[otbn] Factor loop stack out of state.py
No functional change; just breaking up a big file.
Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>
diff --git a/hw/ip/otbn/dv/otbnsim/sim/loop.py b/hw/ip/otbn/dv/otbnsim/sim/loop.py
new file mode 100644
index 0000000..f14102f
--- /dev/null
+++ b/hw/ip/otbn/dv/otbnsim/sim/loop.py
@@ -0,0 +1,126 @@
+# Copyright lowRISC contributors.
+# Licensed under the Apache License, Version 2.0, see LICENSE for details.
+# SPDX-License-Identifier: Apache-2.0
+
+from typing import List, Optional
+
+from .alert import LoopError
+from .trace import Trace
+
+
+class TraceLoopStart(Trace):
+ def __init__(self, iterations: int, bodysize: int):
+ self.iterations = iterations
+ self.bodysize = bodysize
+
+ def trace(self) -> str:
+ return "Start LOOP, {} iterations, bodysize: {}".format(
+ self.iterations, self.bodysize)
+
+
+class TraceLoopIteration(Trace):
+ def __init__(self, iteration: int, total: int):
+ self.iteration = iteration
+ self.total = total
+
+ def trace(self) -> str:
+ return "LOOP iteration {}/{}".format(self.iteration, self.total)
+
+
+class LoopLevel:
+ '''An object representing a level in the current loop stack
+
+ start_addr is the first instruction inside the loop (the instruction
+ following the loop instruction). insn_count is the number of instructions
+ in the loop (and must be positive). restarts is one less than the number of
+ iterations, and must be non-negative.
+
+ '''
+ def __init__(self, start_addr: int, insn_count: int, restarts: int):
+ assert 0 <= start_addr
+ assert 0 < insn_count
+ assert 0 <= restarts
+
+ self.loop_count = 1 + restarts
+ self.restarts_left = restarts
+ self.start_addr = start_addr
+ self.match_addr = start_addr + 4 * insn_count
+
+
+class LoopStack:
+ '''An object representing the loop stack
+
+ The loop stack holds up to 8 LoopLevel objects, corresponding to nested
+ loops.
+
+ '''
+ stack_depth = 8
+
+ def __init__(self) -> None:
+ self.stack = [] # type: List[LoopLevel]
+ self.trace = [] # type: List[Trace]
+
+ def start_loop(self,
+ next_addr: int,
+ loop_count: int,
+ insn_count: int) -> None:
+ '''Start a loop.
+
+ next_addr is the address of the first instruction in the loop body.
+ loop_count must be positive and is the number of times to execute the
+ loop. insn_count must be positive and is the number of instructions in
+ the loop body.
+
+ '''
+ assert 0 <= next_addr
+ assert 0 < insn_count
+ assert 0 < loop_count
+
+ if len(self.stack) == LoopStack.stack_depth:
+ raise LoopError('loop stack overflow')
+
+ self.trace.append(TraceLoopStart(loop_count, insn_count))
+ self.stack.append(LoopLevel(next_addr, insn_count, loop_count - 1))
+
+ def check_insn(self, pc: int, insn_affects_control: bool) -> None:
+ '''Check for branch instructions at the end of a loop body'''
+ if self.stack:
+ top = self.stack[-1]
+ if pc + 4 == top.match_addr:
+ # We're about to execute the last instruction in the loop body.
+ # Make sure that it isn't a jump, branch or another loop
+ # instruction.
