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Architecture Development and Deployment
Tipi
The MESCAL architecture development framework is
called Tipi
(spelled Teepee in earlier publications). Tipi is designed as a
successor to architecture description languages (ADLs).
ADLs of the past focused on modeling the structure or the instruction
set
semantics of an architecture. MIMOLA[1] is an
example of a
structural ADL. Instruction set ADLs include ISDL[2]
and
nML[3]. A current trend in ADLs is to combine the
description of the structure and the instruction set semantics.
Combined ADLs
include EXPRESSION[4] and LISA[5].
One
key aspect of these solutions is that restrictions on the flexibility
of the
architecture are used to manage the complexity of tool (compiler and/or
simulator) generation. Verifying that the architecture, compiler, and
simulator
are consistent after adding new features is complex and not well
defined. The
existing solution is to use a single syntax to describe the restricted
space of
architectures at all points in the design flow. If one wishes to relax
the
restrictions on the architecture, then the problems of consistency and
tool
generation become intractable. The underlying issue is that architects,
compiler
designers, and simulator writers are concerned with dissimilar and
disjoint
facets of the architecture, but must find some way to keep these
disparate
facets consistent.
The Multiple Views Approach
The proposed solution to this problem is to
maintain a single,
simple, formal description of the architecture with an extremely
minimal set of
restrictions on the design space. This allows a very broad class of
architectures to be described. A view of this model is an
abstraction
that encapsulates the information required by a facet of the
architecture. Each
view is implemented with a synonymous tool in the Tipi framework for
interacting with the architecture using the corresponding abstraction.
Correctly
implemented views do not introduce semantics not present in the model,
and thus
are consistent with the model by construction. For more technical
background and a case study, see the design flow described in [6][8][9].In order
to learn how Tipi is embedded in the Mescal framework, see the overview
article in [7].
Views for Architecture Development
Views for Architecture Deployment
References
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[1]
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R. Leupers and P. Marwedel, "Retargetable
Code Generation based on Structural Processor Descriptions," Design
Automation for Embedded Systems, vol. 3, no. 1, Jan 1998, pp.1-36.
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[2]
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G. Hadjiyiannis, S. Hanono and S. Devadas,
"ISDL: An Instruction Set Description Language for Retargetability,"
Proc. 34th Design Automation Conference (DAC 97), Anaheim, CA., June
1997, pp. 299-302.
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[3]
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A. Fauth, J. Van Praet and M. Freericks,
"Describing Instruction Set Processors Using nML," Proc. European
Design and Test Conference, Paris, France, Mar. 1995, pp. 503-507.
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[4]
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A. Halambi et al., "Expression: A Language
for Architecture Exploration through Compiler/Simulator
Retargetability," Proc. Design Automation and Test in Europe (DATE 99),
Mar. 1999, Munich, Germany, 485-490.
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[5]
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S. Pees et al., "LISA-Machine Description
Language for Cycle-Accurate Models of Programmable DSP Architectures,"
Proc. 36th Design Automation Conference (DAC 99), New Orleans, LA.,
June 1999, pp. 933-938.
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[6]
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S. J. Weber, M. W.
Moskewicz, M. Loew, and K. Keutzer,
Multi-View
Operation-Level Design -- Supporting the Design of Irregular ASIPs,
University of California, Berkeley, UCB/ERL M03/12, April, 2003 |
[7]
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A. Mihal, C. Kulkarni, C.
Sauer, K. Vissers, M. Moskewicz, M. Tsai, N. Shah, S. Weber, Y. Jin, K.
Keutzer, S. Malik,
A
Disciplined Approach to the Development of Architectural Platforms,
6-16, 19, IEEE Design and Test of Computers, 2002 |
[8]
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S. J. Weber, M. W. Moskewicz, M. Gries, C. Sauer, K. Keutzer, Fast Cycle-Accurate Simulation and Instruction Set Generation for Constraint-Based Descriptions of Programmable Architectures, Int. Conference on Hardware/Software Codesign (CODES), September, 2004 |
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