List<t> generic type - Fastest way to copy into an unmanaged array?

[Daniel Mori]

Hi, Im hoping someone can give me some advice.
Im doing some development using VS Whidbey 2005 beta 1.

Im about to implement some highly time critical code related to a
managed collection of floats.

I basically require the fastest way to convert a managed array of
floats into an unmanaged array of floats.

As far as the managed collection is implemented, ive read that the
following would be the most type-safe and efficient (no
boxing/unboxing):

List<float> myFloats

However, Ive also read that the Marshal.Copy method is an extremely
fast way of copying a tradional managed array into an unmanaged array.
But if i do this method (i,e use a tradional .net array), I have the
boxing/unboxing issues.

For this particular case, I must sacrifice all I can for conversion
speed.

Can anyone recommend the fastest way to store and convert an array of
floats (managed -> unmanaged)?

thanks for reading.

 

[Tomas Restrepo \(MVP\)]

Daniel,

Hi, Im hoping someone can give me some advice.
Im doing some development using VS Whidbey 2005 beta 1.

Im about to implement some highly time critical code related to a
managed collection of floats.

I basically require the fastest way to convert a managed array of
floats into an unmanaged array of floats.

As far as the managed collection is implemented, ive read that the
following would be the most type-safe and efficient (no
boxing/unboxing):

List<float> myFloats

However, Ive also read that the Marshal.Copy method is an extremely
fast way of copying a tradional managed array into an unmanaged array.

It is indeed.

But if i do this method (i,e use a tradional .net array), I have the
boxing/unboxing issues.

Huh? Why boxing here? As long as you use an array of float, you won't need
boxing/unboxing. Granted, you'll end up copying a value here and there from
the stack to the managed heap where the array is stored, but it definitely
does *not* imply boxing at all (unless you for some reason declare the array
as Object* __gc[], which you probably aren't doing).

 

[Daniel Mori]

Daniel,

Hi, Im hoping someone can give me some advice.
Im doing some development using VS Whidbey 2005 beta 1.

Im about to implement some highly time critical code related to a
managed collection of floats.

I basically require the fastest way to convert a managed array of
floats into an unmanaged array of floats.

As far as the managed collection is implemented, ive read that the
following would be the most type-safe and efficient (no
boxing/unboxing):

List<float> myFloats

However, Ive also read that the Marshal.Copy method is an extremely
fast way of copying a tradional managed array into an unmanaged array.

It is indeed.

But if i do this method (i,e use a tradional .net array), I have the
boxing/unboxing issues.

Huh? Why boxing here? As long as you use an array of float, you won't need
boxing/unboxing. Granted, you'll end up copying a value here and there from
the stack to the managed heap where the array is stored, but it definitely
does *not* imply boxing at all (unless you for some reason declare the array
as Object* __gc[], which you probably aren't doing).

You're quite right. I mis-read documentation on array and collection
type boxing/unboxing.

Thankyou for your assistance.
Regards.