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| author | David Monniaux <david.monniaux@univ-grenoble-alpes.fr> | 2019-04-27 23:11:17 +0200 |
|---|---|---|
| committer | David Monniaux <david.monniaux@univ-grenoble-alpes.fr> | 2019-04-27 23:11:17 +0200 |
| commit | 13a7c021f6447cebbb6bf2716bedb7f9bcb5ddd3 (patch) | |
| tree | 4d8f152d07a8eb48546c212639b93fd624735cc1 /mppa_k1c | |
| parent | c647ca1fa4edc09bea86d5088c2956954269ffa7 (diff) | |
| download | compcert-kvx-13a7c021f6447cebbb6bf2716bedb7f9bcb5ddd3.tar.gz compcert-kvx-13a7c021f6447cebbb6bf2716bedb7f9bcb5ddd3.zip | |
compute the highest bit in a number
Diffstat (limited to 'mppa_k1c')
| -rw-r--r-- | mppa_k1c/ExtValues.v | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/mppa_k1c/ExtValues.v b/mppa_k1c/ExtValues.v index 58e8054f..2faa6b0a 100644 --- a/mppa_k1c/ExtValues.v +++ b/mppa_k1c/ExtValues.v @@ -82,3 +82,13 @@ Definition insfl stop start prev fld := Val.orl (Val.andl prev (Val.notl mask)) (Val.andl (Val.shll fld (Vint (Int.repr start))) mask) else Vundef. + +Fixpoint highest_bit (x : Z) (n : nat) : N := + match n with + | O => 0%N + | S n1 => + let n' := N_of_nat n in + if Z.testbit x (Z.of_N n') + then n' + else highest_bit x n1 + end. |