Vector -Floating Point Architecture (VFP)

diff -r 5072524fcc79 -r 80ef3a206772 Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita --- a/Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita Fri Jul 02 12:51:36 2010 +0100 +++ b/Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita Fri Jul 16 17:23:46 2010 +0100 @@ -1,41 +1,39 @@ - - - - - -Vector -Floating Point Architecture (VFP)Describes the implementation of the ARM Vector Floating Point Architecture -(VFPv2) on Symbian platform. -

ARM provide a hardware floating point coprocessor that provides floating -point computation that is fully compliant with IEEE Std 754-1985.We refer -to the coprocessor as the VFP unit.

Symbian platform supports the use of VFPv2 on platforms where the required -hardware is present in both RunFast mode and in IEEE-without-exceptions mode. -See ARM's Vector Floating-point Coprocessor Technical reference Manual for -more details on the coprocessor, its architecture, and its execution modes.

You should read the information in Floating -point support about applications and user side code as this is also -applicable to code running on the kernel side. However there are a number -of restrictions that must be observed:

You cannot use -VFP instructions in any interrupt service routine.
You cannot use -VFP instructions when the kernel is locked, for example, in an IDFC or after -calling NKern::Lock()
You cannot use -VFP instructions in any section of code which runs with a fast mutex held.

Using VFP instructions in these situations can lead to data being corrupted, -or the kernel panicking. If you rely on the compiler to generate VFP instructions, -rather than using inline assembler, it is extremely important that you do -not use any floating point values in these situations. The compiler may generate -VFP instructions for the most trivial floating point operations and even for -simple assignments.

+ + + + + +Vector Floating Point Architecture (VFP)Describes the implementation of the ARM Vector Floating +Point Architecture (VFPv2) on Symbian platform. +

ARM provide a hardware floating point coprocessor that provides +floating point computation that is fully compliant with IEEE Std 754-1985.We +refer to the coprocessor as the VFP unit.

Symbian platform supports the use of VFPv2 on platforms where the +required hardware is present in both RunFast mode and in IEEE-without-exceptions mode. See ARM's Vector Floating-point +Coprocessor Technical reference Manual for more details on the coprocessor, +its architecture, and its execution modes.

You should read Floating point support in Symbian^3 Tools Guide +> Building. The guide contains information about applications and +user-side code, which is also applicable to code running +on the kernel side. However there are a number of restrictions that +must be observed:

You cannot use VFP instructions in any interrupt service routine.
You cannot use VFP instructions when the kernel is locked, for example, in +an IDFC or after calling NKern::Lock()
You cannot use VFP instructions in any section of code which runs with a fast +mutex held.

Using VFP instructions in these situations can lead to data being +corrupted, or the kernel panicking. If you rely on the compiler to +generate VFP instructions, rather than using inline assembler, it +is extremely important that you do not use any floating point values +in these situations. The compiler may generate VFP instructions for +the most trivial floating point operations and even for simple assignments.

\ No newline at end of file