Thumb and ARM compilation: Why interwork?

Lebeau

187

« on: 28 / July / 2011, 22:52:19 »

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I remove CTHUMB flag and compile all the way to ARM and optimize -Os.

The ARM code is 299KB instead of 238KB in interwork therefore about 17% bigger but it works very well. I like the ARM generated assembler.

I didn't enable all optional compiling flags like PTP, Sokoban, ... but could I anticipate limiting effects compiling in ARM ?

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philmoz

3137

Re: Thumb and ARM compilation: Why interwork?

« Reply #1 on: 28 / July / 2011, 23:15:15 »

Quote from: Lebeau on 28 / July / 2011, 22:52:19

I remove CTHUMB flag and compile all the way to ARM and optimize -Os.

The ARM code is 299KB instead of 238KB in interwork therefore about 17% bigger but it works very well. I like the ARM generated assembler.

I didn't enable all optional compiling flags like PTP, Sokoban, ... but could I anticipate limiting effects compiling in ARM ?

Actually that's 25% larger, and memory is the main reason for using Thumb code.
On the cameras released so far this year the available Canon heap memory is even more limited - the SX220 and IXUS 310 will only work reliably in EXMEM, and even that is quite limited (only around 768K available for the IXUS 310).

Phil.

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CHDK ports:
sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
g12 (1.00c, 1.00e, 1.00f & 1.00g)
sx130is (1.01d & 1.01f)
ixus310hs (1.00a & 1.01a)
sx40hs (1.00d, 1.00g & 1.00i)
g1x (1.00e, 1.00f & 1.00g)
g5x (1.00c, 1.01a, 1.01b)

Lebeau

187

Re: Thumb and ARM compilation: Why interwork?

« Reply #2 on: 29 / July / 2011, 07:42:28 »

You're right, it is 25%

I will stop posting at late hour.

So no limiting effect ! ?

I would understand your statement that "... will only work reliably in EXMEM...". EXMEM is not only some memory out of the continuum memory space ?

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philmoz

3137

Re: Thumb and ARM compilation: Why interwork?

« Reply #3 on: 29 / July / 2011, 07:45:42 »

Quote from: Lebeau on 29 / July / 2011, 07:42:28

I would understand your statement that "... will only work reliably in EXMEM...". EXMEM is not only some memory out of the continuum memory space ?

http://chdk.wikia.com/wiki/ExMem_-_enabling_and_loading_CHDK_into_extended_memory.

It allows us to move CHDK out of the Canon firmware heap memory where it is normally located. If the heap free space gets too small the firmware crashes.

Phil.

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CHDK ports:
sx30is (1.00c, 1.00h, 1.00l, 1.00n & 1.00p)
g12 (1.00c, 1.00e, 1.00f & 1.00g)
sx130is (1.01d & 1.01f)
ixus310hs (1.00a & 1.01a)
sx40hs (1.00d, 1.00g & 1.00i)
g1x (1.00e, 1.00f & 1.00g)
g5x (1.00c, 1.01a, 1.01b)