "Unknown label for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.rsrc = validate_register(operands[0]); if (instruction.rsrc == INVALID) { fprintf(stderr, "Invalid source register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.rsrc2 = validate_register(operands[1]); if (instruction.rsrc2 == INVALID) { fprintf(stderr, "Invalid source register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } return instruction; } /* Parses the LI instruction with given operands */ inst_t parse_LI(char *operands[], int nops, int nline) { inst_t instruction; if (nops != 2) { fprintf(stderr, "Incorrect number of operands for LI instruction in line %d\n", nline); exit(1); } instruction.opcode = LI; instruction.rdest = validate_register(operands[0]); if (instruction.rdest == INVALID) { fprintf(stderr, "Invalid register for LI instruction in line %d\n", nline); exit(1); } if (!valid_number(operands[1])) { fprintf(stderr, "Invalid immediate value for LI instruction in line %d\n", nline); exit(1); } instruction.imm = atoi(operands[1]); return instruction; } /* Parses the register arithmetic/logic instruction with given operands */ inst_t parse_R(int opcode, char *operands[], int nops, int nline) { inst_t instruction; if (nops != 3) { fprintf(stderr, "Incorrect number of operands for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.opcode = opcode; instruction.rdest = validate_register(operands[0]); if (instruction.rdest == INVALID) { fprintf(stderr, "Invalid destination register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.rsrc = validate_register(operands[1]); if (instruction.rsrc == INVALID) { fprintf(stderr, "Invalid source register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.rsrc2 = validate_register(operands[2]); if (instruction.rsrc2 == INVALID) { fprintf(stderr, "Invalid source register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } return instruction; } /* Parses the immediate arithmetic/logic instruction with given operands */ inst_t parse_I(int opcode, char *operands[], int nops, int nline) { inst_t instruction; if (nops != 3) { fprintf(stderr, "Incorrect number of operands for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.opcode = opcode; instruction.rdest = validate_register(operands[0]); if (instruction.rdest == INVALID) { fprintf(stderr, "Invalid destination register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.rsrc = validate_register(operands[1]); if (instruction.rsrc == INVALID) { fprintf(stderr, "Invalid source register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } if (!valid_number(operands[2])) { fprintf(stderr, "Invalid immediate value for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.imm = atoi(operands[2]); return instruction; } /* Parses the memory instruction with given operands */ inst_t parse_M(int opcode, char *operands[], int nops, int nline) { int rsrc, rdest; inst_t instruction; char *end, *reg, *off; if (nops != 2) { fprintf(stderr, "Incorrect number of operands for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.opcode = opcode; rdest = validate_register(operands[0]); if (rdest == INVALID) { fprintf(stderr, "Invalid destination register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } if (opcode == LW) instruction.rdest = rdest; else instruction.rsrc = rdest; end = &operands[1][strlen(operands[1])-1]; if (*end != ')') { fprintf(stderr, "Invalid format for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } *(end--) = 0; while(end > operands[1] && *end != '(') end--; if (*end != '(' || end <= operands[1]) { fprintf(stderr, "Invalid format for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } *end = 0; reg = trim(end + 1); rsrc = validate_register(reg); if (rsrc == INVALID) { fprintf(stderr, "Invalid base register for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } if (opcode == LW) instruction.rsrc = rsrc; else instruction.rsrc2 = rsrc; off = operands[1]; if (!valid_number(off)) { fprintf(stderr, "Invalid offset value for %s instruction in line %d\n", instructions[opcode], nline); exit(1); } instruction.imm = atoi(off); return instruction; } /* Parses the HLT instruction with given operands */ inst_t parse_HLT(char *operands[], int nops, int nline) { inst_t instruction; if (nops != 0) { fprintf(stderr, "Incorrect number of operands for HLT instruction in line %d\n", nline); exit(1); } instruction.opcode = HLT; return instruction; } /* Parses the instruction with the name inst and operands oper, returns a inst_t structure with the opcode and operands of instruction */ inst_t parse_instruction(char *inst, char *oper, int nline) { int opcode, nops; char *operands[3]; inst_t instruction; opcode = search_instruction(inst); if (opcode == INVALID) { fprintf(stderr, "Invalid instruction %s found in line %d\n", inst, nline); exit(1); } nops = parse_operand(oper, operands); if (nops == INVALID) { fprintf(stderr, "Too many operands for instruction %s in line %d\n", instructions[opcode], nline); exit(1); } switch(opcode) { case J: instruction = parse_J(operands, nops, nline); instruction.rsrc_req = 0; instruction.rsrc2_req = 0; break; case BEQ: case BNE: instruction = parse_B(opcode, operands, nops, nline); instruction.rsrc_req = 1; instruction.rsrc2_req = 1; break; case LI: instruction = parse_LI(operands, nops, nline); instruction.rsrc_req = 0; instruction.rsrc2_req = 0; break; case AND: case OR: case ADD: case SUB: case MULT: instruction = parse_R(opcode, operands, nops, nline); instruction.rsrc_req = 1; instruction.rsrc2_req = 1; break; case ANDI: case ORI: case ADDI: case SUBI: case MULTI: instruction = parse_I(opcode, operands, nops, nline); instruction.rsrc_req = 1; instruction.rsrc2_req = 0; break; case LW: instruction = parse_M(opcode, operands, nops, nline); instruction.rsrc_req = 1; instruction.rsrc2_req = 0; break; case SW: instruction = parse_M(opcode, operands, nops, nline); instruction.rsrc_req = 1; instruction.rsrc2_req = 1; break; case HLT: instruction = parse_HLT(operands, nops, nline); instruction.rsrc_req = 0; instruction.rsrc2_req = 0; break; } switch(opcode) { case J: case BEQ: case BNE: case LI: case HLT: instruction.ex_stages = 0; break; case AND: case OR: case ANDI: case ORI: case LW: case SW: instruction.ex_stages = 1; break; case ADD: case SUB: case ADDI: case SUBI: instruction.ex_stages = 2; break; case MULT: case MULTI: instruction.ex_stages = 3; break; } instruction.stalled = 0; return instruction; } /* makes a second pass to parse all instructions, save them on the instruction table translating all label references to addresses */ void second_pass(FILE *input) { char