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-The following describes the current state of the NetWinder's floating point
-emulator.
-
-In the following nomenclature is used to describe the floating point
-instructions. It follows the conventions in the ARM manual.
-
-<S|D|E> = <single|double|extended>, no default
-{P|M|Z} = {round to +infinity,round to -infinity,round to zero},
- default = round to nearest
-
-Note: items enclosed in {} are optional.
-
-Floating Point Coprocessor Data Transfer Instructions (CPDT)
-------------------------------------------------------------
-
-LDF/STF - load and store floating
-
-<LDF|STF>{cond}<S|D|E> Fd, Rn
-<LDF|STF>{cond}<S|D|E> Fd, [Rn, #<expression>]{!}
-<LDF|STF>{cond}<S|D|E> Fd, [Rn], #<expression>
-
-These instructions are fully implemented.
-
-LFM/SFM - load and store multiple floating
-
-Form 1 syntax:
-<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn]
-<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn, #<expression>]{!}
-<LFM|SFM>{cond}<S|D|E> Fd, <count>, [Rn], #<expression>
-
-Form 2 syntax:
-<LFM|SFM>{cond}<FD,EA> Fd, <count>, [Rn]{!}
-
-These instructions are fully implemented. They store/load three words
-for each floating point register into the memory location given in the
-instruction. The format in memory is unlikely to be compatible with
-other implementations, in particular the actual hardware. Specific
-mention of this is made in the ARM manuals.
-
-Floating Point Coprocessor Register Transfer Instructions (CPRT)
-----------------------------------------------------------------
-
-Conversions, read/write status/control register instructions
-
-FLT{cond}<S,D,E>{P,M,Z} Fn, Rd Convert integer to floating point
-FIX{cond}{P,M,Z} Rd, Fn Convert floating point to integer
-WFS{cond} Rd Write floating point status register
-RFS{cond} Rd Read floating point status register
-WFC{cond} Rd Write floating point control register
-RFC{cond} Rd Read floating point control register
-
-FLT/FIX are fully implemented.
-
-RFS/WFS are fully implemented.
-
-RFC/WFC are fully implemented. RFC/WFC are supervisor only instructions, and
-presently check the CPU mode, and do an invalid instruction trap if not called
-from supervisor mode.
-
-Compare instructions
-
-CMF{cond} Fn, Fm Compare floating
-CMFE{cond} Fn, Fm Compare floating with exception
-CNF{cond} Fn, Fm Compare negated floating
-CNFE{cond} Fn, Fm Compare negated floating with exception
-
-These are fully implemented.
-
-Floating Point Coprocessor Data Instructions (CPDT)
----------------------------------------------------
-
-Dyadic operations:
-
-ADF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - add
-SUF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - subtract
-RSF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse subtract
-MUF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - multiply
-DVF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - divide
-RDV{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse divide
-
-These are fully implemented.
-
-FML{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast multiply
-FDV{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast divide
-FRD{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - fast reverse divide
-
-These are fully implemented as well. They use the same algorithm as the
-non-fast versions. Hence, in this implementation their performance is
-equivalent to the MUF/DVF/RDV instructions. This is acceptable according
-to the ARM manual. The manual notes these are defined only for single
-operands, on the actual FPA11 hardware they do not work for double or
-extended precision operands. The emulator currently does not check
-the requested permissions conditions, and performs the requested operation.
-
-RMF{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - IEEE remainder
-
-This is fully implemented.
-
-Monadic operations:
-
-MVF{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - move
-MNF{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - move negated
-
-These are fully implemented.
-
-ABS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - absolute value
-SQT{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - square root
-RND{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - round
-
-These are fully implemented.
-
-URD{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - unnormalized round
-NRM{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - normalize
-
-These are implemented. URD is implemented using the same code as the RND
-instruction. Since URD cannot return a unnormalized number, NRM becomes
-a NOP.
-
-Library calls:
-
-POW{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - power
-RPW{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - reverse power
-POL{cond}<S|D|E>{P,M,Z} Fd, Fn, <Fm,#value> - polar angle (arctan2)
-
-LOG{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - logarithm to base 10
-LGN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - logarithm to base e
-EXP{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - exponent
-SIN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - sine
-COS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - cosine
-TAN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - tangent
-ASN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arcsine
-ACS{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arccosine
-ATN{cond}<S|D|E>{P,M,Z} Fd, <Fm,#value> - arctangent
-
-These are not implemented. They are not currently issued by the compiler,
-and are handled by routines in libc. These are not implemented by the FPA11
-hardware, but are handled by the floating point support code. They should
-be implemented in future versions.
-
-Signalling:
-
-Signals are implemented. However current ELF kernels produced by Rebel.com
-have a bug in them that prevents the module from generating a SIGFPE. This
-is caused by a failure to alias fp_current to the kernel variable
-current_set[0] correctly.
-
-The kernel provided with this distribution (vmlinux-nwfpe-0.93) contains
-a fix for this problem and also incorporates the current version of the
-emulator directly. It is possible to run with no floating point module
-loaded with this kernel. It is provided as a demonstration of the
-technology and for those who want to do floating point work that depends
-on signals. It is not strictly necessary to use the module.
-
-A module (either the one provided by Russell King, or the one in this
-distribution) can be loaded to replace the functionality of the emulator
-built into the kernel.