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/*****************************************************************************
Licensed to Accellera Systems Initiative Inc. (Accellera) under one or
more contributor license agreements. See the NOTICE file distributed
with this work for additional information regarding copyright ownership.
Accellera licenses this file to you under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with the
License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
implied. See the License for the specific language governing
permissions and limitations under the License.
*****************************************************************************/
/*****************************************************************************
simple_cpu.cpp --
Original Author: Martin Janssen, Synopsys, Inc., 2002-02-15
*****************************************************************************/
/*****************************************************************************
MODIFICATION LOG - modifiers, enter your name, affiliation, date and
changes you are making here.
Name, Affiliation, Date:
Description of Modification:
*****************************************************************************/
#include "systemc.h"
#define READ 0
#define WRITE 1
SC_MODULE( exec_decode )
{
SC_HAS_PROCESS( exec_decode );
sc_in<unsigned> instruction;
sc_signal<unsigned>& program_counter;
unsigned pc; // Program counter
unsigned cpu_reg[32]; // Cpu registers
unsigned *data_mem; // The data memory
exec_decode( sc_module_name NAME,
sc_signal<unsigned>& INSTRUCTION,
sc_signal<unsigned>& PROGRAM_COUNTER )
: program_counter(PROGRAM_COUNTER)
{
instruction(INSTRUCTION);
SC_METHOD( entry );
// sensitive only to the clock
sensitive << instruction;
pc = 0x000000; // Power up reset value
for (int i =0; i<32; i++) cpu_reg[i] = 0;
// Initialize the data memory from file datamem
FILE *fp = fopen("simple_cpu/datamem", "r");
if (fp == (FILE *) 0) return; // No data mem file to read
// First field in this file is the size of data memory desired
int size;
fscanf(fp, "%d", &size);
data_mem = new unsigned[size];
if (data_mem == (unsigned *) 0) {
printf("Not enough memory left\n");
return;
}
unsigned mem_word;
size = 0;
while (fscanf(fp, "%x", &mem_word) != EOF) {
data_mem[size++] = mem_word;
}
// Start off simulation by writing program_counter
program_counter.write(pc);
}
// Functionality
void entry();
};
void
exec_decode::entry()
{
unsigned instr;
unsigned opcode;
unsigned regnum1, regnum2, regnum3;
unsigned addr;
int i;
instr = instruction.read();
opcode = (instr & 0xe0000000) >> 29; // Extract opcode
switch(opcode) {
case 0x0: // Halt
printf("CPU Halted\n");
printf("\tPC = 0x%x\n", pc);
for (i = 0; i < 32; i++)
printf("\tR[%d] = %x\n", i, cpu_reg[i]);
// Don't write pc and execution will stop
break;
case 0x1: // Store
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
addr = (instr & 0x00ffffff); // Extract address
printf("Store: Memory[0x%x] = R[%d]\n", addr, regnum1);
data_mem[addr] = cpu_reg[regnum1];
pc = pc + 1;
program_counter.write(pc);
break;
case 0x2: // Load
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
addr = (instr & 0x00ffffff); // Extract address
printf("Load: R[%d] = Memory[0x%x]\n", regnum1, addr);
cpu_reg[regnum1] = data_mem[addr];
pc = pc + 1;
program_counter.write(pc);
break;
case 0x3: // Add
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
regnum2 = (instr & 0x00f80000) >> 19; // Extract register number
regnum3 = (instr & 0x0007c000) >> 14; // Extract register number
printf("R[%d] = R[%d] + R[%d]\n", regnum3, regnum1, regnum2);
cpu_reg[regnum3] = cpu_reg[regnum1] + cpu_reg[regnum2];
pc = pc + 1;
program_counter.write(pc);
break;
case 0x4: // Subtract
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
regnum2 = (instr & 0x00f80000) >> 19; // Extract register number
regnum3 = (instr & 0x0007c000) >> 14; // Extract register number
printf("R[%d] = R[%d] - R[%d]\n", regnum3, regnum1, regnum2);
cpu_reg[regnum3] = cpu_reg[regnum1] - cpu_reg[regnum2];
pc = pc + 1;
program_counter.write(pc);
break;
case 0x5: // Multiply
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
regnum2 = (instr & 0x00f80000) >> 19; // Extract register number
regnum3 = (instr & 0x0007c000) >> 14; // Extract register number
printf("R[%d] = R[%d] * R[%d]\n", regnum3, regnum1, regnum2);
cpu_reg[regnum3] = cpu_reg[regnum1] * cpu_reg[regnum2];
pc = pc + 1;
program_counter.write(pc);
break;
case 0x6: // Divide
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
regnum2 = (instr & 0x00f80000) >> 19; // Extract register number
regnum3 = (instr & 0x0007c000) >> 14; // Extract register number
printf("R[%d] = R[%d] / R[%d]\n", regnum3, regnum1, regnum2);
if (cpu_reg[regnum2] == 0) {
printf("Division exception - divide by zero\n");
}
else {
cpu_reg[regnum3] = cpu_reg[regnum1] / cpu_reg[regnum2];
}
pc = pc + 1;
program_counter.write(pc);
break;
case 0x7: // JNZ
regnum1 = (instr & 0x1f000000) >> 24; // Extract register number
addr = (instr & 0x00ffffff); // Extract address
printf("JNZ R[%d] 0x%x\n", regnum1, addr);
if (cpu_reg[regnum1] == 0x0)
pc = pc + 1;
else
pc = addr;
program_counter.write(pc);
break;
default: // Bad opcode
printf("Bad opcode 0x%x\n", opcode);
pc = pc + 1;
program_counter.write(pc);
break;
}
}
SC_MODULE( fetch )
{
SC_HAS_PROCESS( fetch );
sc_in<unsigned> program_counter;
sc_signal<unsigned>& instruction;
unsigned *prog_mem; // The program memory
fetch( sc_module_name NAME,
sc_signal<unsigned>& PROGRAM_COUNTER,
sc_signal<unsigned>& INSTRUCTION )
: instruction(INSTRUCTION)
{
program_counter(PROGRAM_COUNTER);
SC_METHOD( entry );
sensitive << program_counter;
// Initialize the program memory from file progmem
FILE *fp = fopen("simple_cpu/progmem", "r");
if (fp == (FILE *) 0) return; // No prog mem file to read
// First field in this file is the size of program memory desired
int size;
fscanf(fp, "%d", &size);
prog_mem = new unsigned[size];
if (prog_mem == (unsigned *) 0) {
printf("Not enough memory left\n");
return;
}
unsigned mem_word;
size = 0;
while (fscanf(fp, "%x", &mem_word) != EOF) {
prog_mem[size++] = mem_word;
}
instruction.write(0);
}
// Functionality
void entry();
};
void fetch::entry()
{
unsigned pc, instr;
pc = program_counter.read();
instr = prog_mem[pc];
instruction.write(instr);
}
int
sc_main(int ac, char *av[])
{
sc_signal<unsigned> pc;
sc_signal<unsigned> instr;
exec_decode ED("ED", instr, pc);
fetch F("F", pc, instr);
// instead of a testbench routine, we include the testbench here
sc_start(1, SC_NS);
sc_start( 10, SC_NS );
fflush( stdout );
return 0;
}
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