514 lines
13 KiB
C
514 lines
13 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <assert.h>
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#include <stdbool.h>
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inline uint32_t sign_extend(uint32_t word, uint32_t size)
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{
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const uint32_t mask = 1U << (size - 1);
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return (word ^ mask) - mask;
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}
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struct Instruction
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{
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uint8_t opcode;
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uint8_t rs1;
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uint8_t rs2;
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uint8_t rd;
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uint8_t funct3;
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uint8_t funct7;
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uint32_t imm;
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};
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struct Instruction decode_r_type(uint32_t word)
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{
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struct Instruction instruction = {0};
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instruction.opcode = word & 0x7F;
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instruction.rd = (word >> 7) & 0x1F;
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instruction.funct3 = (word >> 12) & 0x07;
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instruction.rs1 = (word >> 15) & 0x1F;
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instruction.rs2 = (word >> 20) & 0x1F;
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instruction.funct7 = word >> 25;
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return instruction;
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};
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struct Instruction decode_i_type(uint32_t word)
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{
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struct Instruction instruction = {0};
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instruction.opcode = word & 0x7F;
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instruction.rd = (word >> 7) & 0x1F;
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instruction.funct3 = (word >> 12) & 0x07;
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instruction.rs1 = (word >> 15) & 0x1F;
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instruction.imm = sign_extend(word >> 20, 12);
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return instruction;
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};
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struct Instruction decode_s_type(uint32_t word)
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{
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struct Instruction instruction = {0};
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instruction.opcode = word & 0x7F;
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instruction.funct3 = (word >> 12) & 0x07;
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instruction.rs1 = (word >> 15) & 0x1F;
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instruction.rs2 = (word >> 20) & 0x1F;
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instruction.imm = sign_extend(((word >> 7) & 0x1F) | (word >> 25), 12);
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return instruction;
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};
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struct Instruction decode_b_type(uint32_t word)
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{
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struct Instruction instruction = decode_s_type(word);
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instruction.imm = ((instruction.imm << 11) & 0x800) | (instruction.imm & 0xfffff7ff);
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return instruction;
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};
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struct Instruction decode_u_type(uint32_t word)
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{
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struct Instruction instruction = {0};
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instruction.opcode = word & 0x7F;
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instruction.rd = (word >> 7) & 0x1F;
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instruction.imm = word & 0xFFFFF000;
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return instruction;
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};
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struct Instruction decode_j_type(uint32_t word)
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{
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struct Instruction instruction = {0};
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instruction.opcode = word & 0x7F;
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instruction.rd = (word >> 7) & 0x1F;
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instruction.imm = sign_extend(
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((word & 0x80000000) >> 11) |
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((word & 0x000FF000) >> 0) |
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((word & 0x00100000) >> 9) |
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((word & 0x7FE00000) >> 20), 21);
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return instruction;
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}
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struct Hart
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{
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uint32_t pc;
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uint32_t regs[32];
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};
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void execute_op_imm(struct Hart* hart, uint32_t instruction)
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{
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const struct Instruction inst = decode_i_type(instruction);
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if (inst.rd == 0) return;
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switch (inst.funct3)
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{
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case 0: // ADDI
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hart->regs[inst.rd] = hart->regs[inst.rs1] + inst.imm;
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break;
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case 1: // SLLI
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hart->regs[inst.rd] = hart->regs[inst.rs1] << (inst.imm & 0x1F);
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break;
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case 2: // SLTI
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hart->regs[inst.rd] = (int32_t)hart->regs[inst.rs1] < (int32_t)inst.imm ? 1 : 0;
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break;
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case 3: // SLTIU
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hart->regs[inst.rd] = hart->regs[inst.rs1] < inst.imm ? 1 : 0;
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break;
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case 4: // XORI
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hart->regs[inst.rd] = hart->regs[inst.rs1] ^ inst.imm;
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break;
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case 5: // SRLI, SRAI
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{
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const uint32_t shamt = inst.imm & 0x1F;
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uint32_t res = hart->regs[inst.rs1] >> shamt;
