EXCHANGE

Exercise exchange operation

Signed-off-by: Danno Ferrin <danno@numisight.com>

src/ethereum_test_tools/vm/opcode.py

@@ -5014,6 +5014,36 @@ class Opcodes(Opcode, Enum):
 
     """
 
+    EXCHANGE = Opcode(0xE8, data_portion_length=1)
+    """
+    !!! Note: This opcode is under development
+
+    EXCHANGE[mn]
+    ----
+
+    Description
+    ----
+    Exchanges two stack positions.  Two nybbles, n is high 4 bits + 1, then  m is 4 low bits + 1.
+    Exchanges tne n+1'th item with the n + m + 1 item.
+
+    Inputs
+    ----
+    n + m + 1, or ((imm >> 4) + (imm &0x0F) + 3) from the raw immediate,
+
+    Outputs
+    ----
+    n + m + 1, or ((imm >> 4) + (imm &0x0F) + 3) from the raw immediate,
+
+    Fork
+    ----
+    EOF_FORK
+
+    Gas
+    ----
+    3
+
+    """
+
     CREATE3 = Opcode(0xEC, popped_stack_items=4, pushed_stack_items=1, data_portion_length=1)
     """
     !!! Note: This opcode is under development

tests/prague/eip663_dupn_swapn_exchange/test_exchange.py

@@ -0,0 +1,67 @@
+"""
+abstract: Tests [EIP-663: SWAPN, DUPN and EXCHANGE instructions](https://eips.ethereum.org/EIPS/eip-663)
+    Tests for the SWAPN instruction.
+"""  # noqa: E501
+
+import pytest
+
+from ethereum_test_tools import Account, Environment, StateTestFiller, TestAddress, Transaction
+from ethereum_test_tools.eof.v1 import Container, Section
+from ethereum_test_tools.eof.v1.constants import NON_RETURNING_SECTION
+from ethereum_test_tools.vm.opcode import Opcodes as Op
+
+from ..eip3540_eof_v1.spec import EOF_FORK_NAME
+from . import REFERENCE_SPEC_GIT_PATH, REFERENCE_SPEC_VERSION
+
+REFERENCE_SPEC_GIT_PATH = REFERENCE_SPEC_GIT_PATH
+REFERENCE_SPEC_VERSION = REFERENCE_SPEC_VERSION
+
+
+@pytest.mark.valid_from(EOF_FORK_NAME)
+def test_exchange_all_valid_immediates(
+    tx: Transaction,
+    state_test: StateTestFiller,
+):
+    """
+    Test case for all valid SWAPN immediates.
+    """
+    n = 256
+    s = 34
+    values = range(0x3E8, 0x3E8 + s)
+
+    eof_code = Container(
+        sections=[
+            Section.Code(
+                code=b"".join(Op.PUSH2(v) for v in values)
+                + b"".join(Op.EXCHANGE(x) for x in range(0, n))
+                + b"".join((Op.PUSH1(x) + Op.SSTORE) for x in range(0, s))
+                + Op.STOP,
+                code_inputs=0,
+                code_outputs=NON_RETURNING_SECTION,
+                max_stack_height=s + 1,
+            )
+        ],
+    )
+
+    pre = {
+        TestAddress: Account(balance=1_000_000_000),
+        tx.to: Account(code=eof_code),
+    }
+
+    # this does the same full-loop exchange
+    values_rotated = list(range(0x3E8, 0x3E8 + s))
+    for e in range(0, n):
+        a = (e >> 4) + 1
+        b = (e & 0x0F) + 1 + a
+        tmp = values_rotated[a]
+        values_rotated[a] = values_rotated[b]
+        values_rotated[b] = tmp
+
+    post = {tx.to: Account(storage=dict(zip(range(0, s), reversed(values_rotated))))}
+
+    state_test(
+        env=Environment(),
+        pre=pre,
+        post=post,
+        tx=tx,
+    )