+ if insn_affects_control:
+ raise LoopError('control instruction at end of loop')
+
+ def step(self, next_pc: int) -> Optional[int]:
+ '''Update loop stack. If we should loop, return new PC'''
+ if self.stack:
+ top = self.stack[-1]
+
+ if next_pc == top.match_addr:
+ assert top.restarts_left >= 0
+
+ # 1-based iteration number
+ loop_idx = top.loop_count - top.restarts_left
+
+ if not top.restarts_left:
+ self.stack.pop()
+ ret_val = None
+ else:
+ top.restarts_left -= 1
+ ret_val = top.start_addr
+
+ self.trace.append(TraceLoopIteration(loop_idx, top.loop_count))
+ return ret_val
+
+ return None
+
+ def changes(self) -> List[Trace]:
+ return self.trace
+
+ def commit(self) -> None:
+ self.trace = []
+
+ def abort(self) -> None:
+ self.trace = []
diff --git a/hw/ip/otbn/dv/otbnsim/sim/state.py b/hw/ip/otbn/dv/otbnsim/sim/state.py
index ce31274..690b7a8 100644
--- a/hw/ip/otbn/dv/otbnsim/sim/state.py
+++ b/hw/ip/otbn/dv/otbnsim/sim/state.py
@@ -6,135 +6,18 @@
from shared.mem_layout import get_memory_layout
-from .alert import BadAddrError, LoopError
+from .alert import BadAddrError
from .csr import CSRFile
from .dmem import Dmem
from .ext_regs import OTBNExtRegs
from .flags import FlagReg
from .gpr import GPRs
+from .loop import LoopStack
from .reg import RegFile
from .trace import Trace, TracePC
from .wsr import WSRFile
-class TraceLoopStart(Trace):
- def __init__(self, iterations: int, bodysize: int):
- self.iterations = iterations
- self.bodysize = bodysize
-
- def trace(self) -> str:
- return "Start LOOP, {} iterations, bodysize: {}".format(
- self.iterations, self.bodysize)
-
-
-class TraceLoopIteration(Trace):
- def __init__(self, iteration: int, total: int):
- self.iteration = iteration
- self.total = total
-
- def trace(self) -> str:
- return "LOOP iteration {}/{}".format(self.iteration, self.total)
-
-
-class LoopLevel:
- '''An object representing a level in the current loop stack
-
- start_addr is the first instruction inside the loop (the instruction
- following the loop instruction). insn_count is the number of instructions
- in the loop (and must be positive). restarts is one less than the number of
- iterations, and must be non-negative.
-
- '''
- def __init__(self, start_addr: int, insn_count: int, restarts: int):
- assert 0 <= start_addr
- assert 0 < insn_count
- assert 0 <= restarts
-
- self.loop_count = 1 + restarts
- self.restarts_left = restarts
- self.start_addr = start_addr
- self.match_addr = start_addr + 4 * insn_count
-
-
-class LoopStack:
- '''An object representing the loop stack
-
- The loop stack holds up to 8 LoopLevel objects, corresponding to nested
- loops.
-
- '''
- stack_depth = 8
-
- def __init__(self) -> None:
- self.stack = [] # type: List[LoopLevel]
- self.trace = [] # type: List[Trace]
-
- def start_loop(self,
- next_addr: int,
- loop_count: int,
- insn_count: int) -> None:
- '''Start a loop.
-
- next_addr is the address of the first instruction in the loop body.
- loop_count must be positive and is the number of times to execute the
- loop. insn_count must be positive and is the number of instructions in
- the loop body.
-
- '''
- assert 0 <= next_addr
- assert 0 < insn_count
- assert 0 < loop_count
-
- if len(self.stack) == LoopStack.stack_depth:
- raise LoopError('loop stack overflow')
-
- self.trace.append(TraceLoopStart(loop_count, insn_count))
- self.stack.append(LoopLevel(next_addr, insn_count, loop_count - 1))
-
- def check_insn(self, pc: int, insn_affects_control: bool) -> None:
- '''Check for branch instructions at the end of a loop body'''
- if self.stack:
- top = self.stack[-1]
- if pc + 4 == top.match_addr:
- # We're about to execute the last instruction in the loop body.
- # Make sure that it isn't a jump, branch or another loop
- # instruction.
- if insn_affects_control:
- raise LoopError('control instruction at end of loop')
-
- def step(self, next_pc: int) -> Optional[int]:
- '''Update loop stack. If we should loop, return new PC'''
- if self.stack:
- top = self.stack[-1]
-
- if next_pc == top.match_addr:
- assert top.restarts_left >= 0
-
- # 1-based iteration number
- loop_idx = top.loop_count - top.restarts_left
-
- if not top.restarts_left:
- self.stack.pop()
- ret_val = None
- else:
- top.restarts_left -= 1
- ret_val = top.start_addr
-
- self.trace.append(TraceLoopIteration(loop_idx, top.loop_count))
- return ret_val
-
- return None
-
- def changes(self) -> List[Trace]:
- return self.trace
-
- def commit(self) -> None:
- self.trace = []
-
- def abort(self) -> None:
- self.trace = []
-
-
class OTBNState:
def __init__(self) -> None:
self.gprs = GPRs()
