nwfpe.rst (3821B)
1Introduction 2============ 3 4This directory contains the version 0.92 test release of the NetWinder 5Floating Point Emulator. 6 7The majority of the code was written by me, Scott Bambrough It is 8written in C, with a small number of routines in inline assembler 9where required. It was written quickly, with a goal of implementing a 10working version of all the floating point instructions the compiler 11emits as the first target. I have attempted to be as optimal as 12possible, but there remains much room for improvement. 13 14I have attempted to make the emulator as portable as possible. One of 15the problems is with leading underscores on kernel symbols. Elf 16kernels have no leading underscores, a.out compiled kernels do. I 17have attempted to use the C_SYMBOL_NAME macro wherever this may be 18important. 19 20Another choice I made was in the file structure. I have attempted to 21contain all operating system specific code in one module (fpmodule.*). 22All the other files contain emulator specific code. This should allow 23others to port the emulator to NetBSD for instance relatively easily. 24 25The floating point operations are based on SoftFloat Release 2, by 26John Hauser. SoftFloat is a software implementation of floating-point 27that conforms to the IEC/IEEE Standard for Binary Floating-point 28Arithmetic. As many as four formats are supported: single precision, 29double precision, extended double precision, and quadruple precision. 30All operations required by the standard are implemented, except for 31conversions to and from decimal. We use only the single precision, 32double precision and extended double precision formats. The port of 33SoftFloat to the ARM was done by Phil Blundell, based on an earlier 34port of SoftFloat version 1 by Neil Carson for NetBSD/arm32. 35 36The file README.FPE contains a description of what has been implemented 37so far in the emulator. The file TODO contains a information on what 38remains to be done, and other ideas for the emulator. 39 40Bug reports, comments, suggestions should be directed to me at 41<scottb@netwinder.org>. General reports of "this program doesn't 42work correctly when your emulator is installed" are useful for 43determining that bugs still exist; but are virtually useless when 44attempting to isolate the problem. Please report them, but don't 45expect quick action. Bugs still exist. The problem remains in isolating 46which instruction contains the bug. Small programs illustrating a specific 47problem are a godsend. 48 49Legal Notices 50------------- 51 52The NetWinder Floating Point Emulator is free software. Everything Rebel.com 53has written is provided under the GNU GPL. See the file COPYING for copying 54conditions. Excluded from the above is the SoftFloat code. John Hauser's 55legal notice for SoftFloat is included below. 56 57------------------------------------------------------------------------------- 58 59SoftFloat Legal Notice 60 61SoftFloat was written by John R. Hauser. This work was made possible in 62part by the International Computer Science Institute, located at Suite 600, 631947 Center Street, Berkeley, California 94704. Funding was partially 64provided by the National Science Foundation under grant MIP-9311980. The 65original version of this code was written as part of a project to build 66a fixed-point vector processor in collaboration with the University of 67California at Berkeley, overseen by Profs. Nelson Morgan and John Wawrzynek. 68 69THIS SOFTWARE IS DISTRIBUTED AS IS, FOR FREE. Although reasonable effort 70has been made to avoid it, THIS SOFTWARE MAY CONTAIN FAULTS THAT WILL AT 71TIMES RESULT IN INCORRECT BEHAVIOR. USE OF THIS SOFTWARE IS RESTRICTED TO 72PERSONS AND ORGANIZATIONS WHO CAN AND WILL TAKE FULL RESPONSIBILITY FOR ANY 73AND ALL LOSSES, COSTS, OR OTHER PROBLEMS ARISING FROM ITS USE. 74-------------------------------------------------------------------------------