feat: Initialize the basic implementation

.github/workflows/test.yml

@@ -0,0 +1,23 @@
+name: Github Actions
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  cup_test:
+    runs-on: ubuntu-22.04
+    steps:
+      - name: checkout code
+        uses: actions/[email protected]
+      - name: setup Rust Cargo
+        run: |
+          sudo apt install cargo 
+
+      - name: run tests
+        run: |
+          cargo test --package emurv --test cpu_test -- tests --nocapture
+
+

.gitignore

@@ -1,14 +1,7 @@
-# Generated by Cargo
-# will have compiled files and executables
-debug/
-target/
-
-# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
-# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
-Cargo.lock
-
 # These are backup files generated by rustfmt
 **/*.rs.bk
 
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
+
+/target

Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "emurv"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

src/cpu.rs

@@ -0,0 +1,193 @@
+// pub mod cpu;
+
+use crate::memory;
+use crate::opcode::*;
+use crate::registers;
+
+#[derive(Debug)]
+pub struct CPU {
+    // integer registers
+    pub xregs: registers::XREGS,
+    pc: u64,
+
+    pub bus: memory::BUS,
+}
+
+impl CPU {
+    pub fn new() -> Self {
+        let mut cpu: CPU = CPU {
+            xregs: registers::XREGS::new(),
+            pc: memory::MEM_BASE,
+            bus: memory::BUS::new(),
+        };
+        cpu.xregs.regs[2] = memory::MEM_BASE + memory::MEM_SIZE; // Set stack pointer
+        cpu.pc = memory::MEM_BASE;
+        return cpu;
+    }
+
+    fn fetch(self) -> u32 {
+        let instr: u32 = self.bus.load(self.pc, 32);
+        return instr;
+    }
+
+    fn execute(&mut self, instr: u32) {
+        let opcode = instr & 0x7f;
+        let funct3 = (instr >> 12) & 0x7;
+        let funct7 = (instr >> 25) & 0x7f;
+        self.xregs.regs[0] = 0; // x0 hardwired to 0 at each cycle
+
+        match instr {
+            LUI => (),
+            AUIPC => (),
+            JAL => (),
+            JALR => (),
+            B_TYPE => match funct7 {
+                BEQ => exec_beq(self, instr),
+                BNE => exec_bne(self, instr),
+                BLT => exec_blt(self, instr),
+                BGE => exec_bge(self, instr),
+                BLTU => exec_bltu(self, instr),
+                BGEU => exec_bgeu(self, instr),
+                _ => panic!(),
+            },
+            LOAD => match funct3 {
+                LB => exec_lb(self, instr),
+                LH => exec_lh(self, instr),
+                LW => exec_lw(self, instr),
+                LD => exec_ld(self, instr),
+                LBU => exec_lbu(self, instr),
+                LHU => exec_lhu(self, instr),
+                LWU => exec_lwu(self, instr),
+                _ => panic!(),
+            },
+            S_TYPE => match funct3 {
+                SB => exec_sb(self, instr),
+                SH => exec_sh(self, instr),
+                SW => exec_sw(self, instr),
+                SD => exec_sd(self, instr),
+                _ => panic!(),
+            },
+            I_TYPE => match funct3 {
+                ADDI => exec_addi(self, instr),
+                SLLI => exec_slli(self, instr),
+                SLTI => exec_slti(self, instr),
+                SLTIU => exec_sltiu(self, instr),
+                XORI => exec_xori(self, instr),
+                SRI => match funct7 {
+                    SRLI => exec_srli(self, instr),
+                    SRAI => exec_srai(self, instr),
+                    _ => panic!(),
+                },
+                ORI => exec_ori(self, instr),
+                ANDI => exec_andi(self, instr),
+                _ => {
+                    panic!("malformed I type instruction");
+                }
+            },
+            R_TYPE => match funct3 {
+                ADDSUB => match funct7 {
+                    ADD => exec_add(self, instr),
+                    SUB => exec_sub(self, instr),
+                    _ => (),
+                },
+                SLL => exec_sll(self, instr),