buffer[BUFSIZ], *line; char *next, *inst, *oper; int nline = 1; inst_t instruction; int lbl; ninst = 0; while (!feof(input)) { if (fgets(buffer, BUFSIZ, input)) { line = trim(buffer); if (line[0]) { str_to_upper(line); next = get_next_word(line); if (line[strlen(line) - 1] == ':') { line[strlen(line) - 1] = 0; lbl = search_label(line); inst = trim(next); oper = get_next_word(inst); } else { lbl = -1; inst = line; oper = trim(next); } instruction = parse_instruction(inst, oper, nline); instruction.label = lbl; inst_table[ninst++] = instruction; } nline++; } } } /* Loads all the instructions from the given file into the instruction table */ void load_instructions(char *filename) { FILE *input; input = fopen(filename, "rt"); if (input == NULL) { fprintf(stderr, "Unable to open instruction file \"%s\"\n", filename); exit(1); } first_pass(input); rewind(input); second_pass(input); fclose(input); } /* Loads all the memory data from the given file */ void load_memory_data(char *filename) { FILE *input; char buffer[BUFSIZ], *line; int data, bit; input = fopen(filename, "rt"); if (input == NULL) { fprintf(stderr, "Unable to open memory file \"%s\"\n", filename); exit(1); } while (!feof(input)) { if (fgets(buffer, BUFSIZ, input)) { line = trim(buffer); if (line[0]) { if (strlen(line)!=32) { fprintf(stderr, "Invalid word size found in memory file\n"); exit(1); } data = 0; for (bit=0; bit<32; bit++) { if (line[bit] != '0' && line[bit] != '1') { fprintf(stderr, "Invalid bit value found in memory file\n"); exit(1); } data = (data << 1) | (line[bit] - '0'); } memory[mem_size++] = data; } } } fclose(input); } /* save the instruction stats */ void save_instruction_stats(inst_t inst) { char label[MAX_LABEL_LEN + 2]; char ops[MAX_OP_LINE]; char cycles[5][MAX_OP_LINE]; stats_entry_t stat; int i, j; if (inst.label != INVALID) sprintf(label, "%s:",labels[inst.label].name); else sprintf(label, " "); switch(inst.opcode) { case J: sprintf(ops, "%s", labels[inst.addr].name); inst.ex_cycle = 0; inst.mem_cycle = 0; inst.wb_cycle = 0; break; case BEQ: case BNE: sprintf(ops, "R%d, R%d, %s", inst.rsrc, inst.rsrc2, labels[inst.addr].name); inst.ex_cycle = 0; inst.mem_cycle = 0; inst.wb_cycle = 0; break; case LI: sprintf(ops, "R%d, %d", inst.rdest, inst.imm); break; case AND: case OR: case ADD: case SUB: case MULT: sprintf(ops, "R%d, R%d, R%d", inst.rdest, inst.rsrc, inst.rsrc2); break; case ANDI: case ORI: case ADDI: case SUBI: case MULTI: sprintf(ops, "R%d, R%d, %d", inst.rdest, inst.rsrc, inst.imm); break; case LW: sprintf(ops, "R%d, %d(R%d)", inst.rdest, inst.imm, inst.rsrc); break; case SW: sprintf(ops, "R%d, %d(R%d)", inst.rsrc, inst.imm, inst.rsrc2); break; case HLT: sprintf(ops, " "); inst.ex_cycle = 0; inst.mem_cycle = 0; inst.wb_cycle = 0; break; } for (i = 0; i < 5; i++) cycles[i][0] = 0; if (inst.if_cycle != 0) sprintf(cycles[0], "%-6d", inst.if_cycle); if (inst.id_cycle != 0) sprintf(cycles[1], "%-6d", inst.id_cycle); if (inst.ex_cycle != 0) sprintf(cycles[2], "%-6d", inst.ex_cycle); if (inst.mem_cycle != 0) sprintf(cycles[3], "%-6d", inst.mem_cycle); if (inst.wb_cycle != 0) sprintf(cycles[4], "%-6d", inst.wb_cycle); sprintf(stat.line, "%-8s %-8s %-20s %s %s %s %s %s", label, instructions[inst.opcode], ops, cycles[0], cycles[1], cycles[2], cycles[3], cycles[4]); stat.pos = inst.if_cycle; if (n_stats == 0) stats[n_stats++] = stat; else { for (i = 0; i < n_stats; i++) { if (stats[i].pos > stat.pos) break; } for (j = n_stats; j>i; j--) stats[j] = stats[j - 1]; stats[i] = stat; n_stats++; } } /* Simulates one cycle of an instruction cache read */ inst_t i_cache_read(int PC) { int tag = PC >> 5; int index = (PC >> 3) & 0x3; int offset = PC & 0x7; int i; if (!i_cache_reading) { i_cache_accesses++; if (i_cache[index].valid && i_cache[index].tag == tag) { i_cache_hits++; return i_cache[index].data[offset]; } else { i_cache_reading = I_CACHE_BLKSIZE*MEM_DELAY; i_cache_index = index; i_cache_offset = offset; i_cache_mem_addr = (PC >> 3) << 3; i_cache[index].tag = tag; return nop; } } else { i_cache_reading--; if (i_cache_reading == 0) { i_cache[i_cache_index].valid = 1; for (i = 0; i < I_CACHE_BLKSIZE; i++) i_cache[i_cache_index].data[i] = inst_table[i_cache_mem_addr + i]; return i_cache[i_cache_index].data[i_cache_offset]; } else return nop; } } /* Simulates one cycle of a data cache read */ int d_cache_read(int addr, int *miss) { int real_addr; int tag; int index; int offset; int i; real_addr = (addr - 0x100) >> 2; tag = real_addr >> 4; index = (real_addr >> 2) & 0x3; offset = real_addr & 0x3; if (!d_cache_reading) { d_cache_accesses++; if (d_cache[index].valid && d_cache[index].tag == tag) { d_cache_hits++; *miss = 0; return d_cache[index].data[offset]; } else { d_cache_reading = D_CACHE_BLKSIZE*MEM_DELAY+1; d_cache_index = index; d_cache_offset = offset; d_cache_mem_addr = (real_addr >> 2) << 2; d_cache[index].tag = tag; *miss = 1; return 0; } } else { if (!i_cache_reading && !d_cache_writing) d_cache_reading--; if (d_cache_reading == 0) { d_cache[d_cache_index].valid = 1; for (i = 0; i < D_CACHE_BLKSIZE; i++) d_cache[d_cache_index].data[i] = memory[d_cache_mem_addr + i]; *miss = 0; return d_cache[d_cache_index].data[d_cache_offset]; } else { *miss = 1; return 0; } } } /* Simulates one cycle of a data cache write */ int d_cache_write(int val, int addr) { int real_addr; int tag; int index; int offset; int i; real_addr = (addr - 0x100) >> 2; tag = real_addr >> 4; index = (real_addr >> 2) & 0x3; offset = real_addr & 0x3; if (!d_cache_writing) { d_cache_accesses++; if (d_cache[index].valid && d_cache[index].tag == tag) { d_cache_hits++; d_cache[index].data[offset] = val; write_buffer[buffer_pos].data = val; write_buffer[buffer_pos].addr = real_addr; buffer_pos++; return 0; } else { d_cache_writing = D_CACHE_BLKSIZE*MEM_DELAY+1; d_cache_index_w = index; d_cache_offset_w = offset; d_cache_mem_addr_w = (real_addr >> 2) << 2; d_cache[index].tag = tag; return 1; } } else { if (!i_cache_reading) d_cache_writing--; if (d_cache_writing == 0) { d_cache[d_cache_index_w].valid = 1; for (i = 0; i < D_CACHE_BLKSIZE; i++) d_cache[d_cache_index_w].data[i] = memory[d_cache_mem_addr_w + i]; d_cache[d_cache_index_w].data[d_cache_offset_w] = val; write_buffer[buffer_pos].data = val; write_buffer[buffer_pos].addr = d_cache_mem_addr_w; buffer_pos++; return 0; } else return 1; } } /* updates the memory using the write buffer one word at a time */ void update_memory() { int i; if (!i_cache_reading && !d_cache_reading && !d_cache_writing) { if (!buffer_updating && buffer_pos) buffer_updating = 3; else { buffer_updating--; if (buffer_updating == 