| .option norvc |
| |
| .text |
| .global _start |
| _start: |
| lla t0, trap |
| csrw mtvec, t0 |
| |
| # These are all illegal instructions |
| csrw time, x0 |
| .insn i CUSTOM_0, 0, x0, x0, 0x321 |
| csrw time, x0 |
| .insn i CUSTOM_0, 0, x0, x0, 0x123 |
| csrw cycle, x0 |
| |
| # Success! |
| li a0, 0 |
| j _exit |
| |
| trap: |
| # When an instruction traps, compare it to the insn in memory. |
| csrr t0, mepc |
| csrr t1, mtval |
| lwu t2, 0(t0) |
| bne t1, t2, fail |
| |
| # Skip the insn and continue. |
| addi t0, t0, 4 |
| csrw mepc, t0 |
| mret |
| |
| fail: |
| li a0, 1 |
| |
| # Exit code in a0 |
| _exit: |
| lla a1, semiargs |
| li t0, 0x20026 # ADP_Stopped_ApplicationExit |
| sd t0, 0(a1) |
| sd a0, 8(a1) |
| li a0, 0x20 # TARGET_SYS_EXIT_EXTENDED |
| |
| # Semihosting call sequence |
| .balign 16 |
| slli zero, zero, 0x1f |
| ebreak |
| srai zero, zero, 0x7 |
| j . |
| |
| .data |
| .balign 16 |
| semiargs: |
| .space 16 |
