Add transient hostios

include/hostio.h

@@ -36,7 +36,7 @@ VM_HOOK(account_codehash) void account_codehash(const uint8_t * address, uint8_t
  * that of the EVM. This means that, under the hood, this hostio is accessing the 32-byte
  * value stored in the EVM state trie at offset `key`, which will be `0` when not previously
  * set. The semantics, then, are equivalent to that of the EVM's [`SLOAD`] opcode.
- * 
+ *
  * [`SLOAD`]: https://www.evm.codes/#54
  */
 VM_HOOK(storage_load_bytes32) void storage_load_bytes32(const uint8_t * key, uint8_t * dest);
@@ -46,11 +46,31 @@ VM_HOOK(storage_load_bytes32) void storage_load_bytes32(const uint8_t * key, uin
  * of the EVM. This means that, under the hood, this hostio is storing a 32-byte value into
  * the EVM state trie at offset `key`. Furthermore, refunds are tabulated exactly as in the
  * EVM. The semantics, then, are equivalent to that of the EVM's [`SSTORE`] opcode.
- * 
+ *
  * [`SSTORE`]: https://www.evm.codes/#55
  */
 VM_HOOK(storage_store_bytes32) void storage_store_bytes32(const uint8_t * key, const uint8_t * value);
 
+/**
+ * Reads a 32-byte value from transient storage. Stylus's storage format is identical to
+ * that of the EVM. This means that, under the hood, this hostio is accessing the 32-byte
+ * value stored in the EVM transient storage at offset `key`, which will be `0` when not previously
+ * set. The semantics, then, are equivalent to that of the EVM's [`TLOAD`] opcode.
+ * 
+ * [`TLOAD`]: https://www.evm.codes/#5c
+ */
+VM_HOOK(transient_load_bytes32) void transient_load_bytes32(const uint8_t * key, uint8_t * dest);
+
+/**
+ * Stores a 32-byte value to permanent storage. Stylus's storage format is identical to that
+ * of the EVM. This means that, under the hood, this hostio is storing a 32-byte value into
+ * the EVM transient storage at offset `key`. Furthermore, refunds are tabulated exactly as in the
+ * EVM. The semantics, then, are equivalent to that of the EVM's [`TSTORE`] opcode.
+ * 
+ * [`TSTORE`]: https://www.evm.codes/#5d
+ */
+VM_HOOK(transient_store_bytes32) void transient_store_bytes32(const uint8_t * key, const uint8_t * value);
+
 /**
  * Gets the basefee of the current block. The semantics are equivalent to that of the EVM's
  * [`BASEFEE`] opcode.

include/storage.h

@@ -23,7 +23,7 @@ extern "C" {
 
 /**
  * storage_load / store load or store a value from storage accordingly.
- * 
+ *
  * The value of the first "storage" pointer is not used.
  * generated headers provide:
  *  a const storage pointer when working for a view-only function
@@ -42,6 +42,27 @@ inline void storage_store(void *storage, const uint8_t *key, const uint8_t *valu
     storage_store_bytes32(key, value);
 }
 
+/**
+ * transient_load / store load or store a value from transient storage accordingly.
+ * 
+ * The value of the first "storage" pointer is not used.
+ * generated headers provide:
+ *  a const storage pointer when working for a view-only function
+ *  a non const pointer for a mutating function
+ *  no pointer (so don't call transient_load) for a pure function
+ *
+ */
+inline void transient_load(const void* storage, const uint8_t *key, uint8_t *dest) {
+    transient_load_bytes32(key, dest);
+}
+
+/**
+ * see documentation for transient_load
+ */
+inline void transient_store(void *storage, const uint8_t *key, const uint8_t *value) {
+    transient_store_bytes32(key, value);
+}
+
 /**
  * calculate slot for a map with base slot "storage" to put "key"
  * If key requires padding it must be applied before calling this function