Le 03/01/2018 à 22:52, Richard Henderson a écrit :
> On 01/02/2018 03:40 PM, Laurent Vivier wrote:
>> +void HELPER(chk)(CPUM68KState *env, int32_t val, int32_t ub)
>> +{
>> + if (val < 0 || val > ub) {
>> + CPUState *cs = CPU(m68k_env_get_cpu(env));
>> +
>> + /* Recover PC and CC_OP for the beginning of the insn. */
>> + cpu_restore_state(cs, GETPC());
>> +
>> + /* Adjust PC and FLAGS to end of the insn. */
>> + env->pc += 2;
>> + helper_flush_flags(env, env->cc_op);
>> + env->cc_n = val;
>> +
>> + cs->exception_index = EXCP_CHK;
>> + cpu_loop_exit(cs);
>> + }
>> +}
>> +
>
> I thought you said for 68040, N is always unset for val >= 0.
> That would suggest
>
> helper_flush_flags(env, env->cc_op);
> env->cc_n = val;
> if (val < 0 || val > ub) {
> ...
> }
ok, my though was it is better to not update the flag if it is not
needed (it should be undefined), but what you suggest is closer to the
real hardware so I will update it.
> Did you examine the real hw change to the other flags?
yes, C is modified, and the logic is:
C = 0 <= ub ? val < 0 || ub < val : val < 0 && ub < val;
All other flags are not modified.
I'm going to update the patch to reflect the change of N and C by the
real hardware.
> Because they're officially undefined, which suggests
>
> env->cc_n = val;
> env->cc_op = CC_OP_LOGIC;
>
>> +void HELPER(chk2)(CPUM68KState *env, int32_t val, int32_t lb, int32_t ub)
>> +{
>> + helper_flush_flags(env, env->cc_op);
>> +
>> + env->cc_z = val != lb && val != ub;
>> + env->cc_c = lb <= ub ? val < lb || val > ub : val > ub && val < lb;
>> +
>> + if (env->cc_c) {
>> + CPUState *cs = CPU(m68k_env_get_cpu(env));
>> +
>> + cpu_restore_state(cs, GETPC());
>> + env->cc_op = CC_OP_FLAGS;
>
> A comment that we're reverting a change made during unwind would be helpful
> here.
Ok
Thanks,
Laurent