0) { memory[write_buffer[0].addr] = write_buffer[0].data; buffer_pos--; for (i = 0; i < buffer_pos; i++) write_buffer[i] = write_buffer[i + 1]; } } } } /* Simulates the execution of the instruction */ inst_t execute(inst_t inst) { inst.PC = 0; inst.wb = 1; inst.mem_rd = 0; inst.mem_wr = 0; switch (inst.opcode) { case J: inst.PC = labels[inst.addr].addr; inst.wb = 0; break; case BEQ: if (inst.rsrc_val == inst.rsrc2_val) inst.PC = labels[inst.addr].addr; inst.wb = 0; break; case BNE: if (inst.rsrc_val != inst.rsrc2_val) inst.PC = labels[inst.addr].addr; inst.wb = 0; break; case LI: inst.rdest_val = inst.imm; break; case AND: inst.rdest_val = inst.rsrc_val & inst.rsrc2_val; break; case OR: inst.rdest_val = inst.rsrc_val | inst.rsrc2_val; break; case ADD: inst.rdest_val = inst.rsrc_val + inst.rsrc2_val; break; case SUB: inst.rdest_val = inst.rsrc_val - inst.rsrc2_val; break; case MULT: inst.rdest_val = inst.rsrc_val * inst.rsrc2_val; break; case ANDI: inst.rdest_val = inst.rsrc_val & inst.imm; break; case ORI: inst.rdest_val = inst.rsrc_val | inst.imm; break; case ADDI: inst.rdest_val = inst.rsrc_val + inst.imm; break; case SUBI: inst.rdest_val = inst.rsrc_val - inst.imm; break; case MULTI: inst.rdest_val = inst.rsrc_val * inst.imm; break; case LW: inst.mem_rd = 1; inst.mem_addr = inst.rsrc_val + inst.imm; break; case SW: inst.wb = 0; inst.mem_wr = 1; inst.mem_data = inst.rsrc_val; inst.mem_addr = inst.rsrc2_val + inst.imm; break; case HLT: case NOP: inst.wb = 0; break; } return inst; } /* Simulate the loaded program */ void simulate() { int PC; int halted, stalled; inst_t pipeline[7]; int i, cycles = 0; int enable_if, miss, data, slot; nop.opcode = NOP; nop.rdest = INVALID; nop.rsrc = INVALID; nop.rsrc2 = INVALID; nop.rsrc_req = 0; nop.rsrc2_req = 0; nop.wb = 0; nop.if_cycle = 0; nop.ex_stages = 0; nop.stalled = 0; for(i=0; i<7; i++) pipeline[i] = nop; PC = 0; halted = 0; stalled = 0; enable_if = 1; while (!halted) { if (pipeline[ID_EX1].opcode != HLT && enable_if && !stalled) { pipeline[IF_ID] = i_cache_read(PC); if (pipeline[IF_ID].opcode != NOP) { pipeline[IF_ID].if_cycle = cycles + 1; pipeline[IF_ID].id_cycle = 0; pipeline[IF_ID].ex_cycle = 0; pipeline[IF_ID].mem_cycle = 0; pipeline[IF_ID].wb_cycle = 0; pipeline[IF_ID].stalled = 0; PC++; } } pipeline[ID_EX1].stalled = 0; if (pipeline[ID_EX1].opcode == HLT) enable_if = 0; slot =(pipeline[ID_EX1].ex_stages == 0)? 1 : 0; if(pipeline[ID_EX1].rsrc_req) { if (pipeline[ID_EX1].rsrc == pipeline[EX1_EX2].rdest) { if (pipeline[EX1_EX2].ex_stages <= 1 - slot && !pipeline[EX1_EX2].mem_rd) pipeline[ID_EX1].rsrc_val = pipeline[EX1_EX2].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc == pipeline[EX2_EX3].rdest) { if (pipeline[EX2_EX3].ex_stages <= 2 - slot && !pipeline[EX2_EX3].mem_rd) pipeline[ID_EX1].rsrc_val = pipeline[EX2_EX3].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc == pipeline[EX3_MEM].rdest) { if (!pipeline[EX3_MEM].mem_rd) pipeline[ID_EX1].rsrc_val = pipeline[EX3_MEM].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc == pipeline[MEM_WB].rdest) { if (!pipeline[MEM_WB].mem_rd) pipeline[ID_EX1].rsrc_val = pipeline[MEM_WB].