fix: address suggestions

miden-lib/asm/kernels/transaction/api.masm

@@ -1076,7 +1076,7 @@ end
 #! The input block height delta is added to the reference block in order to output an upper limit
 #! up until which the transaction will be considered valid (not expired).
 #!
-#! Inputs: [block_height_delta, ...]
+#! Inputs: [KERNEL_PROCEDURE_HASH, block_height_delta, ...]
 #! Output: [...]
 #!
 #! Where:
@@ -1091,7 +1091,7 @@ end
 #! Gets the transaction expiration delta.
 #!
 #! Inputs: [...]
-#! Output: [block_height_delta, ...]
+#! Output: [KERNEL_PROCEDURE_HASH, block_height_delta, ...]
 #!
 #! Where:
 #! - block_height_delta is the stored expiration time delta (1 to 0xFFFF).

miden-lib/asm/kernels/transaction/lib/tx.masm

@@ -21,6 +21,9 @@ const.EXPIRY_UPPER_LIMIT=0xFFFF+1
 # The note type must be PUBLIC, unless the high bits are `0b11`. (See the table below.)
 const.ALL_NOTE_TYPES_ALLOWED=3 # 0b11
 
+# Max U32 value, used for initializing the expiration block number
+const.MAX_BLOCK_NUM=0xFFFFFFFF
+
 # ERRORS
 # =================================================================================================
 
@@ -227,8 +230,17 @@ end
 #! Where:
 #! - block_height_delta is the stored expiration time delta (1 to 0xFFFF).
 export.get_expiration_delta
-    exec.memory::get_expiration_block_num exec.get_block_number
-    sub
+    exec.memory::get_expiration_block_num
+    # => [stored_expiration_block_num]
+
+    dup eq.MAX_BLOCK_NUM
+    if.true
+        # The delta was not set
+        drop push.0
+    else
+        # Calculate the delta
+        exec.get_block_number sub
+    end
 end
 
 

miden-lib/asm/miden/tx.masm

@@ -200,11 +200,15 @@ export.execute_foreign_procedure
     # => [<values returned from the foreign procedure>]
 end
 
-#! Updates the transaction expiration block delta.
+#! Updates the transaction expiration delta.
 #!
-#! The input block_height_delta is added to the block reference number in order to determine an upper
-#! limit at which the transaction will be considered valid (not expired).
-#! This value can be later decreased, but not increased.
+#! The transaction expiration delta specifies how close to the transaction's reference block the
+#! transaction must be included into the chain. For example, if the transaction's reference block
+#! is 100 and transaction expiration delta is 10, the transaction can be included into the chain
+#! by block 110. If this does not happen, the transaction is considered expired and cannot be
+#! included into the chain.
+#!
+#! Once set, transaction expiration delta can be decreased, but not increased.
 #!
 #! Inputs: [block_height_delta, ...]
 #! Output: [...]
@@ -225,7 +229,7 @@ export.update_expiration_block_delta
     dropw dropw dropw dropw
 end
 
-#! Gets the transaction expiration delta.
+#! Returns the transaction expiration delta, or 0 if the delta has not been set.
 #!
 #! Inputs: [...]
 #! Output: [block_height_delta, ...]

miden-lib/src/transaction/procedures/kernel_v0.rs

@@ -74,5 +74,5 @@ pub const KERNEL0_PROCEDURES: [Digest; 34] = [
     // update_expiration_block_num
     digest!(0x268af21ef3c89bcc, 0x4142290b918c7df8, 0x4d220ca00ecb6ec2, 0xa36b719508d30cb2),
     // get_expiration_delta
-    digest!(0x4f8ba89ed03ed171, 0x847f80cf50f96733, 0xf41141e83cb42597, 0x6f21b93bdafe7270),
+    digest!(0xc315b9b152b64c75, 0x4eb3b30ec94a0887, 0xa8bb394f6805a266, 0xa05857dac130cf87),
 ];

miden-tx/src/tests/kernel_tests/test_epilogue.rs

@@ -262,9 +262,13 @@ fn test_no_expiration_delta_set() {
     let code_template = "
     use.kernel::prologue
     use.kernel::epilogue
+    use.kernel::tx
 
     begin
         exec.prologue::prepare_transaction
+
+        exec.tx::get_expiration_delta assertz
+
         exec.epilogue::finalize_transaction
     end
     ";