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if ((inst.imm & 0x400) && shamt > 0) { res = sign_extend(res, 32 - shamt); }
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hart->regs[inst.rd] = res;
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break;
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}
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case 6: // ORI
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hart->regs[inst.rd] = hart->regs[inst.rs1] | inst.imm;
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break;
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case 7: // ANDI
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hart->regs[inst.rd] = hart->regs[inst.rs1] & inst.imm;
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break;
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default:
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assert(!"Unhandled OP-IMM");
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}
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}
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void execute_op(struct Hart* hart, uint32_t instruction)
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{
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const struct Instruction inst = decode_r_type(instruction);
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if (inst.rd == 0) return;
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switch (inst.funct3)
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{
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case 0: // ADD, SUB
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if (instruction & 0x40000000)
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{
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hart->regs[inst.rd] = hart->regs[inst.rs1] - hart->regs[inst.rs2];
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}
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else
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{
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hart->regs[inst.rd] = hart->regs[inst.rs1] + hart->regs[inst.rs2];
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}
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break;
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case 1: // SLL
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hart->regs[inst.rd] = hart->regs[inst.rs1] << (hart->regs[inst.rs2] & 0x1F);
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break;
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case 2: // SLT
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hart->regs[inst.rd] = (int32_t)hart->regs[inst.rs1] < (int32_t)hart->regs[inst.rs2] ? 1 : 0;
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break;
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case 3: // SLTU
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hart->regs[inst.rd] = hart->regs[inst.rs1] < hart->regs[inst.rs2] ? 1 : 0;
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break;
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case 4: // XOR
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hart->regs[inst.rd] = hart->regs[inst.rs1] ^ hart->regs[inst.rs2];
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break;
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case 5: // SRL, SRA
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{
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const uint32_t shamt = hart->regs[inst.rs2] & 0x1F;
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uint32_t res = hart->regs[inst.rs1] >> shamt;
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if ((instruction & 0x40000000) && shamt > 0) { res = sign_extend(res, 32 - shamt); }
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hart->regs[inst.rd] = res;
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break;
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}
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case 6: // OR
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hart->regs[inst.rd] = hart->regs[inst.rs1] | hart->regs[inst.rs2];
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break;
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case 7: // AND
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hart->regs[inst.rd] = hart->regs[inst.rs1] & hart->regs[inst.rs2];
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break;
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default:
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assert(!"Unhandled OP-IMM");
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}
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}
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void execute_branch(struct Hart* hart, uint32_t instruction)
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{
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const struct Instruction inst = decode_b_type(instruction);
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const uint32_t r1 = hart->regs[inst.rs1];
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const uint32_t r2 = hart->regs[inst.rs2];
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bool take_branch = false;
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switch (inst.funct3)
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{
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case 0: take_branch = (r1 == r2); break;
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case 1: take_branch = (r1 != r2); break;
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case 4: take_branch = (r1 < r2); break;
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case 5: take_branch = (r1 >= r2); break;
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case 6: take_branch = ((int32_t)r1 < (int32_t)r2); break;
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case 7: take_branch = ((int32_t)r1 >= (int32_t)r2); break;
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}
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if (take_branch)
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{
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hart->pc += inst.imm;
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}
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else
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{
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hart->pc += 4;
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}
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}
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void execute(struct Hart* hart, uint32_t instruction)
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{
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switch (instruction & 0x7f)
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{
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case 0x13:
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execute_op_imm(hart, instruction);
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hart->pc += 4;
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break;
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case 0x17: // AUIPC
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{
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struct Instruction inst = decode_u_type(instruction);
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if (inst.rd != 0)
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{
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hart->regs[inst.rd] = inst.imm + hart->pc;
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}
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hart->pc += 4;
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break;
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}
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case 0x33:
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execute_op(hart, instruction);
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hart->pc += 4;
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break;
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case 0x37: // LUI
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{
