[ECO-2489] Add emojicoin arena Move prototype (#408)

Co-authored-by: Matt <90358481+xbtmatt@users.noreply.github.com>

cfg/cspell-dictionary.txt

@@ -1,9 +1,10 @@
-ADBEEF
+adbeef
 aland
 allowlister
 aptn
 aptos
 aptoslabs
+auid
 autoscale
 barthelemy
 bento
@@ -66,6 +67,7 @@ marino
 mayen
 melilla
 merperson
+metadatas
 moai
 mosquitto
 mqtt

src/move/emojicoin_arena/Move.toml

@@ -0,0 +1,18 @@
+[addresses]
+arena = "_"
+integrator = "_"
+
+[dependencies.EmojicoinDotFun]
+local = "../emojicoin_dot_fun"
+
+[dev-addresses]
+arena = "0xaaa"
+coin_factory = "0xbbb"
+emojicoin_dot_fun = "0xc0de"
+integrator = "0xddd"
+
+[package]
+authors = ["Econia Labs (developers@econialabs.com)"]
+name = "EmojicoinArena"
+upgrade_policy = "compatible"
+version = "1.0.0"

src/move/emojicoin_arena/README.md

@@ -0,0 +1,11 @@
+# Emojicoin Arena
+
+## A note on pseudo-randomness
+
+Since randomness is not supported in `init_module` per [`aptos-core` #15436],
+pseudo-random substitute implementations are used for the first crank. For a
+detailed rationale that explains how this is effectively random in practice, see
+[this `emojicoin-dot-fun` pull request comment].
+
+[this `emojicoin-dot-fun` pull request comment]: https://github.com/econia-labs/emojicoin-dot-fun/pull/408#discussion_r1887856202
+[`aptos-core` #15436]: https://github.com/aptos-labs/aptos-core/issues/15436

src/move/emojicoin_arena/sources/pseudo_randomness.move

@@ -0,0 +1,36 @@
+module arena::pseudo_randomness {
+
+    use aptos_framework::transaction_context;
+    use std::bcs;
+    use std::vector;
+
+    friend arena::emojicoin_arena;
+
+    /// Pseudo-random substitute for `aptos_framework::randomness::u64_range`, since
+    /// the randomness API is not available during `init_module`.
+    public(friend) inline fun u64_range(min_incl: u64, max_excl: u64): u64 {
+        let range = ((max_excl - min_incl) as u256);
+        let sample = ((u256_integer() % range) as u64);
+
+        min_incl + sample
+    }
+
+    /// Pseudo-random substitute for `aptos_framework::randomness::next_32_bytes`, since
+    /// the randomness API is not available during `init_module`.
+    inline fun next_32_bytes(): vector<u8> {
+        bcs::to_bytes(&transaction_context::generate_auid_address())
+    }
+
+    /// Pseudo-random substitute for `aptos_framework::randomness::u256_integer`, since
+    /// the randomness API is not available during `init_module`.
+    inline fun u256_integer(): u256 {
+        let raw = next_32_bytes();
+        let i = 0;
+        let ret: u256 = 0;
+        while (i < 32) {
+            ret = ret * 256 + (vector::pop_back(&mut raw) as u256);
+            i = i + 1;
+        };
+        ret
+    }
+}