From 9ebf44d84754adc5b64fcf612c6816c02c80462d Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@debian.org>
Date: Sat, 2 Feb 2019 19:29:23 -0500
Subject: Imported Upstream version 8.9.0

---
 theories/Strings/HexString.v | 229 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 229 insertions(+)
 create mode 100644 theories/Strings/HexString.v

(limited to 'theories/Strings/HexString.v')

diff --git a/theories/Strings/HexString.v b/theories/Strings/HexString.v
new file mode 100644
index 00000000..9ea93c90
--- /dev/null
+++ b/theories/Strings/HexString.v
@@ -0,0 +1,229 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2017     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+Require Import Ascii String.
+Require Import BinNums.
+Import BinNatDef.
+Import BinIntDef.
+Import BinPosDef.
+
+Local Open Scope positive_scope.
+Local Open Scope string_scope.
+
+Local Notation "a || b"
+  := (if a then true else if b then true else false).
+Definition ascii_to_digit (ch : ascii) : option N
+  := (if ascii_dec ch "0" then Some 0
+      else if ascii_dec ch "1" then Some 1
+      else if ascii_dec ch "2" then Some 2
+      else if ascii_dec ch "3" then Some 3
+      else if ascii_dec ch "4" then Some 4
+      else if ascii_dec ch "5" then Some 5
+      else if ascii_dec ch "6" then Some 6
+      else if ascii_dec ch "7" then Some 7
+      else if ascii_dec ch "8" then Some 8
+      else if ascii_dec ch "9" then Some 9
+      else if ascii_dec ch "a" || ascii_dec ch "A" then Some 10
+      else if ascii_dec ch "b" || ascii_dec ch "B" then Some 11
+      else if ascii_dec ch "c" || ascii_dec ch "C" then Some 12
+      else if ascii_dec ch "d" || ascii_dec ch "D" then Some 13
+      else if ascii_dec ch "e" || ascii_dec ch "E" then Some 14
+      else if ascii_dec ch "f" || ascii_dec ch "F" then Some 15
+      else None)%N.
+
+Fixpoint pos_hex_app (p q:positive) : positive :=
+  match q with
+  | 1 => p~0~0~0~1
+  | 2 => p~0~0~1~0
+  | 3 => p~0~0~1~1
+  | 4 => p~0~1~0~0
+  | 5 => p~0~1~0~1
+  | 6 => p~0~1~1~0
+  | 7 => p~0~1~1~1
+  | 8 => p~1~0~0~0
+  | 9 => p~1~0~0~1
+  | 10 => p~1~0~1~0
+  | 11 => p~1~0~1~1
+  | 12 => p~1~1~0~0
+  | 13 => p~1~1~0~1
+  | 14 => p~1~1~1~0
+  | 15 => p~1~1~1~1
+  | q~0~0~0~0 => (pos_hex_app p q)~0~0~0~0
+  | q~0~0~0~1 => (pos_hex_app p q)~0~0~0~1
+  | q~0~0~1~0 => (pos_hex_app p q)~0~0~1~0
+  | q~0~0~1~1 => (pos_hex_app p q)~0~0~1~1
+  | q~0~1~0~0 => (pos_hex_app p q)~0~1~0~0
+  | q~0~1~0~1 => (pos_hex_app p q)~0~1~0~1
+  | q~0~1~1~0 => (pos_hex_app p q)~0~1~1~0
+  | q~0~1~1~1 => (pos_hex_app p q)~0~1~1~1
+  | q~1~0~0~0 => (pos_hex_app p q)~1~0~0~0
+  | q~1~0~0~1 => (pos_hex_app p q)~1~0~0~1
+  | q~1~0~1~0 => (pos_hex_app p q)~1~0~1~0
+  | q~1~0~1~1 => (pos_hex_app p q)~1~0~1~1
+  | q~1~1~0~0 => (pos_hex_app p q)~1~1~0~0
+  | q~1~1~0~1 => (pos_hex_app p q)~1~1~0~1
+  | q~1~1~1~0 => (pos_hex_app p q)~1~1~1~0
+  | q~1~1~1~1 => (pos_hex_app p q)~1~1~1~1
+  end.
+
+Module Raw.
+  Fixpoint of_pos (p : positive) (rest : string) : string
+    := match p with
+       | 1 => String "1" rest
+       | 2 => String "2" rest
+       | 3 => String "3" rest
+       | 4 => String "4" rest
+       | 5 => String "5" rest
+       | 6 => String "6" rest
+       | 7 => String "7" rest
+       | 8 => String "8" rest
+       | 9 => String "9" rest
+       | 10 => String "a" rest
+       | 11 => String "b" rest
+       | 12 => String "c" rest
+       | 13 => String "d" rest
+       | 14 => String "e" rest
+       | 15 => String "f" rest
+       | p'~0~0~0~0 => of_pos p' (String "0" rest)
+       | p'~0~0~0~1 => of_pos p' (String "1" rest)
+       | p'~0~0~1~0 => of_pos p' (String "2" rest)
+       | p'~0~0~1~1 => of_pos p' (String "3" rest)
+       | p'~0~1~0~0 => of_pos p' (String "4" rest)
+       | p'~0~1~0~1 => of_pos p' (String "5" rest)
+       | p'~0~1~1~0 => of_pos p' (String "6" rest)
+       | p'~0~1~1~1 => of_pos p' (String "7" rest)
