diff options
Diffstat (limited to 'main.c')
| -rw-r--r-- | main.c | 144 |
1 files changed, 140 insertions, 4 deletions
@@ -2,6 +2,7 @@ #include <stdlib.h>
#include <inttypes.h>
#include <assert.h>
+#include <stdbool.h>
inline uint32_t sign_extend(uint32_t word, uint32_t size)
{
@@ -91,7 +92,9 @@ struct Hart void execute_op_imm(struct Hart* hart, uint32_t instruction)
{
- struct Instruction inst = decode_i_type(instruction);
+ const struct Instruction inst = decode_i_type(instruction);
+ if (inst.rd == 0) return;
+
switch (inst.funct3)
{
case 0: // ADDI
@@ -130,7 +133,9 @@ void execute_op_imm(struct Hart* hart, uint32_t instruction) void execute_op(struct Hart* hart, uint32_t instruction)
{
- struct Instruction inst = decode_r_type(instruction);
+ const struct Instruction inst = decode_r_type(instruction);
+ if (inst.rd == 0) return;
+
switch (inst.funct3)
{
case 0: // ADD, SUB
@@ -174,31 +179,94 @@ void execute_op(struct Hart* hart, uint32_t instruction) }
}
+void execute_branch(struct Hart* hart, uint32_t instruction)
+{
+ const struct Instruction inst = decode_b_type(instruction);
+ const uint32_t r1 = hart->regs[inst.rs1];
+ const uint32_t r2 = hart->regs[inst.rs2];
+ bool take_branch = false;
+
+ switch (inst.funct3)
+ {
+ case 0: take_branch = (r1 == r2); break;
+ case 1: take_branch = (r1 != r2); break;
+ case 4: take_branch = (r1 < r2); break;
+ case 5: take_branch = (r1 >= r2); break;
+ case 6: take_branch = ((int32_t)r1 < (int32_t)r2); break;
+ case 7: take_branch = ((int32_t)r1 >= (int32_t)r2); break;
+ }
+
+ if (take_branch)
+ {
+ hart->pc += inst.imm;
+ }
+ else
+ {
+ hart->pc += 4;
+ }
+}
+
void execute(struct Hart* hart, uint32_t instruction)
{
switch (instruction & 0x7f)
{
case 0x13:
execute_op_imm(hart, instruction);
+ hart->pc += 4;
break;
case 0x17: // AUIPC
{
struct Instruction inst = decode_u_type(instruction);
- hart->regs[inst.rd] = inst.imm + hart->pc;
+ if (inst.rd != 0)
+ {
+ hart->regs[inst.rd] = inst.imm + hart->pc;
+ }
+ hart->pc += 4;
break;
}
case 0x33:
execute_op(hart, instruction);
+ hart->pc += 4;
break;
case 0x37: // LUI
{
struct Instruction inst = decode_u_type(instruction);
- hart->regs[inst.rd] = inst.imm;
+ if (inst.rd != 0)
+ {
+ hart->regs[inst.rd] = inst.imm;
+ }
+ hart->pc += 4;
+ break;
+ }
+ case 0x63:
+ execute_branch(hart, instruction);
+ break;
+ case 0x67: // JALR
+ {
+ struct Instruction inst = decode_i_type(instruction);
+ assert(inst.funct3 == 0);
+ if (inst.rd != 0)
+ {
+ hart->regs[inst.rd] = hart->pc + 4;
+ }
+ hart->pc = (hart->regs[inst.rs1] + inst.imm) & 0xFFFFFFFE;
+ break;
+ }
+ case 0x6F: // JAL
+ {
+ struct Instruction inst = decode_j_type(instruction);
+ if (inst.rd != 0)
+ {
+ hart->regs[inst.rd] = hart->pc + 4;
+ }
+ hart->pc += inst.imm;
break;
}
default:
assert(!"Unhandled opcode");
}
+
+ assert(hart->regs[0] == 0);
}
void test_addi()
@@ -289,9 +357,11 @@ void test_lui_auipc() {
struct Hart hart = {0};
+ hart.pc = 0;
execute(&hart, 0x0007b0b7); // lui x1, 503808
assert(hart.regs[1] == 503808);
+ hart.pc = 0;
execute(&hart, 0x0007b097); // auipc x1, 503808
assert(hart.regs[1] == 503808);
@@ -360,6 +430,69 @@ void test_op() assert(hart.regs[3] == 0xFFFFFFFE);
}
+void test_jal()
+{
+ struct Hart hart = {0};
+
+ hart.pc = 12;
+
+ execute(&hart, 0x12c000ef); // jal x1, 300
+ assert(hart.regs[1] == 16);
+ assert(hart.pc == 312);
+
+ execute(&hart, 0xed5ff0ef); // jal x1, -300
+ assert(hart.regs[1] == 316);
+ assert(hart.pc == 12);
+}
+
+void test_jalr()
+{
+ struct Hart hart = {0};
+
+ hart.pc = 12;
+ hart.regs[1] = 300;
+
+ execute(&hart, 0x00a08167); // jalr x2, 10(x1)
+ assert(hart.regs[2] == 16);
+ assert(hart.pc == 310);
+
+ execute(&hart, 0xff608167); // jalr x2, -10(x1)
+ assert(hart.regs[2] == 314);
+ assert(hart.pc == 290);
+}
+
+void test_branch()
+{
+ struct Hart hart = {0};
+
+ hart.pc = 100;
+ hart.regs[1] = 2;
+ hart.regs[2] = 0xFFFFFFFC;
+
+ execute(&hart, 0x00208c63); // beq x1, x2, 24
+ assert(hart.pc == 104);
+
+ hart.pc = 100;
+ execute(&hart, 0x00209c63); // bne x1, x2, 24
+ assert(hart.pc == 124);
+
+ hart.pc = 100;
+ execute(&hart, 0x0020cc63); // blt x1, x2, 24
+ assert(hart.pc == 124);
+
+ hart.pc = 100;
+ execute(&hart, 0x0020dc63); // bge x1, x2, 24
+ assert(hart.pc == 104);
+
+ hart.pc = 100;
+ execute(&hart, 0x0020ec63); // bltu x1, x2, 24
+ assert(hart.pc == 104);
+
+ hart.pc = 100;
+ execute(&hart, 0x0020fc63); // bgeu x1, x2, 24
+ assert(hart.pc == 124);
+}
+
void test()
{
test_addi();
@@ -368,6 +501,9 @@ void test() test_slli_srli_srai();
test_lui_auipc();
test_op();
+ test_jal();
+ test_jalr();
+ test_branch();
}
int main(int argc, char* argv[])
|