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struct Instruction inst = decode_u_type(instruction);
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if (inst.rd != 0)
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{
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hart->regs[inst.rd] = inst.imm;
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}
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hart->pc += 4;
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break;
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}
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case 0x63:
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execute_branch(hart, instruction);
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break;
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case 0x67: // JALR
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{
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struct Instruction inst = decode_i_type(instruction);
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assert(inst.funct3 == 0);
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if (inst.rd != 0)
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{
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hart->regs[inst.rd] = hart->pc + 4;
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}
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hart->pc = (hart->regs[inst.rs1] + inst.imm) & 0xFFFFFFFE;
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break;
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}
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case 0x6F: // JAL
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{
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struct Instruction inst = decode_j_type(instruction);
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if (inst.rd != 0)
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{
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hart->regs[inst.rd] = hart->pc + 4;
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}
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hart->pc += inst.imm;
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break;
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}
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default:
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assert(!"Unhandled opcode");
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}
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assert(hart->regs[0] == 0);
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}
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void test_addi()
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{
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struct Hart hart = {0};
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execute(&hart, 0x00500093); // addi x1, x0, 5
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assert(hart.regs[1] == 5);
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execute(&hart, 0xffe00093); // addi, x1, x0, -2
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assert(hart.regs[1] == 0xfffffffe);
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}
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void test_slti_sltiu()
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{
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struct Hart hart = {0};
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hart.regs[1] = 5;
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execute(&hart, 0x00f0b113); // sltiu x2, x1, 15
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assert(hart.regs[2] == 1);
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execute(&hart, 0x0050b113); // sltiu x2, x1, 15
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assert(hart.regs[2] == 0);
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execute(&hart, 0x0010b113); // sltiu x2, x1, 15
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assert(hart.regs[2] == 0);
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execute(&hart, 0x00f0a113); // slti x2, x1, 15
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assert(hart.regs[2] == 1);
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execute(&hart, 0x0050a113); // slti x2, x1, 15
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assert(hart.regs[2] == 0);
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execute(&hart, 0x0010a113); // slti x2, x1, 15
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assert(hart.regs[2] == 0);
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execute(&hart, 0xffb0a113); // slti x2, x1, -5
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assert(hart.regs[2] == 0);
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hart.regs[1] = (uint32_t)-20;
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execute(&hart, 0xffb0a113); // slti x2, x1, -5
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assert(hart.regs[2] == 1);
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}
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void test_andi_ori_xori()
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{
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struct Hart hart = {0};
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hart.regs[1] = 6;
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execute(&hart, 0x00c0c113); // xori x2, x1, 12
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assert(hart.regs[2] == 10);
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execute(&hart, 0x00c0e113); // ori x2, x1, 12
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assert(hart.regs[2] == 14);
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execute(&hart, 0x00c0f113); // andi x2, x1, 12
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assert(hart.regs[2] == 4);
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}
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void test_slli_srli_srai()
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{
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struct Hart hart = {0};
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hart.regs[1] = 6;
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execute(&hart, 0x00209113); // slli x2, x1, 2
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assert(hart.regs[2] == 24);
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execute(&hart, 0x0020d113); // srli x2, x1, 2
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assert(hart.regs[2] == 1);
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execute(&hart, 0x4020d113); // srai x2, x1, 2
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assert(hart.regs[2] == 1);
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hart.regs[1] = (uint32_t)-6;
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execute(&hart, 0x0020d113); // srli x2, x1, 2
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assert(hart.regs[2] == 0x3FFFFFFE);
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execute(&hart, 0x4020d113); // srai x2, x1, 2
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assert(hart.regs[2] == 0xFFFFFFFE);
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}
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void test_lui_auipc()
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{
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struct Hart hart = {0};
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hart.pc = 0;
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execute(&hart, 0x0007b0b7); // lui x1, 503808
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assert(hart.regs[1] == 503808);
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hart.pc = 0;
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execute(&hart, 0x0007b097); // auipc x1, 503808
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assert(hart.regs[1] == 503808);
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hart.pc = 12;
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execute(&hart, 0x0007b097); // auipc x1, 503808
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assert(hart.regs[1] == 503820);