+       | p'~1~0~0~0 => of_pos p' (String "8" rest)
+       | p'~1~0~0~1 => of_pos p' (String "9" rest)
+       | p'~1~0~1~0 => of_pos p' (String "a" rest)
+       | p'~1~0~1~1 => of_pos p' (String "b" rest)
+       | p'~1~1~0~0 => of_pos p' (String "c" rest)
+       | p'~1~1~0~1 => of_pos p' (String "d" rest)
+       | p'~1~1~1~0 => of_pos p' (String "e" rest)
+       | p'~1~1~1~1 => of_pos p' (String "f" rest)
+       end.
+
+  Fixpoint to_N (s : string) (rest : N)
+    : N
+    := match s with
+       | "" => rest
+       | String ch s'
+         => to_N
+              s'
+              match ascii_to_digit ch with
+              | Some v => N.add v (N.mul 16 rest)
+              | None => N0
+              end
+       end.
+
+  Fixpoint to_N_of_pos (p : positive) (rest : string) (base : N)
+    : to_N (of_pos p rest) base
+      = to_N rest match base with
+                  | N0 => N.pos p
+                  | Npos v => Npos (pos_hex_app v p)
+                  end.
+  Proof.
+    do 4 try destruct p as [p|p|]; destruct base; try reflexivity;
+      cbn; rewrite to_N_of_pos; reflexivity.
+  Qed.
+End Raw.
+
+Definition of_pos (p : positive) : string
+  := String "0" (String "x" (Raw.of_pos p "")).
+Definition of_N (n : N) : string
+  := match n with
+     | N0 => "0x0"
+     | Npos p => of_pos p
+     end.
+Definition of_Z (z : Z) : string
+  := match z with
+     | Zneg p => String "-" (of_pos p)
+     | Z0 => "0x0"
+     | Zpos p => of_pos p
+     end.
+Definition of_nat (n : nat) : string
+  := of_N (N.of_nat n).
+
+Definition to_N (s : string) : N
+  := match s with
+     | String s0 (String so s)
+       => if ascii_dec s0 "0"
+          then if ascii_dec so "x"
+               then Raw.to_N s N0
+               else N0
+          else N0
+     | _ => N0
+     end.
+Definition to_pos (s : string) : positive
+  := match to_N s with
+     | N0 => 1
+     | Npos p => p
+     end.
+Definition to_Z (s : string) : Z
+  := let '(is_neg, n) := match s with
+                         | String s0 s'
+                           => if ascii_dec s0 "-"
+                              then (true, to_N s')
+                              else (false, to_N s)
+                         | EmptyString => (false, to_N s)
+                         end in
+     match n with
+     | N0 => Z0
+     | Npos p => if is_neg then Zneg p else Zpos p
+     end.
+Definition to_nat (s : string) : nat
+  := N.to_nat (to_N s).
+
+Lemma to_N_of_N (n : N)
+  : to_N (of_N n)
+    = n.
+Proof.
+  destruct n; [ reflexivity | apply Raw.to_N_of_pos ].
+Qed.
+
+Lemma to_Z_of_Z (z : Z)
+  : to_Z (of_Z z)
+    = z.
+Proof.
+  cbv [of_Z to_Z]; destruct z as [|z|z]; cbn;
+    try reflexivity;
+    rewrite Raw.to_N_of_pos; cbn; reflexivity.
+Qed.
+
+Lemma to_nat_of_nat (n : nat)
+  : to_nat (of_nat n)
+    = n.
+Proof.
+  cbv [to_nat of_nat];
+    rewrite to_N_of_N, Nnat.Nat2N.id; reflexivity.
+Qed.
+
+Lemma to_pos_of_pos (p : positive)
+  : to_pos (of_pos p)
+    = p.
+Proof.
+  cbv [of_pos to_pos to_N]; cbn;
+    rewrite Raw.to_N_of_pos; cbn; reflexivity.
+Qed.
+
+Example of_pos_1 : of_pos 1 = "0x1" := eq_refl.
+Example of_pos_2 : of_pos 2 = "0x2" := eq_refl.
+Example of_pos_3 : of_pos 3 = "0x3" := eq_refl.
+Example of_pos_7 : of_pos 7 = "0x7" := eq_refl.
+Example of_pos_8 : of_pos 8 = "0x8" := eq_refl.
+Example of_pos_9 : of_pos 9 = "0x9" := eq_refl.
+Example of_pos_10 : of_pos 10 = "0xa" := eq_refl.
+Example of_pos_11 : of_pos 11 = "0xb" := eq_refl.
+Example of_pos_12 : of_pos 12 = "0xc" := eq_refl.
+Example of_pos_13 : of_pos 13 = "0xd" := eq_refl.
+Example of_pos_14 : of_pos 14 = "0xe" := eq_refl.
+Example of_pos_15 : of_pos 15 = "0xf" := eq_refl.
+Example of_pos_16 : of_pos 16 = "0x10" := eq_refl.
+Example of_N_0 : of_N 0 = "0x0" := eq_refl.
+Example of_Z_0 : of_Z 0 = "0x0" := eq_refl.
+Example of_Z_m1 : of_Z (-1) = "-0x1" := eq_refl.
+Example of_nat_0 : of_nat 0 = "0x0" := eq_refl.
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