70 lines
2.5 KiB
Python
70 lines
2.5 KiB
Python
from typing import TYPE_CHECKING
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import math
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from .generators import ReadbackAssignmentGenerator
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from ..utils import get_always_ff_event
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if TYPE_CHECKING:
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from ..exporter import RegblockExporter
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from systemrdl.node import AddrmapNode
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class Readback:
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def __init__(self, exp:'RegblockExporter', do_fanin_stage: bool):
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self.exp = exp
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self.do_fanin_stage = do_fanin_stage
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@property
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def top_node(self) -> 'AddrmapNode':
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return self.exp.top_node
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def get_implementation(self) -> str:
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gen = ReadbackAssignmentGenerator(self.exp)
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array_assignments = gen.get_content(self.top_node)
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array_size = gen.current_offset
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# Enabling the fanin stage doesnt make sense if readback fanin is
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# small. This also avoids pesky corner cases
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if array_size < 4:
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self.do_fanin_stage = False
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context = {
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"array_assignments" : array_assignments,
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"array_size" : array_size,
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"get_always_ff_event": get_always_ff_event,
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"cpuif": self.exp.cpuif,
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"do_fanin_stage": self.do_fanin_stage,
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}
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if self.do_fanin_stage:
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# If adding a fanin pipeline stage, goal is to try to
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# split the fanin path in the middle so that fanin into the stage
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# and the following are roughly balanced.
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fanin_target = math.sqrt(array_size)
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# Size of fanin group to consume per fanin element
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fanin_stride = math.floor(fanin_target)
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# Number of array elements to reduce to.
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# Round up to an extra element in case there is some residual
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fanin_array_size = math.ceil(array_size / fanin_stride)
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# leftovers are handled in an extra array element
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fanin_residual_stride = array_size % fanin_stride
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if fanin_residual_stride != 0:
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# If there is a partial fanin element, reduce the number of
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# loops performed in the bulk fanin stage
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fanin_loop_iter = fanin_array_size - 1
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else:
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fanin_loop_iter = fanin_array_size
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context['fanin_stride'] = fanin_stride
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context['fanin_array_size'] = fanin_array_size
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context['fanin_residual_stride'] = fanin_residual_stride
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context['fanin_loop_iter'] = fanin_loop_iter
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template = self.exp.jj_env.get_template(
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"readback/templates/readback.sv"
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)
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return template.render(context)
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