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc == pipeline[LAST].rdest) pipeline[ID_EX1].rsrc_val = pipeline[LAST].rdest_val; else pipeline[ID_EX1].rsrc_val = registers[pipeline[ID_EX1].rsrc]; } if(pipeline[ID_EX1].rsrc2_req) { if (pipeline[ID_EX1].rsrc2 == pipeline[EX1_EX2].rdest) { if (pipeline[EX1_EX2].ex_stages <= 1 -slot && !pipeline[EX1_EX2].mem_rd) pipeline[ID_EX1].rsrc2_val = pipeline[EX1_EX2].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc2 == pipeline[EX2_EX3].rdest) { if (pipeline[EX2_EX3].ex_stages <= 2-slot && !pipeline[EX2_EX3].mem_rd) pipeline[ID_EX1].rsrc2_val = pipeline[EX2_EX3].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc2 == pipeline[EX3_MEM].rdest) { if (!pipeline[EX3_MEM].mem_rd) pipeline[ID_EX1].rsrc2_val = pipeline[EX3_MEM].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc2 == pipeline[MEM_WB].rdest) { if (!pipeline[MEM_WB].mem_rd) pipeline[ID_EX1].rsrc2_val = pipeline[MEM_WB].rdest_val; else pipeline[ID_EX1].stalled = 1; } else if (pipeline[ID_EX1].rsrc2 == pipeline[LAST].rdest) pipeline[ID_EX1].rsrc2_val = pipeline[LAST].rdest_val; else pipeline[ID_EX1].rsrc2_val = registers[pipeline[ID_EX1].rsrc2]; } if (!pipeline[ID_EX1].stalled) { pipeline[ID_EX1] = execute(pipeline[ID_EX1]); if (pipeline[ID_EX1].PC) { PC = pipeline[ID_EX1].PC; save_instruction_stats(pipeline[IF_ID]); pipeline[IF_ID] = nop; } } pipeline[ID_EX1].id_cycle = cycles + 1; pipeline[EX1_EX2].stalled = 0; pipeline[EX1_EX2].ex_cycle = cycles + 1; pipeline[EX2_EX3].stalled = 0; pipeline[EX2_EX3].ex_cycle = cycles + 1; pipeline[EX3_MEM].stalled = 0; pipeline[EX3_MEM].ex_cycle = cycles + 1; pipeline[MEM_WB].stalled = 0; if (pipeline[MEM_WB].mem_wr) { data = d_cache_write(pipeline[MEM_WB].mem_data, pipeline[MEM_WB].mem_addr); if (miss) pipeline[MEM_WB].stalled = 1; } else if (pipeline[MEM_WB].mem_rd) { data = d_cache_read(pipeline[MEM_WB].mem_addr, &miss); if (!miss) { pipeline[MEM_WB].rdest_val = data; pipeline[MEM_WB].mem_rd = 0; } else pipeline[MEM_WB].stalled = 1; } pipeline[MEM_WB].mem_cycle = cycles + 1; pipeline[LAST].stalled = 0; if (pipeline[LAST].wb) registers[pipeline[LAST].rdest] = pipeline[LAST].rdest_val; pipeline[LAST].wb_cycle = cycles + 1; if (pipeline[LAST].opcode != NOP) { save_instruction_stats(pipeline[LAST]); if (pipeline[LAST].opcode == HLT) halted = 1; pipeline[LAST] = nop; } update_memory(); /* Advance pipeline */ stalled = 0; for (i = 6; i > 0; i--) { if(pipeline[i].opcode == NOP) stalled = 0; if (!pipeline[i-1].stalled) { if (!stalled) { pipeline[i] = pipeline[i-1]; pipeline[i-1] = nop; } } else stalled = 1; } cycles++; } } /* Print the instruction statistics on a file */ void print_results(FILE *output) { int i; for (i = 0; i < n_stats; i++) fprintf(output, "%s\n", stats[i].line); fprintf(output, "\nTotal number of access requests for instruction cache: %d\n", i_cache_accesses); fprintf(output, "Number of instruction cache hits: %d\n", i_cache_hits); fprintf(output, "\nTotal number of access requests for data cache: %d\n", d_cache_accesses); fprintf(output, "Number of data cache hits: %d\n", d_cache_hits); } int main(int argc, char **argv) { FILE *output; if (argc != 4) { printf("Invalid number of arguments!\n"); printf("Usage:\n"); printf(" %s inst.txt data.txt output.txt\n", argv[0]); exit(1); } load_instructions(argv[1]); load_memory_data(argv[2]); simulate(); output = fopen(argv[3], "wt"); print_results(output); fclose(output); print_results(stdout); return 0; }