External Interrups with assembly code

I would like to use external interrupts for an application using ARDUINO Due.Since the application is time critical, I will need to code in assembly with direct register manipulation.
Does anybody has a reference for an example of external interrupt with the Due?

Since the application is time critical, I will need to code in assembly with direct register manipulation.
Does anybody has a reference for an example of external interrupt with the Due?

The "need assembly" part of that is probably wrong. Hardly anyone programs ARM in assembly. Unlike AVR, there is little to gain by using asm in an ARM ISR - on an AVR you can bypass some expensive parts of the ISR entry, and there are some instructions that can bypass that entirely. On an ARM, C-compatible context saving is done in hardware.
You MIGHT be able to shave some cycles from the double-layer of vectoring currently done by the "attachInterrupt()" Arduino code, but probably only by ... not double-vectoring.

hardware/sam/1.6.11/cores/arduino/WInterrupts.c (which implements attachInterrupt()) is probably the best example of handling the interrupts.

Thank you for this feedback.
Can we expect from this library a significant speed improvement relatively to the ARDUINO Interrupt library, especially concerning DUE?

What prevents you from trying ?

Can we expect from this library a significant speed improvement relatively to the ARDUINO Interrupt library

No. That is the Arduino (Due) Interrupt library; it's the only example I know of for dealing with the pinchange interrupts on the SAM3X.

The code potentially scans all the bits in the port that have changed state. One potential speedup is to simply store the bits along with a timestamp, and process them separately at a lower rate...
But you haven't said what you're doing, why you think the existing code is too slow, or how fast it needs to be, so who knows...

I need to detect a code of 30 digits from a serial synchronous input at a bit rate of 5 Mbits/sec. The serial input includes serial data and separate clock. So I thought to input a bit at each positive transition of the clock, shift it in a Due register and compare to the code. All that to occur within one input clock cycle (200 nanosec).

I need to detect a code of 30 digits from a serial synchronous input at a bit rate of 5 Mbits/sec. The serial input includes serial data and separate clock. So I thought to input a bit at each positive transition of the clock, shift it in a Due register and compare to the code. All that to occur within one input clock cycle (200 nanosec).

I don't think you'll be able to use interrupts on the clock for this. A Cortex M3 interrupt takes 12 clocks on input and 10 clocks on output. At 84MHz, that's 261ns, even if everything else is perfect (no wait-states to access flash, etc.)
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/ka16366.html

The Due has a pretty powerful "Synchronous Serial Controller" (SSC), and you'd probably be best off trying to figure out how to bend that to your will. (30bit frames might be a problem. Or did you mean 30 bytes?)