+                SLT => exec_slt(self, instr),
+                SLTU => exec_sltu(self, instr),
+                XOR => exec_xor(self, instr),
+                SR => match funct7 {
+                    SRL => exec_srl(self, instr),
+                    SRA => exec_sra(self, instr),
+                    _ => (),
+                },
+                OR => exec_or(self, instr),
+                AND => exec_and(self, instr),
+                _ => {
+                    panic!("malformed I type instruction");
+                }
+            },
+            FENCE => exec_fence(self, instr),
+            _ => panic!(),
+        }
+    }
+}
+
+// RV32I
+// see page 64 at https://riscv.org/wp-content/uploads/2016/06/riscv-spec-v2.1.pdf
+pub fn exec_lui(cpu: &mut CPU, instr: u32) {}
+pub fn exec_auipc(cpu: &mut CPU, instr: u32) {}
+pub fn exec_jal(cpu: &mut CPU, instr: u32) {}
+pub fn exec_jalr(cpu: &mut CPU, instr: u32) {}
+pub fn exec_beq(cpu: &mut CPU, instr: u32) {}
+pub fn exec_bne(cpu: &mut CPU, instr: u32) {}
+pub fn exec_blt(cpu: &mut CPU, instr: u32) {}
+pub fn exec_bge(cpu: &mut CPU, instr: u32) {}
+pub fn exec_bltu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_bgeu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lb(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lh(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lw(cpu: &mut CPU, instr: u32) {}
+pub fn exec_ld(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lbu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lhu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_lwu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sb(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sh(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sw(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sd(cpu: &mut CPU, instr: u32) {}
+pub fn exec_addi(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] + imm as u64;
+}
+pub fn exec_slti(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] =
+        ((cpu.xregs.regs[rs1(instr) as usize] as i64) < (imm as i64)) as u64;
+}
+pub fn exec_sltiu(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = (cpu.xregs.regs[rs1(instr) as usize] < imm as u64) as u64;
+}
+pub fn exec_xori(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] ^ imm as u64;
+}
+pub fn exec_ori(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] | imm as u64;
+}
+pub fn exec_andi(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] & imm as u64;
+}
+pub fn exec_slli(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] << imm as u64;
+}
+pub fn exec_srli(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = cpu.xregs.regs[rs1(instr) as usize] >> imm as u64;
+}
+pub fn exec_srai(cpu: &mut CPU, instr: u32) {
+    let imm = imm_I(instr);
+    cpu.xregs.regs[rd(instr) as usize] = (cpu.xregs.regs[rs1(instr) as usize] as i64 >> imm) as u64;
+}
+pub fn exec_add(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sub(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sll(cpu: &mut CPU, instr: u32) {}
+pub fn exec_slt(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sltu(cpu: &mut CPU, instr: u32) {}
+pub fn exec_xor(cpu: &mut CPU, instr: u32) {}
+pub fn exec_srl(cpu: &mut CPU, instr: u32) {}
+pub fn exec_sra(cpu: &mut CPU, instr: u32) {}
+pub fn exec_or(cpu: &mut CPU, instr: u32) {}
+pub fn exec_and(cpu: &mut CPU, instr: u32) {}
+pub fn exec_fence(cpu: &mut CPU, instr: u32) {}
+pub fn exec_fence_i(cpu: &mut CPU, instr: u32) {}
+pub fn exec_ecall(cpu: &mut CPU, instr: u32) {}
+pub fn exec_ebreak(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrw(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrs(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrc(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrwi(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrsi(cpu: &mut CPU, instr: u32) {}
+pub fn exec_csrrci(cpu: &mut CPU, instr: u32) {}

src/lib.rs

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+pub mod cpu;
+pub mod memory;
+pub mod opcode;
+pub mod registers;

