Specs for opcode TIMESTAMP (0x42)

specs/opcode/41COINBASE.md

@@ -36,4 +36,4 @@ then push the `address` to the stack.
 
 ## Code
 
-Please refer to `src/zkevm_specs/evm/execution/coinbase.py`.
+Please refer to `src/zkevm_specs/evm/execution/block_coinbase.py`.

specs/opcode/42TIMESTAMP.md

@@ -0,0 +1,39 @@
+# Timestamp op code
+
+## Procedure
+
+The `TIMESTAMP` opcode pushes the timestamp of the current block onto the stack.
+
+## EVM behavior
+
+The `TIMESTAMP` opcode loads a `timestamp` (8 bytes of data) from the block context and then
+pushes it onto the stack.
+
+## Circuit behavior
+
+1. construct block context table
+2. do busmapping lookup for stack write operation
+3. other implicit check: bytes length
+
+## Constraints
+
+1. opId = 0x42
+2. State transition:
+   - gc + 1 (1 stack write)
+   - stack_pointer - 1
+   - pc + 1
+   - gas + 2
+3. Lookups:  2
+   - `timestamp` is on the top of stack
+   - `timestamp` is in the block context table
+4. Others:
+   - `timestamp` fits into 8 bytes
+
+## Exceptions
+
+1. stack overflow: stack is full, stack pointer = 0
+2. out of gas: remaining gas is not enough
+
+## Code
+
+Please refer to `src/zkevm_specs/evm/execution/block_timestamp.py`.

src/zkevm_specs/evm/execution/__init__.py

@@ -12,6 +12,7 @@
 from .jumpi import *
 from .push import *
 from .block_coinbase import *
+from .block_timestamp import *
 from .caller import *
 from .slt_sgt import *
 from .callvalue import *
@@ -27,6 +28,7 @@
     ExecutionState.CALLVALUE: callvalue,
     ExecutionState.CALLDATASIZE: calldatasize,
     ExecutionState.COINBASE: coinbase,
+    ExecutionState.TIMESTAMP: timestamp,
     ExecutionState.JUMP: jump,
     ExecutionState.JUMPI: jumpi,
     ExecutionState.PUSH: push,

src/zkevm_specs/evm/execution/block_timestamp.py

@@ -0,0 +1,22 @@
+from ..instruction import Instruction, Transition
+from ..table import BlockContextFieldTag
+from ..opcode import Opcode
+
+
+def timestamp(instruction: Instruction):
+    opcode = instruction.opcode_lookup(True)
+    instruction.constrain_equal(opcode, Opcode.TIMESTAMP)
+    timestamp = instruction.stack_push()
+    # in real circuit also check timestamp raw data is 64 bit length (8 bytes)
+    # check block table for timestamp
+    instruction.constrain_equal(
+        timestamp,
+        instruction.block_context_lookup(BlockContextFieldTag.Timestamp),
+    )
+
+    instruction.step_state_transition_in_same_context(
+        opcode,
+        rw_counter=Transition.delta(1),
+        program_counter=Transition.delta(1),
+        stack_pointer=Transition.delta(-1),
+    )

tests/evm/test_timestamp.py

@@ -0,0 +1,65 @@
+import pytest
+
+from zkevm_specs.evm import (
+    ExecutionState,
+    StepState,
+    verify_steps,
+    Tables,
+    RWTableTag,
+    RW,
+    Block,
+    Bytecode,
+)
+from zkevm_specs.util import rand_range, rand_fp, RLC, U64
+
+TESTING_DATA = (0, 1, 2 ** 64 - 1, rand_range(2 ** 64))
+
+
+@pytest.mark.parametrize("timestamp", TESTING_DATA)
+def test_timestamp(timestamp: U64):
+    randomness = rand_fp()
+
+    block = Block(timestamp=timestamp)
+
+    bytecode = Bytecode().timestamp()
+    bytecode_hash = RLC(bytecode.hash(), randomness)
+
+    tables = Tables(
+        block_table=set(block.table_assignments(randomness)),
+        tx_table=set(),
+        bytecode_table=set(bytecode.table_assignments(randomness)),
+        rw_table=set(
+            [
+                (9, RW.Write, RWTableTag.Stack, 1, 1023, RLC(timestamp, randomness, 8), 0, 0),
+            ]
+        ),
+    )
+
+    verify_steps(
+        randomness=randomness,
+        tables=tables,
+        steps=[
+            StepState(
+                execution_state=ExecutionState.TIMESTAMP,
+                rw_counter=9,
+                call_id=1,
+                is_root=True,
+                is_create=False,
+                code_source=bytecode_hash,
+                program_counter=0,
+                stack_pointer=1024,
+                gas_left=2,
+            ),
+            StepState(
+                execution_state=ExecutionState.STOP,
+                rw_counter=10,
+                call_id=1,
+                is_root=True,
+                is_create=False,
+                code_source=bytecode_hash,
+                program_counter=1,
+                stack_pointer=1023,
+                gas_left=0,
+            ),
+        ],
+    )