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This makes the code pretty easily portable to other architectures if someone wants to make a more modern SIMM programmer. I also was pretty careful to split responsibilities of the different components and give the existing components better names. I'm pretty happy with the organization of the code now. As part of this change I have also heavily optimized the code. In particular, the read and write cycle routines are very important to the overall performance of the programmer. In these routines I had to make some tradeoffs of code performance versus prettiness, but the overall result is much faster programming. Some of these performance changes are the result of what I discovered when I upgraded my AVR compiler. I discovered that it is smarter at looking at 32-bit variables when I use a union instead of bitwise operations. I also shaved off more CPU cycles by carefully making a few small tweaks. I added a bypass for the "program only some chips" mask, because it was adding unnecessary CPU cycles for a feature that is rarely used. I removed the verification feature from the write routine, because we can always verify the data after the write chunk is complete, which is more efficient. I also added assumptions about the initial/final state of the CS/OE/WE pins, which allowed me to remove more valuable CPU cycles from the read/write cycle routines. There are also a few enormous performance optimizations I should have done a long time ago: 1) The code was only handling one received byte per main loop iteration. Reading every byte available cut nearly a minute off of the 8 MB programming time. 2) The code wasn't taking advantage of the faster programming command available in the chips used on the 8 MB SIMM. The end result of all of these optimizations is I have programming time of the 8 MB SIMM down to 3:31 (it used to be 8:43). Another minor issue I fixed: the Micron SIMM chip identification wasn't working properly. It was outputting the manufacturer ID again instead of the device ID.
98 lines
4.2 KiB
C
98 lines
4.2 KiB
C
/*
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LUFA Library
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Copyright (C) Dean Camera, 2012.
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dean [at] fourwalledcubicle [dot] com
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www.lufa-lib.org
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*/
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/*
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Copyright 2012 Dean Camera (dean [at] fourwalledcubicle [dot] com)
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Permission to use, copy, modify, distribute, and sell this
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software and its documentation for any purpose is hereby granted
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without fee, provided that the above copyright notice appear in
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all copies and that both that the copyright notice and this
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permission notice and warranty disclaimer appear in supporting
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documentation, and that the name of the author not be used in
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advertising or publicity pertaining to distribution of the
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software without specific, written prior permission.
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The author disclaim all warranties with regard to this
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software, including all implied warranties of merchantability
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and fitness. In no event shall the author be liable for any
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special, indirect or consequential damages or any damages
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whatsoever resulting from loss of use, data or profits, whether
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in an action of contract, negligence or other tortious action,
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arising out of or in connection with the use or performance of
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this software.
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*/
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/** \file
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* \brief Compiler specific definitions for code optimization and correctness.
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*
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* \copydetails Group_CompilerSpecific
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*
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* \note Do not include this file directly, rather include the Common.h header file instead to gain this file's
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* functionality.
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*/
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/** \ingroup Group_Common
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* \defgroup Group_CompilerSpecific Compiler Specific Definitions
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* \brief Compiler specific definitions for code optimization and correctness.
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*
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* Compiler specific definitions to expose certain compiler features which may increase the level of code optimization
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* for a specific compiler, or correct certain issues that may be present such as memory barriers for use in conjunction
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* with atomic variable access.
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*
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* Where possible, on alternative compilers, these macros will either have no effect, or default to returning a sane value
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* so that they can be used in existing code without the need for extra compiler checks in the user application code.
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*
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* @{
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*/
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#ifndef __LUFA_COMPILERSPEC_H__
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#define __LUFA_COMPILERSPEC_H__
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/* Preprocessor Checks: */
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#if !defined(__INCLUDE_FROM_COMMON_H)
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#error Do not include this file directly. Include LUFA/Common/Common.h instead to gain this functionality.
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#endif
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/* Public Interface - May be used in end-application: */
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/* Macros: */
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#if defined(__GNUC__) || defined(__DOXYGEN__)
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/** Forces GCC to use pointer indirection (via the device's pointer register pairs) when accessing the given
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* struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
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* a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before
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* use, it will force GCC to use pointer indirection on the elements rather than direct store and load
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* instructions.
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*
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* \param[in, out] StructPtr Pointer to a structure which is to be forced into indirect access mode.
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*/
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#define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
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/** Forces GCC to create a memory barrier, ensuring that memory accesses are not reordered past the barrier point.
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* This can be used before ordering-critical operations, to ensure that the compiler does not re-order the resulting
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* assembly output in an unexpected manner on sections of code that are ordering-specific.
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*/
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#define GCC_MEMORY_BARRIER() __asm__ __volatile__("" ::: "memory");
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/** Determines if the specified value can be determined at compile-time to be a constant value when compiling under GCC.
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*
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* \param[in] x Value to check compile-time constantness of.
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*
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* \return Boolean true if the given value is known to be a compile time constant, false otherwise.
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*/
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#define GCC_IS_COMPILE_CONST(x) __builtin_constant_p(x)
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#else
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#define GCC_FORCE_POINTER_ACCESS(StructPtr)
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#define GCC_MEMORY_BARRIER()
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#define GCC_IS_COMPILE_CONST(x) 0
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#endif
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#endif
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/** @} */
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