diff options
| -rw-r--r-- | hw/mips_timer.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/hw/mips_timer.c b/hw/mips_timer.c index 13217b2..67b8735 100644 --- a/hw/mips_timer.c +++ b/hw/mips_timer.c @@ -7,10 +7,15 @@ /* XXX: do not use a global */ uint32_t cpu_mips_get_random (CPUState *env) { - static uint32_t seed = 0; + static uint32_t lfsr = 1; + static uint32_t prev_idx = 0; uint32_t idx; - seed = seed * 314159 + 1; - idx = (seed >> 16) % (env->tlb->nb_tlb - env->CP0_Wired) + env->CP0_Wired; + /* Don't return same value twice, so get another value */ + do { + lfsr = (lfsr >> 1) ^ (-(lfsr & 1u) & 0xd0000001u); + idx = lfsr % (env->tlb->nb_tlb - env->CP0_Wired) + env->CP0_Wired; + } while (idx == prev_idx); + prev_idx = idx; return idx; } |