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}
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void test_op()
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{
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struct Hart hart = {0};
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hart.regs[1] = 3;
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hart.regs[2] = 4;
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hart.regs[4] = (uint32_t)-1;
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execute(&hart, 0x002081b3); // add, x3, x1, x2
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assert(hart.regs[3] == 7);
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execute(&hart, 0x402081b3); // sub x3, x1, x2
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assert(hart.regs[3] == 0xFFFFFFFF);
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execute(&hart, 0x0020a1b3); // slt x3, x1, x2
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assert(hart.regs[3] == 1);
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execute(&hart, 0x001121b3); // slt x3, x2, 1
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assert(hart.regs[3] == 0);
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execute(&hart, 0x001131b3); // sltu x3, x2, x1
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assert(hart.regs[3] == 0);
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execute(&hart, 0x0020b1b3); // sltu x3, x1, x2
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assert(hart.regs[3] == 1);
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execute(&hart, 0x0040a1b3); // slt x3, x1, x4
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assert(hart.regs[3] == 0);
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hart.regs[1] = 6;
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hart.regs[2] = 12;
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execute(&hart, 0x0020e1b3); // or x3, x1, x2
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assert(hart.regs[3] == 14);
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execute(&hart, 0x0020c1b3); // xor x3, x1, x2
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assert(hart.regs[3] == 10);
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execute(&hart, 0x0020f1b3); // and x3, x1, x2
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assert(hart.regs[3] == 4);
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hart.regs[1] = 6;
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hart.regs[2] = 2;
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execute(&hart, 0x002091b3); // sll x3, x1, x2
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assert(hart.regs[3] == 24);
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execute(&hart, 0x0020d1b3); // srl x3, x1, x2
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assert(hart.regs[3] == 1);
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execute(&hart, 0x4020d1b3); // sra x3, x1, x2
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assert(hart.regs[3] == 1);
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hart.regs[1] = (uint32_t)-6;
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hart.regs[2] = 2;
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execute(&hart, 0x4020d1b3); // sra x3, x1, x2
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assert(hart.regs[3] == 0xFFFFFFFE);
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}
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void test_jal()
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{
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struct Hart hart = {0};
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hart.pc = 12;
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execute(&hart, 0x12c000ef); // jal x1, 300
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assert(hart.regs[1] == 16);
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assert(hart.pc == 312);
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execute(&hart, 0xed5ff0ef); // jal x1, -300
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assert(hart.regs[1] == 316);
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assert(hart.pc == 12);
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}
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void test_jalr()
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{
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struct Hart hart = {0};
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hart.pc = 12;
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hart.regs[1] = 300;
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execute(&hart, 0x00a08167); // jalr x2, 10(x1)
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assert(hart.regs[2] == 16);
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assert(hart.pc == 310);
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execute(&hart, 0xff608167); // jalr x2, -10(x1)
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assert(hart.regs[2] == 314);
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assert(hart.pc == 290);
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}
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void test_branch()
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{
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struct Hart hart = {0};
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hart.pc = 100;
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hart.regs[1] = 2;
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hart.regs[2] = 0xFFFFFFFC;
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execute(&hart, 0x00208c63); // beq x1, x2, 24
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assert(hart.pc == 104);
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hart.pc = 100;
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execute(&hart, 0x00209c63); // bne x1, x2, 24
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assert(hart.pc == 124);
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hart.pc = 100;
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execute(&hart, 0x0020cc63); // blt x1, x2, 24
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assert(hart.pc == 124);
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hart.pc = 100;
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execute(&hart, 0x0020dc63); // bge x1, x2, 24
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assert(hart.pc == 104);
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hart.pc = 100;
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execute(&hart, 0x0020ec63); // bltu x1, x2, 24
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assert(hart.pc == 104);
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hart.pc = 100;
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execute(&hart, 0x0020fc63); // bgeu x1, x2, 24
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assert(hart.pc == 124);
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}
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void test()
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{
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test_addi();
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test_slti_sltiu();
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test_andi_ori_xori();
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test_slli_srli_srai();
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test_lui_auipc();
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test_op();
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test_jal();
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test_jalr();
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test_branch();
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}
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int main(int argc, char* argv[])
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{
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test();
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return EXIT_SUCCESS;
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}
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