diff -r 4816d766a08a -r f345bda72bc4 Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita --- a/Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita Tue Mar 30 11:42:04 2010 +0100 +++ b/Symbian3/PDK/Source/GUID-5E358AB4-03A7-5859-ABF2-A8B64B74AF56.dita Tue Mar 30 11:56:28 2010 +0100 @@ -1,41 +1,41 @@ - - - - - -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:

- -

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 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.

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