src/memory.rs

@@ -0,0 +1,109 @@
+// pub mod memory;
+
+pub const MEM_BASE: u64 = 0x80000000; // defined in QEMU
+pub const MEM_SIZE: u64 = 1024;
+
+#[derive(Debug)]
+pub struct BUS {
+    mem: MEMORY,
+}
+
+impl BUS {
+    pub fn new() -> Self {
+        BUS { mem: MEMORY::new() }
+    }
+    pub fn load(self, addr: u64, size: u64) -> u32 {
+        return self.mem.load(addr, size) as u32;
+    }
+    pub fn store(&mut self, addr: u64, size: u64, value: u64) {
+        self.mem.store(addr, size, value);
+    }
+}
+
+#[derive(Debug)]
+pub struct MEMORY {
+    mem: [u8; MEM_SIZE as usize],
+}
+
+impl MEMORY {
+    fn new() -> Self {
+        MEMORY {
+            mem: [0; MEM_SIZE as usize],
+        }
+    }
+
+    fn load(self, addr: u64, size: u64) -> u64 {
+        match size {
+            8 => return self.load8(addr),
+            16 => return self.load16(addr),
+            32 => return self.load32(addr),
+            64 => return self.load64(addr),
+            _ => panic!("wrong load size"),
+        }
+    }
+    fn store(&mut self, addr: u64, size: u64, value: u64) {
+        match size {
+            8 => self.store8(addr, value),
+            16 => self.store16(addr, value),
+            32 => self.store32(addr, value),
+            64 => self.store64(addr, value),
+            _ => panic!("wrong store size"),
+        }
+    }
+
+    // load funcs
+    fn load8(self, addr: u64) -> u64 {
+        let index = (addr - MEM_BASE) as usize;
+        return self.mem[index] as u64;
+    }
+    fn load16(self, addr: u64) -> u64 {
+        let index = (addr - MEM_BASE) as usize;
+        return self.mem[index] as u64 | ((self.mem[index + 1] as u64) << 8);
+    }
+    fn load32(self, addr: u64) -> u64 {
+        let index = (addr - MEM_BASE) as usize;
+        return self.mem[index] as u64
+            | ((self.mem[index + 1] as u64) << 8)
+            | ((self.mem[index + 2] as u64) << 16)
+            | ((self.mem[index + 3] as u64) << 24);
+    }
+    fn load64(self, addr: u64) -> u64 {
+        let index = (addr - MEM_BASE) as usize;
+        return self.mem[index] as u64
+            | ((self.mem[index + 1] as u64) << 8)
+            | ((self.mem[index + 2] as u64) << 16)
+            | ((self.mem[index + 3] as u64) << 24)
+            | ((self.mem[index + 4] as u64) << 32)
+            | ((self.mem[index + 5] as u64) << 40)
+            | ((self.mem[index + 6] as u64) << 48)
+            | ((self.mem[index + 7] as u64) << 56);
+    }
+
+    // store funcs
+    fn store8(&mut self, addr: u64, value: u64) {
+        let index = (addr - MEM_BASE) as usize;
+        self.mem[index] = (value & (std::u8::MAX as u64)) as u8;
+    }
+    fn store16(&mut self, addr: u64, value: u64) {
+        let index = (addr - MEM_BASE) as usize;
+        self.mem[index] = (value & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 1] = ((value >> 8) & (std::u8::MAX as u64)) as u8;
+    }
+    fn store32(&mut self, addr: u64, value: u64) {
+        let index = (addr - MEM_BASE) as usize;
+        self.mem[index] = (value & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 1] = ((value >> 8) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 2] = ((value >> 16) & (std::u8::MAX as u64)) as u8;
+    }
+    fn store64(&mut self, addr: u64, value: u64) {
+        let index = (addr - MEM_BASE) as usize;
+        self.mem[index] = (value & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 1] = ((value >> 8) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 2] = ((value >> 16) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 3] = ((value >> 24) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 4] = ((value >> 32) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 5] = ((value >> 40) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 6] = ((value >> 48) & (std::u8::MAX as u64)) as u8;
+        self.mem[index + 7] = ((value >> 56) & (std::u8::MAX as u64)) as u8;
+    }
+}